Glaucoma refers to a group of eye diseases that causes progressive damage to the optic nerve within the eye. It is usually caused due to an increase in the pressure inside the eye [Intra ocular pressure (IOP)].The optic nerve is the nerve responsible for vision, thus once it is damaged it would lead to gradual loss of vision and sometimes total blindness.
The pressure inside the eye is maintained by a fluid called aqueous humour. This fluid is produced inside the eye (these are not tears) and drains through fine channels. If these drainage channels are blocked or the eye produces too much of this fluid then the pressure of the eye rises.
RISK FACTORS FOR GLAUCOMA
- Age : The risk of glaucoma rises greater than 40 years of age
- Raised intraocular pressure(IOP)
- Family History of Glaucoma
- Conditions that affect, or are related to, blood flow: Diabetes, low blood pressure, and hypertension
- Thyroid disorder
- Extremes of refractive error : High/pathological myopia(associated with POAG) or Hypermetropia(associated with PACG)
- Eye injuries or eye surgeries
- Use of steroids (Topical /Oral /Inhalational etc.)
HOW IS GLAUCOMA DETECTED?
Glaucoma is detected through a comprehensive eye examination that includes the following:
- Visual acuity test: This eye chart test measures how well you see at various distances.
- Tonometry: This is the measurement of pressure (intraocular pressure /IOP) inside the eye by using an instrument.
- Gonioscopy: It is the visualization of the drainage angle of the eye which the doctor performs using an instrument. This helps to determine whether the angle is open or closed.
- Dilated eye examination: In this examination, drops are given to dilate the pupil to visualize the optic nerve and the other structures inside the eye.
- Visual field test: This test measures the peripheral (side vision). It helps to determine whether the patient has lost any peripheral vision which is an early sign of glaucoma.
- OCT (Optical Coherence Tomography): This is a test to see the status of the optic nerve head and the thickness of the retinal nerve fiber layer within the eye. In glaucoma there is thinning of the retinal nerve fiber layer.
- Pachymetry: This is the measurement of the thickness of the cornea.
TREATMENT FOR GLAUCOMA
- Eye Drops (Anti – Glaucoma medication): These either reduce the formation of fluid in the eye or increase its outflow, thereby lowering eye pressure.
- Laser treatment
- Surgical Procedures: (Trabeculectomy, Glaucoma Drainage Devices etc.)
Glaucoma cannot be cured, but it can definitely be controlled. Appropriate treatment and regular follow-up can preserve residual vision from further damage.
Early detection and treatment of Glaucoma before it causes significant vision loss is the ideal way to deal with the disease.
Anyone who is above the age of 40 should get examined periodically for Glaucoma.
Glaucoma is not an infectious disease, but it might be genetic. So, if anyone in the family history, has or had glaucoma, it is advisable for the other family members to undergo an eye check-up.
Periodic eye check-ups are mandatory for someone who has been diagnosed with glaucoma.
The different types of Glaucoma are as follows:
Primary Open Angle Glaucoma (POAG): Progresses slowly with gradual loss of vision. Some patients have POAG but have normal eye pressure, this is referred to as Normal Tension Glaucoma (NTG). This type of glaucoma responds well to treatment with anti-glaucoma eye drops. In case of failure, surgery may be required in order to reduce eye pressure.
Angle Closure Glaucoma (ACG): An acute angle closure attack of the eye may result in decreased vision, haloes around lights, eye ache, headache, nausea and/or vomiting. The initial intraocular pressure is reduced by medical treatment or laser treatment (Peripheral Iridotomy/PI). If they fail, then surgery might be necessary. A laser treatment in the fellow eye is done to prevent the chance of a similar attack.
Congenital Glaucoma: This type of glaucoma is rare and occurs at birth or soon after. The signs and symptoms include enlargement of the eyes, watering, unusual sensitivity to light or haziness of the anterior transparent portion of the eye called the cornea. Initial treatment begins with eye drops but surgical treatment is compulsory for this type of glaucoma found in children, and should be performed as early as possible.
Secondary Glaucoma: Secondary glaucomas are the ones that develop secondary to, or as complications of other conditions, such as eye trauma, unoperated mature or hypermature cataract, diabetes, eye surgery, or intraocular tumors.
The signs or symptoms of glaucoma can vary depending on the type.
Primary open angle glaucoma (POAG)- Most POAG patients do not have any signs or symptoms prior to the disease. The first sign which the patient may notice is the loss of peripheral, or side vision, but this could lie ignored late until the disease. Patients suffer the chances of losing quite a bit of vision before they become aware of the disease. That is why glaucoma is often called the "sneak thief of vision."
Primary angle closure glaucoma (PACG)- During the initial stages, this type of glaucoma is also asymptomatic, which is why the patient is not aware of the condition. As the disease develops, the patient may notice blurred vision or the appearance of haloes or colored rings around lights. In the later stage, the patient may complain of pain and/or redness in the eye.