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What happens in an eye check-up?

Many people put off an eye check-up because they do not know what will happen, or they worry about the drops and the bright lights. Most of a check-up is reading letters and looking at lights. If any instrument needs to touch the eye, a numbing drop is put in first. Here is each step in order, so you know what to expect. For what a check-up at ReNew Vision covers, see eye check-ups in Vasco.

Before the eye doctor sees you: your history

You will be asked:

• what the problem is, how long it has been there, and whether it affects one eye or both
• whether you wear spectacles or contact lenses, and how old they are
• about past eye problems, eye injuries or eye surgery
• about your general health: diabetes, high BP, thyroid problems, asthma, allergies
• which medicines you take, including eye drops
• whether anyone in your family has glaucoma, high spectacle power or a squint
• about your work, screen use and driving

Bringing a written list of medicines and recent sugar and BP reports saves time and avoids mistakes.

Step 1: the vision test

You read letters or numbers on a chart, one eye at a time, with the other eye covered. Children who do not read yet are shown pictures or shapes. Each eye is tested with your current spectacles and without them, for distance and then for reading. Sometimes you look through a small pinhole: if the letters get clearer, better spectacles are likely to help.

Step 2: the spectacle power test

Lenses are tried in front of each eye, and you are asked which looks clearer: this one, or this one? There are no wrong answers. If two lenses look the same, say so. The power is then fine-tuned for distance, reading and, if you need it, the screen. In children, drops are sometimes used to relax the eye's focusing so that hidden power is not missed; these drops can last longer, sometimes a day or more. Read more about the eye test for glasses.

Step 3: the eye pressure test

Eye pressure is measured with a tonometer. Depending on the instrument used, you feel a short puff of air, or a small probe touches the surface of the eye gently after a numbing drop. Either way it takes a few seconds. Raised pressure is one of the main risk factors for glaucoma, although one reading alone does not make a diagnosis. After a numbing drop, do not rub your eyes until the numbness has worn off.

Step 4: the front of the eye under the microscope

You rest your chin on a support and your forehead against a band, and the eye doctor looks at your eye through a microscope with a bright, narrow beam of light, called a slit lamp. Nothing touches the eye. This shows the lids and lashes, the white of the eye, the cornea (the clear window at the front), the iris and the lens. Cataract, dry eye, infections and pterygium are seen here.

Step 5: drops to widen the pupils

In bright light the pupil is small, which hides most of the retina. Dilating drops widen it so that the whole retina and the lens can be examined. They may sting for a moment, and they usually take about half an hour to work, sometimes longer. Not every visit needs them; the eye doctor decides.

For a few hours afterwards, usually four to six and sometimes longer, close-up vision is blurred and bright light feels harsh. This is expected and wears off.

Very rarely, in an eye with a narrow drainage angle, dilating drops can trigger a sudden rise in eye pressure. If you develop eye pain, a red eye, blurred vision with coloured haloes around lights, a headache or vomiting after an eye check-up, call 072489 88039 at once. Emergency eye care is available 24 hours; see eye emergencies.

Step 6: the retina and the optic nerve

The eye doctor looks through your widened pupil with a bright light and a magnifying lens, and asks you to look up, down and to each side. The light leaves a coloured after-image for a minute or so. This part of the check-up looks at:

• the optic nerve, where glaucoma damage shows
• the blood vessels, where diabetes and high BP leave signs
• the macula, the centre of the retina used for reading and faces
• the edges of the retina, where tears and detachments start

Step 7: talking it through

At the end, the eye doctor explains what was found, whether anything needs treatment, and when to come back. If you need spectacles, you get a prescription. If cataract surgery is being planned, a lens-power test (biometry) is arranged. If you need a test that is not done at ReNew Vision, the eye doctor will explain the next step.

Useful questions to ask:

• Apart from my spectacle power, are my eyes healthy?
• Is there anything I should watch for at home?
• When should I come back?
• Do I need separate spectacles for reading or the screen?

Can I drive after an eye check-up?

Not after dilating drops. Blurred close vision and glare make driving, and riding a two-wheeler, unsafe until your vision is back to normal. Bring someone who can drive, or plan to take a taxi or bus home, and bring sunglasses. If no dilating drops were used, you can usually go home as you came; ask if you are unsure.

How long does it take?

A spectacle power test alone is quicker. A full check-up with drops takes longer, because the drops need time to work before the retina can be examined. The Eye OPD runs Monday to Saturday, 4 pm to 7 pm, so if you expect drops, come early in the OPD. How often to come back depends on your age and health; read how often to get your eyes checked.

Questions patients ask

Do the eye drops used in an eye check-up hurt?

They may sting for a moment. Dilating drops then blur close vision and make bright light feel harsh for a few hours. This is expected and wears off.

How long does blurring from dilating drops last?

Usually four to six hours, sometimes longer. Drops used to relax focusing in children can last longer, sometimes a day or more. The eye doctor will tell you what to expect.

Can I drive after an eye check-up?

Not after dilating drops. Bring someone who can drive, or plan to take a taxi or bus home. If no dilating drops were used, you can usually go home as you came.

Can I wear contact lenses to an eye check-up?

Bring them, with their case, and bring your spectacles too. You may be asked to take the lenses out before some tests, such as the eye pressure test and the examination of the front of the eye.

Can I go back to work after an eye check-up?

If dilating drops were used, reading and screen work will be hard for a few hours, so plan a light rest of the day. Work that needs clear vision, or driving, should wait until your vision is normal again.

Why does the eye doctor shine a bright light in my eyes?

To see the lens, the retina and the optic nerve clearly. The light can be dazzling and leaves an after-image for a minute or so, but it does not harm the eye.

This page is general eye-health information, not personal medical advice. Your eye doctor advises you after examining your eyes.