Cataracts
Progressive opacification of the crystalline lens scatters and blocks incoming light, causing gradual, painless blurring of vision that only surgery (replacing the lens) can reverse, because the damaged protein structure cannot be cleared or treated medically.
Definition
A cataract is opacification of the crystalline lens, causing progressive, painless visual loss. It is the leading cause of reversible blindness worldwide and is treated by surgical lens replacement.
First principles
The disease is structural opacification of lens protein, not an active inflammatory process
The lens is a transparent, avascular structure made of tightly packed, highly ordered crystallin proteins with no capacity for cell turnover or repair. Over time, accelerated by ageing, ultraviolet exposure, diabetes, steroid use and smoking, these proteins undergo oxidative damage and aggregate or denature, disrupting their regular packing. Disordered protein aggregates scatter light instead of allowing it to pass through cleanly, which is the entire mechanism of a cataract: a physical light-scattering problem, not inflammation or infection, which is why there is no anti-inflammatory or antimicrobial treatment for it.
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