Glaucoma is a group of diseases with progressive optic nerve damagecaused by increased pressure within the eye (Intra-ocular pressure). This damage is seen as a pattern called “cupping,” and by blind spots in the peripheral vision. Advanced glaucoma can lead to permanently blurred or dimmed vision, or further to even blindness.
Early and moderate stage glaucoma generally has no symptoms. This is why it is important to be examined by an ophthalmologist regularly to determine if you are likely to develop the disease.Increased eye pressure (IOP) is the most common risk factor for developing the disease. Treatment of glaucoma does not restore vision, but can prevent its further deterioration/loss.That is why screening and early detection of glaucoma are so important.
Glaucoma usually occurs bilaterally (both eyes), but one eye may be more affected than the other.
Types of glaucoma?
There are 2 main types of glaucoma found in adults:
- Open-angle glaucoma:This is the most common type. This type of glaucoma has no early warning signs and can go unnoticed for years.
- Angle-closure glaucoma:Here, the normal drainage passage in the eye is narrowed and then becomes blocked.
Glaucoma is more commonly found in people over the age of 35. You are more likely to get glaucoma if you have :
- African-American ethnicity.
- Family History of glaucoma.
- Diabetes mellitis.
- Under Corticosteroid medications.
- Previous Eye injury.
Symptoms of Glaucoma
Most glaucoma patients, initially do not notice any symptoms, until there is lossof some ofperipheral vision. Often, this is not recognized by the patient until the disease has advanced.
Symptoms may include :
- Pain. (NOTE: Consult your ophthalmologist/ emergency room if you have sudden, severe pain in the eye ,headache or/and blurring of vision.)
- Red eye.
- Hazy/ blurry vision.
- Halos around lights.
- Narrowing of vision (tunnel vision).
Comprehensive dilated eye examination includes the following:
- Visual acuity test : Snellen’s chart
- Visual field test :This measures the peripheral vision &helps; to detectany loss of peripheral vision.
- Dilated eye exam. In this test the pupils are dilated & ophthalmologist examines your retina and optic nerve forany signs of damage.
- Tonometry : measurement of pressure in the eye using an instrument called a tonometer. Numbing drops (topical anaesthetic) may be used.
- Pachymetry :measurement of the thickness of your cornea.
Vision lost from the disease cannot be restored.Immediate treatment for early-stage, open-angle glaucoma can delay progression of the disease. That’s why early diagnosis is very important.
Glaucoma treatments include medicines, laser trabeculoplasty, conventional surgery, or a combination of any of these. While these treatments may save remaining vision, they do not improve sight already lost from glaucoma.
Medication :Eyedrops/ tablets are the most common early treatment for glaucoma to lower IOP. Some cause the eye to produce less aqueous fluid & others lower pressure by helping drainage of fluid. Kindly reveal all history of medicationbeing taken as these may interfere with other medicines.
Laser trabeculoplasty. Laser trabeculoplastyaids in better fluid drainage out of the eye. In many patients, after laser there may still be the need to continue with the glaucoma medicines.
This is performed in the OPD under topical anaesthetic drops application to the eye& using a special lens to the eye. Through this lens a high-intensity light beam is aimed and reflected on the trabecular meshwork (TM). One may see flashes of bright light (green or red).In this procedure, several evenly spaced burns are made that stretch the drainage holes in the TM. This allows better drainage of aquous humor.
This may cause side effects such as inflammation for which some drops are prescribed after the procedure. The patient will need to make several follow-up visits to have the IOP monitored.
If glaucoma is present in both eyes, only one eye will be treated at a time. The other eye is treated after a few days/weeks. Studies show that laser surgery can be very good at reducing the pressure in some patients. However, its effects can wear off over time. Your doctor may suggest further treatment.
Conventional surgery : Conventional surgery makes a new opening for the fluid to leave the eye& is often done after conservative measures i.emedicines and laser surgery have failed to control IOP.
Trabeculectomy is the conventional surgery performed in the O.T after appropriate anaesthesia. A small piece of tissue is removed & a new channel is created for the fluid to drain from the eye. This fluid will drain between the eye tissue layers and create a blister-like “filtration bleb.” After surgery one has to put drops in the eye to prevent infection and inflammation& one may also need to continuwiwththe anti-glaucoma medication.
Conventional surgery is performed on one eye at a time usually four to six weeks apart. It is considered to be around 70- 80 % effective at lowering IOP. If the new drainage site narrows/fails, a second operation may be required. Conventional surgery works bestthe surgery has better results if one has’nt had any previous eye surgery, e.gcataract surgery.Sometimes after surgery , the vision may not be as good as it was before & can also cause side effects, including cataract, corneal complications, inflammation, infection, or low IOP.
Angle Closure Glaucoma
In angle-closure glaucoma, the aquous does not drain through the angle & it gets blocked by part of the iris. Such patients may have a sudden increase in IOP i.e eye pressure. Symptoms may include severe pain, redness of the eye and blurred vision. One needs to seek treatment immediately if any of the above symptoms are present & this is a medical emergency. If your ophthalmologist is not available, go to the nearest hospital as a delay in treatment can risk the the visual potential of the eye. Usually, prompt laser surgery and medication can clear the blockage, decrease the IOP, and protect vision.
Low/Normal tension glaucoma
In low-tension or normal-tension glaucoma, optic nerve damage and narrowed side vision occur in people with normal eye pressure. Lowering eye pressure at least 30 percent through medicines slows the disease in some people. Glaucoma may worsen in others despite low pressures.
A comprehensive medical history is important to identify other potential risk factors, such as low blood pressure, that contribute to low-tension glaucoma. If no risk factors are identified, the treatment options for low-tension glaucoma are the same as for open-angle glaucoma.
In congenital glaucoma, children are born with a defect in the angle of the eye that slows the normal drainage of fluid. These children usually have obvious symptoms, such as cloudy eyes, sensitivity to light, and excessive tearing. Conventional surgery typically is the suggested treatment, because medicines are not effective and can cause more serious side effects in infants and be difficult to administer. Surgery is safe and effective. If surgery is done promptly, these children usually have an excellent chance of having good vision.
Secondary glaucomas can develop as complications of other medical conditions. For example, a severe form of glaucoma is called neovascular glaucoma, and can be a result from poorly controlled diabetes or high blood pressure. Other types of glaucoma sometimes occur with cataract, certain eye tumors, or when the eye is inflamed or irritated by a condition called uveitis. Sometimes glaucoma develops after other eye surgeries or serious eye injuries. Steroid drugs used to treat eye inflammations and other diseases can trigger glaucoma in some people. There are two eye conditions known to cause secondary forms of glaucoma.
Pigmentary glaucoma occurs when pigment from the iris sheds off and blocks the meshwork, slowing fluid drainage.
Pseudoexfoliation glaucoma occurs when extra material is produced and shed off internal eye structures and blocks the meshwork, again slowing fluid drainage.
Depending on the cause of these secondary glaucomas, treatment includes medicines, laser surgery, or conventional or other glaucoma surgery.