Due to inclement weather we will not be open on Wednesday March 21.
We will reopen on Thursday March 22 time to be announced
info@extonvisioncenter.com | 121 John Robert Thomas Dr, Exton, PA 19341
Exton Vision Center
Accepting New Patients
In the network with most insurance plans

Comprehensive Eye Exams

Why Are Eye Exams Important?

Many eye and vision conditions have no telling symptoms, so patients may be unaware a problem exists. Regular eye exams, which allow for early diagnosis and treatment, are essential for maintaining eye health and avoiding potential vision impairment or vision loss.

During the exam, we not only evaluate your vision to determine if there is a need for glasses or contacts (due to nearsightedness, farsightedness, astigmatism), but we also examine the health of your eyes. Example of health considerations are dryness, focusing problems, eye diseases such as glaucoma, and systemic diseases like diabetes. From the results of your extensive examination, we will recommend treatment vital to maintaining the health of your eyes.

What to Expect During a Comprehensive Eye Exam?

Your comprehensive eye exam will feature a variety of tests that range from simple to complex. Each procedure helps to evaluate the overall health, strength, and vision of your eyes. The comprehensive eye exam can also expose potential risks for developing certain eye and systemic diseases.

Tests performed during the comprehensive eye exam are intended to examine all parts of your eye. These tests may include muscle tests, visual acuity tests, tests for color blindness, visual field tests, glaucoma tests, and in some cases, specialized tests recommended by your doctor. Read more

Visual Field Testing

During your routine eye exam, the eye doctor may want to determine your “side vision” or what you can see peripherally. We may use confrontation visual field testing, during which one of your eyes is covered, and your other eye focuses on an object in front of you. The doctor then holds up a number of fingers in your peripheral view and asks you how many fingers he or she has up.

You may need to undergo more comprehensive, formal types of visual field testing with automated equipment.

Color Deficiency Tests

Are you truly seeing a full spectrum of color? Your eye doctor can determine if you are. Color deficiency can be diagnosed through a series of tests. The most common screening test is called the Ishihara Color Vision Test. This test consists of a series of circular plates embedded with colored spots; these spots form a numerical pattern that cannot be seen by someone who is color deficient.

Contrast Sensitivity Test

Contrast sensitivity testing is very important to the health of your eyes. During this test, we will examine the acuity of your eyes—your ability to distinguish objects of similar color, and your ability to differentiate between lights and darks. Individuals who suffer from poor contrast sensitivity may have trouble performing tasks like night driving, and may suffer from eye strain in poorly lit environments.

Eye Exam Cost and When To Have an Eye Exam

A routine eye exam is paramount to your vision and eye health. It is recommended that you schedule a comprehensive eye exam on a regular basis, according to the doctor's recommendation. This may depend on many factors, including age, risk factors for eye diseases, and whether you currently wear glasses or contacts. Because vision plays a large role in the cognitive development of children, we recommend regular eye exams for children as well.

The fee for an eye exam varies, depending on the tests included and if the exam involves contact lenses. Many vision plans cover a portion of eye care services. Please refer to your insurance information before you schedule an appointment.

How To Read Eyeglass Prescriptions

At first glance, your prescription may be confusing with some unfamiliar abbreviations and numbers. But with the information listed here, you'll be seeing a lot clearer.
  • OD represents your right eye.
  • OS represents your left eye.
  • OU refers to both eyes.
  • Sphere (SPH): This number represents strength of nearsightedness or farsightedness.
  • Cylinder (CYL): This number represents the amount of curvature/astigmatism (blur due to the shape of the cornea) in the eye.
  • Axis: This number represents the direction of the curvature of the eye surface. This number ranges from 1 to 180.
  • Add: This number represents ‘added' power needed to focus in on close range activities--like reading, and is used for bifocal/trifocal prescriptions.
  • Prism: Very few prescriptions indicate prism, but this is prescribed to correct patients who suffer from eye muscle and/or focusing imbalances.
Remember, your glasses prescription does not entitle you to contact lenses and is strictly for the purchase of eyeglasses. If you're seeking contact lenses, you will have to set up a separate examination with your eye doctor.

Refractive Errors and Refraction: How the Eye Sees

Your eyes are windows to the world. We see when light reflects off objects and enters our eyes, passing through the clear outer cornea, the lens, and then creating an image on the retina which is transmitted to the brain. Refractive errors cause this image to be distorted or blurred. The most common types of refractive errors are nearsightedness, farsightedness, and astigmatism.

After an extensive eye examination, common refractive errors can be corrected with prescription eyeglasses or contact lenses. You can also treat refractive errors with LASIK, PRK, Visian ICL, and other correction surgeries. Eyesight is precious and should never be taken for granted. That's why it's important to schedule a routine comprehensive eye exam with your eye doctor.

The Eye Chart and 20/20 Vision

There are a number of different eye charts which can determine how well you see from a distance. The classic example is the Snellen eye chart. The Snellen eye chart shows 11 rows of capital letters which get progressively smaller as you read from top to bottom. The 20/20 line is usually the third line from the bottom. 20/20 vision is considered “normal,” and means that you are able to read a letter from 20 feet away that most people should be able to read at 20 feet away. Eye charts in offices are calibrated for different test distances, so that the rooms do not have to be 20 feet long.

Glaucoma Management

Glaucoma is a disease of the optic nerve, associated with an increased pressure in the eye, that typically progresses with no symptoms and can lead to vision loss. We screen for glaucoma at the time of your comprehensive eye exam with eye pressure measurements and evaluation of the optic nerve. If glaucoma is suspected, additional testing may be required such as visual field testing, optic nerve imaging and analysis, and corneal thickness. Once diagnosed, our eye doctors may manage glaucoma with medication or in other cases, refer patients to highly skilled glaucoma specialists.

Full Service Optical Dispensary

We have added additional experienced optical team members who can advise our patients on the best options available for them.

Our dispensary offers the most up to date technology in ophthalmic lenses and carries the latest in fashion and designer frames. We also provide safety and sports wear as well as prescription sunglasses to help patients with all of their eyewear needs.

We will ensure that your glasses are fitted properly and handle any necessary repairs.

Cataract Testing

Cataracts cause varying degrees of visual loss. The main indication for cataract surgery is when a person's visual function no longer meets his or her needs and cataract extraction will provide improved vision. This level of visual impairment is subjective and differs considerably among individuals. Nevertheless, insurance carriers typically choose 20/40 Snellen visual acuity as the threshold for cataract surgery, since this level of sight is required for driving. However, visual acuity can be quite variable depending upon the testing conditions, test distance, and type of cataract. Therefore, it may be difficult to appreciate the impact of a cataract on the patient's vision especially when he or she can see better than 20/40.

We are often limited in our ability to adequately comprehend what a patient describes as decreased, blurry, or poor vision, because we can only test isolated components of visual function like Snellen acuity, contrast sensitivity, glare, color vision, and visual field. These tests give us incomplete information about a patient's visual performance. For example, a patient may see 20/20 in each eye, but complain that while the ... Read more
Visual acuity is tested monocularly with high contrast (i.e., black letters on a white background). While this is the standard method of assessing vision, it is quite artificial and is not representative of real world conditions. Contrast sensitivity testing is more realistic but less commonly measured. Contrast sensitivity evaluates the ability to differentiate between an object and its background using low contrast letters or sine-wave gratings with different spatial frequencies. Whenever visual acuity is decreased, so is contrast sensitivity, but sometimes contrast sensitivity can be affected significantly more than visual acuity. Therefore, to better assess a patient's visual difficulty, contrast sensitivity should be tested when the visual acuity is better than expected based on the patient's complaints.

Another helpful measurement is glare testing. This is often performed with a brightness acuity test (BAT) to simulate glare from a light source. Patients with cataracts may have good distance visual acuity in a dim room, but experience a significant reduction in acuity from a bright light. This is the characteristic situation with a central posterior subcapsular cataract that scatters light and blocks the entrance pupil when the pupil constricts.

Other tests can be performed to assess the visual potential in a cataract patient with coexisting ocular pathology or to rule out macular or optic nerve pathology when the cataract interferes with a clear view of the posterior pole. The potential acuity meter (PAM) test projects an eye chart directly onto the retina through lens opacities. This is often useful in estimating how much the cataract is contributing to the patient's visual loss. Alternatively, color vision can be used to assess the optic nerve and macula. Color vision testing is a sensitive indicator of optic nerve function and can be tested quickly with Ishihara pseudoisochromatic or Hardy-Rand-Rittler plates. In addition, gross macular function can be evaluated with red perception by asking the patient to identify the color of a red eye drop cap. Optical coherence tomography (OCT) is probably the most helpful test for diagnosing macular pathology, especially subtle findings and when a premium IOL implant is being considered. Visual field testing is also helpful since it will identify scotomas from suspected retinal or optic nerve pathology. The presence of generalized depression in an otherwise normal field test is characteristic of a significant cataract. Finally, we should not forget the basics: pupil testing is performed in all patients with decreased vision because the presence of a relative afferent pupillary defect indicates optic nerve or widespread retinal dysfunction.

Therefore, although we usually diagnose a visually significant cataract from the patient's symptoms, the Snellen acuity, and the presence of a cataract on slit-lamp examination, there are a variety of other tests at our disposable. These are particularly helpful when the visual acuity is better than expected, the acuity does not correlate with the severity of the patient's visual complaints, or there is other ocular pathology that may be contributing to the reduced vision.

Fundus Photography

Don't be surprised if someday, your eye doctor orders photographs of the back of your eye. These pictures are necessary to document the health of the optic nerve, vitreous, macula, retina and its blood vessels. The photographs are used for comparison, documentation, and sometimes to diagnose certain eye conditions.

Because fundus photography is a highly specialized form of medical imaging, it can't be done with an ordinary camera. It requires a customized camera that is mounted to a microscope with intricate lenses and mirrors. These high-powered lenses are designed so the photographer can visualize the back of the eye by focusing light through the cornea, pupil and lens.

Before beginning, the pupil is dilated with drops. Otherwise, it would automatically constrict from the bright light of the camera flash. The patient is asked to stare at a fixation device so the eyes are still. While the photographer is taking the pictures, the patient will see a series of bright flashes. The entire process usually takes approximately five to ten minutes.