Questions

1. What are the average dimensions in height and width of the orbital opening?

a. 30 mm h × 35 mm w.

b. 35 mm h × 40 mm w.

c. 35 mm h × 45 mm w.

d. 45 mm h × 35 mm w.

2. What is the average volume of the human orbit?

a. 30 mL.

b. 35 mL.

c. 40 mL.

d. 45 mL.

3. Which bones comprise the orbital roof?

a. greater wing of the sphenoid and frontal bone.

b. frontal bone and sphenoid bone (lesser wing).

c. greater wing of sphenoid bone and palatine bone.

d. ethmoid bone and frontal bone.

4. Which one of the following bones is not part of the medial orbital wall?

a. maxilla.

b. ethmoid.

c. sphenoid.

d. palatine.

5. Which orbital wall is the strongest?

a. medial.

b. inferior.

c. lateral.

d. superior.

6. How many axons compose a healthy adult optic nerve?

a. 3 million.

b. 3.6 million.

c. 600,000.

d. 1.2 million.

7. Which of the following is an eccrine gland?

a. Krause.

b. Moll.

c. Wolfring.

d. lacrimal.

8. Which of the following about Müller’s muscle is not true?

a. It consists of smooth muscle fibers.

b. It receives parasympathetic innervation.

c. It originates from the levator muscle.

d. It attaches to the tarsus.

9. The conjunctiva

a. contains two geographical zones—palpebral and bulbar.

b. contains lymphoid tissue.

c. fuses with the optic nerve sheath.

d. is composed of keratinized squamous epithelium.

10. Which of the following is not true?

a. Vortex veins drain the uveal system.

b. Vortex veins are located radially posterior to the rectus muscles.

c. Most eyes have at least four vortex veins.

d. The location of the vortex veins correspond to the equator of the eye.

11. What is the correct order of tear components from anterior to posterior?

a. mucin, aqueous, lipid.

b. lipid, aqueous, mucin.

c. aqueous, mucin, lipid.

d. aqueous, lipid, mucin.

12. Which of the following is not true about the cornea?

a. The tear-corneal epithelium surface forms a positive lens of approximately 40 D.

b. The central cornea is steeper than the peripheral cornea.

c. The average central corneal thickness is 500 to 550 µm.

d. The anterior surface of the cornea is less curved than the posterior surface of the cornea.

13. What are average adult corneal diameters?

a. 11 mm horizontally and vertically.

b. 12 mm horizontally and vertically.

c. 12 mm horizontally and 11 mm vertically.

d. 11 mm horizontally and 12 mm vertically.

14. The corneal stroma does not contain

a. type II collagen.

b. type I collagen.

c. type V collagen.

d. type III collagen.

15. The correct order of angle structures, from anterior to posterior, is

a. scleral spur (SS), pigmented trabecular meshwork (TM), nonpigmented TM, Schwalbe’s line (SL), and ciliary body band (CBB).

b. SL, pigmented TM, nonpigmented TM, CBB, and SS.

c. SL, pigmented TM, nonpigmented TM, SS, and CBB.

d. SL, nonpigmented TM, pigmented TM, SS, and CBB.

16. The trabecular meshwork

a. contains cells with contractile properties.

b. is divided into four separate layers.

c. is not affected by HSV.

d. is the only area of egress for ocular fluid.

17. The site of greatest resistance to aqueous outflow is the

a. corneoscleral meshwork.

b. uveal meshwork.

c. posterior, pigmented trabecular meshwork.

d. juxtacanalicular trabecular meshwork.

18. The locations of attachment of the uveal tract to the sclera do NOT include

a. optic nerve.

b. scleral spur.

c. entry of the vortex veins.

d. exit of the vortex veins.

19. The iris does not

a. contain dilator muscle derived from mesoderm.

b. have a posterior pigmented layer, which is continuous with the ciliary body and subsequently the retina.

c. contain a sphincter muscle, which is derived from neuroectoderm.

d. have both parasympathetic and sympathetic innervations.

20. The ciliary body

a. does not affect intraocular pressure.

b. is lined by a double layer of nonpigmented and pigmented epithelium.

c. contains large nonfenestrated capillaries, fibroblasts, and collagen.

d. is an avascular tissue.

21. The ciliary muscle

a. contains striated muscle fibers.

b. is mainly innervated by the parasympathetic system.

c. is responsible for the development of presbyopia.

d. has two major divisions.

22. Which of the following in regard to the iris is correct?

a. The iris is composed of six layers, three of which are epithelial.

b. Clump cells are part of the anterior border layer of the iris.

c. The iris dilator and iris sphincter are posterior to the iris pigment epithelium.

d. The cell bodies of the anterior iris pigment epithelium give rise to the iris dilator muscle.

23. The lens contributes ___ D of focusing power to the ocular system.

a. 10.

b. 20.

c. 40.

d. 60.

24. Select the correct description of autonomic innervation to the eye.

a. The iris sphincter muscle receives sympathetic innervation via the short ciliary nerves; the iris dilator muscle receives parasympathetic innervation via the short ciliary nerves.

b. The iris sphincter muscle receives parasympathetic innervation via the short ciliary nerves; the iris dilator muscle receives sympathetic innervation by the short ciliary nerves.

c. The iris sphincter muscle receives parasympathetic innervation via the short ciliary nerves; the iris dilator muscle receives sympathetic innervation via the long ciliary nerves.

d. The iris sphincter muscle receives parasympathetic innervation via the long ciliary nerves; the iris dilator muscle receives sympathetic innervation via long ciliary nerves.

25. The choriocapillaris

a. contains a large nonfenestrated vascular network.

b. allows passage of fluorescein dye.

c. is devoid of pericytes.

d. is located posterior to the retina and anterior to Bruch’s membrane.

26. The newborn equatorial lens diameter in a normal eye is

a. 4.5 mm.

b. 5.5 mm.

c. 6.5 mm.

d. 7.5 mm.

27. Choose the correct statement.

a. The inner plexiform layer is anterior to the inner nuclear layer.

b. The external limiting membrane is posterior to the rod/cone segments.

c. The ganglion cell layer carries the axons of the ganglion cells.

d. The outer plexiform layer contains the nuclei of the photoreceptors.

28. Which one of the following concerning retinal photoreceptors is correct?

a. Rods contain photopigment discs that are not attached to the cell membrane and synapse with bipolar cells at a rod pedicle.

b. Cones contain photopigment discs that are not connected to the cell membrane and synapse with bipolar cells at a cone pedicle.

c. Rods contain photopigment discs that are attached to the cell membrane and synapse with bipolar cells at the rod spherule.

d. Cones contain photopigment discs that are attached to the cell membrane and synapse with bipolar cells at a cone pedicle.

29. Select the correct neuronal sequence for intraretinal processing.

a. photoreceptor to Müller cell to ganglion cell.

b. photoreceptor to bipolar cell to ganglion cell.

c. photoreceptor to horizontal cell to amacrine cell.

d. photoreceptor to horizontal cell to ganglion cell.

30. In the entire retina, rods outnumber cones by a ratio of approximately

a. 2:1.

b. 5:1.

c. 20:1.

d. 50:1.

31. Which one of the following regarding Müller cells is correct?

a. The footplates of the Müller cells form the internal limiting membrane.

b. Müller cells are the only nonneural (glial) cellular element found within the neural retina.

c. Müller cells do not generate any detectable light-induced transretinal voltages.

d. Müller cells intimately envelop virtually all retinal neurons.

32. A cilioretinal artery contributes to some portion of the macular circulation in approximately

a. 5% of individuals.

b. 15% of individuals.

c. 50% of individuals.

d. 90% of individuals.

33. The inner retinal circulation’s deepest level of penetration is the

a. ganglion cell layer.

b. inner plexiform layer.

c. inner nuclear layer.

d. outer plexiform layer.

34. Which of the following statements regarding the retinal pigment epithelium is incorrect?

a. The RPE absorbs light.

b. The RPE cells are involved in active transport and have no polarity.

c. Photoreceptor outer segments are phagocytized by RPE cells.

d. Vitamin A metabolism is a key function of RPE cells.

35. Which of the following is not true about the macula?

a. It is clinically located between the superior and inferior arcade.

b. It can be affected by diabetes and cause vision loss.

c. Histologically, it contains only one layer of ganglion cells.

d. Zeaxanthin and lutein pigments are present in the macula.

36. Upon entering the cranial cavity, the optic nerve runs

a. lateral to the internal carotid artery and inferior to the anterior cerebral artery.

b. medial to the internal carotid artery and inferior to the anterior cerebral artery.

c. medial to the internal carotid artery and superior to the anterior cerebral artery.

d. lateral to the internal carotid artery and superior to the anterior cerebral artery.

37. Which of the following concerning ganglion axon decussation is true?

a. Greater than fifty percent of fibers cross in the chiasm.

b. Fewer numbers of ganglion cells cross than do not cross in the chiasm.

c. A much greater proportion of macular fibers cross than peripheral fibers.

d. A much greater proportion of peripheral fibers cross than macular fibers.

38. Which one of the extraocular muscles is served by a single nucleus that is shared by both oculomotor nerve nuclei?

a. superior rectus.

b. medial rectus.

c. inferior oblique.

d. levator palpebrae superioris.

39. Which is the only muscle supplied by the oculomotor nerve that receives crossed innervation?

a. superior rectus.

b. medial rectus.

c. inferior oblique.

d. levator palpebrae superioris.

40. Which one of the following concerning the pupillomotor fibers of the third cranial nerve is true?

a. They run central in the nerve, in the superior division.

b. They run central in the nerve, in the inferior division.

c. They run peripheral in the nerve, in the superior division.

d. They run peripheral in the nerve, in the inferior division.

41. Which one of the following is true regarding cranial nerve V?

a. The supratrochlear nerve is a terminal division of V1.

b. V2 exits the skull base at the foramen ovale.

c. V3 exits the skull base through the foramen rotundum.

d. V2 supplies sensation to the external ear.

42. Which of the following is true about ocular development?

a. The secondary vitreous has vascularity.

b. In the fetal nucleus, the inverted Y suture is located anterior to upright Y suture.

c. During gestation, the number of axons present in the optic nerve increases and then decreases several weeks prior to birth.

d. Alcohol intake during gestation has no affect on optic nerve development.

43. Which segment of the optic nerve is the longest?

a. intraocular.

b. intracanalicular.

c. intracranial.

d. intraorbital.

44. Mesenchymal structures of the head, including the eye, are all derived from

a. mesoderm.

b. neural crest cells.

c. a combination of neural crest cells and mesoderm.

d. a combination of neural crest cells and ectoderm.

45. Neural crest cells give rise to the following structures:

a. optic nerve sheath, uveal melanocytes, choroidal stroma, ciliary muscle, and iris stroma.

b. the entire sclera, optic nerve sheath, uveal melanocytes, entire choroid.

c. orbital bones, fat, trochlear cartilage, extraocular muscles, and orbital connective tissues.

d. ciliary body, ciliary epithelium, iris stroma, orbital bones, and orbital connective tissues.

46. The mesoderm gives rise to

a. the pupillomotor muscles, ciliary muscle, and extraocular muscles.

b. all vascular endothelia, extraocular muscles, and the trochlea.

c. all vascular endothelia, pupillomotor muscles, and all blood vessels.

d. all vascular endothelia, all extraocular muscles, and temporal sclera.

47. All of the following structures originate from the surface ectoderm except

a. the lacrimal gland.

b. the lens.

c. the substantia propria of the conjunctiva.

d. the corneal epithelium.

48. What factor distinguishes anophthalmia from microphthalmia?

a. stage of globe development.

b. the presence or absence of a globe.

c. globe size.

d. the presence or absence of organic abnormalities of a globe.

49. What factor distinguishes microphthalmia from nanophthalmia?

a. the size of the globe.

b. the presence or absence of a globe.

c. the presence or absence of lid fusion.

d. the presence or absence of organic abnormalities of a globe.

50. Cystic protrusion in the palpebral fissure may be all of the following except

a. cystic coloboma.

b. orbital encephalocele.

c. microphthalmos.

d. nanophthalmos.

51. In reference to dermoids, which of the following is not true?

a. Dermoids are epidermal hamartomas.

b. Locations include the orbit and conjunctiva.

c. The solid variety is most frequently found at the limbus.

d. There is an association with Goldenhar’s syndrome.

52. Which one of the following statements regarding anterior segment dysgenesis is incorrect?

a. All varieties may be inherited as autosomal dominant traits and may be either unilateral or bilateral.

b. Posterior embryotoxon is the mildest form of the peripheral varieties.

c. In Peters’ anomaly, the central cornea is always opacified, and the lens is always densely adherent to the posterior corneal surface.

d. Rieger’s syndrome is Rieger’s anomaly plus facial and musculoskeletal anomalies.

53. Which one of the following concerning aniridia is false?

a. Rudimentary iris can be seen.

b. Aniridia is always familial.

c. Retinal abnormalities can be present in this condition.

d. There is an association of aniridia with Wilms’ tumor, genitourinary anomalies, and mental retardation.

54. The following statements refer to childhood lens disorders. Choose the correct answer.

a. Microspherophakia is commonly associated with Marfan syndrome.

b. Cataracts, glaucoma, aminoaciduria, and female gender are characteristic findings in Lowe’s syndrome.

c. Cataracts in the congenital rubella syndrome are generally dense nuclear cataracts.

d. Defects in the rubella syndrome are typically limited to the eye.

55. All of the following regarding persistent fetal vasculature (PFV) are true except

a. It is most often unilateral in presentation.

b. It portends good long-term visual prognosis.

c. It is differentiated from retinoblastoma by the presence of microphthalmos or cataract.

d. It may calcify.

56. Choose the incorrect statement regarding tear secretion apparatus and function.

a. ACTH and androgens can stimulate tear secretion from the main lacrimal gland.

b. The glands of Wolfring are located along the orbital margin of each tarsus, with the glands of Krause in the conjunctival fornix.

c. The accessory glands of Krause and Wolfring account for approximately 50% of total lacrimal secretory mass.

d. Both sympathetic and parasympathetic nerve stimuli are important for reflex tear secretion.

57. In reference to Descemet’s membrane/corneal endothelium complex, which of the following is not true?

a. The endothelial cell count in a young adult with no previous ocular surgery is about 5,000 cells/mm squared.

b. Posterior keratoconus can be differentiated from Peters’ anomaly by the presence of fetal Descemet’s membrane.

c. Fetal Descemet’s membrane can be differentiated from adult Descemet’s membrane by its banding pattern.

d. The corneal endothelium actively maintains corneal deturgescence via a pump system dependent on Na⁺/K⁺-ATPase function and carbonic anhydrase.

58. What is not true regarding prostaglandins?

a. The cyclooxygenase reaction culminates in the production of prostaglandins, prostacyclin, and thromboxane.

b. In general, prostaglandins cause mydriasis.

c. Corticosteroids inhibit both the cyclooxygenase and lipoxygenase pathways of arachidonic acid metabolism.

d. The effect of prostaglandins on intraocular pressure is complex, with low doses decreasing intraocular pressure and high doses increasing intraocular pressure.

59. Which enzyme is not present normally in the aqueous humor?

a. carbonic anhydrase.

b. lysozyme.

c. hyaluronidase.

d. lactate dehydrogenase.

60. The partial pressure of oxygen in aqueous humor is

a. 40 mm Hg.

b. 55 mm Hg.

c. 75 mm Hg.

d. 85 mm Hg.

61. Lens epithelial cells are mitotically most active at which of the following sites?

a. anterior pole.

b. posterior pole.

c. lens equator.

d. ring around the anterior lens.

62. Which of the following statements is incorrect in regard to lens protein?

a. Gamma crystallins are the smallest.

b. Crystallins are only expressed in the lens.

c. Alpha crystallin is the largest of the lens crystallins.

d. Beta crystallin is the most abundant of the lens crystallins.

63. Which glands are primarily responsible for secreting the lipid layer of the tear film?

a. glands of Krause.

b. glands of Wolfring.

c. tarsal meibomian glands.

d. lacrimal gland-palpebral lobe.

64. Choose the incorrect statement.

a. The glands of Wolfring are located along the proximal tarsal margin.

b. The tear film contains only IgA.

c. The lacrimal gland is innervated by sympathetic and parasympathetic nerves.

d. The levator aponeurosis divides the lacrimal gland.

65. What is amount of aqueous humor produced by humans every minute?

a. 0.5 μL/min.

b. 1.0 μL/min.

c. 2.0 μL/min.

d. 4.0 μL/min.

66. The normal aging process of vitreous liquefaction is associated with

a. diffuse decreases in hyaluronic acid concentration.

b. diffuse decreases in collagen concentration.

c. focal decreases in collagen concentration.

d. motion-induced collagen damage.

67. Which of the following statements is true in regard to myopia?

a. Myopia is associated with alterations in vitreous concentration of collagen and hyaluronic acid.

b. Myopia cannot be surgically corrected.

c. Myopia is associated with a decreased incidence of retinal detachment.

d. Myopia is not associated with choroidal neovascularization.

68. Choose the correct statement regarding posterior vitreous detachment (PVD).

a. A complete PVD includes detachment of the vitreous from the anterior border of the vitreous base.

b. PVD frequently presents as a chronic insidious event.

c. PVD is thought to be protective against retinal detachment secondary to proliferative diabetic retinopathy.

d. Occurs only under the natural aging process of the eye.

69. Eyes that have undergone removal of the vitreous

a. have decreased water content.

b. have increased vitreous viscosity.

c. may experience accelerated cataract formation.

d. may have decreased oxygen tension at the retinal surface.

70. Which of the following is true?

a. Vitamin A is transported in the serum as all-cis retinol.

b. Trans-to-cis isomerization occurs in the RPE.

c. Aldehyde and alcohol conversion occurs in the RPE.

d. The normal retina contains two types of cones.

71. Which one of the following concerning the effects of light on rod outer segment metabolism is false?

a. In the dark, high cyclic guanosine monophosphate (cGMP) levels keep sodium channels open and rod outer segments depolarized.

b. Light absorption leads to configurational changes in rhodopsin and activation of transducin.

c. Transducin, through an amplification cascade, activates phosphodiesterase (PDE).

d. Falling intracellular cGMP leads to closure of sodium channels, with subsequent further depolarization of the rod outer segment.

72. Which of the below is false regarding the retina?

a. The retina is primarily dependent on anaerobic metabolism (glycolysis).

b. The retina contains glial elements as well as neural elements.

c. Phototransduction occurs in outer segment of the photoreceptor cells.

d. Amacrine cells function as interneurons.

73. All of the following are effective methods of increasing ocular absorption of topically applied materials (without increasing systemic absorption) except

a. adding a second eyedrop immediately after the first.

b. waiting 5 to 10 minutes between different medications.

c. nasolacrimal sac compression.

d. closing the eyes quietly for 3 to 5 minutes after administration.

74. All of the following factors increase the amount of medication penetrating the cornea except

a. higher concentration of the drug.

b. higher viscosity of the vehicle.

c. higher pH of the drug.

d. higher lipid solubility of the drug.

75. Unwanted side effects of direct cholinergic agonists include all of the following except

a. induced hyperopia.

b. decreased vision in older patients.

c. headache in younger patients.

d. possible aggravation or induction of angleclosure glaucoma.

76. Which of the following medications must be used with caution in patients taking a monoamine oxidase inhibitor?

a. cyclopentolate.

b. brimonidine.

c. prednisolone.

d. prostaglandin analog.

77. Following a unilateral dose of apraclonidine, it is easy to identify the eye that received the medication by looking for

a. lid retraction.

b. increased conjunctival injection.

c. miosis.

d. cell and flare.

78. Beta-adrenergic agonists generally

a. increase aqueous humor production, decrease outflow facility, and increase intraocular pressure.

b. increase aqueous humor production, increase outflow facility, and increase intraocular pressure.

c. increase aqueous humor production, increase outflow facility, and decrease intraocular pressure.

d. decrease aqueous humor production, decrease outflow facility, and decrease intraocular pressure.

79. In what anatomic location is dipivefrin converted to epinephrine?

a. angle.

b. conjunctiva.

c. cornea.

d. aqueous humor.

80. Carbonic anhydrase inhibitors (CAIs) should be used with great caution in all of the following types of patients except

a. patients with a distant history nephrolithiasis that is currently inactive.

b. patients with chronic liver failure.

c. patients on thiazide diuretics.

d. patients on digoxin.

81. Which one of the following concerning glucocorticoid effects is false?

a. They inhibit capillary formation.

b. They do not affect IgE titers.

c. They act through impairing the efferent limb of the immune response.

d. They impair epithelial healing.

82. Which of the following corticosteroids has the highest relative potency?

a. dexamethasone 0.1%.

b. fluorometholone 0.1%.

c. prednisolone 1%.

d. hydrocortisone 0.5%.

83. Which of the following corticosteroids has the smallest effect on intraocular pressure elevation?

a. dexamethasone 0.1%.

b. hydrocortisone 0.5%.

c. medrysone 1%.

d. prednisolone 1%.

84. Given a history of a hypersensitivity reaction to penicillins, the probability of a similar reaction to a cephalosporin is approximately

a. 1%.

b. 5%.

c. 10%.

d. 15%.

85. Which one of the following concerning antibiotic mechanisms is false?

a. Sulfonamides act by inhibiting bacterial DNA synthesis.

b. Tetracycline is poorly water soluble but may be dissolved in eye drops containing mineral oil.

c. Chloramphenicol use is most strongly associated with aplastic anemia when used orally.

d. Aminoglycoside efficacy is mostly dependent on anaerobically supported antibiotic uptake.

86. Which class of medication is known to cause auditory/vestibular dysfunction and nephrotoxicity?

a. aminoglycoside.

b. sulfonamide.

c. tetracycline.

d. penicillin.

87. Which antibiotic has been associated with macular infarction?

a. penicillin.

b. gentamicin.

c. doxycycline.

d. ceftazidime.

88. Which one of the following concerning vancomycin is false?

a. It inhibits bacterial replication by blocking cell wall synthesis.

b. Empirical use in neutropenic patients is recommended for infection prophylaxis.

c. It is one of the drugs of choice in filtering bleb-related endophthalmitis.

d. Because of its poor gastrointestinal uptake, it is an excellent drug for pseudomembranous colitis.

89. Which one of the following concerning ocular antiviral agents is false?

a. Vidarabine is an analog of adenine, whereas idoxuridine and trifluridine are analogs of thymidine.

b. Trifluridine is more soluble than vidarabine or idoxuridine.

c. Trifluridine is more effective than vidarabine and idoxuridine.

d. Cross-resistance to different agents is commonly seen.

90. What is the diameter of the anatomic human fovea?

a. 0.5 mm (500 μm).

b. 1.0 mm (1,000 μm).

c. 1.5 mm (1,500 μm).

d. 2.0 mm (2,000 μm).

91. Which one of the following agents presents the lowest risk of corneal or conjunctival toxicity as a preoperative antiseptic?

a. chlorhexidine gluconate 4% (Hibiclens).

b. povidone-iodine solution.

c. hydrogen peroxide.

d. benzalkonium chloride.

92. Which of the following preoperative regimens most effectively reduces conjunctival bacterial colony counts?

a. topical antibiotic for 3 days preoperatively.

b. topical povidone-iodine for 3 days preoperatively.

c. topical antibiotic for 3 days preoperatively, followed by topical povidone-iodine at the time or surgery.

d. topical povidone-iodine at the time of surgery, followed immediately by vigorous saline

flush.

93. Potential side effects of topical prostaglandins or their analogs include each of the following except

a. bradycardia.

b. red eye.

c. iris hyperpigmentation.

d. uveitis.

94. What does the anterior lamellae of the upper eyelid consist of?

a. skin, orbicularis, and associated fascial and vascular components.

b. capsulopalpebral fascia, tarsus, and orbital septum.

c. Müller’s muscle, conjunctiva, and levator aponeurosis.

d. orbital septum, orbital fat, and levator aponeurosis.

95. All of the following are potential ocular side effects of sildenafil except

a. photophobia.

b. decreased color vision or changes in color perception.

c. conjunctival hyperemia.

d. miosis.

96. Which is false regarding chronic progressive external ophthalmoplegia (CPEO)?

a. The eyelids are often involved in CPEO.

b. CPEO can include muscle paralysis.

c. CPEO is inherited in an autosomal recessive pattern.

d. CPEO can be associated with heart block and retinitis pigmentosa.

97. Mitochondrial DNA is implicated in all of the following except

a. neuropathy, ataxia, and retinitis pigmentosa (NARP) phenotype.

b. Leber’s hereditary optic neuropathy.

c. Leigh’s syndrome.

d. Duchenne muscular dystrophy.

98. Which of the listed disorders, in their carrier states, do not display ocular findings?

a. ocular albinism.

b. choroideremia.

c. retinitis pigmentosa.

d. Best disease.

99. Amacrine cells are located in which layer?

a. outer plexiform layer.

b. outer nuclear layer.

c. inner nuclear layer.

d. inner plexiform layer.

100. Müller cells

a. extend from the ILM to the photoreceptors.

b. are neuronal in nature.

c. do not constitute the external limiting membrane.

d. play a role in beta-carotene metabolism.

101. The RPE

a. is a double layer of cuboidal epithelial cells.

b. contains a cumulative 8 to 12 million cells in a given individual.

c. has a 100:1 ratio in regard to photorecptors:RPE cells.

d. has neural function.

102. Major roles of the RPE include all of the following except

a. regeneration of visual pigment.

b. consumption of photoreceptor outer segments.

c. absorption of light.

d. transmission of neural impulses between photoreceptors and the choroid.

103. Topical drug penetration is increased by

a. surfactants.

b. low viscosity.

c. water solubility.

d. nonphysiologic pH.

104. Side effects of pilocarpine include all of the following except

a. salivation.

b. vomiting/diarrhea.

c. bronchial dilation.

d. diaphoresis.

105. Pilocarpine is used in the treatment of which of the following?

a. accommodative esotropia.

b. chronic control of pupillary-block angle closure glaucoma.

c. uveitis.

d. band keratopathy.

106. Which of the following is an indirect-acting muscarinic agonist?

a. pilocarpine.

b. carbachol.

c. phospholine iodide.

d. isopto carbachol.

107. Which of the following mydriatics is the longest acting?

a. cyclopentolate.

b. tropicamide.

c. scopolamine.

d. homatropine.

108. Which of the following mydriatics has a duration of action of approximately 2 days?

a. homatropine.

b. atropine.

c. scopolamine.

d. cyclopentolate.

109. Muscarinic antagonists help in all of the following except

a. refraction in children.

b. malignant glaucoma.

c. angle closure.

d. iridocyclitis.

110. Adverse effects of cholinergic antagonists include all of the following except

a. confusion.

b. mydriasis.

c. diarrhea.

d. urinary retention.

111. Which of the following medications can induce uveitis and hypotony?

a. cidofovir.

b. valacyclovir.

c. acyclovir.

d. zidovudine.

112. Which of the following systemic antibiotics has good intraocular penetration?

a. penicillin.

b. moxifloxacin.

c. gentamicin.

d. erythromycin.

113. What class of medication has been reported to cause reactivation of herpetic keratitis?

a. prostaglandins.

b. carbonic anhydrase inhibitors.

c. beta adrenergic antagonists.

d. adrenergic agonists.

114. Which regional anesthetic has the shortest duration of action?

a. lidocaine.

b. bupivacaine.

c. mepivacaine.

d. procaine.

115. Which drug below is a polyene?

a. ketoconazole.

b. natamycin.

c. fluconazole.

d. itraconazole.

116. What is a serious side effect of the sulfonamide drug class?

a. heart block.

b. ototoxicity.

c. Stevens-Johnson syndrome.

d. hypotony.

117. In reference to Down’s syndrome, which of the following is true?

a. It is the second most common chromosomal syndrome in humans.

b. Maternal age is not a risk factor.

c. Patients display various forms of congenital heart disease.

d. Patients do not have an increased risk for development of Alzheimer’s disease.

118. Which of the following is true regarding autosomal recessive inheritance?

a. Males and females are affected in equal proportions.

b. The mutant gene will cause the clinical disease.

c. Consanguinity plays no role.

d. The ratio of normal to affected siblings is usually 4:1.

119. Which of the following medications increases uveoscleral outflow?

a. apraclonidine.

b. pilocarpine.

c. epinephrine.

d. timolol.

120. What is true about local anesthesia in ocular surgery?

a. After administration, large nerve fibers are blocked first.

b. After administration, sensory nerve fibers are blocked before parasympathetic/sympathetic fibers.

c. Amide local anesthetics are preferred over ester agents for retrobulbar blockade due to longer duration and less toxicity.

d. Chronic use is not associated with morbidity.

Answers

20. b. The cilary body produces aqueous humor and also participates in trabecular and uveoscleral outflow. While the ciliary body does contain capillaries, most are FENESTRATED. The cilary body is made of two areas, the pars plicata and pars plana. The pars plicata is a deeply vascular tissue.

21. b. The ciliary muscle is nonstriated, smooth muscle. It has three major divisions—longitudinal, radial, and circular. The aging and weakening of the ciliary muscle over time is NOT associated with presbyopia—rather, the age-related lens changes are at fault. The ciliary muscle has its main innervation from CNIII parasympathetic fibers through the short ciliary nerves.

22. d. The iris is composed of five layers: the anterior border layer, the iris stroma, the muscular layer, the anterior pigment epithelium, and the posterior pigment epithelium. The clump cells of Koganei are part of the iris stroma. The dilator and sphincter muscles make up the muscular layer of the iris, which is anterior to the iris pigment epithelium. The color of the iris is determined by the number and size of melanin pigment granules of the stromal melanocytes.

23. b. The lens contributes 20 D of focusing power to the ocular system. As previously stated, the air–tear interface provides about 40 D of power, bringing the total focusing power to 60 D.

24. c. Parasympathetic fibers originate from the Edinger-Westphal subnucleus in the midbrain, follow the inferior division of the oculomotor nerve as it bifurcates in the cavernous sinus, continue with the branch supplying the inferior oblique muscle, and then synapse in the ciliary ganglion. Postganglionic fibers are transmitted via the short ciliary nerves to the iris sphincter. Sympathetic fibers originate in the ipsilateral posterolateral hypothalamus and pass through the brainstem to synapse in the intermediolateral gray matter of the spinal cord between the levels of C8-T2 (ciliospinal center of Budge). The second-order neurons exit the spinal cord, pass over the lung apex, and synapse in the superior cervical ganglion. Third-order neurons travel with the internal carotid plexus, enter the cavernous sinus, and travel with the ophthalmic division of the trigeminal nerve (V1) to the orbit. Thereafter, the fibers travel within the nasociliary nerve and then the long ciliary nerves to the iris.

25. b. The choriocapillaries consist of several fenestrated vessles that easily allow the passage of fluorescein dye. The larger choroidal vessels do NOT allow leakage of fluorescein dye. The vessels are surrounded with pericytes. The choriocapillaries is located posterior to the retina and posterior to Bruch’s membrane.

26. c. Newborn lens diameter is approximately 6.5 mm at birth.

27. a. The layers of the retina listed from anterior to posterior are internal limiting membrane, nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layers, outer plexiform layer, outer nuclear layer, external limiting membrane, rod/cone segments, and RPE. The nerve fiber layer is constituted of the axons of the ganglion cells. Photoreceptor nuclei reside in the outer nuclear layer.

28. d. Rods and cones are characterized by three components: the synaptic body, inner segment, and outer segment. The synaptic body of a rod is called a spherule, whereas that of the cone is called a pedicle. Photopigment is stored in discs in the outer segments. In rods, the discs are not attached to the cell membrane, but cone discs are continuous with it.

29. b. Intraretinal processing occurs from photoreceptors to bipolar cells to ganglion cells with modulation by horizontal (outer plexiform layer) and amacrine (inner plexiform layer) cells.

30. c. Approximately 120 million rods and 6 million cones interact with 1.2 million ganglion cells in an eye. Therefore, the ratio of rods to cones is approximately 20:1. (Some studies cite a ratio as low as 12:1.)

31. a. The external limiting membrane (ELM) is highly fenestrated and composed of attachment sites of adjacent photoreceptors and Müller cells. The internal limiting membrane (ILM) is formed by footplates of Müller cells and attachments to the basal lamina of retinal astrocytes. The nuclei of Müller cells are located in the inner nuclear layer. Although Müller cells are the most prevalent glial element, two other cell types are found: microglia are found in small numbers throughout the retina; astrocytes are found in the proximal ganglion cell and nerve fiber layers of the human retina. Note that oligodendrocytes, the myelinating fiber of the central nervous system, are normally absent.

32. b. A cilioretinal artery contributes to the vascular supply of the retina in approximately 50% of individuals and 30% of eyes. Also, in 15% of individuals, it contributes to macular circulation.

33. c. Retinal blood vessels usually do not extend beyond the inner third of the inner nuclear layer.

34. b. The RPE cells are involved in active transport and are polarized.

35. c. Histologically, the macula consists of greater than one ganglion cell layer of thickness.

36. b. After exiting the optic foramen, the optic nerve is surrounded by the anterior cerebral artery superiorly, the internal carotid artery laterally, and the ophthalmic artery inferiorly.

37. a. Approximately 53% of optic nerve fibers are crossed and 47% uncrossed. Macular and peripheral fibers cross in roughly identical proportions.

38. d. Only the levator is served by a single subnu-cleus. It sits dorsal, central, and at the inferior end of the group of subnuclei that compose the second and third cranial nerve nuclei. The superior recti have two subnuclei, each controlling the contralateral nerve. In contrast, the inferior obliques and the medial recti each have individual subnuclei that control the ipsilateral nerve. The superior oblique is served by the fourth cranial nerve. The lateral rectus is supplied by the sixth cranial nerve.

39. a. The superior recti have two subnuclei, each controlling the contralateral nerve.

40. d. The pupillomotor fibers of the third cranial nerve run in the inferior division, which carries them to the ciliary ganglion. They are among the axons in the periphery of the nerve, making them easily susceptible to compression.

41. a. Cranial nerve V is split into three major divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3). V1 then splits into three branches: frontal, lacrimal, and nasociliary. The frontal nerve further divides into the supraorbital and supratrochlear nerves. V2 exits the skull base at the foramen rotundum. V3 exits the skull at the foramen ovale. V3 supplies sensation to the external ear and tympanum.

42. c. The secondary vitreous is avascular. The anterior Y suture is upright; the posterior Y suture is inverted. Fetal alcohol syndrome is frequently associated with optic nerve hypoplasia. The number of axons during gestation increases from about 2 to 4 million from 10 weeks of gestation to 16 weeks of gestation. By approximately 33 weeks, the axons are decreased to 1.2 million.

43. d. The intraorbital portion is the longest. The intraocular portion is the shortest.

44. c. Neural crest cells and mesoderm both contribute to the mesenchymal structures of the head. (Mesenchyme is the embryonic tissue that gives rise to connective tissue.) The stroma of the iris and the muscular layer of orbital vessels are examples of neural crest contributions. The endothe-lium of those same vessels is of mesodermal origin.

45. a. Neural crest gives rise to ciliary musculature, corneal stroma and endothelium (but not corneal epithelium), most of the sclera (except for a temporal portion, which is of mesodermal origin), choroidal stroma, some of the orbital bones, orbital cartilage, orbital connective tissue, nerve sheaths, and uveal melanocytes. Extraocular muscles form from paraxial mesoderm.

46. d. Blood vessel endothelia, extraocular muscles, and temporal sclera are all mesodermal in origin. The mesoderm also contributes to the formation of the vitreous. The pupillomotor muscles are neuroectodermal in origin. The trochlea is from neural crest.

47. c. Conjunctival epithelium is derived from surface ectoderm, but the substantia propria is derived from neural crest.

48. b. Anophthalmia is the absence of an identifiable eye. Microphthalmia describes the presence of a small, disorganized eye.

49. d. In nanophthalmia, the eye is smaller than normal with a disproportionately large lens, but otherwise unremarkable.

50. d. Nanophthalmos is, by definition, a small, but otherwise normal eye. Cysts are not seen in association with it. The other answers are associated with cyst formation.

51. a. Dermoids are choristomas: normal cells and/or tissue present in abnormal locations.

52. c. In Peters’ anomaly, the central cornea is always opacified because of the central defect in Descemet’s membrane and the absence of endothelium. The lens may be adherent to the cornea, but this is not always seen. Axenfeld anomaly, Axenfeld’s syndrome, Rieger’s anomaly, and Rieger’s syndrome are now considered a single entity known as Axenfeld-Rieger syndrome, which has been associated with mutations in the RIEG1/PIXT2 gene and the forkhead gene FKHL7. Axenfeld-Rieger syndrome is most commonly inherited in an autosomal dominant fashion, and can lead to glaucoma in 50% of cases.

53. b. There is nearly always some rudimentary iris tissue present in aniridia, although it may be diffi-cult to see clinically. Aniridia is caused by a defect of the PAX6 gene on chromosome 11p13, and may be SPORADIC or FAMILIAL. Sporadic aniridia is associated with Wilms’ tumor (usually because of deletion of the PAX6 gene and the adjacent Wt1 Wilms’ tumor gene). Aniridia is not typically found in patients with autosomal-dominant Wilms’ rumor. When aniridia is associated with mental retardation, Wilms’ tumor, ambiguous genitalia, or other genitourinary anomalies, there is usually a small deletion in the short arm of chromosome 11. Foveal and optic nerve hypoplasia can be associated with aniridia.

54. c. Microspherophakia is observed most often with Weill-Marchesani syndrome, not Marfan’s syndrome. Patients with Marfan’s syndrome are usually tall and lean, in contrast to patients with Weill-Marchesani syndrome, who are short and stocky. Marfan’s syndrome is often associated with ectopia lentis. Lowe’s syndrome is inherited in an X-linked recessive fashion and is thus found almost exclusively in men. Any organ in the body may be damaged by rubella, and the rubella syndrome is characterized by the triad of cataracts, deafness, and cardiac defects. Juvenile glaucoma and cataract rarely coincide with congenital rubella infection.

55. b. The visual prognosis in PHPV (also known as PFV, or persistent fetal vasculature) is currently poor. Early cataract extraction and membrane excision may preserve some vision. An eye with leukocoria that is small is unlikely to harbor retinoblastoma. Likewise, retinoblastoma does not typically cause cataract.

56. c. The glands of Krause and Wolfring, which produce the basal tear secretion account for approximately 10% of total lacrimal secretory mass.

57. a. The actual count is closer to 3,000 cells/mm squared.

58. b. Topical administration of type E and type F prostaglandins, as well as arachidonic acid, causes miosis. High doses of prostaglandins will cause an increase in intraocular pressure. Low doses of some prostaglandins, in contrast, appear to lower intraocular pressure in some animal species. By blocking phospholipase, corticosteroids effectively inhibit both the lipoxygenase and cyclooxygenase pathways.

59. d. Carbonic anhydrase, although present in only trace amounts in the aqueous, has a high enough turnover that it is felt to be functionally significant. Hyaluronidase is present in aqueous and may participate in regulation of resistance to aqueous outflow. Lysozyme is present and provides antibacterial protection. Lactate dehydrogenase, not normally detectable in aqueous, may be a marker for retinoblastoma.

60. b. This is approximately one-third the concentration found in the earth’s atmosphere and is entirely derived from anterior chamber blood flow.

61. d. Lens epithelial cells are located anteriorly underneath the lens capsule. Epithelial cells in a ring around the anterior lens, or the germinative zone, exhibit the highest level of DNA synthesis (the S-phase in the cell cycle). Newly formed cells migrate toward the lens equator, where they differentiate into lens fiber cells.

62. b. Crystallins are expressed in several other tissues besides the lens. Alpha crystallins are the largest, with molecular weights of over 500,000 Da. Beta crystallins are the most abundant, making up about 55% of the water-soluble protein. Gamma crystallins are the smallest.

63. c. The meibomian glands are most responsible for the lipid layer of the tear film.

64. b. The tear film contains IgA, IgG, IgD, IgM, and IgE. The other answers are true.

65. c. Aqueous humor is produced at a rate of approximately 2 μL/min.

66. c. Syneresis (i.e., vitreous liquefaction) is associated with a focal decrease in collagen concentration. More than half of the vitreous is usually liquid by the age of 80. Patients with Stickler’s syndrome often undergo vitreous syneresis before the age of 30.

67. a. Both collagen and hyaluronic acid concentration are lower by 20% to 30% in myopic eyes (axial length >26 mm), compared to eyes with a normal axial length.

68. c. PVD is thought to decrease the likelihood of retinal detachment related to proliferative diabetic retinopathy. It prevents new vessels on optic disc/ new vessels elsewhere (NVD/NVE) from growing on a vitreous scaffold. The PVD extends to the posterior border of the vitreous base. It does not go anterior to the base where the vitreous and retina are tightly adherent. PVD frequently occurs as an acute event. PVD can be induced surgically as well as occur naturally.

69. c. Cataract formation can occur after vitrectomy as a result of higher levels of oxygen present in the postvitrectomized eye. This higher oxygen tension may also lead to improvement in ischemic retinal disease after vitrectomy.

70. b. Vitamin A, stored hepatically, is transported in serum as all-trans retinol. Conversion between aldehyde and alcohol (and vice versa) occurs in the photoreceptors, whereas the trans-to-cis isomerization takes place in the RPE. There are typically three types of cones in normal retinas.

71. d. Photoreceptors are more active electrically (depolarized) in the dark. With light absorption, transducin (via PDE) lowers cGMP, which hyper-polarizes the cell and decreases synaptic exchange with bipolar cells.

72. a. The retina is primarily oxygen dependent (unlike the lens).

73. a. Adding a second drop will likely minimally increase systemic absorption and may also simply wash out the first drop—a normally dispensed 50 mL drop contains far more than the 10 mL of fluid normally found in the eye and cul-de-sac. Local anesthetic disrupts corneal epithelial barrier functions, enhancing local uptake. Blinking increases drainage of topical medications into the nasolacrimal drainage system and subsequently into the systemic vascular system.

74. c. pH extremes trigger reflex tearing, with subsequent dilution of the drug. Benzalkonium chloride, like local anesthetics, disrupts the corneal epithelium.

75. a. Miosis and induced myopia are generally problematic in younger patients. In the elderly, aggravation of cataractous visual loss may be important. Because cholinergic agonists cause forward displacement of the iris-lens diaphragm, angle closure can rarely result from their use. Headache may also occur.

76. b. Brimonidine and apraclonidine must be used with caution in patients taking MAO inhibitors/ tricyclic antidepressant therapy.

77. a. Apraclonidine is a selective alpha-2 adrenergic agonist. Side effects of apraclonidine that have been reported include lid retraction, conjunctival blanching, mydriasis, lethargy, xerostomia, and allergic reactions. The first three are directly attributable to its adrenergic activity.

78. c. Beta-adrenergic agonists (e.g., epinephrine) are thought to decrease intraocular pressure, despite their tendency to increase aqueous humor production, by increasing uveoscleral outflow. Their use in the medical management of glaucoma has decreased considerably.

79. c. Dipivalyl epinephrine (Dipivefrin) is a prodrug of epinephrine. Epinephrine is released into the anterior chamber when the pivalyl groups are cleaved by corneal esterases.

80. a. Unlike a recent history of renal stones (fewer than 5 years earlier), a remote history of spontaneous nephrolithiasis is not thought to be a contraindication to CAI therapy. CAls potentiate hepatic encephalopathy and the potassium-wasting effects of thiazides (hypokalemia is a side effect of CAIs). Sensitivity to digoxin is increased by hypokalemia. Psychiatric disturbances also may be exacerbated by CAls. Patients with a sulfa allergy should not be given carbonic anhydrase inhibitors.

81. d. At the tissue level, glucocorticoids suppress early inflammatory responses such as local vascular congestion, edema, and hyperthermia as well as late inflammatory responses such as capillary and fibroblast proliferation and deposition of collagen. Glucocorticoids do not affect IgE immunoglobulin titers or the afferent limb of cell-mediated immunity, nor do they significantly deter epithelial healing (stromal healing and collagen synthesis, however, are affected).

82. a. Dexamethasone has the greatest relative potency. It is followed, in order of decreasing potency, by fluorometholone, prednisolone, medrysone, tetrahydrotriamcinolone, hydrocortisone.

83. c. Medrysone. The order of IOP elevation in decreasing order is as follows: dexamethasone, prednisolone, fluorometholone, hydrocortisone, tetrahydrotriamcinolone, medrysone.

84. c. Approximately 10% of patients with a history of a hypersensitivity reaction to penicillin will have cross-reactivity to the cephalosporins.

85. d. Sulfonamides indirectly inhibit bacterial DNA synthesis by blocking the synthesis of folic acid (folic acid is a cofactor in nucleic acid synthesis). Only aerobic bacteria are susceptible to aminoglycosides. Anaerobic organisms are resistant to aminoglycosides because the mechanism by which they are taken up by microorganisms is driven by aerobic metabolism.

86. a. Aminoglycosides cause these side effects, which are dose related when given systemically.

87. b. Gentamicin has been associated with macular infarction.

88. b. Vancomycin acts by the inhibition of cell wall synthesis. It is primarily active against gram-positive bacteria including methicillin-resistant strains of Staphylococcus, although plasmid-mediated resistance has resulted in Staphylococcal resistance. Because of increasing resistance to vancomycin, the CDC has recommended avoiding the use of empiric vancomycin in neutropenic patients unless clear evidence for a beta-lactam resistant gram-positive infection can be demonstrated.

89. d. Trifluridine and idoxuridine are thymidine analogs, whereas vidarabine is an adenine analog. All of these agents inhibit DNA synthesis and are effective in treating herpes simplex. Trifluridine is more effective than the other two. Cross-resistance to these agents has not yet been reported.

90. c. Note that the diameter of the anatomic fovea and that of the optic nerve head are roughly equal.

91. b. Each of the others can create significant con-junctival hyperemia or corneal epithelial toxicity.

92. c. Studies have shown that preoperative (72 hours) antibiotics reduces bacterial counts to a greater degree than 3 days of preoperative povidone-iodine. Adding povidone iodine at the time of surgery exerts a synergistic effect. Some studies have suggested that saline flushes actually increase bacterial colony counts.

93. a. Bradycardia is not a known side effect of the prostaglandin analogs.

94. a. The anterior lamellae consist of the skin, orbi-cularis, and associated fascial and vascular components. A vertical insufficiency of the anterior lamella can lead to congenital ectropion.

95. d. Sildenafil (Viagra) can cause mydriasis. All of the other answers have been reported to occur.

96. c. CPEO is inherited through maternal mitochondrial DNA. It involves progressive lid ptosis and paralysis of ocular muscles. In Kearns-Sayre syndrome, CPEO is associated with retinitis pigmentosa and heart block.

97. d. Duchenne muscular dystrophy is X-linked recessive. All of the other syndromes are associated with mitochondrial DNA mutations. NARP phenotype and Leigh’s syndrome are related to the percentage of mutant mitochondrial DNA. They are associated with a base-pair mutation at position 8993 in the ATPase-6 gene.

98. d. Best disease is autosomal dominant, thus it has no carrier state. All of the other disorders have ocular findings in their carrier states.

99. c. Amacrine cells are located in the inner nuclear layer of the retina.

100. a. Müller cells traverse the entire retina. They are glial in nature and form the external limiting membrane. They may affect vitamin A cone metabolism.

101. b. There are 4 to 6 million RPE cells per eye. The RPE is a single layer of cuboidal cells. The ratio of photoreceptor cells to RPE cells is about 45 to 50:1. The RPE has no neural function.

102. d. The RPE is involved in the first three functions. Other functions of the RPE include adhesion of the retina, removal of waste products, and nutrient and ion transport.

103. a. Surfactants reduce the corneal epithelium barrier effect and thus allow increased topical drug delivery. High viscosity and lipid solubility increase topical penetration. Extremes of pH are not good for drug penetration.

104. c. Bronchospasm is associated with pilocarpine use. The other answers are true.

105. a. Pilocarpine can help in management of accommodative esotropia. Pilocarpine treatment does not replace laser iridotomy for chronic angle closure. The other answers are not correct.

106. c. Phosphoine iodide is an indirect-acting muscarinic.

107. c. Scopolamine is the longest acting of the group.

108. d. Cyclopentolate. The order from shortest to longest duration are as follows: phenylephrine 2.5% (3–5 hours), tropicamide (4–6 hours), cyclopentolate (2 days), homatropine (3 days), scopolamine (4–7 days), atropine (7–14 days).

109. c. Muscarinic antagonists may exacerbate angle closure.

110. c. Constipation is usually caused as a side effect, not diarrhea.

111. a. Cidofovir can be associated with hypotony and uveitis.

112. b. Fluoroquinolones have excellent intraocular penetration when given systemically. The other classes of medications do not penetrate the blood/ocular barrier well.

113. a. Other side effects include darkening of iris and periocular skin, conjunctival hyperemia, hypertrichosis of eyelashes, cystoid macular edema, and uveitis.

114. d. Procaine has the shortest duration of action. In order of decreasing duration: bupivacaine, lidocaine, mepivacaine, and then procaine.

115. b. Amphotericin B and natamycin are polyenes. Ketoconazole and miconazole are imidazoles. Fluconazole and itraconazole are triazoles.

116. c. Toxic epidermal necrolysis and Stevens-Johnson syndrome have been associated with sulfonamides.

117. c. Ocular findings in Down’s syndrome include upslanting palpebral fissures, epicanthal folds, chronic blepharitis, strabismus, nystagmus, aberrant retinal vasculature, iris stromal hypoplasia, Brushfield spots, keratoconus, cataract, myopia, and optic atrophy. Other features include mental retardation, short height, hypotonia, brachycephaly, hypoplasia of fifth finger, wide spaced first and second toes, small ears, congenital hear defects, infertility, dental hypoplasia, palmar crease, shortened life span, and increased risk of Alzheimer’s disease.

118. a. Both sexes are affected equally. The mutant gene generally does not cause the clinical disease (hence recessive). The ratio of normal to affected is 3:1. Consanguinity is a possible reason for this type of inheritance pattern.

119. a. Primary mode of action is listed below for several classes of medications. Decrease aqueous humor formation: timolol, betaxolol, carteolol, levobunolol, apraclonidine, brimonidine. Increase trabecular meshwork outflow: pilocarpine, epinephrine, dipivalyl epinephrine. Increase uveoscleral outflow: latanoprost, travoprost, bimatoprost, apraclonidine, brimonidine.

120. c. Local anesthetics block smaller, unmyelinated fibers first. Clinically, sympathetic/parasympathetic fibers are blocked first and then the sensory fibers, followed by larger myelinated motor fibers.

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