GLACOMA: an insidious enemy
Most people think that Glaucoma is almost exclusively a single disease. To the contrary, glaucoma is not considered a single disease, but a diverse group of pathologies that share a chronic and progressive damage to the optic nerve and to the retinal nerve fiber layer.
These diseases are important because the damage they cause is irreversible and set in silently, until they manifest their presence causing significant problems. The mechanisms through which glaucoma develops are still largely unknown, although predisposing factors are certainly present:
- Elevated intraocular pressure (reference values are, statistically, between 15-21 mm Hg)
- Familiarity for glaucoma
- Central corneal thickness
- Vascular Factors
Intraocular pressure, which is also the most important predisposing factors, is easier to control. Statistics in hand, it seems that even 50% of patients who have a relative with glaucoma are not aware of having the disease. Moreover, those who have a first degree relative with glaucoma, run a risk of 4 to 10 times greater of developing the disease.
However, the slightly elevated intraocular pressure does not always explain the onset of glaucoma, and there are cases in which intraocular hypertension is harmless. The status of the optic disc and visual field study may show, if present, changes to the optic nerve and remove all diagnostic doubts.
Among the specific tests, the routine and more useful for diagnosis of glaucoma are:
The GDx is a test that allows the indirect measurement of the thickness of nerve fibers that make up the optic nerve by analyzing the propagation delay of a beam of light through the microtubules.
The pachymetry allows the measurement of corneal thickness, which is approximately half a millimeter thick (520-540Î¼). It seems, in fact, that people with thicker corneas are more protected from the onset of glaucoma.
The visual field test is of simple implementation, but requires a bit of attention and concentration by the patient. The test utilizes a device that projects light spots of various intensities in different positions on the bottom of it. The patient must press a button whenever sees the bright point.
The measurement of intraocular pressure is also quick and painless.
The drugs used in glaucoma aim to reduce the pressure inside the eye with two different mechanisms: decreasing aqueous humor formation or facilitating its outflow, thus avoiding damage to the optic nerve. Their effect, however, persists only so long as they are administered, which is why the therapy, once initiated, typically lasts for life.
There are many medications available for glaucoma, such as carbonic anhydrase inhibitors: acetazolamide, diclophenamide, dorzolamide, and brinzolamide. Speaking of parasurgical and surgical therapies, we are referring to laser (non-invasive, performed as outpatient), and the actual surgery. Each type of therapy has its value depending on the type of glaucoma.
From the foregoing, it is possible to infer that glaucoma is a disease which is easy to diagnose, and for which, luckily, a lot can be done. It is advisable to go for an eye check up to clear any doubt (regardless of age) when the disease has a familiar tendency. As always, early diagnosis allows a head start against a very manageable, but subtle, disease that gives signs of its presence when the damage has already been established.
Mattia Davide della Rocca
Graduating in Medicine and Surgery at Second University of Naples