(Dr. Rita Dash)
Glaucoma has a reputation as the "silent thief of sight," and for good reason. It is one of the leading causes of irreversible blindness worldwide, yet a large proportion of patients remain unaware of the disease until there is already significant and permanent vision loss. Understanding why glaucoma escapes early detection is critical for improving public awareness and preventing avoidable blindness.
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The Quiet Progression Of Open-Angle Glaucoma
The most common form, primary open-angle glaucoma, progresses insidiously. In its early and even moderate stages, glaucoma typically causes no pain, no redness, and no obvious visual symptoms. Central vision, which people rely on for reading, recognizing faces, and daily tasks, is preserved until late in the disease. Instead, glaucoma initially damages peripheral (side) vision, which the brain compensates for remarkably well. As a result, patients continue to function normally and do not perceive any deficit until the visual field loss becomes advanced.
Slow Damage, Strong Adaptation
Another important reason why glaucoma is not easily noticed is the slow pace of the disease. The loss of the retinal ganglion cells and the damage to the optic nerve occur over many years. The slowness of this tempo enables the patient to adapt subconsciously, which they would not do in the case of sudden loss of vision that would raise concerns for immediate medical help. In fact, by the time patients notice that they are having a problem navigating or bumping into objects while walking or their vision has dimmed in poor light, significant optic nerve damage has already taken place.
The Myth Of 'High Eye Pressure'
IOP, the most important modifiable risk factor for glaucoma, is a contributor to diagnostic confusion. Many patients feel that glaucoma occurs only with "high eye pressure," and yet up to 30–40% of patients, especially in Asian and Indian populations, have normal-tension glaucoma. The latter may be falsely reassured during opportunistic eye checks, if IOP alone is measured without optic disc and visual field assessment.
Why Routine Screening Is Often Missed
Lack of routine screening has further contributed to delayed diagnosis. Unlike cataract, which presents early with blurring of vision, the diagnosis of glaucoma requires proactive detection by comprehensive eye examination including optic nerve assessment, visual field, and OCT. Unfortunately, glaucoma screening is not widely practiced, and awareness is poor, particularly in developing countries.
Who Is At Higher Risk?
Certain high-risk groups include people over 40 years, people with diabetes, hypertension, high myopia, steroid use, and a family history of glaucoma. These are particularly vulnerable. Yet many people remain unscreened due to the absence of symptoms and misconceptions about eye health.
Early Detection Can Save Vision
The tragedy of glaucoma is that vision loss is irreversible, but its progression can be markedly slowed if it is detected early. If diagnosed early and treated promptly with medications, laser, or surgery, functional vision can be preserved for a lifetime. It is a painless, slowly progressive process that spares central vision until late and requires targeted screening for detection. Public education, routine eye examinations after the age of 40 years, and focused screening of high-risk individuals are also essential in the fight against this silent cause of blindness.
Dr. Rita Dash is the Senior Consultant - Ophthalmology at Manipal Hospital, Bhubaneshwar
[Disclaimer: The information provided in the article is shared by experts and is intended for general informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition.]