Causes of Cataract

Most cataract is aging - but age is not the whole story. Several accelerators matter, especially in India, and some are preventable.

The main driver: age

Protein changes in the lens are cumulative. Most people develop some lens clouding after 60; by 75, most have a clinically meaningful cataract. Aging is the tide everything else rides on.

The accelerators

• Diabetes: high sugar changes lens chemistry (sorbitol buildup) - cataracts come earlier and progress faster; young diabetics get cataracts too
• Sunlight (UV): decades of outdoor work without eye protection accelerate lens damage - a real factor for India's outdoor workforce
• Steroid medicines: long-term steroids (tablets, injections, sometimes strong creams) are a well-known cause of posterior cataract
• Eye injury: a blow or penetrating injury can cloud the lens - sometimes years later
• Smoking: a clear, dose-related cataract risk
• Poor nutrition and chronic diarrhea in early life: linked to earlier cataract in population studies
• Family tendency and high myopia also shift risk

The non-age types

• Congenital cataract: babies born with cloudy lenses (infections in pregnancy, genetic) - needs early detection and treatment to save developing vision
• Secondary cataract: after eye inflammation, eye surgery, or radiation
• Traumatic and metabolic cataracts as above

What does NOT cause it

Reading in dim light, watching screens, and "eye strain" do not cause cataract - they tire eyes but do not cloud lenses. Cataract is not contagious and not caused by cataract in the family environment.

The classical cause list

Classical eye texts attribute timira (early clouding) to vata-pitta aggravation, aging, and misuse of the eyes - and they were careful to separate what strains the eye from what clouds the lens, listing dooshana (harm) from heat, smoke, and suppression of urges alongside age. The modern list adds the measurable accelerators: UV, steroids, diabetes, smoking.

The classical nidana list

Sushruta's Uttara Tantra (ch. 1) and Madhava Nidana (ch. 59) list the eye-straining life: staring at minute objects, reading in poor or flickering light, facing intense glare (ati-atapa), sudden cold water after heat; suppressing natural urges - tears, sneezing, vomiting; chronic grief and anger; day sleeping and night waking; and a diet heavy in the sour, pungent, salty and dry, with black gram and alcohol. Strip the language and the list is recognizable: glare, strain, metabolic excess and an inflamed internal environment.

One-line summary

Age clouds every lens eventually; diabetes, sunlight, steroids, smoking and injury cloud it sooner - and babies can be born with it, which is why newborn eye checks matter.