- Galactosemia is a rare, congenital disease that prevents infants from metabolizing galactose, a sugar found in milk. Galactosemia occurs in about two out of every 100,000 births. As a result of the inability to process galactose, it accumulates in the blood and lens of the eye. The galactose in the lens absorbs water and disrupts the lens fibers, forming vacuoles, or pockets of liquid in the tissue. Bilateral cataracts form from these vacuoles. Cataracts may be avoided or reduced in severity by early removal of milk and milk products from the diet. Dense opacities may be surgically removed within the first month. Early extraction limits the possibility of developing amblyopia.
Glare testing attempts to gauge true vision under battlefield conditions, that is, in the real world of driving, walking, and working. It can document the levels of glare which creates a disability and can help determine if tints applied to glasses can be beneficial in minimizing the effects. A special glare tester, as the Brightness Acuity Tester (BAT), is used but its use is controversial among ophthalmologists. Another use for the instrument is to measure the time it takes to recover sight after the retina is dazzled with very bright light. This mimics entering a darkened area after exposure to sunlight, or being “blinded” by oncoming headlights during night driving. Many patients report disabling glare and blurred vision that is more intense outdoors than in a darkened room. While the glare-recovery time normally increases with age, very slow recovery can also be the result of a disease or vitamin deficiency.
Glaucoma is a condition resulting from abnormally high pressure inside the eyeball. If undetected, abnormally high eye pressure can gradually diminish visual acuity, starting with peripheral vision and eventually leading to blindness. If the disease is diagnosed early, its damage can be prevented or slowed with the use of eyedrops which reduces pressure by diminishing fluid production within the eye or by increasing the fluid drained from the eye. (See more separately.)
Glaucoma test (tonometry) measures the internal pressure of the eye. If there is glaucoma present, the pressure within the eye is unusually high. Two common techniques are used to measure this pressure, with both measuring the amount of force needed to momentarily flatten (applanate) the cornea. With the air-puff tonometry, the doctor shoots puffs of air at the cornea. With applanation tonometry, the doctor pushes the tip of a tiny, flat-tipped cone against the eye. This test may be unnerving, but is painless, thanks to numbing eyedrops applied before the test.
Gonioscope, or gonioprism, is essentially a mirrored contact lens fitted with tiny mirrors to view the angle opening between the cornea and iris inside the eye. The information gained can differentiate between open or closed angle glaucoma; inspect for tumors and lesions; recognize injury-induced tears; and evaluate effectiveness of laser treatments.
Gonioscopy is a test to determine the width of the angle of the eye’s anterior chamber. This angle, formed by the cornea and the iris, is the place where fluid drains from the eye. If the angle becomes narrow or blocked, the fluid cannot drain effectively, pressure builds up within the eye and glaucoma develops. The angle of the chamber is examined with a gonioscope. Gonioscopy is performed during glaucoma screening and the routine eye examination of a person with glaucoma. The procedure detects abnormalities or changes in the angle of the chamber and assists the examiner in prescribing treatment. It is also a routine part of a presurgical eye examination for those undergoing cataract surgery. The surgeon may administer cycloplegic or dilating drops prior to surgery, which could further restrict a narrow angle and cause complications. In addition, if an anterior chamber intraocular lens (IOL) implant is planned, the gonioscopy could indicate the amount of space, or lack thereof, available to accommodate the implant. Genioscopy may be performed on any patient prior to the application of cycloplegic drops. During an examination, or other procedure, cycloplegic drops may be used in a patient with narrow angle if care is taken to ensure that the pupil has returned to normal size after the procedure.
Gonococcal ophthalmia, or ophthalmia neonatorum, is a severe infection of the conjunctiva caused by gonnorhea, a type of veneral or sexually transmitted disease that is seen in some newborns. It is the most frequently reported communicable disease in North America. Gonorrhea is caused by the gonococcus bacteria and may result in blindness when contracted congenitally. The disease is passed from mother to child during birth. As the child moves through the birth canal, the eyes come in contact with the bacteria growing in or near the cervix. Early symptoms include swelling and redness of the cornea, conjunctiva, and eyelids. Without treatment, the condition may progress to damaging the cornea, which results in blindness. Adults may contract gonococcal ophthalmia by exposing the eyes to anything carrying the bacteria and may exhibit more severe signs and symptoms than newborns, including a copious pus-like discharge. Blindness is the outcome of untreated cases. Treatment involves the use of local antibiotic drops or ointments and likely systemic or injected antibiotics.