What changes in the eye after sixty

A good deal of sight loss in older people is treated as an inevitable part of growing old, and a good deal of it is not inevitable at all. The distinction is worth making clearly, because the assumption that poor vision is simply age is one of the larger contributors to avoidable blindness in Nigeria.

What is genuinely just ageing

Presbyopia. The lens stiffens and near focus is lost. Universal, complete by around sixty-five, and corrected with reading spectacles or a varifocal.

Needing more light. The pupil becomes smaller with age and the lens yellows, so less light reaches the retina. An eighty-year-old may need several times the light a twenty-year-old does for the same task. This is a lighting problem rather than a medical one, and good task lighting transforms it.

Slower adaptation to darkness, and slower recovery from glare.

Some colour shift. A yellowing lens filters blue, so blues and violets look duller and can be harder to distinguish from each other.

Drier eyes, from reduced tear production.

Floaters. The vitreous gel liquefies and its collagen clumps, casting shadows. Long-standing floaters that have not changed are normal.

What is disease, and is treatable

Cataract. Extremely common with age, and it is not a normal part of ageing so much as a universal one — which is a distinction without a difference except that it is treatable. Surgery restores vision reliably. Glare at night, fading colours, needing more light than you used to: worth an examination, not acceptance.

Glaucoma. Risk rises steeply with age. Symptomless until late. Treatable, and untreatable once the damage is done.

Age-related macular degeneration. Affects the central vision used for reading and recognising faces, leaving peripheral vision intact. The "wet" form can progress rapidly and has effective treatment that is highly time-sensitive — which makes prompt reporting of new distortion critically important.

Diabetic retinopathy. Common, silent, treatable.

Posterior capsule opacification after cataract surgery — vision dims again months or years later, and is restored in minutes with a laser. Frequently mistaken for the cataract returning, and frequently endured unnecessarily.

The symptom that should never wait

Straight lines appearing bent or wavy, or a blurred or missing patch in the centre of vision, in one eye. Cover each eye in turn and look at a door frame or a tiled floor.

That is the presentation of wet macular degeneration, and treatment given early preserves substantially more vision than treatment given late. It is not a symptom to mention at the next routine visit in six months.

Equally urgent: a sudden shower of new floaters, flashing lights, or a curtain or shadow across the vision, which may indicate a retinal tear or detachment.

The falls connection

Poor vision is a well-established risk factor for falls in older people, and a fall resulting in a hip fracture is a life-changing event. Two specific and under-recognised points:

First, cataract surgery reduces fall risk — the benefit is not only to sight.

Second, varifocal and bifocal lenses increase fall risk on stairs, because the reading portion sits at the bottom of the lens exactly where the foot needs to be seen clearly. An older person who is unsteady is often safer with separate distance and reading spectacles, and should be told so rather than left to discover it.

Practical measures at home

Brighter, better-positioned lighting, particularly on stairs and in the kitchen. Contrast — a light switch that stands out from the wall, a dark edge marking on a step, a coloured toilet seat. Removing loose rugs and trailing cables. Keeping spectacles clean, which sounds trivial and is not.

How often to be seen

Annually after sixty, and sooner for any change. The examination should include the retina and the optic nerve, not merely a prescription check — the conditions that matter most produce no symptoms until late, and finding them is the entire purpose.