Glaucoma, also known as 'sneak thief of sight', is one of the leading causes of blindness in the world. After cataract, it is the next most common cause of blindness in India with over 4% of population being affected by it. In the initial stages, glaucoma does not have any symptoms and in fact almost 50% of patients detected with glaucoma do not know that they have it. It is an irreversible disease and if not detected and treated timely, it might lead to blindness.
Glaucoma occurs due to irreversible damage to the optic nerve (this nerve connects the eye to the brain and is responsible for vision). Various mechanisms of damage have been proposed but the most important and modifiable reason is supposed to be a high Intra-Ocular-Pressure (IOP) of the eye.
What causes Glaucoma?
Aqueous humour is the clear fluid, which circulates inside the eye and nourishes some parts of the eye where there is no blood supply. Normally, there is a balance between production and drainage of this fluid resulting in a constant pressure within the eye. If the drainage of this fluid is compromised due to any reason, pressure of the fluid gradually builds up in the eye and subsequently leads to glaucoma.
However, a high IOP is not the only criteria for diagnosing glaucoma. You could still have glaucoma with apparently 'normal pressures'. Sometimes a seemingly low IOP might be associated with damage to the optic nerve and subsequent loss in your visual field.
What are the different types of Glaucoma?
Open Angle Glaucoma
This is the more common type of glaucoma. It is a painless, gradual process, wherein the IOP fluctuates in the eye and leads to damage to the optic nerve. The progression of this type of glaucoma is so slow that most of the patients do not realize that any such process is going on in their eyes. Your eye care specialist generally detects this type of glaucoma during a comprehensive eye examination. Diagnosis may be delayed to a stage, which is irreversible; therefore the importance of a regular eye check up after the age of 40, when you start using near glasses, cannot be over-emphasized.
Another common presentation of open angle glaucoma is a frequent change of glasses. So, if you are over 40 years of age and are worried about having to visit the optician for frequent change of glasses, do get your eyes checked up for glaucoma.
Angle Closure Glaucoma
This type of glaucoma sometimes presents as severe eye pain with redness and headache (an acute attack) caused by sudden blockade of the drainage channels leading to a sharp rise of pressure in the eye.
These patients may present with:
Severe pain in the eye associated with redness, nausea and vomiting.
Blurring of vision
Rainbow coloured haloes around a light source in the evening.
All of the above symptoms aggravate during the evening or dusk hours.
An angle closure glaucoma attack is an emergency and you need to see your eye care specialist immediately. Based on the evaluation, your doctor might initially bring down the pressures of the eye by some injections, eye drops and tablets and subsequently perform a LASER to open the fluid blockade.
Sometimes on a routine eye examination, your doctor might tell you that you are an 'Angle Closure Suspect' which means that your eyes have a tendency of angles (drainage channels) being blocked sometime in the future. He might therefore advise a LASER procedure for the eyes to preventing an acute attack in the future.
If you have an attack in one eye, LASER is required for both the eyes.
What are the risk factors for developing glaucoma?
Remember, ' Glaucoma Has No Warning Signs'. If you fall in the following category of people, a comprehensive eye examination is warranted by an eye care specialist to determine whether you have glaucoma or not.
Someone in your family has been diagnosed as having glaucoma.
You are over 45 years of age.
You wear glasses with plus/minus power.
You are a diabetic or hypertensive.
You have had any significant injury in either eye.
You have used medications like steroids (cortisone) for any reason.
Your Eye Pressures (IOP) have been detected in the higher levels.
You have a history of Migraine type of headaches
If you have one or more of the above conditions, it puts you at an increased risk of developing glaucoma.
How is glaucoma detected?
A regular detailed eye examination helps the ophthalmologist to decide whether you have glaucoma or not. After the examination, if he feels that there is a suspicion of glaucoma in your eyes, he might order a series of specialised eye test to confirm the diagnosis and to judge the severity of the disease.
Some of the tests for glaucoma done at the Glaucoma Clinic at our centre as parts of an international protocol are as follows:
Applanation Tonometry (AT) - Measures the pressure in your eyes.
Pachymetry - Measures the thickness of the corneas (The transparent front layer of the eyeball). This helps the ophthalmologist to decide whether any adjustment is required in the eye pressure recordings.
Gonioscopy - Helps the doctor decide whether you have an open angle or narrow angle glaucoma.
Visual Field Testing/Automated Perimetry (VF/AP) - Tests the visual field of the eyes and gives an insight about the extent of damage caused to the optic nerve by glaucoma. Depending upon the severity of glaucoma in your eyes, the field tests are repeated every 6 months or yearly.
Retinal Nerve Fibre Layer Analysis (RNFL) - This tells us about the loss of nerve fibres around the optic nerve.Remember, very early glaucoma cannot be diagnosed on a field test since you need about 20-40% damage to have occurred before a field test shows any changes. The RNFL test, on the contrary, diagnoses very early glaucoma defects hence the clinician can catch the disease at an early stage and start treatment accordingly. Remember, 'The earlier, the better'.
Apart from the above tests, we also take photographs of the optic nerve of your eyes so that we can compare them in the future and document any progression of the disease.
How is glaucoma treated?
This is usually in the form of eye drops which are to be used either once or twice a day. They help in reducing the pressure inside the eyes by either decreasing the production of aqueous humour or increasing its outflow. Use of eye drops is generally associated with some redness of the eyes, along with burning and stinging sensation in the eyes. You may also have dry eyes after using anti-glaucoma eye drops for a long time. If you are already a dry eye patient, your dryness related symptoms might worsen. If these side effects are intolerable, your ophthalmologist might substitute your eye drops with another.
Please share any systemic problems like blood pressure (low or high) or asthma or a severe heart problem with your eye surgeon as this might help him in deciding which eye drops are safe to be prescribed in your case.
There is a specific technique of using eye drops. As shown in the photograph, hold your lower eyelid, look up at the ceiling and pour one drop from the bottle on the inner corner of the eye without touching the eye. Close your eyes for about 15-30 seconds after instilling the eye drop. After instilling the eye drop, press the lacrimal sac near the base of the nose with your finger (as shown in the photograph). This technique is known as 'punctal occlusion' and helps in preventing the eye drop from getting absorbed into the blood system, thereby preventing side effects on other parts of the body.
Image for instilling eyedrops
Your eye surgeon will specify the timings of using the eye drops. Try to stick to the schedule as much as possible (+/- half hour). This is because the anti-glaucoma eye drops act on the eye around a specified time frame. If you do not stick to the timings, there are chances that the eye drop might not work as effectively as it should and your glaucoma will progress despite using treatment. If by chance you forget to use the eye drop at the specified time, you can put the drop whenever you remember it.
Do not forget to use the eye drop on the day of your scheduled follow-up visit.
If for example, your eye check up is due after 2 days and your eye drops get over before that, do not wait for the eye check up. Get hold of a new bottle and start using it immediately. Do not skip any dose of treatment.
If eye drops are not enough to lower the eye pressure, certain tablets are prescribed to achieve the desired effect. However, everyone does not tolerate these tablets and may have weakness in arms and legs along with tingling sensation in the fingers and toes. Some patients also have some bowel irregularities, and after a very prolonged use, some patients may develop kidney stones.
Primary angle closure glaucoma is primarily treated with LASER (YAG peripheral iridotomy or YAG PI). LASER helps in opening up the narrow angle and thus treating the glaucoma. Normally it takes about 5 min for the procedure. After the LASER procedure you may be required to use some eye drops for about 2 weeks. Anti-glaucoma medication may be required even after laser treatment in some patients.
The other type of laser procedure is called Argon Laser Trabeculoplasty (ALT). This is not a commonly performed procedure but may be done in selected cases of Open Angle Glaucoma.
Surgery for glaucoma is done to enhance outflow of fluid from the eye. This surgery is also known as Glaucoma Filtering Surgery (GFS) or trabeculectomy. Your eye surgeon takes a decision for surgery when he feels that either you are not tolerating the eye drop/tablets too well or the damage because of glaucoma is continuously progressing despite maximum medical therapy. Sometimes early surgery is indicated when the damage caused by glaucoma is too advanced and there is not enough time to wait for a response to medical therapy.
Another type of surgery is known as Glaucoma Valve surgery. This procedure is done only on selected patients having complicated glaucoma or previous filtering surgery has failed.
One point to remember is that all the above forms of treatment are meant to stop the progression of glaucoma and not treat it. Remember, glaucoma cannot be CURED or prevented but it can be kept under control with appropriate treatment.
What is your role in treatment?
Your glaucoma specialist will discuss in detail regarding the status of glaucoma in your eye. Feel free to ask any doubts/queries regarding the disease or medications. As a patient, your eye health is our prime concern. However, glaucoma is a chronic problem and you must go for regular checkups as your doctor instructs. Do not stop or alter any eye drops without consulting your doctor. Come to the hospital for regular field and other tests so that your doctor can monitor the glaucoma process in your eye with more precision.
Above all, remember that glaucoma is generally a very slow process and you will not go blind over-night. Therefore, relax, be realistic about it and try not to think about the problem too much. Lead a normal lifestyle as you would if you didn't had glaucoma. Use your eye drops on time and come for regular eye checkups as advised.
At Prakash Netra Kendr, you are assured of the highest quality of eye care services. Feel free to contact us if you have any doubts/queries regarding your eye problem.
The Eye is the Lamp of the Body. So if your Eye is healthy, your whole body will be full of Light