What a comprehensive eye exam actually checks

Seeing clearly and having healthy eyes are different things

You can read the bottom line of the chart and still have early glaucoma. You can have sharp vision in each eye and a tear in the retina you have not noticed. Healthify NZ's glaucoma page puts it simply: most types develop slowly, so you may not have any symptoms early on.

That is the reason an eye exam is longer than a sight test. The prescription is the part you feel; the health checks are the part that protects you. Most of what follows takes a few minutes each, and nothing in a routine exam should hurt.

If you are booking your first visit with us, what happens at your first appointment walks through the visit in order. This guide explains what each test is looking for.

What each part of the exam looks for

Different clinics order the steps differently, and your optometrist adds or skips tests based on your history. The core of a comprehensive exam, as described by Healthify NZ and the American Academy of Ophthalmology, is this:

• History. Your symptoms, general health, medicines, and family history of glaucoma, diabetes or macular disease. This decides which extra tests are worth doing.
• Visual acuity. Reading letters at distance and near, one eye at a time. It measures how clearly you see, not why.
• Refraction. Comparing lens options to find the prescription that gives the sharpest vision. This is the 'which is clearer, one or two' part.
• Eye movement, alignment and pupils. How the eyes move together and how the pupils react to light. Problems here can point to muscle or nerve issues.
• Slit lamp. A microscope look at the eyelids, tear film, cornea, iris and lens, for dry eye, scratches, cataract and corneal thinning.
• Eye pressure. A puff of air or a gentle touch after numbing drops. The American Academy of Ophthalmology notes raised pressure is one sign of glaucoma.
• Retina and optic nerve. Looking at the back of the eye, with a widefield photo, dilating drops, or both, for signs of glaucoma, macular degeneration and diabetic changes.
• Visual field. A check for blind spots, which Healthify notes can come from eye disease or from the brain, such as glaucoma or stroke.

Where the scans fit

At NVISION a widefield retinal photo is included with every eye exam, and it becomes the picture next year's photo is compared with. Other scans are added when your history or the exam findings call for them: an OCT scan to see the layers of the retina and optic nerve, a visual field test if glaucoma or a nerve problem is suspected, corneal topography for keratoconus or contact lens fitting, and an axial length measurement for a child's myopia control.

Those are separate items, and they are listed on our consultation fees page. RANZCO's Choosing Wisely guidance is that routine visual fields and OCT are not indicated when there is no relevant history, symptom or sign, so a clean exam with no risk factors may end without them. Our guide to which eye scan you need compares the five, and our technology page describes the equipment.

A screening is not an exam

A driver licence eyesight check, a school vision screen, a workplace test or an online chart all do one thing: they tell you whether you can see a certain size of letter. They do not look at the retina, measure pressure or check the field of vision. Passing one is reassuring about the letters and says nothing about the health of the eye.

The reverse is also true. A child can pass a school screen and still have a prescription that is rising fast, and an adult can pass a licence check with early glaucoma. Healthify NZ's advice is that adults should generally have eye examinations every two years, and children and teenagers every one to two years because their eyes are still changing. Our posts on understanding your eye exam and how often to get an eye exam go further.

How often, by age and risk

Guidance differs a little between bodies, and your optometrist sets your interval. Healthify NZ suggests adults generally every two years. The American Optometric Association recommends at least every two years for low-risk adults aged 18 to 64 and yearly from 65, with at least yearly exams for anyone at risk. Glaucoma NZ recommends a glaucoma check by age 45, repeated every five years if normal, and a comprehensive exam every two years from 50.

Risk moves you to the shorter end. Diabetes, a family history of glaucoma or macular degeneration, contact lens wear, past eye injury or steroid use all count. The American Academy of Ophthalmology advises contact lens wearers to be seen yearly and people over 65 every year or two. If anything changes between visits, book sooner rather than waiting for the interval.

When this practice is the wrong place

A routine exam is the wrong booking for an emergency. Call 111 or go to the nearest hospital emergency department for sudden loss of vision, a shadow or curtain across your vision, flashes with a sudden shower of floaters, a chemical splash, a red and painful eye with light sensitivity, or an eye injury. Hours matter for some of these, and a clinic appointment next week is the wrong tool.

For a problem that is new but not sudden, such as a gritty eye for a week, a stye, or a prescription that feels off, an optometrist is the right first call and no referral is needed. If you are not sure which group you are in, Healthline on 0800 611 116 is free and open 24 hours.

What happens after the exam

Our optometrists explain what was found, show you the images, and set out the plan: a prescription, a follow-up interval, an added scan, or a referral to your GP or an ophthalmologist if something needs treatment we cannot provide. Dr Ryan Mahmoud is an authorised glaucoma prescriber, one of a limited number in New Zealand.

If dilating drops were used, Healthify NZ advises not driving for a few hours, and the National Eye Institute suggests bringing sunglasses. Plan a lift if a dilated check is likely. Book a comprehensive eye exam when you are ready.