Eye Exams
Preparing for an Eye Exam
For both adults and children, an eye exam is a critical part in maintaining your overall health and well-being, and therefore, regular eye exams should be incorporated into your health routine. Comprehensive eye exams assess your vision and the health of your eye, looking for early signs of disease that may not have obvious symptoms. You should not wait until you experience a vision problem or symptoms of an eye condition to schedule a routine exam.
Depending on your age, family history, general health and eye health, it is recommended to have an eye exam every one to two years. Of course if you experience any serious symptoms that affect your eyes or your vision, you should contact your eye doctor immediately.
The Difference Between an Optometrist (OD) and an Ophthalmologist (MD or DO)
Confusion about the difference between optometrists and ophthalmologists is common, and many people are not aware of how the two eye care professionals differ.
Optometrists
Optometrists or Doctors of Optometry attend optometry school which is usually at least four years of graduate level training. They are able to perform eye exams, provide prescriptions for eyeglasses and contact lenses, and diagnose and treat eye diseases as as glaucoma, dry eyes, or eye infections that may require medication or drops. They can consult with and co-manage patients in pre- or post-op surgical care, however they do not perform surgery.
Ophthalmologists
Ophthalmologists are medical doctors that attend medical school and later specialize in ophthalmology. They are able to do all of the services mentioned above but also perform eye surgeries such as cataract surgery, refractive surgery such as LASIK and deal with more urgent eye conditions such as retinal detachment.
Infant and Child Eye Exams
According to the American Optometric Association (AOA) children should have their eyes examined by an eye doctor at 6 months, 3 years, at the start of school and then at least every 2 years following. If there are any signs that there may be a vision problem or if the child has certain risk factors (such as developmental delays, premature birth, crossed eyes, family history or previous injuries) more frequent exams are recommended. A child that wears eyeglasses or contact lenses should have his or her eyes examined yearly.
Adult Eye Exams
Healthy adults under 40 with good vision and who do not wear eyeglasses or contact lenses are recommended to have an eye exam at least every two years. Those that do use vision correction or have a health issue such as diabetes, high blood pressure or another health condition that can have an impact on your eye health should schedule a yearly exam, unless the eye doctor recommends more frequent visits.
Once you reach 40, you become susceptible to a number of age-related eye conditions such as presbyopia, cataracts or macular degeneration, therefore annual or bi-annual exams are strongly recommended.
As you continue to age, particularly after age 55, the risks of eye disease increase, and early detection can be critical to preventing significant vision loss or blindness. Scheduling a yearly eye exam can make all the difference in maintaining your independence and quality of life.
How to Prepare for Your Exam
Prior to your exam you should decide whether you will be seeking special services such as a contact lens exam or LASIK consultation. These services may cost extra. Check with the doctor’s office or your insurance provider to see if they cover any of the exam expenses.
You need to know if you have medical insurance, vision plan coverage or both. Medical insurance usually does not cover “wellness/refractive” exams for glasses or contact lenses. Vision plans will cover exams for glasses or contacts, but usually cannot be used for red eyes, floaters, or other medical eye health problems. Please bring your insurance cards with you.
In addition to bringing your current pair of glasses or contacts if applicable, it is important to be aware of your personal and family history and to have a list of medications or supplements you are currently taking. Your pupils will probably be dilated as apart of your exam, so plan accordingly.
Why are Eye Exams Important?
During a complete eye exam, your eye doctor will not only determine your prescription for eyeglasses or contact lenses, but will also check your eyes for common eye diseases, assess how your eyes work together as a team and evaluate your eyes as an indicator of your overall health.
What is the eye doctor checking for?
In addition to evaluating whether you have nearsightedness, farsightedness or astigmatism, your eye doctor will check your eyes for eye diseases and other problems that could lead to vision loss. Here are some examples of the conditions that your eye doctor will be looking for:
Amblyopia
This occurs when the eyes are misaligned or when one eye has a much different prescription than the other. The brain will “shut off” the image from the turned or blurry eye. If left untreated, amblyopia can stunt the visual development of the affected eye, resulting in permanent vision impairment. Amblyopia is often treated by patching the stronger eye for periods of time.
Strabismus
Strabismus is defined as crossed or turned eyes. Your eye doctor will check your eyes’ alignment to be sure that they are working together. Strabismus causes problems with depth perception and can lead to amblyopia.
Eye Diseases
Many eye diseases, such as glaucoma and diabetic eye disease, have no obvious symptoms in their early stages. Your eye doctor will check the health of your eyes inside and out for signs of early problems. In most cases, early detection and treatment of eye diseases can help reduce your risk for permanent vision loss.
Other Diseases
Your eye doctor can detect early signs of some systemic conditions and diseases by looking at your eye’s blood vessels, retina and so forth. They may be able to tell you if you are developing high blood pressure, high cholesterol or other problems.
For example, diabetes can cause small blood vessel leaks or bleeding in the eye, as well as swelling of the macula (the most sensitive part of the retina), which can lead to vision loss. It’s estimated that one-third of Americans who have diabetes don’t know it; your eye doctor may detect the disease before your primary care physician does, especially if you’re overdue for a physical.
What’s the difference between a vision screening and a complete eye exam?
Vision screenings are general eye tests that are meant to help identify people who are at risk for vision problems. Screenings include brief vision tests performed by a school nurse, pediatrician or volunteers. The eye test you take when you get your driver’s license renewed is another example of a vision screening.
A vision screening can indicate that you need to get an eye exam, but it does not serve as a substitute for a comprehensive eye exam.
No matter who you are, regular eye exams are important for seeing more clearly, learning more easily and preserving your vision for life.
Your Comprehensive Eye Exam
Your eyes are one of the most complex organs in your body. A comprehensive eye exam to assess your visual system and eye health involves a number of different of tests. Unlike a simple vision screening, which only assesses your vision, a comprehensive eye exam includes a battery of tests in order to do a complete evaluation of the health of your eyes and your vision.
The tests that you will undergo in a comprehensive eye examination may vary from eye doctor to eye doctor but here are are some common exams that you may encounter:
Patient Background and History
One of the most important parts in a comprehensive eye exam is your patient health history. This information will alert your doctor to any conditions that should be monitored closely, such as an allergy to any medications, current or family history of systemic or eye pathology or environmental conditions that could be affecting your vision or eye health. This will also help your doctor to determine any preventative eye care measures that are relevant to keep your eyes healthy for years to come.
Visual Acuity
Visual acuity is a measurement of your vision using an eye chart, the Snellen Eye Chart. In this test the patient is seated at a standard distance and is asked to read letters or symbols of various sizes, which get smaller as you move down the chart. The results are the familiar ratio of 20/20, 20/40 etc. which is a comparison of your vision compared to the average person with good vision, which is typically 20/20. For example, a patient that has 20/40 vision, can only see at 20 feet what the normal person can see from a distance of 40 feet. This test is a preliminary test of how clearly you are seeing in each eye but it does not give you a prescription for corrective lenses.
Refraction
Those who don’t have 20/20 vision have what is referred to in most cases as a “Refractive Error.” The patient may have nearsightedness, farsightedness, astigmatism or other eye conditions that prevent the patient from seeing 20/20. A refraction will tell the doctor which prescription lenses will correct your eyesight to achieve 20/20 vision or whichever amount your vision is correctable to.
A refraction may include a couple of steps.
Retinoscopy
Retinoscopy is a test that allows the doctor to obtain an approximate prescription for eyeglasses. In this test the doctor uses a hand-held instrument called a retinoscope that shines a light into the patient’s eye. The doctor then analyzes the reflex of the light from the patient’s eye to determine the patient’s prescription for glasses.
An instrument called a phoropter is something most patients associate with an eye exam. This space age appearing instrument, positioned in front of the patient’s face during the eye exam, gives the doctor the ability to determine the patient’s focusing ability as well as their eye alignment. The phoropter also determines which, out of the hundreds and hundreds of potential eyeglass prescriptions, will help the patient see as clear as possible. Using the phoropter, the doctor will ask the patient which series of lenses makes their vision the clearest.
While retinoscopy is quite effective for children and nonverbal patients, there are now a number of computerized or automated instruments available today to help doctors accurately determine a patient’s eyeglass prescription.
Autorefractors and Aberrometers
Autorefractors and aberrometers are computerized machines that are able to measure your refractive error to determine your prescription for glasses or contact lenses. These instruments are usually used in addition to testing described earlier:
An autorefractor is similar to retinoscopy, which electronically analyses the light reflex from the patient’s eye.
An aberrometer measures distortions or aberrations in the cornea and lens of the eye that disrupt proper focus of light on the retina. Using wavefront technology, the instrument measures the rays of light as they pass through your eye to look for imperfections which may indicate a refractive error.
Eye Focusing and Eye Teaming Tests
During the comprehensive eye exam, your eye doctor will also want to test how your eyes function individually and together from a mechanical perspective. In order to see clearly and comfortably, your eyes need to work together as a team.
Eye Health
The final and most important aspect of a comprehensive eye exam is a check of your overall eye health. These tests (below) are done to identify any eye conditions or diseases, both inside the eye as well as the external parts of the eye, that could affect your vision and general health.
Slit Lamp Test
The slit lamp or biomicroscope is an instrument that allows the doctor to examine the internal and external parts of the eye in detail, such as the conjunctiva, iris, lens, cornea, retina and the optic nerve. The patient rests their forehead and chin on a headrest to stabilize the head, while the doctor looks into the eye with the slit lamp microscope, which is magnified with a high-intensity light. A slit lamp test enables the doctor to evaluate the eyes for signs of normal aging and eye pathology, such as conjunctivitis, cataracts, macular degeneration or retinal detachment. Early diagnosis and treatment of eye diseases are essential for preventing vision loss.
Tonometry
Tonometry is a test to detect glaucoma by measuring the pressure inside your eye or IOP (intraocular pressure). Glaucoma can cause vision loss and even blindness if the IOP in the eye is too high and damages the optic nerve.
The applanation tonometer, typically attached to a slit lamp, is one of the most common instruments used to measure the pressure in the eye. Prior to doing this test the doctor will numb the patient’s eyes using an anesthetic, before gently applanating (putting pressure on) the patient’s cornea to measure the pressure in the eye.
Pupil Dilation
During your comprehensive eye exam, your doctor may decide to do a dilated eye exam. In this test, your doctor will instill dilating drops in each eye, which would enlarge your pupils to give the doctor a better view of certain parts of the back of the eye. Dilation is done at the discretion of the doctor, with some patients dilated every year and others at specified intervals; the frequency of dilation will vary for each patient.
Typically the drops take around 20 to 30 minutes to take effect and may last up to several hours following the exam; each patient is different. Since more light enters your eyes when your pupils are dilated, you will be more sensitive to bright light, especially sunlight. Although your doctor may provide disposable sunglasses, you may want to bring a pair of sunglasses to wear after the exam to make it more comfortable until the drops wear off.
A comprehensive eye exam is an important part of your overall general health maintenance and should be scheduled on a regular basis. The findings from your comprehensive eye exam can give your doctor important information about your overall health, particularly diabetes and high blood pressure.