Optometry is a specialized health care profession that examines the eyes and related structures to detect defects or abnormalities. 

Optometrists are eye care professionals who provide comprehensive primary eye care.

Optometrists are doctors who have a specialized degree. 

They are trained and licensed to practice for eye-related conditions, in addition to providing eye care.

Slit-Lamp Examination

When you visit an eye doctor, they don’t just check if you can read the third line on your eye chart clearly. 

They also make sure your eyes are healthy.

Slit lamps are special microscopes and lights that let your doctor see both inside and outside of your eye in 3-D. 

They’ll use it along with an ophthalmoscope to examine the back of your eye.

An eye doctor usually performs a slit-lamp examination as part of a regular check-up.


The slit lamp is a combination of several pieces of equipment. 

There is a binocular microscope, an adjustable light source, a frame to rest your head on during the exam, and a base that moves in an arc.

The light can be used in a variety of ways by your doctor. 

They can alter its size, increase its brightness, and apply color filters. 

As a result, your doctor can concentrate on particular parts of your eyes and face.

You may want to bring someone to drive you home if you drive to your appointment. 

A few eye exams include dilation. 

The outside world may seem overly bright and uncomfortable for a few hours until they return to normal size. 

You may also have blurry vision for a few hours.


You will be asked to remove your glasses or contact lenses before the exam begins. 

To keep your head steady, put your chin and forehead against the microscope rests. 

Also, your doctor may place a few drops of dye in your eyes to highlight areas of interest. 

Then they’ll turn off the room lights and turn on the slit lamp.

During the examination, your doctor will adjust the light from the slit lamp to view certain parts of your eyes through the microscope. 

The doctor will examine:

  • The skin around the eye
    • During your doctor’s examination, they can check for skin diseases and abrasions.
  • Your eyelids and eyelashes
    • Your doctor will look for conditions such as styes (oil gland infections), folliculitis (hair follicle infections), and tumors.
  • The surface of the eye
    • Your eyelids and the whites of your eyes fall within this category. 
    • Swelling or infection may occur here. These conditions are often caused by sexually transmitted diseases, allergies, or viruses.
  • The sclera
    • This is the outermost layer that protects the eyeball. 
    • The episclera is located next to the sclera and helps keep it healthy. 
    • In these areas, allergies, autoimmune disorders (where the body attacks itself), and gout (a type of arthritis) are common.
  • The cornea
    • The cornea is the part of the eye that helps you see clearly. 
    • Slit-lamp exams can reveal that your cornea isn’t as clear as it once was. A number of factors can contribute to blurred vision.
  • The iris
    • The colored disc that surrounds the pupil changes to allow more or less light to pass through your eye.
    • A variety of diseases and conditions can affect the iris, including freckles and melanoma. 
  • The lens
    • This part of the eye is used to diagnose cataracts (clouding of the lens). 
    • The lens is located behind the pupil.

Using a special magnifying lens in combination with the slit lamp, your doctor can also view the retina and the optic nerve in the back of your eye. 

They will dilate your pupils with eye drops before doing this exam.

Your doctor can determine if you have glaucoma or diabetes by examining your retina and optic nerve. 

In addition, the exam may reveal tumors, blood clots, and hardening of the arteries due to high blood pressure.

The results of your eye exam will be communicated to you as soon as possible.

Your eye doctor may suggest you see your regular doctor if your exam reveals you have a disease that affects other parts of your body. 

Your doctor may prescribe you a prescription or suggest further testing if you have a specific condition.

Retina Examination

Your optometrist performs a retina examination to examine the structures found in the retina. Your pupils are dilated before the examination. 

A bright light and a microscope are used by your eye doctor to assess the optic nerve, retina, and blood vessels. There are four steps in this process.

Dilating the Eyes

Your eye doctor will first dilate your eyes with drops that cause the pupil to widen. This allows for more light to enter and provides a clearer view of the interior.

Tonometry Test

Tonometry uses a probe to measure the pressure inside your eye, also known as intraocular pressure (IOP). 

Your doctor can use this measurement to determine whether you may be at risk of glaucoma.

If left untreated, glaucoma can eventually lead to vision loss. 

Glaucoma usually occurs when the fluid that bathes and nourishes the eye drains too slowly, causing pressure to build up.

Eventually, the increased pressure can harm your optic nerve and cause vision loss if left untreated. 

Glaucoma is one of the leading causes of blindness in adults over 60, according to the American Academy of Ophthalmology (AAO).

Glaucoma can cause painful changes that progress for years without you realizing it. 

Tonometry tests can help detect the changes early.

Tonometry Test Procedure

During the tonometry test, your eye doctor will put numbing eye drops in your eye so that you do not feel anything touching your eye.

Your doctor may touch a small piece of paper that contains orange dye to the surface of your eye once it is numb. 

This can improve the accuracy of the test.

The doctor will then place a “slit-lamp” in front of you. 

The technician will ask you to rest your chin and forehead on the supports provided, then move the lamp toward your eye until the tip of the tonometer probe touches your cornea.

By flattening your cornea just a bit, the tonometer can measure your eye’s pressure. 

The tension will be adjusted until you get a good reading. 

You won’t feel any pain during this procedure since your eye is numb.

Tonometry tests are a safe method. 

When the tonometer touches your eye, there is a very small risk of scratching your cornea. 

Even if this happens, your eye will usually heal itself within a few days.

What Do The Results Of The Test Mean?

A normal test result means the pressure in your eye is within a normal range, which means you probably don’t have glaucoma or other pressure-related eye problems.

Normal eye pressure ranges from 12 to 22 millimeters Hg, according to the Glaucoma Research Foundation.

mm Hg stands for millimeters of mercury, which is the unit of measurement for eye pressure.

You may have glaucoma or pre-glaucoma if your test shows a pressure reading over 20 mm Hg. 

Your doctor will do additional testing to confirm the diagnosis of glaucoma if you have high eye pressure.

If you are diagnosed with glaucoma or pre-glaucoma, your doctor will discuss treatment options with you.

Visual Field Test

During this test, the entire field of vision is measured. 

This includes both the center and peripheral fields. 

Each eye is tested separately. 

Test devices today also measure a patient’s ability to maintain a straight gaze.

Visual Acuity Test

You will need to read an eye chart for this test. Most people have had this test before.

What Is A Retinal Exam Able To Diagnose?

A retina exam can identify conditions like hypertension, diabetic retinopathy, detached retina, and macular degeneration. 

In some cases, problems don’t exhibit obvious symptoms, which makes a test necessary for early detection.

Refraction Test

Refraction tests are usually administered as part of routine eye exams. 

The test is also sometimes referred to as a vision test. 

This test tells your eye doctor exactly what prescription you need for your glasses or contact lenses.

20/20 is normally considered to be optimum, or perfect vision. A person with 20/20 vision can read letters that are 3/8 of an inch tall from 20 feet away.

You have a refractive error if you don’t have 20/20 vision. 

A refractive error occurs when the light does not bend properly as it passes through the lens of your eye. 

A refraction test will tell your doctor what prescription lens you should use to achieve 20/20 vision.

First, your doctor will analyze how light bends as it passes through your cornea and lens. 

Your eye doctor can then determine whether you need corrective lenses and, if so, what type of prescription you require. 

During this part of the test, your doctor may use a computerized refractor or simply shine a light into your eyes.

During the computerized test, you look through a device that measures how much light reflects from your retina.

A doctor can also perform this test without using a machine. 

In this case, the doctor will shine a light into each of your eyes and measure how much light is bouncing off your retina to determine your refractive score.

Your doctor will then determine what prescription you need. 

In this part of the test, you will sit in front of a piece of equipment called a Phoroptor. 

It looks like a large mask with holes for your eyes. 

Approximately 20 feet in front of you will be a chart of letters. 

Your doctor may use a chart with small pictures of common items for children who cannot yet identify letters.

As your eye doctor tests one eye at a time, you will be asked to read the smallest row of letters you can see. 

Each time the lens on the Phoroptor is changed, your doctor will ask you which lens is clearer. 

If you are not sure, ask your doctor to repeat the process. 

After your eye doctor has completed testing one eye, he or she will repeat the process for the other eye. 

Eventually, they will come up with a combination that is closest to giving you 20/20 vision.

Optometry Frequently Asked Questions

Optometry is a specialized health care profession that examines the eyes and related structures to detect defects or abnormalities. 

Optometrists provide comprehensive eye care to patients.

The profession of optometry is chiefly concerned with examining the eyes for defects and errors of refraction, prescribing corrective lenses or exercises for the eyes, diagnosing diseases of the eyes, and treating them or referring them for treatment.

An optometrist is not a medical doctor. 

After completing three or more years of college and four years of optometry school, they earn a doctor of optometry (OD) degree.

You will have to cover one eye with the palm of your hand, a piece of paper, or a small paddle while you read the tiniest line of letters on the chart that you can. 

Children and adults who cannot read are provided with numbers, lines, or pictures. 

You can guess the letter if you are not sure.

The normal vision acuity (clearness or sharpness of vision) measured at a distance of 20 feet is 20/20. 

20/20 vision allows you to see clearly at 20 feet what should be visible at a distance.

Refraction is an eye test that is conducted during a comprehensive eye exam to determine a patient’s prescription for eyeglasses or contacts. 

As part of the refraction test, the patient sits in a chair looking through a special device known as a Phoroptor or refractor and focusing on an eye chart 20 feet away.

Slit lamp examinations can detect many diseases of the eye, such as cataracts, corneal damage, and dry eye syndrome.