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A Comprehensive Eye Exam: What is the Doctor Checking For?

Side perspective of an eye doctor using a microscope and slit lamp to view a patients eye

A Comprehensive Eye Exam: What is the Doctor Checking For?

Most of us have been to an eye exam and spent time with an optometrist studying our vision. There are machines to check your eye pressure, and lights that illuminate your retina, and charts with big letters. But what are all these tests looking for?

An eye doctor conducts a comprehensive eye exam with a primary goal in mind- determining and evaluating your visual health. By studying the shape, strength, and acuity of your eyes, an optometrist can recommend prescriptions and provide preventative eye care solutions.

Let’s break down the different components of an eye exam and what it tells the doctor about your ocular health.

The First Rule of Prevention

The vast majority of eye conditions can be prevented or at least slowed down with an early diagnosis and effective eye care strategy. Many diseases result in negative eye changes that are irreversible and incurable if left unattended.

That’s why regular eye exams are so important- they give optometrists the ability to diagnose eye diseases early and to act quickly to protect your eyes.

How Often Should I Get My Eyes Checked?

Everyone should get their eyes examined once per year. This keeps your eye doctor on top of changes in your eyes. Even people with healthy vision are recommended to see the eye doctor annually.

If you have a medical history or other visual irregularities, your optometrist can build an exam schedule that best suits your own ocular needs.

Checking the Shape of Your Eye

In most people’s lifetimes, they will experience some form of shape-changing in their eyes. In fact, only 35% of American adults have 20/20 or “normal” vision. Changes in your eye shape affect how light is refracted through your eye and can lead to vision disorders.

Your visual acuity measurement (eye chart) will give your optometrist clues about the potential shape of your eye. They will use a slit lamp to examine the entirety of your eye and view each component individually. By identifying this eye shape, the doctor can confirm some common conditions that affect eyesight.


Also known as myopia, this condition is quite popular, affecting about 25% of the population. Nearsighted patients can see objects clearly at a close distance but struggle to see things far away.

This condition occurs when the eyeball is elongated and the cornea moves further away from the retina. Light is refracted incorrectly, blurring distant focus. Myopia is hereditary and is typically initially discovered in people under the age of 20.


Hyperopia is essentially the opposite of nearsightedness. This is another refractive error, but instead due to the distance between the retina and cornea being too short. People with this disorder can see things far away quite clearly, but have trouble reading and focusing on close items.

Both myopia and hyperopia are common enough but can lead to more serious eye conditions when they go unnoticed. Your eye doctor checks for these mutations so that they can create a prescription that will correct these refractive errors.


Astigmatism is another example of irregular curvature in the cornea or lens. Doctors check for a football-type shape of your eye which, again, refracts light towards the retina at an irregular angle.

By checking for these physical deformities in the shape of your eye, an optometrist has a baseline for refining a corrective eyeglass or contact lens prescription. These prescriptions are finetuned with further testing, like using a phoropter, a machine with multiple lens strengths. But microscope exams (slit lamp) let a doctor check for general shape abnormalities.

Side angle close up of an amber colored human eye with a front lens that is not perfectly round but shaped like a football

Looking for Eye Diseases

Many of the processes in an eye examination are designed to test for dangerous eye conditions. There are hundreds of known eye diseases, but a standard comprehensive eye exam can reliably check for some of the most common ocular ailments.


Diabetes is common enough that many optometrists specifically conduct diabetic eye exams. When diabetes exists, it makes the eye more vulnerable to other diseases.

After a standard eye exam, special drops will be applied to dilate your pupils. This allows your eye doctor to get a better view of the eye’s structure and to take digital images of the retina. In this process, they are checking for early stages of diabetic retinopathy, a condition that scars the eye and distorts vision.


Glaucoma refers to diseases that stem from damage to the optic nerve, often due to high pressure in the eye. When left unattended, glaucoma can lead to partial or total vision loss.

Eye doctors check for this disease with a field vision test. This non-invasive procedure tests peripheral vision strength, which can often indicate the presence of glaucoma. Tonometry is another test used to check for glaucoma, measuring for eye pressure outside the normal range.

Age-related Macular Degeneration

A common eye disease that develops as we age is known as age-related macular degeneration, (AMD). This disease is characterized by changes to the macula and central vision loss.

By checking for this disease annually, optometrists can identify the first signs of AMD and take steps to prevent its progress. This includes changes in diet and a focus on increased nutrition. Checking for this disease is done with an OCT or fluorescein angiography.


Another common condition that occurs in older patients is the presence of cataracts. Cataracts are the blurring or loss of clarity in our optic lenses. This condition can almost always be treated with corrective eyewear or cataract surgery.

The eye exam process highlights the severity of your cataracts and gives optometrists the information for building a game plan. Checking for this condition is the first step in getting your vision back to full health. An eye lens can’t be replaced unless we know there is something wrong.

Evaluating Health With An Eye Exam

Eye doctors check for these diseases because saving your vision is dependent on diagnosing eye disease early. With an early diagnosis, it is much easier to manage and treat eye diseases. When a disease has progressed to a point that symptoms are obvious to a patient, there are usually already significant vision damages.

Along with checking for serious eye diseases, eye exams provide doctors the chance to look for color blindness, dry eye, and other conditions that may not be life-threatening, but deplete your vision. Monitoring your ocular well-being and understanding the shape of your eye are essential pillars of your visual health.

Optometrists use eye tests to develop accurate prescriptions which help you see better. Most eye exams take less than 60 minutes. What a small sacrifice for happy vision and the peace of mind in knowing that your eye doctor is keeping your visual health in check.