The degree of loss depends on the location and extent of the opacity. Rarely, the cataract swells, producing secondary glaucoma and pain. Such cataracts are particularly troublesome in bright light. Diagnosis Gradual loss of vision beginning in middle age or later is characteristic of glaucoma as well as cataract. Before the pupils are dilated for an ophthalmoscopic examination, increased intraocular pressure and a shallow anterior chamber must be ruled out.
Small cataracts stand out as dark defects in the red reflex.
A large cataract may obliterate the red reflex. Slit-lamp examination provides more details about the character, location, and extent of the opacity. Treatment Frequent refractions and eyeglass prescription changes help maintain useful vision during cataract development. Many ophthalmologists recommend that UV-coated glasses or sunglasses be worn while in the sunlight. Disabling glare can also be an indication for surgery and is most common with posterior subcapsular cataracts.