CAUSES :
- NORMAL AGING
- DIABETES
- OCULAR TRAUMA
- UVEITIS
- GENETIC DISEASES LIKE MYOTONIC DYSTROPHY, NEUROFIBROMATOSIS TYPE 2, GALACTOSEMIA
- RADIATION THERAPY
- CORTICOSTEROID THERAPY
. Congenital: Usually obscure
. Drugs (corticosteroids in first trimester, sulfonamides, etc.)
. Metabolic - diabetes in mother, galactosemia in fetus
. Intrauterine infection - first trimester (rubella, herpes, mumps)
. Maternal malnutrition
. Other cataract types:
. Have in common that a biochemical/osmotic imbalance disrupts lens clarity
. Local changes in lens protein distribution lead to light scattering manifest as lens opacity
--------------------------------------------------------------------------
DIFFERENTIAL DIAGNOSIS :
β’ An opaque appearing eye may be due to surface opacities of the cornea (scarring), lens opacities, tumor, retinal detachment, gliotic retinal scar. Biomicroscopic examination (slit lamp) or careful ophthalmoscopic exam should provide diagnosis. A visual acuity worse than 20/30, not easily correctable by glasses, and
explainable by the degree of cataract noted on examination makes the diagnosis.
β’ In the elderly, visual impairment often due to multiple factors, e.g., cataract and macular degeneration both contributing to visual loss
β’ Age-related cataract - significant if symptoms and ophthalmic exam support cataract as major cause of vision impairment
β’ Congenital - lens opacity in absence of other ocular pathology such as tumor, nerve glioma, retinopathy of prematurity may be consistent with the visual loss. May cause severe amblyopia.
β’ Note: No cataract produces an afferent pupillary reaction defect (Marcus Gunn pupil). Abnormal pupillary reactions mandate further evaluation for other pathology.
* FUNDUS EXAMINATION
* RETINOSCOPY
SPECIAL TESTS
β’ Visual quality assessment: Glare testing, contrast sensitivity are sometimes indicated. (Hyperglycemic state as in poor diabetic control creates osmotic change within lens and may alter measurement of visual acuity and refractive state.)
β’ Retinal/macular function assessment: Potential acuity meter testing,
fluorescein retinal angiography sometimes required