Glaucoma is the world’s leading cause of irreversible blindness, yet few sufferers are aware that they have the disease. What makes this condition difficult to detect is the lack of any early warning signs or symptoms. Once the first visible symptoms occur, there is already serious damage done to the eyes’ optic nerves.
Glaucoma definition
Glaucoma is an eye disorder in which the optic nerve is damaged, permanently affecting the vision and progresses to complete blindness if it is left untreated. It is often, but not always, associated with increased pressure of the fluid in the eye. The term ‘ocular hypertension’ is used for cases where the intraocular pressure (IOP) is always raised without any associated optic nerve damage. On the other hand, the term ‘normal’ or ‘low tension glaucoma’ is used for the typical visual field loss when associated with a normal or low IOP.
There are two types of glaucoma, “open angle” which accounts for about 90% of cases and “closed angle” glaucoma which occurs in less than 10% of cases.
Signs and Symptoms
Open-angle glaucoma is painless and does not have acute attacks. The only signs are gradually progressive visual field loss, and optic nerve changes that can be seen when looking into the eye with an ophthalmoscope. This disease builds up over a period of time and the lack of warning signs at the onset makes it difficult to detect. If left untreated, a sufferer will slowly lose their peripheral vision. In certain types of the illness, symptoms such as blurry vision, halos around lights, nausea and vomiting might occur.
Closed-angle glaucoma is characterized by sudden ocular pain, seeing halos around lights, red eyes, very high intraocular pressure (>30 mmHg), nausea and vomiting, sudden decreased vision and a fixed, mid-dilated pupil. Acute angle closure is an ocular emergency and needs to be referred to an ophthalmologist as soon as possible.
Causes of glaucoma
There are several causes of glaucoma. People at risk are advised to have a dilated eye examination at least once a year.
- Increased ocular pressure is the largest risk factor but only 50% of patients with open angle glaucoma actually have a raised ocular pressure.
- People of African descent are three times more likely to develop glaucoma.
- Elderly people have thinner corneal thickness and are at higher risk of developing glaucoma.
- If there is a family history of glaucoma people have a six percent chance of also being affected.
- East Asian and Inuit population groups have a higher risk of developing closed-angle glaucoma due to the shallower depth of the anterior chamber of their eyes.
- Secondary glaucoma is caused by the prolonged use of steroid eye drops, and conditions where the blood flow to the eye is restricted as in diabetic retinopathy, central retinal vein occlusion and trauma to the eye.
- Unstable blood pressure and dips are linked to optic nerve damage and correlate with deterioration of visual field.
Diagnosis
During a standard eye examination ophthalmologists, orthoptists and optometrists screen for glaucoma. The eye pressure is tested, changes in size or shape of the eye is noted, anterior chamber angle is examined and the optic nerve is observed for any visible damage to it, or change in the cup-to-disc ratio. They also check the rim appearance and vascular changes in the retina.
Examination for glaucoma should be done with more attention in patients with higher risk factors.
How Vision Looks In Different Stages
Management and treatment
The modern goals of managing glaucoma are to avoid optic nerve damage, and to preserve the visual field and total quality of life for patients with minimal side effects. This requires careful selection of treatments for the individual patient. Although intraocular pressure is only one of the major risk factors for glaucoma, lowering it via various medicated eye drops and/or surgical techniques is currently the way glaucoma is treated.
Medication
Intraocular pressure can be lowered with medication, usually eye drops which have to be administered for the rest of the patients’ lives. Several different classes of medications are used to treat glaucoma, with many different medications in each class. Each of these medicines may have local and systemic side effects. Poor patient compliance with medications and follow-up visits is the main reason for increased vision loss in glaucoma patients. A study found that half the patients failed to fill their prescriptions the first time, and one-fourth failed to refill their prescriptions a second time. Patient education and communication must be on-going to ensure successful treatment plans for this lifelong disease.
Surgery
There are various surgical techniques used to treat glaucoma including laser and conventional surgeries. Conventional surgery makes a new opening in the meshwork in the eye, which helps fluid to leave the eye and lowers intraocular pressure. Generally, these operations are a temporary solution, as there is not yet a cure for glaucoma.
Conclusion
Medicine often refers to glaucoma as the ‘silent sight thief’, due to the absence of signs and symptoms in most cases. However, regular eye exams could aid in the early detection and effective treatment, limiting the damage and effect this disease has. Eyesight is extremely valuable and should not be neglected or taken for granted. Recommend to patients that they get tested and to be diligent in using their eye drops.
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