Perhaps the most interesting part of an ophthalmologist’s professional life is the challenge presented in diagnosing diseases of the eye. It is toward this end that his or her training has been directed, first as a medical doctor, then as a specialist. Although refraction will often occupy much of an ophthalmologist’s time, it is merely a step in the process of defining disease.
For the ophthalmic assistant, the study of disease processes can aid in making the examination of the eye more rewarding. Despite the assistant’s limitations in training and instrumentation, there are many common eye disorders seen daily that should be appreciated. The function of this chapter is not to make diagnosticians out of ophthalmic assistants, but to enrich their career through the study of the various disorders that are commonly seen.
Conjunctiva
The conjunctiva commences at the lid margin, lines the inner surface of the lids, forms a cul-de-sac, and then lines the surface of the eye itself, becoming circumferentially attached to the cornea at the limbus. It is translucent, moist, and membranous; has a rich vasculature; and is kept supple by the tear film.
Hyperemia
Hyperemia, or redness, of the conjunctiva is perhaps the most common condition seen. Everyone gets red eyes at one time or another. The redness is caused by dilation of the normal vascular channels in the conjunctiva. It can result from such transitory and innocuous events as exposure to dust, wind or air pollutants, fatigue, excessive reading, exposure to strong light or heat, poor ventilation, excessive dryness, and even the moderate consumption of alcoholic beverages. Many people equate red eyes with infection or inflammation and become alarmed. It is for this reason that proprietary medications “to get the red out” are so successful with their in-depth media advertising. Many people think that by getting the red out they are nipping a disease process in the bud, as well as removing a socially unacceptable disorder.
Transitory redness of the eyes requires no treatment because it is not a disease. People who find some relief with the use of eyewashes or astringent drops get only a temporary abatement of their symptoms and become addicted to eye-whitening drops for the rest of their lives. When the medication wears off, the conjunctival vessels have a tendency to dilate again so that the redness becomes more prominent than before: the so-called rebound reaction.
Subconjunctival hemorrhage
Subconjunctival hemorrhage is caused by a ruptured conjunctival blood vessel. It usually produces an irregular red patch because of pooling of blood under the conjunctiva ( Fig. 23.1 ). Its appearance is particularly gruesome and alarming because it is accentuated by the white of the sclera ( Fig. 23.2 ). Invariably, a collection of blood, like any other bruise under the skin, spreads and seems to enlarge as the blood is disseminated. Eventually, the blood pigment breaks down to its component parts until it is absorbed. This process can take anywhere from 7 days to 3 weeks, depending on the size of the hemorrhage.
Subconjunctival hemorrhage occurs most often in older adult patients with diabetes or hypertension, but commonly no cause can be found. A predisposing cause appears to be events that produce a sudden rise in venous pressure, such as coughing, straining, lifting, sneezing, or vomiting. There is no required treatment for this condition, which is entirely innocuous, other than reassurance. Occasionally, a subconjunctival hemorrhage is part of a general bleeding disorder, but it must be emphasized that such an event is rare. If there is a history of recurrent hemorrhages, patients should be sent to their family doctor to rule out high blood pressure, diabetes, or blood disorder. Cold compresses on the first day followed by warm compresses may speed up recovery.
Conjunctivitis
Conjunctivitis is an inflammation of the conjunctiva characterized by redness of the conjunctiva, swelling, a discharge that can be watery or purulent, and congestion of the tissues ( Fig. 23.3 ). The patient commonly complains of a burning or grittiness of the eyes. Characteristically, the discharge accumulates during sleep, and its resultant drying on the lashes makes the lids difficult to open in the morning. Usually the lids have to be bathed to open the eyes.
Conjunctivitis may have an infectious, allergic, or toxic cause. The most common infectious agents are viruses, bacteria, and chlamydial organisms. A virus is the most common cause of conjunctivitis. Unlike bacterial or chlamydial conjunctivitis, the discharge is characteristically watery. Adenovirus is the most common viral conjunctivitis. Certain serotypes of this infectious agent may be responsible for epidemic keratoconjunctivitis (EKC) or pharyngoconjunctival fever (PCF). EKC is highly contagious and is often associated with epidemic outbreaks in a localized area. This disease is characterized by conjunctival and corneal involvement. PCF differs from EKC in that patients usually exhibit symptoms of a sore throat just preceding or at the time of their ocular symptoms.
Staphylococcus aureus is the most common cause of bacterial conjunctivitis . The organism is also responsible for such common conditions as boils or impetigo of the skin. Gonococcal conjunctivitis can be a severe infection resulting in blindness if appropriate treatment is delayed. The disease can be seen in newborns, who contact the organism while traveling through the birth canal. The sequelae of neonatal conjunctivitis can be so devastating that it is mandatory in most countries for either antibacterial drops or ointment, or 1% silver nitrate to be placed into the lower conjunctival sac of all newborns immediately after birth. Gonococcal conjunctivitis also can be seen in adults and is characterized by a significant purulent discharge. These patients and their sexual contacts need to be evaluated for a venereal disease that was probably the source of the conjunctivitis.
Haemophilus influenzae , another bacterial organism, can cause pinkeye, especially in children.
Chlamydial conjunctivitis can be caused by inclusion conjunctivitis or trachoma. The disease is characterized by a red eye and often a mucoid discharge. Inclusion conjunctivitis is the more prevalent of the two in North America and occurs in newborns and young adults. Trachoma is a more severe disease that can give rise to extensive scarring of the lids, conjunctiva, and cornea. It is an epidemic in some parts of the world, such as North Africa, the Middle East, and South Asia, where poor hygiene, poor sanitation, deficient diets, and crowding are the norm. It is a major cause of blindness in the world.
The features that distinguish acute conjunctivitis, acute iritis, and acute glaucoma are shown in Fig. 23.4 and Table 23.1 . In cases of acute conjunctivitis, a swab for a smear and culture may be required in selected cases, especially in patients with ophthalmia neonatorum (conjunctivitis of the newborn), membranous conjunctivitis (diphtheria), and purulent conjunctivitis (gonococcal).
| Factor | Acute conjunctivitis | Acute iritis | Acute glaucoma |
|---|---|---|---|
| Pain | None to grittiness or foreign body sensation | Moderate to severe | Severe |
| Discharge | Watery or purulent | None | Tearing only |
| Sensitivity to light (photophobia) | Mild | Severe | Moderate |
| Cornea | Bright and clear | Clear or hazy | Hazy |
| Pupil | Normal | Constricted or small | Dilated, oval, fixed to light |
| Intraocular pressure | Normal | Usually normal | Elevated |
Allergic conjunctivitis is basically a hypersensitivity reaction ( Fig. 23.5 ). It may occur as a component of hay fever or as an independent ocular allergy. There may be large formations of papules or cobblestones under the eyelid. At times, the conjunctivitis may be an allergic response to an invading organism, such as tuberculosis, protein, or staphylococcal bacillus. Contact allergies to drugs are a common occurrence and one of the main reasons why an inflammation can progress despite copious applications of medication. Neomycin and sulfur preparations are particularly sensitizing. Many pharmaceutical agents are available to bring relief. Agents such as cromolyn, lodoxamide, olopatadine, naphazoline/antazoline, and a corticosteroid may be helpful.
Chemical conjunctivitis is often seen in the summer and is caused by irritation from chlorine in swimming pools. It may also occur in industrial workers after exposure to irritating fumes.
Evidently, the treatment of conjunctivitis depends on identifying its cause and applying the appropriate therapy. Local antibiotic drops that are effective for a bacterial conjunctivitis would obviously be of no value for a viral infection.
In most offices, the diagnosis of conjunctivitis is made largely on clinical grounds and, if serious enough, enhanced with laboratory studies. For example, in a membranous conjunctivitis caused by diphtheria, swabs are taken from the discharge for a smear preparation, and samples are cultured for growth identification and drug sensitivity. Routine cultures and sensitivity tests are rarely done because the time lag in obtaining the results of such investigation does not warrant the delay in treatment. When the conjunctivitis is potentially serious, the ophthalmologist will do appropriate laboratory investigations but will institute therapy first. If the trial of therapy does not work, it can later be altered when the precise etiologic agent has been identified and the exact drug to which it is sensitive has been determined.
Episcleritis
Episcleritis is characterized by a salmon-pink hue of the superficial layer of the eye, with involvement of the conjunctiva and episclera ( Fig. 23.6 ). At least one-third of the lesions are tender to touch. Simple episcleritis may be sectorial in 70% or generalized in 30% of patients. In nodular episcleritis, the nodules that form are movable with a cotton-tipped swab, unlike nodular scleritis.
Pinguecula/pterygium
A pinguecula is a triangular, wedge-shaped thickening of the conjunctiva, usually found encroaching on the nasal limbus. If it invades the cornea, it is then referred to as a pterygium ( Fig. 23.7 ). These lesions appear as yellowish or white vascularized masses. They are common in tropical climates where people spend a great deal of time outdoors and are exposed to sunlight and the harmful effects of ultraviolet light. Pingueculae usually do not cause symptoms. Occasionally, they may cause some irritation, or may be a cosmetic blemish. Treatment with artificial tears, vasoconstrictors, or, rarely, surgical excision may be indicated. Pterygia can occasionally extend across the cornea and eventually encroach on the visual axis and cause loss of vision. If there is documented evidence of growth, if the lesion is close to the visual axis, or is of cosmetic concern, then surgical excision is indicated. Unfortunately, there is a high incidence of recurrence with a simple excision, and therefore surgical removal is commonly combined with mitomycin C application or beta-radiation. Amniotic membranes or conjunctival grafts have been grafted in place and introduced to reduce recurrence.
Conjunctival nevus
A nevus is a benign neoplasm that appears on the conjunctiva at birth or in early childhood. The most common appearance is that of a flat, slightly elevated brown spot that is occasionally cystic. It usually becomes pigmented late in childhood or adolescence. It is uncommon for a nevus to become malignant. This condition should be differentiated from the acquired pigmented lesion that can occur by the age of 40 to 50 years and that can, with growth, turn into a malignant melanoma.
Cornea
The cornea, which forms the anterior one-sixth of the globe and functionally is the main refracting surface of the eye, is the structure most vulnerable to injury or inflammation. It is almost completely exposed so that it receives the brunt of chemical injuries to the eye, foreign bodies, particulate matter, and organisms that can invade it from such contiguous sources as the conjunctiva and the lacrimal sac. It is avascular tissue, which means that it is robbed of the defense mechanisms that normally are marshaled against any inflammatory insult elsewhere in the body. The corneal epithelium provides a strong barrier against bacterial invasion. The integrity of this surface is best appreciated by applying fluorescein to its surface and noting any defects in the integrity of this layer by staining and the accumulation of fluorescein pools.
Keratoconus
Keratoconus is an abnormality in which the cornea progressively becomes thinned and bulges forward in a conical fashion ( Fig. 23.8 ). It is bilateral in 90% of patients and occasionally can be inherited. Keratoconus is often found more frequently in patients who have hay fever, atopic dermatitis, and eczema. Frequent eye rubbing has been recognized as a cause of keratoconus.
The disease results in irregular corneal astigmatism that defies correction by ordinary spectacles. Rigid contact lenses, and sometimes a piggyback of soft and rigid lenses (see Ch. 16 ), have been used to correct the visual defect. If the patient is unable to be fitted properly with contact lenses because of high irregular astigmatism, keratoplasty is necessary to restore vision.
Keratoconus in the very late stages is recognized by Munson’s sign . This is observed when the examiner has the patient look down and notes from above the indentation of the lower lid by the cone of the cornea. The diagnosis may be made by slit-lamp examination showing Vogt’s striae or stress lines of the cornea; by the keratometer or retinoscope, which shows the presence of irregular corneal astigmatism; or by use of computerized videokeratography or tomography, which may show corneal irregularity of the anterior surface, elevation of both the anterior and or posterior surfaces, and abnormal steepening. Computerized topography and tomography (see Ch. 41 ) are now the most popular method to detect keratoconus.
Corneal cross-linking has become a popular technique in the treatment of keratoconus. Cross-linking with ultraviolet light and riboflavin drops often arrests the progress of keratoconus and keractesia. (For more information see Ch. 37 .)
Herpes simplex keratitis
Herpes simplex keratitis is a common corneal inflammatory disorder created by the herpes simplex virus, which is the offending agent of the common cold sore. The first exposure to herpes simplex virus in 90% of cases results in subclinical, usually mild, disease. Characteristically, the young child is infected by salivary contamination from an adult who has labial herpes. The incubation period is 3 to 9 days. The clinical features of herpes simplex are both ocular and nonocular. The symptoms are relatively mild and consist of an irritating foreign body sensation, mild tearing with no frank pus or purulent discharge, and some haziness of vision accompanied by sensitivity to light. The classic herpes lesion is the dendritic figure, which, when stained with fluorescein, reveals a branchlike erosion of the cornea, as a single lesion or as multiple disturbances ( Fig. 23.9 ).
The virus will remain dormant in the sensory nerves to the face, where it can be aroused by a variety of precipitating factors, including emotional stress, trauma, menstruation, sunlight, or the use of either local or systemic steroid drugs. When aroused, the virus will travel down the sensory nerves to the face, lids, conjunctiva, and cornea to produce a recurrence of the disease. These recurrences may be frequent, adding insult to each previous episode, so that reduction of vision over the years is a common complication. If only the epithelium is involved, no scarring occurs. However, the inflammatory process commonly extends deep down toward the stroma, which heals with vascular proliferation from the limbus and results in corneal scarring.
This condition can be a diagnostic danger because it appears to be a simple conjunctivitis. Many patients treat themselves or are treated by their family physician with antibiotics for several days before arriving in the ophthalmologist’s office. Local antibiotics are of no value in this condition because it is caused by a virus. In many instances, self-medication severely aggravates the condition because many antibiotic preparations are coupled with steroids, which cause the virus to proliferate even more, thus ensuring the spread of the ulcer and further necrosis of tissue.
The treatment of herpes keratitis is instillation of trifluridine (Viroptic) drops and or oral antiviral agents like Acyclovir. The cornea heals in 7 to 14 days in approximately 85% of cases. Some ophthalmologists prefer to remove the offending virus by scraping off the diseased epithelium. This can be done at the slit lamp with a dull blade.
Other forms of the disease include the following:
- 1.
Gingivostomatitis . Symptoms are fever, malaise, and lymphadenopathy, along with sore throat.
- 2.
Pharyngitis . Often pharyngitis occurs with vesicles on the tonsils.
- 3.
Cutaneous disease . This usually manifests as type I, which occurs above the waist, or type II, below the waist. The disease is seen in wrestlers and rugby players.
- 4.
General infection . Type II infection, which is more common than type I, is characterized by fever, myalgia, extensive vesicular lesions, and inguinal and pelvic lymphadenopathy.
Recurrent herpes simplex
The virus develops a symbiosis with human beings. Any of the previously mentioned precipitating factors (trauma, fever, etc.), which provoke viral shedding and the immunologic functions, may be causative factors in episodes of recurrence. The trigeminal ganglion is a reservoir for the type I disease. The virus has a 50% recurrence rate over 5 years and may be highly localized in the lymph nodes, chin, eyes, and genitals. Cultures are usually unnecessary because this is chiefly a clinical diagnosis.
Superficial punctate keratitis
Superficial punctate keratitis consists of fine erosions in the corneal epithelium that can be diagnosed by means of the slit lamp and fluorescein staining. These lesions are common and can be seen in dry eye conditions, infections, such as adenovirus and herpes simplex, and chemical injuries. Treatment varies, depending on the cause of the superficial punctate keratitis.
Herpes zoster ophthalmicus
Herpes zoster ophthalmicus (HZO) is caused by the varicella virus, which causes chickenpox in children. In the adult, it is ushered in by a severe neuralgic type of pain, which usually includes the upper lid and extends upward beyond the brow to envelop the forehead through the scalp almost to the vertex of the head. After the pain, a vesicular eruption of the skin usually occurs and the skin surface becomes swollen, red, and heavily blistered ( Fig. 23.10 ). The severe pain and vesicular phase last approximately 2 weeks. With healing, the skin is often pockmarked with deep, pitted scars and sensitivity to normal sensation is depressed. The incidence of HZO is 10% of all herpes zoster infections. HZO is frequently seen by an ophthalmologist first.
