Glaucoma is a disease encompassing a group of conditions resulting in optic nerve damage, often resulting in loss of vision. Abnormal high pressure inside your eye (intraocular pressure) usually causes this damage.
Glaucoma can damage your vision so gradually that you may not notice any loss of vision until the disease reaches an advanced stage.
Open angle glaucoma
Narrow angle glaucoma/Angle closure glaucoma
This is an asymptomatic form of glaucoma which often progresses to the advanced stages before detection. The progression of disease is slower than angle closure glaucoma and can be halted with proper medical and laser therapy, however, one may need to under go a surgery in case of an advanced stage.
This form of glaucoma is more symptomatic than open angle glaucoma and more likely to cause blindness. Laser therapy and surgery are often needed.
- Gradual loss of peripheral vision (usually in both eyes)
- Tunnel vision in the advanced stages
- Heaviness, eye pain
- Severe eye pain
- Nausea and vomiting (accompanying the severe eye pain)
- Sudden onset of visual disturbance, often in low light
- Halos around lights
- Redness in the eye
Both open-angle and narrow angle glaucoma can be in primary or secondary stage. They are called primary when the cause is unknown and secondary when the condition can be traced to a known cause, such as an eye injury, medications, certain eye conditions, inflammation, tumor, advanced cataract or diabetes. In secondary glaucoma, the signs and symptoms can include those of the primary condition as well as a typical glaucoma symptoms. In a few cases, the glaucoma may be due to both open angle and narrow angle changes in which case it is termed a mixed glaucoma.
For reasons that are not fully understood, increased pressure within the eye (raised intraocular pressure) is usually, but not always, associated with the optic nerve damage that characterizes glaucoma. This pressure is due to a fluid buildup (aqueous humor) that flows in and out of the eye. This fluid normally exits your eye through a drainage system at the angle where the iris and the cornea meet. When the drainage system does not work properly, the fluid can’t filter out of the eye at its normal rate, and pressure builds within your eye.
The drainage angle formed by the cornea and the iris remains open, but the drainage channels (trabecular meshwork) in the angle are partially blocked, causing the fluid to drain out of the eye too slowly. This causes fluid to back up in your eye, and pressure gradually increases within your eye.
In this , the iris bulges forward to narrow or block the drainage angle formed between the cornea and the iris. As a result, fluid can’t adequately flow through and exit your eye, and your eye pressure may increase to very high amounts abruptly. Additionally, there may be blockage of fluid flow between the iris and the lens (acute angle closure glaucoma). Sometimes dilatation of pupil can trigger acute angle closure attack.
Abnormal development of the fluid outflow system may result in raised intraocular pressure.
In some cases, glaucoma may develop in the presence of normal eye pressure. In these cases, the causes could include:
- Low night time blood pressure
- Cardiac illness (blockage of blood vessels supplying blood to the head
If your internal eye pressure (intraocular pressure) is higher than normal, you are at increased risk of developing glaucoma, though not everyone with elevated intraocular pressure develops the disease.
You may be at a higher risk of angle-closure glaucoma if you are 40 years or above. For certain groups the risk of developing glaucoma is much higher and occurs at a younger age than that of other groups.
If you have a family history of glaucoma, you have a greater risk of developing it. Glaucoma is known to have a genetic link.
Several medical conditions like diabetes, heart diseases, high blood pressure and hypothyroidism may increase your risk of developing glaucoma.
Severe eye injuries can cause increased eye pressure. Other eye conditionsthat could cause increased risk of glaucoma include eye tumors, retinal detachment, eye inflammation and lens dislocation. Certain types of eye surgeries may also trigger glaucoma. Smaller sized eyes are at an increased risk of narrow angle glaucoma.
Using corticosteroid medications, especially eye-drops for a long period of time may increase your risk of developing secondary glaucoma (steroidinduced glaucoma).
Your eye doctor will review your medical history and conduct a comprehensive eye examination. Your eye doctor may perform several tests to diagnose glaucoma, including:
Your eye doctor will test your ability to see from a distance.
Tonometry is a simple, painless procedure that measures your internal eye pressure (intraocular pressure), after numbing your eyes with drops. Usually it’s the initial screening test for glaucoma and there are two main types of Tonometers:
- Applanation Tonometer
- Non contact Tonometer
To check for damage in your optic nerve, your eye doctor will uses instruments to look directly through the pupil at the back of your eye (fundus). This can reveal slight changes that may indicate the onset of glaucoma.
The eye doctor will use a special instrument called a gonioscope to view inside your eye to diagnose the type of glaucoma. The instrument will be gently placed upon the eye after putting some eye drops, to numb the eyes, for this test.
To check whether your field of vision has been affected by glaucoma, your eye doctor uses a special test to evaluate your peripheral vision.
Your eyes are numbed for this test, which determines the thickness of each cornea, an important factor in diagnosing glaucoma. If you have thick corneas, your eye-pressure reading may read higher than normal even though you may not have glaucoma. Similarly, people with thin corneas can have normal pressure readings and still have glaucoma.
Special imaging tests to evaluate the optic nerve for damage may be done by your eye doctor. These includenon-invasive tests like the Optical Coherence Tomography (OCT) and Heidelberg Retinal Tomography (HRT).
The goal of glaucoma treatment is to lower pressure in your eye (intraocular pressure). To treat your condition, doctors may lower your eye pressure, improve drainage of fluid in your eye or lower the amount of fluid produced in your eye.
Glaucoma treatment often starts with medicated eye-drops. Be sure to use the drops exactly as prescribed, otherwise, your optic nerve damage could get even worse. If your doctor prescribes more than one type of eye-drop, make sure to ask how long to wait between applications and to take the drops for as long as your doctor has prescribed them.
If eye-drops alone don’t bring your eye pressure down to the desired level, your eye doctor may also prescribe oral medications, to reduce your eye pressure. Long terms use of these medications may cause side effects including nausea, vomiting, gastric upset, frequent urination, a tingling sensation in the fingers and toes, depression, stomach upset, and kidney stones among others.
You may have an outpatient procedure called laser trabeculoplasty to treat open-angle glaucoma. After giving you a numbing eye-drop, your eye doctor uses a high-energy laser beam to open clogged drainage canals and help fluid drain more easily from your eye.
For angle closure glaucoma, a laser procedure called a laser peripheral iridotomy may need to be done by your eye doctor and it helps increase the angle space and enhance drainage of aqueous humor (fluid).
Your doctor will need to check your eye pressure several times in the following weeks. It may take a few weeks before the full effect of the surgery becomes apparent.
Laser surgery for glaucoma initially lowers pressure in your eye (intraocular pressure). Over time, however, the intraocular pressure may begin to increase and long term medications may be needed.
You may need surgery to treat glaucoma if you can’t tolerate medications or if they are ineffective. Sometimes a single surgical procedure may not effectively lower your eye pressure. You may need to continue using eye-drops, or you may need to undergo another procedure.
In this procedure, your surgeon creates an opening in the sclera (white area of your eye) and removes a small piece of eye tissue at the base of your cornea through which fluid drains from your eye (the trabecular meshwork). The fluid in your eye can now freely leave the eye through this opening. As a result, your eye pressure will be lowered.
Your eye doctor will check your eye during several follow-up visits, and you will need to use antibiotic and anti-inflammatory eye-drops to fight infection and scarring of the newly created drainage opening.
You may need additional procedures or treatments, as the opening sometimes heals over or other changes occur in your optic nerve.
This may be performed within the eye which entails removing a targeted strip of the trabecular meshwork with a small tool. Your surgeon inserts the tool into the eye’s drainage canal through a small incision at the edge of the cornea and removes the small section of trabecular meshwork. This helps fluid to drain more easily from your eye.
In this procedure, your eye surgeon inserts a small tube in your eye to facilitate draining fluid (aqueous humor) from your eye to reduce the pressure. In trabeculectomy and drainage implants, the fluid is directed to a blister (bleb) on the outer layer of your eyeball where it can be absorbed. The bleb will be seen as an elevation in the white portion of the eye though it is mostly hidden under the upper eyelid.
Regular comprehensive eye exams can help detect glaucoma in its early stages before irreversible damage occurs. As a general rule, if you are 40 years and above ensure you get comprehensive eye check-up done every three to fiveyears and if your are 60 years and above get yourself checked yearly. You may need more frequent screening if you have glaucoma risk factors or are a glaucoma suspect.
Glaucoma eye-drops can significantly reduce the risk of elevated eye pressure that generally progresses to glaucoma. To be effective, these drops must be taken regularly even if you have no symptoms.
While eating a healthy diet won’t prevent glaucoma, it can improve your physical and mental health. It can also help you maintain a healthy weight and control your blood pressure.
Serious eye injuries can lead to glaucoma. Keep your eyes protected when you use power tools or play high-speed racket sports on enclosed courts. Also wear hats and sunglasses if you spend time outside.
Division of ophthalmology at Medanta is one of the leading eye centres in Delhi, NCR, offering state-of-the-art diagnostic and therapeutic services in all subspecialties of ophthalmology. Our division is equipped with specialized Glaucoma clinic with latest equipment for comprehensively diagnosing and treating Glaucoma under the guidance of experienced team ofGlaucoma surgeons.