One of the most common causes for irreversible visual loss is glaucoma. Glaucoma is disease in which there is damage to the nerve fiber layer of the retina that is typically caused by an elevation in the intraocular pressure. It can go undetected until extreme visual loss has taken place. People at risk for glaucoma include those with a family history of glaucoma, diabetics, those with hypertension, individuals of African-American decent, and those of increasing age. In general, most glaucomas are painless and asymptomatic. The visual loss that initially occurs is in the periphery of the visual field, so that most people do not even notice the visual loss. As glaucoma progresses, and if left untreated, it can affect the central vision in an irreversible fashion.Glaucoma is diagnosed on a routine screening eye examination. The initial treatment for glaucoma is the use of eyedrops in order to reduce the intraocular pressure. If eyedrops fail, then laser or even surgical repair is necessary. That’s why it is crucial for an individual to undergo an annual eye examination, especially if there is a risk factor for such a blinding disease.
Symptoms of Glaucoma
a) Frequent change of glasses (none of which is satisfactory).
b) Difficulty in dark adaptation.
c) Bumping into things at unfamiliar places.
d) Blurred or foggy vision.
e) Coloured halos (rainbow coloured rings) around lights.
Some Examples of Progression of Glaucoma
This is an example of normal vision.
This is also an example of how someone sees during the beginning stages of open-angle glaucoma. Because there are no symptoms initially, regular eye examinations are very important.
Early symptoms may include a gradual and often imperceptible failing of peripheral (side) vision.
As the disease progresses, the center of vision may still be clear, however peripheral vision begins to fail.
During the advanced stages of glaucoma, only a small central area of vision remains. If the entire optic nerve is destroyed, then total blindness will result.
1.The Humphrey Computerized Field analyzer.An instrument which evaluates what you can see with your “fields” of from the periphery of your eye while keeping the eye fixated in the middle. It evaluates the extent of loss. In glaucoma the fields progressively decrease till only a central island is left, which if untreated, extinguishes leading to blindness. The Humphrey Analyzer is the Gold standard all over the world. Fields are normally done twice a year.
2.Goldmann Applanation Slit Lamp Biomicroscopy mounted Tonometer.This instrument is exceptionally accurate but requires steady fixation. Can identify pressure accurately even in post-operative and highly myopic eyes.
3.Gonioscopy – To see the angle structure of eye (circulation of fluid inside the eye.
5.Pachy metry – Corneal thickness.