What an Annual Eye Examination Is Actually Looking For

Damage begins in the peripheral field, which the brain fills in seamlessly. Patients typically notice nothing until a substantial proportion of optic nerve fibres has been lost — permanently. OCT imaging measures the nerve fibre layer in microns and detects thinning years before any field defect appears.

Central vision often remains completely normal while the peripheral retinal circulation deteriorates. Wide-field imaging documents this objectively and allows year-on-year comparison, which is why annual screening is advised from the point of diagnosis regardless of how good glycaemic control has been.

Early drusen are visible long before distortion or blurring is noticed, and the neovascular form has a treatment window measured in weeks. Detecting the at-risk eye early means the patient knows what change to report — and reports it in time.

The retina is the only place in the body where blood vessels and nerve tissue can be examined directly and without instrumentation of any kind. Hypertension, raised intracranial pressure, some tumours and a number of neurological conditions leave visible signatures there, and are occasionally identified at a routine eye examination before anywhere else.

A reasonable interval is every two years until forty and annually thereafter — annually at any age with diabetes, a family history of glaucoma, high myopia or previous eye surgery. It takes an hour and a half, and its value lies almost entirely in the findings you would never have noticed yourself.