Tests Commonly Performed During an Eye Exam
Regular eye exams play a crucial role in maintaining healthy eyes for life. In this post, Dr. Gregory Johnson and Dr. Gail Kelley of Intracoastal Eye explain some of the tests that are commonly performed during a routine eye exam.
Visual acuity refers to the sharpness of a person’s vision. We test visual acuity using the Snellen eye chart, which contains lines of letters that progressively get smaller.
The patient stands about 20 feet away from the chart and reads the last line that is visible while covering one eye. Then, the patient repeats the test covering the opposite eye. If the patient wears glasses, he or she is asked to keep them on while completing the test.
Each line correlates with a specific value. The last line the patient is able to read clearly indicates his or her visual acuity. For example, if the last line the patient can read is the 20/20 line, that means he or she can see at 20 feet what a normal eye can see. Each eye receives its own value.
The visual field test measures how much a person can see while looking forward. The test checks for blind spots in peripheral (side) vision.
The cover test evaluates how a person’s eyes work together. The patient is asked to look at objects at different distances with one eye covered; the doctors then observe the uncovered eye to determine whether it must move to focus on the object. If so, there may be a problem with eye alignment.
For patients who wear glasses or contacts, retinoscopy allows us to approximate their prescription. During the test, the patient is asked to focus on a large target as we shine a light at the eyes and flip lenses in front of the eyes. We observe the way light reflects from the eyes to help us estimate the power of eyeglasses the patient needs.
Refraction helps us fine-tune a patient’s exact vision prescription. We flip back and forth between different lens choices and ask the patient which one looks better. We do this several times before determining his or her final prescription.
Slit Lamp Exam
A slit lamp is a microscope that we use to look at the structures inside the eye, like the cornea, iris and lens. The slit lamp exam can reveal problems suggesting cataracts, corneal ulcers and diabetic eye disease.
The glaucoma test measures the pressure inside the eyes. There are a few ways to test for glaucoma; the most common way involves puffing a small burst of air at the patient’s eye and calculating intraocular pressure based on the way the eye resists the air.
A retinal examination evaluates the back of the eye, including the retina, macula and vitreous. We must dilate the pupils with special drops to get a clear view of the retina. This is not painful and the effects of the drops wear off within a few hours.
Book Your Next Eye Exam
If you are ready to book your next eye exam with the doctors at Intracoastal Eye, we invite you to call or email us today.