Glaucoma is a group of eye conditions that lead to irreversible damage of the optic nerve (nerve of the eye that carries visual information to the brain) resulting to permanent loss of vision in the affected eye(s). In many cases, this damage occurs when eye fluid (aqueous) builds up, raising the eye pressure (intraocular pressure). Normally this fluid flows out of the eye through a mesh-like channel called the anterior chamber angle. An imbalance in the production and drainage of this fluid arising from over production or channel blockage, builds up fluid, causing glaucoma. In other cases, some people may have ‘normal’ or ‘low’ tension glaucoma in which optic nerve damage and vision loss have occurred despite a normal eye pressure . Also, the term ‘ocular hypertension’ is used for cases having constantly raised eye pressure without any associated optic nerve damage and they are referred to as glaucoma suspects. Worldwide, glaucoma is the second leading cause of blindness and is sometimes referred to as the “silent thief of sight”.
Two main classification are Open angle and Closed angle glaucoma.
Open angle (chronic) Glaucoma: the commonest type is painless progressing slowly and unnoticed until side vision has drastically reduced as a result of eye pressure build up despite an open drainage channel.
Closed angle (acute) Glaucoma: a sudden and painful build up of eye pressure occurs from blockage of the drainage channel. An ocular emergency, the other eye is often at risk of an attack if one eye is affected. Symptoms may come and go at first, or steadily become worse.
Sometimes glaucoma is present at birth (congenital) while at other times it is due to secondary causes such as agents like corticosteroids, eye diseases such as uveitis, systemic diseases etc.
CAUSES AND RISK FACTORS: Apart from a raised IOP, other predisposing factors include:
1) Heredity/Family history: a higher risk of having glaucoma exists if a member of your family has it. 2) Age: most often occurs in adults over age 40, but it can also occur in young adults, children, and even infants. 3) Race: Africans and African-Americans are at an increased risk compared to Caucasians. 4) Medical conditions: like diabetes and hypothyroidism. A number of studies also suggest a possible correlation between hypertension and the development of glaucoma. 5) Refractive error(s): like shortsightedness (myopia). 6) Prolonged steroid use (steroid-induced glaucoma) especially if eye drops. 7) Other eye conditions: including severe eye (blunt or chemical) injury, retinal detachment, eye tumors, some eye infections and inflammations, certain eye surgeries, conditions that severely restrict blood flow to the eye, such as severe diabetic retinopathy and central retinal vein occlusion (neovascular glaucoma); and uveitis.
SYMPTOMS: include one or more of these including loss of peripheral or side vision, sudden eye pain, headache, decreased/cloudy vision, appearance of rainbow-like halos around lights, redness, feeling of swollen eyes and a fixed, mid-dilated pupil, eye that looks hazy (particularly in infants), nausea or vomiting, and sudden onset of poor vision especially in low light.
TESTS: usually painless and take very little time, includes measurement of the intraocular pressure via tonometry (often the first line of screening for people with glaucoma), fundoscopy (examination of the optic nerve to look for any visible damage), drainage angle examination (gonioscopy), visual field measurement and a whole lot of others.
MANAGEMENT: Glaucoma has no cure. The key is early diagnosis and management to lower eye pressure, prevent/minimize damage to the optic nerve, preserve visual field and enhance the total quality of life for patients. Regular eye examinations with an eye doctor including glaucoma screening can save your sight.
Dr Ukachukwu F.U