Clinical Correlations

Congenital Lens Opacities

Figure 14-3. (A) Coloboma iridis. Note the cleft in the iris (black spot at arrow). (B) Congenital cataracts. Note the lens opacities in both eyes. (C) Congenital glaucoma (buphthalmos). Note the enlarged left eye and the normal right eye. (D) Detached retina. Note rhe retina (arrow) detached from the choroid and sclera. L = lens. (A, From Bergsma D [ed]: Birth Defects: Atlas and Compendium. Baltimore, Williams & Wi kins, 1973, Fig. 6.47. B-D, From Gilbert-Barness E: Potters Atlas of Fetal and Infant Pathology. St Louis, CV Mosby, 1998, pp 366 and 370.)

Figure 14-3. (A) Coloboma iridis. Note the cleft in the iris (black spot at arrow). (B) Congenital cataracts. Note the lens opacities in both eyes. (C) Congenital glaucoma (buphthalmos). Note the enlarged left eye and the normal right eye. (D) Detached retina. Note rhe retina (arrow) detached from the choroid and sclera. L = lens. (A, From Bergsma D [ed]: Birth Defects: Atlas and Compendium. Baltimore, Williams & Wi kins, 1973, Fig. 6.47. B-D, From Gilbert-Barness E: Potters Atlas of Fetal and Infant Pathology. St Louis, CV Mosby, 1998, pp 366 and 370.)

C. Congenital glaucoma (buphthalmos; see Figure 14-3C) is increased intraocular pressure due to abnormal development of the canal of Schlemm or the iridocorneal filtration angle. It is usually genetically determined, but it may result from maternal rubella infection.

D. Detached retina (see Figure 14-3D) may be caused by head trauma or it may be congenital. The site of detachment is between the outer and inner layers of the optic cup (i.e., between the retinal pigment epithelial layer and the layer of rods and cones of the neural retina).

E. Persistent iridopupillary membrane consists of strands of connective tissue that partially cover the pupil; this membrane seldom affects vision.

F. Microphthalmia is a small eye, usually associated with intrauterine infections from the TORCH (toxoplasma, rubella virus, cytomegalovirus, and herpes simplex virus) group of microorganisms.

G. Anophthalmia is absence of the eye. This condition is caused by failure of rhe optic vesicle to form.

H. Cyclopia involves a single orbit and one eye. It is caused by failure of median cerebral structures to develop.

I. Retinocele results from herniation of the retina into the sclera or failure of the choroid fissure to close.

J. Retrolental fibroplasia (retinopathy of prematurity) is an oxygen-induced retinopathy seen in premature infants.

K. Papilledema is edema of the optic disk (papilla) due to increased intracranial pressure. This pressure is reflected into the subarachnoid space, which surrounds the optic nerve (CN II).

L. Retinitis pigmentosa (RP) is hereditary degeneration and atrophy of the retina.

1. RP may be transmitted as an autosomal recessive, autosomal dominant, or X-linked trait.

2. RP may be caused by abetalipoproteinemia (Bassen-Kornzweig syndrome); progression of this disease may be arrested with massive doses of vitamin A.

3- RP is characterized by a degeneration of the rods, night blindness (nyctalopia), and "gun barrel vision."

M. Retinoblastoma (RB) is a retinal tumor that occurs in childhood and develops from precursor cells in the immature retina:

1. The RB gene is located on chromosome 13 and encodes for RB protein, which binds to a gene regulatory protein and causes suppression of the cell cycle. Thus, the RB gene is a tumor-suppressor gene (also called an antioncogene).

2. A mutation in the RB gene will encode an abnormal RB protein such that there is no suppression of the cell cycle. This leads to the formation of RB.

3. Hereditary RB causes multiple tumors in both eyes. Nonhereditary RB causes a tumor in one eye.

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