What is an Eye Exam or Comprehensive Eye Exam?

James E. Croley III, M.D.

James E. Croley III, M.D.

Author and Ophthalmologist

An eye exam is also known as a dilated eye exam or complete eye exam. A normal complete comprehensive eye exam is a thorough examination of the eye which includes dilating the pupil of the eye. Eye doctors or ophthalmologists and optometrists examine the eye using a variety of tests, equipment, and other methods of examining the eye when indicated. A complete eye exam will take around 1 hour or longer. The dilating eye drops can take some time to fully dilate the pupil.


When you arrive in the office for your first visit, you will be asked to fill out a health history questionnaire and insurance information. You will need to sign a variety of papers or documents required by the government. The health questionnaire that you fill out gives the office staff an excellent starting point to begin the eye exam. I know that everyone hates filling out these papers but it is necessary. Even though you are seeing an eye doctor, there are many eye diseases that are related to systemic medical diseases. Your eye doctor needs all your medical information and list of medications.

Chief Complaint or History of Present Eye Problem

The staff will start with taking a history of your eye complaint along with any other related symptoms. A complete and thorough history of your eye complaint is extremely important in helping determine the extent and direction of the eye exam and any additional tests that may be necessary.

Past Eye History

The past eye history includes any eye diseases, surgeries, or injuries that has occurred in the past.

Past Medical History

The past medical history needs to be documented as well. This includes any medical diseases, conditions, surgeries, and/or hospitalizations in the past needs to be placed into the record. As stated before, there are many medical diseases and/or conditions have an important connection or relationship to many eye diseases.

Review of Systems

A review of all the medical systems in the body needs to be taken by the staff. They will ask you if you are presently having any symptoms or problems with the different organ or medical systems in the body.

Social History

A social history needs to be taken as well. You will be questioned about smoking, alcohol consumption, and other social questions.

Family History

You will be asked about your family history of any medical diseases or conditions. This important as well as many diseases have a genetic component. Especially things that effect the eyes such as glaucoma, macular degeneration, and diabetes.

Medication List

It is a Medicare requirement that the eye exam record list all the medications you take and their dosages. It is important that the eye doctor to know all the current medications that you are taking as well. Many of the medications people are taking have ocular side-effects. Therefore, the eye doctor needs to know what medications you are on. If you are on many medications, it is a good idea to bring a list of your medications with you.

Examination Portion of the Eye Exam

Eye Examination Room
Typical Examination Room

Visual Acuity

The distance vision is tested with a chart that is on the wall. The chart is 20 feet away. Many times, the chart is reflected off a mirror to accomplish the 20 feet so that the exam room doesn’t have to be 20 feet long. A near card may be used to test the near vision. Computers or smart TVs are now used for testing the vision. Color vision may be tested in some circumstances when there is a concern about colored blindness and/or questions about the health of the eye. Pin-hole vision is another way of testing vision. You look through an object with tiny holes in it. Many times, glare testing is used for people that are developing cataracts. This is to determine how much your vision is effected by glare at night. Contrast sensitivity may be used in some cases which provides more information about the level and quality of a person’s vision.

Eye Movements or Ocular Motility Assessment

The alignment or direction of the eyes is evaluated to see if there is any deviation such as crossed eyes. The movement of each eye is evaluated by having you follow a light or object. A eye doctor will record any limitation in the movement of your eyes. The quality of how you move your eyes is also evaluated. Your stereopsis or depth perception may be evaluated to see if there is any problems with depth perception.


You commonly see people’s pupils checked on doctor TV shows but very rarely done correctly. Your pupils are tested to see their reaction to light as this can give an indication of the health of the vision system including the central nervous system. The pupils also constrict when you look at near which is called accommodation.

Side Vision

The amount of your side vision can be evaluated by a method called confrontation fields. The eye doctor or staff is seated in front of you with you covering one eye. They hold out fingers in the four quadrants of your side vision and ask you to tell them how many fingers do you see? This is very simple and easy method of finding out if you have any limited side vision. If during the confrontation fields, something is found or suspected, a formal visual field examination will be performed with a computerized visual field instrument that is able to find very small changes in your side vision.

Refraction or Testing for Eyeglasses

A refraction determines the extent of any myopia (nearsightedness), hyperopia (farsightedness), and/or astigmatism (your eye is shaped like a football cut length wise in half instead of a round basketball). Prior to beginning the refraction, you may be taken to a room and your eyes will be tested with a wavefront analyzer (aberrometer) or a computerized autorefractor instrument. These instruments are able to measure your eyes and help determine your eyeglass prescription.


You are brought into a room and placed behind a machine called a phoropter. The phoropter contains all the possible combinations of eye glass prescriptions. The eye doctor or staff give you choices between two different lenses and asked you which lens do you see better with? The eyeglass prescription is fined tuned based on your answers to which lens you state that you see the best with. This prescription is important as it provides more information than just an eyeglass prescription. Your best correctable vision gives the eye doctor information about the quality of your vision and the health of your eyes. All clinical decisions the eye doctor makes about the health of your eyes is based on your best correctable vision. If your best correctable vision is not 20/20 or it has changed from your prior visit, the eye doctor will need to search for the reason your vision has changed. The eye doctor will order a variety of tests to determine the cause of your vision loss.

Unfortunately, most insurances do not cover the cost of the refraction. It is a separate fee. It really should be covered as part of an eye exam as it provides important medical information about the health of the eye. But, Medicare and most insurances have taken the easy way out and have chosen not to cover the cost.

External Eye Exam

The ocular adnexa or eyelids and other structures around the eyes are examined for any abnormalities.

Slit Lamp Exam

A slit lamp is a binocular microscope that is used to examine the tissues of the eye under high magnification. You place your chin on a chin rest and place your forehead up against the band attached to the slit lamp. The slit lamp is used to examine the eyelids, conjunctiva, cornea, iris, and lens. Once your eyes are dilated, the slit lamp can also be used to examine the retina and optic nerve inside the eye.

Slit Lamp Microscope
Slit Lamp Microscope

Glaucoma Test, Eye Pressure, or Intraocular Pressure

Your eye pressure will be measured during your eye exam. There are a variety of different instruments that can be used to measure the eye pressure.

Non-Contact Tonometer

A non-contact tonometer means that the instrument does not touch the eye. Another name is air-puff test which can measure the eye pressure by using a small burst of air against the cornea. The instrument is able to measure the resistance of the cornea to air applied against the eye.

Applanation Tonometer

The Goldmann Applanation Tonometer is the gold standard for accurately measuring the pressure inside the eye. It is attached to the slit lamp microscope. An anesthetic or numbing eye drop is placed on the eye which contains a dye called fluorescein which allows the eye doctor to measure the eye pressure. The tonometer gently presses against the cornea to measure the tension inside the eye. The test is entirely painless as the eye is numb.

Other instruments that can measure the eye pressure are the Tonopen, Icare tonometer, Diaton Transpalpebral tonometer, Pascal tonometer, and Perkins tonometer. It is very important that the eye pressure is measured during the eye exam. Except in cases of a sudden increase in eye pressure as in acute angle glaucoma, you cannot feel that your eye pressure is elevated. Glaucoma does not give any symptoms until a significant loss of side vision has occurred.

Goldmann Applanation Tonometer
Goldmann Applanation Tonometer

Examination of the Retina and Optic Nerve

In order for the eye doctor to be able to see the entire retina, the pupil of the eye needs to be dilated. The pupils are dilated with eye drops that are instilled in the eye. It takes about 20 to 30 minutes or more for the drops to dilate your eyes. The length of time depends on the types of eye drops that are used to dilate the pupils and dark brown eyes take longer than blue eyes. Once your pupils are dilated, the eye doctor will use a variety of different instruments and lenses to look inside the eye to examine the retina and optic nerve for any sign of eye disease.

Indirect Ophthalmoscope
Indirect Ophthalmoscope

When Do I Need to Have My Eyes Examined?

There are no absolute guidelines for a routine dilated eye exam on how often you should have your eyes examined. It is a good idea to have your child’s eyes examined by age 4 before they start school to make sure they have good vision in each eye and no lazy eye as this needs to be treated early. If you have a family history of any eye diseases such as glaucoma, diabetes, macular degeneration, take prescription medications that have ocular side-effects, a job that exposes you to possible hazards to your eyes, ocular complaints or symptoms, or other eye disease, you need to follow the recommendations of an eye doctor. For routine eye exams, you should consider the following.

Age 20 to 60

You should have a routine eye exam every 3 to 5 years. In your 40s you will start to develop presbyopia (unable to focus up close) and will need to change your glass prescription every 2 or 3 years.

Age 65 and above

Once you are over 65, you should have a routine eye exam every 1 to 2 years

For people aged 65 and over, the incidence of cataracts, glaucoma, and macular degeneration increases. Unfortunately, many of these diseases do not give symptoms until the disease has caused significant damage to the eye.


After the examination, the eye doctor will discuss with you the results of the eye exam and provide their recommendations about any diseases or abnormalities found during the exam. The doctor will prescribe medications, order necessary tests if needed, and schedule a return office visit as appropriate.

You will be given a prescription for glasses. If you decide to get a no-line bifocal or progressive bifocal, it is extremely important that you get a proper brand, measurements, and fit. The many different brands of progressive glasses are designed with different technology. The quality of the progressive design and how clear the blending from distance to near progresses is very important. Also, the width of the reading area in the lenses can be dramatically different between many brands brand on the market. Many times, when people complain about their progressive bifocal, the prescription is correct but they feel disoriented or are unhappy with the quality of their vision. If you are going to spend money on glasses that you will be wearing for several years in many cases, it is worth getting the best quality pair of glasses.

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