Glaucoma is a disease where pressure of the eye becomes high damaging the nerve fibres that form the optic nerve. This nerve carries the visual information from eye to the brain and therefore, any damage to the nerve fibers causes defects in the visual area and results in decreased vision. If not treated in time, this may even lead to blindness.
Normally an eye has a certain pressure - 11 to 21 mm Hg (like a balloon filled with water), which is required for the eye to function in a healthy way. This pressure is created by a fluid called aqueous humor, which is continuously formed and drained out from the eye throughout life. Any disturbance in maintaining this delicate balance leads to high pressure, which in turn damages the nerve fibres.
The symptoms of glaucoma vary, depending on the type of glaucoma. These broadly depend on the exit channels for fluid inside the eye situated at the angle of anterior chamber of the eye.
OPEN ANGLE GLAUCOMA is the silent chronic variety. It does not have any symptoms in early stages and is mostly picked up during a routine eye examination by the eye surgeon. Later there can be a feeling of heaviness in and around the eyes, headache, and frequent change in spectacle number or even inability to see certain areas in the field of vision around us.
NARROW ANGLE GLAUCOMA can cause acute pain, redness, headache or seeing coloured rings around light bulbs. These symptoms are more during evening or in dim-light because the pupil dilates, leading to compromised exit channels for fluid to drain out and results in high pressure inside the eye.
SECONDARY GLAUCOMA can occur due to various causes like injury, inflammation, tumors of eye, haemorrhage, drugs like steroids etc. They can present with any of the above symptoms.
CONGENITAL GLAUCOMA is a condition where the exit channels are poorly formed since birth. Due to high pressure the cornea becomes opaque and eye may gradually become large. The child might complain of a decreased vision, glare, watering or enlarged eye. This requires immediate treatment.
Other eye diseases e.g. Uveitis, vitreous haemorrhage, major eye surgery etc.
Difference Between Cataract (Safed Motia) & Glaucoma (Kala Motia)
Cataract is caused due to the opacity in the lens of the eye, which does not allow image to be properly focussed on the retina while glaucoma is due to the rise in pressure of the eye, which damages the optic nerve fibres. Loss of vision is recovered in cataract by surgery (Phacoemulsification with intra-ocular lens implantation) while visual loss in glaucoma is permanent. Sometimes a patient can have both cataract and glaucoma.
What Tests are Done to Diagnose Glaucoma?
It is not enough to record only eye pressure to diagnose glaucoma. Once a patient is suspected to have glaucoma, we study angles of the eye, optic nerve and visual fields. All these are required by the eye surgeon to establish a complete picture of the type and nature of glaucoma. At Max Eye Care, the basic work up of a patient includes:
APPLANATION TONOMETRY it is the most accurate method to measure intraocular pressure.
OPHTHALMOSCOPY to assess the changes in the anterior visible portion of optic nerve, seen through the pupil.
GONIOSCOPY to study the details of exit channels for eye fluid situated at the angle of anterior chamber.
COMPUTERISED PERIMETRY OR VISUAL FIELDS CHARTING to detect loss in visual field corresponding to the nerve fibre damage. This is a very sophisticated test, which shows the changes in both qualitative & quantitative manner and is very crucial for further treatment and to study the progression of the disease.
Disc or Fundus Photographs may be taken to assess the changes in optic nerve head and retinal nerve fibre layer for detailed objective analysis and further comparisons.
Above tests need careful analytical assessment for baseline treatment and future management. Because glaucoma is a progressive disease, a long-term careful follow up is required where these tests are repeated and compared to the previous reports. If any progression in the damage is noted, then the treatment is modified.
The treatment is aimed to keep eye pressure in normal range. For any individual the normal or “target pressure” is different, which is decided by the eye surgeon after studying the reports of all above mentioned tests. The lowering of eye pressure is achieved by eye drops or medicines alone or in combination with a laser procedure.
If the eye pressure is not controlled by the above, glaucoma surgery is required. The modality of treatment is decided by factors like type & stage of glaucoma, damage already done at the time of presentation, response to prior treatment, patient’s ability to put medication regularly etc.
EYE DROPS/MEDICINES the first attempt to control glaucoma is made with eye drops alone or in combination with oral pills. These medicines act by lowering the eye pressure either by decreasing the production of