What is glaucoma?
Glaucoma is the disease of the optic nerve, which results is visual field loss. The optic nerve which contains nerve fibres carries electric signals to the eye. Severe damage to the nerve could result in blindness.
Causes of glaucoma
A fluid called the aqueous humour is being circulated at the front portion of the eye.
The aqueous fluid is being constantly produced and to maintain healthy and normal pressure in the eye (intraocular pressure, IOP), at the same time, an equal amount of fluid should be drained out mainly through the drainage angle.
If the drainage angle is being blocked or closed, fluid cannot be drained out of the eye. This causes the eye pressure to increase, damaging the optic nerve fibres.
Risks Factors of Glaucoma
- Increasing age
- Positive family history of glaucoma
- High intraocular pressure (IOP)
- Systemic Diseases (Diabetes, Cardiovascular diseases)
- Myopia/ Hyperopia
- Trauma to the eye
Types of glaucoma
Open angle glaucoma
Primary Open Angle Glaucoma
The degeneration of the drainage angle causes an increase in the accumulation of material within the angle which reduces in the aqueous draining leading to the increase intraocular pressure.
This results in painless optic disc damage and visual field loss.
Screening for glaucoma (especially for people with a positive family history of glaucoma) – Eye pressure measurement, disc macula photography and a quick screening of visual field every year or two.
Ocular hypertension (Glaucoma suspects) is classified as increased intraocular pressure without optic disc damage or visual field changes. Ocular hypertensives are glaucoma suspects and should be screened every year.
Patients with optic disc damage or visual field changes with intraocular pressures of below 21 mmHg.
Close Angle Glaucoma
OCT scan of a closed drainage angle
It occurs when there is obstruction of the flow of fluid through the drainage angle, this result in the increase in intraocular pressure, optic nerve damage and visual field loss. Blindness can result very quickly if untreated.
Symptoms include sudden eye pain and redness, blurred vision, haloes, nausea, vomiting and headaches. (This is an ocular emergency –call your ophthalmologist and go to A&E immediately!
Secondary glaucoma can be caused by trauma, inflammation and intraocular tumours.
Congenital glaucoma occurs due to the underdevelopment of the drainage structures.
Symptoms include sensitivity to light (photophobia), excessive tearing, enlargement of eyeball, cloudy cornea.
Evaluation of Glaucoma
- Measurement of IOP
- Measurement of central corneal thickness (pachymetry)
- Disc macular photography & photography of the optic nerve
Example: Disc macular photography & Photography of the optic nerve
- Optical Coherence Tomography of the optic disc
Example: Optical Coherence Tomography of the optic disc –to detect for any thinning of the retinal nerve fibres
- Visual field testing (full/ screening)
Example: Visual field testing (Full/ Screening)
These tests might be required to be repeated on a regular basis of every year to monitor for any changes.
Eye drops to reduce the pressure in the eye by decreasing the amount of aqueous fluid produced in the eye or improving the flow of fluid through the drainage angle. It would be required to instill them daily.
Side-effects of eye drops – redness, stinging, itching, and eyelash growth, and blurred vision, changes in heart rate or breathing (Do notify the clinic if you experience any of these side effects or if you have ran out of eye drops)
- Argon Laser Trabeculopasty (for open angle glaucoma)
Laser is being applied to the drainage angle to stimulate aqueous fluid outflow and helps lower the eye pressure (IOP).
- Peripheral Iridotomy (Closed angle glaucoma)
A hole would be created at the peripheral iris to improve the flow of aqueous fluid. This treatment can be carried out to prevent attacks if one is susceptible to having a close angle attack.
- Peripheral Iridoplasty
It is a procedure which an Argon laser is used to create contraction burns in the peripheral iris which results in the shrinking of the iris tissue and opening the drainage angle. It is more commonly carried out when peripheral iridotomy was performed but unsuccessful in widening the drainage angle.
Trabeculotomy is a surgical procedure to reduce the pressure in the eye by making an opening at the drainage angle to allow the fluid to flow easily.
Trabeculectomy is a procedure whereby a portion of the drainage angle is being removed.
The intraocular pressure is lowered by filtering the fluid through the bleb, a pocket created underneath the conjunctiva, through the layers of the eye to the anterior chamber.
The pocket will then be sewn back and will be hidden by the upper eyelid.
Regular eye check-ups are important to prevent unnecessary visual loss, call us to schedule an appointment today!