Clinical Services

Glaucoma Medical therapy

Glaucoma Introduction:
Clinically, glaucoma is generally defined as the rise in intraocular pressure (IOP) beyond that compatible with vision. Some recent research has documented that processes detrimental to retinal function may be active well in advance of the pressure rise in primary glaucoma, but detection of such processes is extremely difficult and does not lend itself well to clinical practice. One thing is certain. By the time the cornea is edematous, the episcleral vessels are injected, the lens is subluxated and the eye is buphthalmic, vision is irreversibly lost. Indeed, vision may be lost long before these signs are evident with irreversible retinal and optic nerve damage occurring within hours. The "30-30" rule states that "pressures higher than 30 mmHg for 30 hours results in loss of vision", but when pressures are very high, vision may be lost in as little as 4 hours.

Stages of Glaucoma:
As stated above, the early stages of glaucoma may be subtle and in primary angle closure a series of transient mild attacks, often occurring late at night, may precede the sustained elevation of intraocular pressure (IOP). Dilation of the pupil, conjunctival congestion, and transient blindness with papilledema are commonly noted. With secondary glaucoma the prodromal signs vary depending upon the predisposing cause. With a sustained acute attack, the episcleral and conjunctival congestion becomes more severe, the cornea becomes edematous, the optic disc is paler and the retinal vessels are narrowed. Finally, the optic disc becomes cupped and the enlargement of the globe occurs with eventual subluxation of the lens.

Glaucoma Therapy:
Glaucoma management requires intensive therapy in which all efforts are directed to rapidly lower intraocular pressure and maintain it in the normal range. A common misconception is that medical therapy alone is sufficient, but, most often, surgical intervention is required (except in certain cases secondary to uveitis). Perhaps no other disease has required so many different medications, been subjected to so many surgical procedures, and frustrated so many clinicians (not to mention their patients), and despite years of combating this blinding disease, we still don’t have a simple cure. Indeed the number of salvage procedures for irreversibly blind eyes is mute testimony to the severity of this problem.

For visual eyes we favor medical control followed by surgical intervention with placement of a shunt in the iridocorneal angle (usually an Ahmed valve or similar device) and/or transcleral laser cyclophotocoagulation. Enucleation, evisceration with intraocular prosthesis, and intravitreal injection of gentamicin are our procedures of choice for eyes, which are irreversibly blind.