The annual eye exam: what is checked, and how it differs from an eye test for glasses
Many people think an eye exam is reading letters off a chart and getting a prescription. That is one part. Most of the eye diseases that cause blindness have no symptoms early on, and are found by the rest of it. Here is what an eye-exam package is made of.
Refraction: the part an optician does too
Short, long and astigmatic sight measured by machine and confirmed by trying lenses, giving a prescription for glasses or contacts. What an ophthalmologist adds is noticing a prescription that is changing unusually fast, and vision that does not improve even with the right lens — a sign of something a lens cannot fix.
Eye health: the part that finds disease before symptoms
Eye pressure — raised pressure is a risk factor for glaucoma, which takes the field of vision from the edges inward without you noticing. A slit-lamp exam of the cornea, the lens (cataract) and the front of the eye. An exam of the retina and optic nerve, where diabetic damage, high blood pressure and macular degeneration show. More detailed packages add retinal photography, and a visual-field test for anyone at risk of glaucoma.
Choosing a package
Under 40 with no chronic condition: a basic set with refraction, eye pressure and slit-lamp exam, every two years. Forty and over, diabetic, hypertensive or with glaucoma in the family: a set with a detailed retinal exam, every year. A package that dilates your pupils means someone else drives you home — each package page says whether it does.
