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COMMON SECONDARY TYPES OF GLAUCOMA
by Dr. Gertrude Gwendale Baron-Reinoso
Secondary glaucomas are glaucomas with identifiable causes. The cause could be a primary ocular condition or disease, a systemic disease, a drug or eye trauma.
This type of glaucoma is caused by eye inflammation or uveitis. In uveitic open angle glaucoma, there is inflammation of the trabecular meshwork (trabeculitis) or blockage of the trabecular meshwork by inflammatory cells and byproducts. In uveitic closed angle glaucoma, adhesion of the iris to the angle structures (synechia) prevents drainage of the aqueous. Treatment involves the use of anti-inflammatory drugs and appropriate measures to lower eye pressure.
In patients with diabetes mellitus, vascular abnormalities result in poor blood supply to the retina. Ischemia triggers the growth of abnormal blood vessels (neovascularization) in the retina as well as in the anterior chamber angle. These abnormal vessels effectively block the drainage channels in the eye. Panretinal photocoagulation for diabetic retinopathy as well as glaucoma surgery are essential for treatment. Aside from diabetes, central retinal blood vessel occlusion can also cause neovascular glaucoma.
Any injury to the eye can lead to traumatic glaucoma. In the acute phase, red blood cells in the anterior chamber (hyphema) can clog up the angle and raise the intraocular pressure. In other cases, blunt trauma can rip the trabecular meshwork as seen in angle-recession glaucoma. This type of glaucoma can occur from weeks to even months after the injury due to scarring of the meshwork. Lens-Induced Glaucoma
A complication of untreated cataract is lens-induced glaucoma. A large cataract (intumescent lens) can cause pupillary block and angle closure (phacomorphic glaucoma). A leaky cataract can cause inflammation in the anterior chamber and increased eye pressure (phacolytic glaucoma). In addition to adequate pressure control, cataract surgery has to be performed.
Long-term use of steroids whether as eye drops, eye ointments, injections or oral medications can trigger a rise in intraocular pressure. It is believed that a cascade of reactions leads to increased resistance to aqueous outflow in the trabecular meshwork. Some individuals are more susceptible to pressure spikes brought about by steroids than others.
Pigmentary glaucoma is a type of secondary glaucoma more commonly found in young adult males. Pigment granules from the iris are dispersed into the anterior chamber eventually blocking the trabecular meshwork. Treatment is like that of primary open angle glaucoma.