Eye Exam Types

Eye examinations are an essential part of maintaining the overall health of your eyes. When visiting the optometrist for an eye exam, you can get a basic physical examination, Wavefront and Refractory examination or a variety of other exams, depending on your needs. This article will review the basic procedures of an eye exam and discuss the various tests and their purposes.

Basic Eye Exams

The basic eye exam begins with a general examination of the health of the eye. The practitioner will ask about any eye problems a patient may be experiencing, as well as question him about his overall health.

Then, the doctor begins a basic physical examination of the eye. The doctor will use a light to examine the cornea, iris and pupil to determine if these parts of the patient’s eye are functioning correctly. During this exam, the doctor will also examine the shape of each eye, looking for any obvious defect.

Along with shape and appearance of the eye, the doctor also tests how well a patient’s eyes work together. Binocular acuity is very important for depth perception and field of vision. In this eye exam, the doctor will place his finger 12 to 14 inches in front of the patient and slowly move it from side to side. The doctor will be watching how a patient’s eyes follow the finger to determine if there is any problem with the eye muscles. This test also evaluates if one eye is compensating for problems with the other.

Visual Acuity Test

The visual acuity test is an integral part of any eye exam. In this test, the doctor will ask the patient to read a series of characters on a Snellen chart, which typically hangs on the wall 20 feet away. This test may also be done with an equivalent hand card held 14 inches away from the patient.

For this examination, each eye is tested independently to determine how sharp a patient’s vision is as compared to the average visual acuity. At the end of each line of characters is a number indicating the average distance from which those with normal vision can read the lines. These numbers indicate the denominator in the 20/20 rating. For example, if the patient cannot read the line at 200 standing at a distance of 20 feet, their eyesight would be in the 20/200 range. The ratio 20/20 represents perfect vision.

Refractory Tests

Refractory examinations are a part of the eye exam that determine the causes behind the lack of visual acuity (i.e., whether or not lack of acuity is due to refractory issues). The term “refract” means to bend. As a result, this test evaluates whether or not the eye can adequately perceive bent or changing light. Refractory problems (the eye’s inability to refract light and focus) can be affected by abnormalities in the length of the eye or the curvature of the eye’s surface.

The Pinhole test is a basic examination that determines if an eye problem is a result of refractory issues or something else. In the pinhole exam, a shield that only allows perpendicular light to enter is placed over the eye. This shield blocks any light that requires refraction to be viewed. The patient will be asked to view a Snellen chart both with the shield in place and without the shield. If they are able to read the chart with the shield in place, their vision problem is most likely refractory in nature.

Once the optometrist determines that the problem is refractory in nature, he will have the patient look through a device called a phoropter. This device has a series of lenses that the doctor can switch until the patient’s vision is clear. Once the patient is able to see clearly, the selected lenses determine the prescription she needs.

Wavefront Examination

Wavefront eye exams are a new method of determining refractory problems and of correctly diagnosing the corrective prescription. In this exam, the patient places his chin on a rest and looks into a machine with a point of light. The machine will measure how the light refracts as it passes through the eye. Once completed, the machine will analyze the data and print out a detailed report that lists any problems in the eye along with a specific prescription for correction.

Slit Lamp Examination

During the course of an eye exam, the doctor may use the Slit Lamp device to perform a more thorough examination of the structure of the patient’s eyes. The doctor will have the patient rest his chin on the device and then view the eyes’ structures using a high-powered light and magnifier.

The Slit Lamp allows an optometrist to see any abnormalities in both the front and back of the eye. This test can identify the presence of cataracts, macular degeneration and many other afflictions. The doctor may also drop an orange dye into the patient’s eye to see whether the patient has any cuts or scratches on the surface of the eye. The patient’s normal tears will wash out the dye.

Getting eye exams on a regular basis is extremely important not only to make sure that you have the proper prescription but also to identify the early stages of debilitating eye conditions. Because many common eye problems develop slowly over time, people don’t notice them until symptoms arise, which usually only happens in late stages of these conditions.

Visiting an eye clinic for annual comprehensive examinations allows eye doctors to quickly assess and correct small problems before they become serious. In many cases, such as incidence of cataracts and glaucoma, early detection can prevent the need for surgery in the future.