Glaucoma: The Thief of Sight That Strikes Without Warning

Glaucoma is often called 'the thief of sight' — and for good reason. It is the world's leading cause of irreversible blindness, affecting an estimated 80 million people globally. In India, an estimated 12 million are affected, yet over half remain undiagnosed. The tragic irony is that glaucoma-related blindness is almost entirely preventable with early detection and treatment. What makes it so dangerous is precisely what makes it so difficult to catch: it causes no pain and no noticeable vision change in its early stages.

What Happens in Glaucoma

The eye continuously produces a clear fluid (aqueous humour) that nourishes the lens and cornea, then drains through a meshwork structure in the drainage angle. In most forms of glaucoma, this drainage is impaired — causing intraocular pressure (IOP) to rise. Elevated IOP compresses the optic nerve fibres at the back of the eye, progressively destroying them. Since peripheral fibres are affected first, central (reading) vision is preserved until very late disease — giving patients a false sense that their eyes are fine.

Types Most Common in India

Two main types predominate in the Indian population:

• Primary Open Angle Glaucoma (POAG) — most common globally; drainage angle is open but functionally inadequate; progresses very slowly over years; no acute pain
• Primary Angle Closure Glaucoma (PACG) — much more common in Indians and Asians compared to Caucasians; drainage angle is anatomically narrow; can cause acute angle closure crisis with severe eye pain, headache, nausea, and sudden vision blur — a medical emergency
• Normal Tension Glaucoma — optic nerve damage despite IOP within the statistically normal range; vascular and neurological factors play a role
• Secondary glaucoma — from uveitis, steroid eye drops, trauma, pseudo-exfoliation syndrome, or pigment dispersion

Risk Factors

If any of these apply to you, you should be under regular ophthalmic monitoring.

• Age over 40 — risk roughly doubles every decade
• Family history — first-degree relatives have 6–10x the population risk
• Indian or East Asian ethnicity — higher risk for angle closure
• Elevated IOP found on previous eye examination
• High myopia (short-sightedness) — for open angle glaucoma
• High hypermetropia (long-sightedness) — for angle closure
• Long-term use of steroid eye drops or systemic steroids
• History of eye surgery or trauma

Comprehensive Glaucoma Assessment

At Zala Clinic, Dr. Mala R. Zala performs a thorough glaucoma evaluation:

• Accurate IOP measurement (Goldman applanation tonometry)
• Gonioscopy — examination of the drainage angle to classify glaucoma type
• Dilated optic disc assessment with stereoscopic biomicroscopy
• OCT (Optical Coherence Tomography) of the retinal nerve fibre layer and ganglion cell complex
• Automated visual field testing (Humphrey perimetry)
• Central corneal thickness — thin corneas underestimate true IOP by up to 4 mmHg
• Disc photography for baseline documentation and serial change detection

Treatment

Glaucoma cannot be cured — but progression can be arrested:

• IOP-lowering eye drops — first line for most patients; prostaglandin analogues (latanoprost, bimatoprost) are highly effective and convenient (once-daily dosing)
• Laser trabeculoplasty (SLT) — an increasingly popular non-invasive alternative to drops; effective and repeatable
• Laser peripheral iridotomy (LPI) — curative for most narrow-angle and angle-closure cases
• Surgical trabeculectomy or MIGS (micro-invasive glaucoma surgery) for medically uncontrolled disease
• Lifelong monitoring — even well-controlled glaucoma requires regular IOP checks, disc evaluation, and visual fields

The only way to find glaucoma early enough to protect vision is a comprehensive eye examination. If you are over 40, have a family history, or belong to a high-risk group — please do not wait for symptoms. Book a glaucoma screening with Dr. Mala R. Zala. It is a simple test that could preserve your sight for life.