Glaucoma is a group of diseases affecting the optic nerve head and damaging the neurons of the optic nerve. The most common underlying factor for this damage is the intra-ocular pressure or IOP. Glaucoma occurs because of poor drainage of the aqueous humor (a fluid secreted inside the eye, which provides nutrition to eye structures).
There are two common types of glaucoma :
Open angle glaucoma – which has few signs and symptoms till there is a significant damage to the optic nerve and is discovered on routine eye examination Closed angle glaucoma – which presents with acute pain in the eye and headache, often associated with blurring of vision and colored haloes around light. The attack may be either severe, forcing the patient to seek immediate ophthalmologist attention or it may occur slowly over a prolonged period of time (creeping angle closure glaucoma seen commonly in our country)
How do I know if I have glaucoma? Unfortunately glaucoma is typically associated with painless and progressive loss of vision that may escape detection by the patient. This once again stresses the importance of a thorough eye history and examination, especially in patients with a family history of glaucoma. Only one type of glaucoma called angle-closure glaucoma is associated with a red, painful eye with blurred vision and even possibly nausea and vomiting. Most patients at risk for this type of glaucoma have structural differences in their eye which could be identified prior to an attack and preventative treatment could be performed.
Who are at risk for glaucoma? 1. People over 40 years of age
2. People who have a family history of glaucoma
3. Steroid users
4. People with prior ocular injuries
5. Patients with ocular hypertension
6. Patients with hypermetropia
7. Patients with Diabetes,Hypertension,Thyroid diseases
How is glaucoma diagnosed ? The doctor can diagnose patients who already have glaucoma by observing their optic nerve damage or visual field loss. The following tests may be part of this evaluation: Tonometry determines the pressure in the eye either by applalanating the surface of cornea by contact method or by non contact tonometer Pachymetry is a relatively new test being used for the management of glaucoma. Pachymetry determines the thickness of the cornea. Thicker corneas may give falsely high eye pressure readings and thinner corneas may give falsely low pressure readings. Visual Field Testing-actually maps the visual fields to detect any early (or late) signs of glaucomatous damage to the optic nerve. This process produces a computerized map of the visual field. Optical Coherence Tomography (OCT) OCT is the latest and most sensitive tool to diagnose and treat glaucoma. It can detect glaucoma at the earliest. OCT can also measure anterior chamber angle, which is important for angle closure glaucoma. All these facilities are available at our centre.
How Is Glaucoma Treated?
Treatment modalities for glaucoma include:
Eye drops – there are now a variety of eye drops available which lower the IOP to keep it controlled to avoid further damage. Most of these eye drops are quite effective and safe for long term usage; however the eye drops should be used regularly, with periodic IOP check up to ensure that the medication is still effective
Laser – Yag laser iridotomy creates an alternative opening in the iris for flow of aqueous humour, which is an effective treatment in some cases of angle closure glaucoma.
Surgery – a trabeculectomy surgery is needed in advanced stages of glaucoma if the disease not controlled by eye drops. This creates an alternative drainage channel for the aqueous humor to drain outside the eye. However the IOP may begin to rise again after sometime necessitating either re-surgery or use of eye drops All treatment modalities in glaucoma only aim to keep the disease controlled. The damage already done to the optic nerve can not be reversed.