What Tests Are Done During an Eye Exam?

Everyone should undergo regular comprehensive eye exams as they form a crucial part of preventative eye care. They aren’t only used to check the quality of your vision or whether you need a new prescription, but also to assess the health of your eyes. This allows for early detection of any problems or diseases which could have long term consequences for your vision.

You can expect to undergo a variety of different tests during your eye exam with us. These may include some or all of the following:


Visual Acuity Testing

This is the most well-known of all eye tests and the one that most patients expect when they attend an eye exam appointment. This test is designed to measure how clear your vision is, which will tell your eye doctor how accurately you can see from different distances.


The test involves sitting and looking at a chart of letters of different sizes. Your eye doctor will ask you to read different sections of the chart to determine how well you can see. This will be measured in a ratio, such as 20/20 or 20/40. The less the bottom number, the better your visual acuity is. This test will also be used to determine if you would benefit from wearing prescription lenses and what that prescription should be.



A keratometer is a diagnostic instrument used to measure the cornea’s curvature. This is important for determining if you are affected by astigmatism or not. Astigmatism occurs when an uneven corneal surface causes light to be refracted onto multiple points on the retina, resulting in blurred vision. Measuring the curve of the cornea tells your eye doctor the extent and axis of your astigmatism and helps them to recommend the correct glasses or contact lenses to correct your vision.



In some instances, the curve of the cornea isn’t measured manually, but instead your eye doctor will refer you for topography. This is where cutting edge technology is used to take an image of the surface of your cornea. This is enhanced and then mapped, enabling the accurate detection of even the smallest abnormalities.


Visual Field Testing

Your visual field is how far you can see without moving your head, encompassing both your central and side (peripheral) vision. This is important since some eye diseases, like glaucoma, start to affect the peripheral vision first. Visual field testing is non-invasive and painless.


Slit Lamp Exam

A slit lamp is a specialist ophthalmology tool that provides a magnified, three-dimensional view of the many different parts of the eye. This allows the eye doctor to check for any abnormalities that could indicate disease or disorder.



Also known as a fundoscopy, an ophthalmoscopy is a test that is carried out to visualize the structures at the very back of the eye, including the retina, optic disc and blood vessels that serve the area. It is sometimes performed using a slit lamp and requires your pupils to be dilated so that your eye doctor can look through them.



Tonometry is a test that is designed to measure the internal pressure of the eye and is normally only recommended where the patient has a risk of or is developing symptoms of glaucoma. There are several different instruments which can be used to do this, and if necessary, you will have your eyes numbed beforehand.


Color Vision Testing

If your eye doctor has reason to suspect that you may have an issue with your Color vision, you may be referred for testing to see if you are affected.


Binocular vision testing

If your eye doctor is concerned that your eyes may not be working in perfect synchronization, you may have a condition called binocular vision dysfunction or BVD and may be referred for testing to confirm a diagnosis.


For more on eye exams, contact Houston Dry Eye Clinic at our office in Houston, Texas. You can call (713) 664-4760 to book an appointment today.