Anterior Segment Developmental Anomalies



Anterior Segment Developmental Anomalies





ANOMALIES OF CORNEAL SIZE AND SHAPE


MICROCORNEA

Microcornea is an uncommon congenital unilateral or bilateral condition. Inheritance is autosomal dominant or recessive.


Signs

• Infant horizontal corneal diameter less than 10 mm; adult horizontal corneal diameter less than 11 mm (Fig. 3-1)

• Shallow anterior chamber, angle-closure or open-angle glaucoma, corneal flattening, and hyperopia

• May have associated nanophthalmos (Table 3-1).

• Other ocular dimensions are normal.



Treatment

• Manage refractive error and search for other ocular and systemic anomalies.


Prognosis

• Varies depending on associated ocular and systemic abnormalities







FIGURE 3-1. Microcornea. This cornea measured 8.5 to 9.0 mm in diameter. Otherwise, the eye was essentially normal.








TABLE 3-1. Association of Microcornea









Ocular

Systemic Syndromes




  • Anterior segment dysgeneses



  • Congenital cataract



  • Congenital glaucoma



  • Corneal leukoma



  • Cornea plana



  • Hyperopia



  • Microphakia



  • Uveal coloboma


  • Cornelia de Lange



  • Ehlers-Danlos



  • Nance-Horan



  • Trisomies 13, 18, 21



  • Turner



  • Waardenburg



  • Weill-Marchesani




MEGALOCORNEA

Megalocornea is an uncommon congenital bilateral condition that is usually inherited in an X-linked recessive manner and is therefore found mostly in males.


Signs

• Clear cornea with a horizontal diameter of greater than 12 mm in the neonate and 13 mm in adults (Fig. 3-2, eFig. 3-2)

• Very deep anterior chamber

• Normal intraocular pressure

• Corneal steepening, high myopia, and astigmatism, but good visual acuity

• Lens subluxation may occur as a result of zonular stretching.

• May develop glaucoma secondary to angle abnormalities



Treatment

• Manage refractive error and search for other ocular and systemic anomalies, especially glaucoma and lens abnormalities.


Prognosis

• Generally good, but depends on associated ocular and systemic abnormalities (Table 3-2)







FIGURE 3-2. Megalocornea. This cornea measured 14 mm in diameter. The cornea is clear except for some calcific degeneration nasally and temporally.








TABLE 3-2. Associations of Megalocornea









Ocular

Systemic Syndromes




  • Astigmatism



  • Axenfeld-Rieger



  • Cataract



  • Congenital glaucoma



  • Ectopia lentis



  • Myopia


  • Albinism



  • Alport



  • Apert



  • Craniosynostosis



  • Down



  • Ehlers-Danlos



  • Marfan



  • Osteogenesis imperfecta



  • Progressive facial hemiatrophy




NANOPHTHALMOS

Nanophthalmos is an uncommon congenital bilateral condition in which the globe has reduced volume but is otherwise grossly normal.


Signs

• Very high hyperopia (e.g., + 12D to + 15D)

• Adult corneal diameter is reduced, but the lens has a normal volume.

• Short axial length (e.g., 16 to 18 mm)

• Shallow anterior chamber

• Thick sclera

• Fundus may show a crowded disc, vascular tortuosity, and macular hypoplasia.


Associated Problems

• Angle-closure glaucoma

• Uveal effusion

• Retinal detachment

• Poorly tolerated intraocular surgery


MICROPHTHALMOS

Microphthalmos is an uncommon unilateral or bilateral condition in which the axial length of the eye is reduced and the eye is malformed (Fig. 3-3). The effects on vision depend on its severity and the presence of associated anomalies. There are two types of microphthalmos: noncolobomatous and colobomatous (Table 3-3).







FIGURE 3-3. Microphthalmos. This microphthalmic eye has a small cornea, abnormal iris, and overall small size. (Courtesy of Peter Laibson, MD.)








TABLE 3-3. Types of Microphthalmos




















Noncolobomatous

Colobomatous


Isolated

Isolated




  • Sporadic



  • Inherited (dominant, recessive, X-linked recessive)


  • Sporadic



  • Inherited (dominant)


With anterior persistent hyperplastic primary vitreous

With systemic syndromes:




  • Patau (trisomy 13)



  • Edward (trisomy 18)



  • Cat-eye (partial trisomy 22)


Intrauterine infections (rubella, toxoplasmosis, cytomegalovirus, varicella)


  • CHARGE



  • Meckel



  • Lenz microphthalmia


CHARGE syndrome is coloboma, heart anomaly, choanal atresia, retardation, and genital or ear anomalies.




BUPHTHALMOS

Buphthalmos is an uncommon, usually bilateral condition in which the globe is enlarged as a result of stretching of the cornea and sclera because of increased intraocular pressure before birth or during the first few years of life.


Signs

• Large cornea with variable scarring; may develop corneal edema later in life

• Horizontal or curvilinear ruptures in Descemet membrane (Haab striae) (Fig. 3-4, eFig. 3-4A and B)

• Very deep anterior chamber

• Angle anomalies

• Myopia

• Optic disc cupping


Associations of Infantile Glaucoma

• Ocular

▪ Aniridia

▪ Anterior segment dysgeneses

▪ Congenital ectropion uveae

• Systemic

▪ Down syndrome

▪ Lowe syndrome

▪ Mucopolysaccharidoses

▪ Neurofibromatosis type I

▪ Nevus of Ota

▪ Patau syndrome (trisomy 13)

▪ Pierre Robin syndrome

▪ Rieger syndrome

▪ Sturge-Weber syndrome



Treatment

• Management of glaucoma by a glaucoma specialist


Prognosis

• Guarded, depending on amount of optic nerve damage prior to diagnosis, efficacy of treatment, and associated ocular and systemic disorders. Haab striae of the cornea do not prevent good vision.







FIGURE 3-4. Haab striae. A. These breaks in Descemet membrane occurred secondary to congenital glaucoma. Note the multiple parallel swirling lines, which are rolled-up edges of Descemet membrane. B. Multiple parallel swirling lines are evident in this eye with congenital glaucoma.


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Oct 13, 2019 | Posted by in OPHTHALMOLOGY | Comments Off on Anterior Segment Developmental Anomalies

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