An Introduction to Glaucoma.
Glaucoma is a disease known to mankind since antiquity. The word glaucoma is derived from the Greek word “glaukos”. When we look into the pupil of an individual who has no ocular disease, we see a black pupillary reflex. However, patients with “glaukos” are said to have a greenish or bluish hue.
Hippocrates, in his aphorisms in 400 BC, also used the term to describe “a kind of blindness which came with aging and was associated with a glazed look of the pupil”. However, when we critically analyze the definition of “glaukos”, we can conclude that this glazed look could have come from glaucoma but also seen in patients with cataract.
It was only in the 10th century AD that the Arabic scholar Abul Hasan Al-Tabari, in his “Book of Hippocratic Treatments”, suggested the association of glaucoma with high intraocular pressure. Subsequently, in 1622, Richard Bannister, an English oculist described glaucoma as a triad.
According to him, glaucoma is characterized by: raised IOP, increased cup: disc ratio and visual field defects. Thus, the main etiological factor in the pathogenesis of glaucoma was assumed to be only high IOP.
Later on, we came to know that glaucoma can occur even when the IOP is in a statistically normal range. This condition is called normal tension glaucoma or low tension glaucoma. It was also seen that despite lowering of IOP some patients continued to progress. Conversely, some individuals with IOP above 21 mmHg do not show glaucomatous changes. This condition is called ocular hypertension.
Ophthalmol Open J. 2017; SE(1): Se1-Se3. doi: 10.17140/OOJ-SE-1-e001
