Adult Eye Exams
During Your Eye Exam continued...
Retinoscopy: The eye doctor may shine a light in your eyes and flip lenses in a machine (phoropter) that you look through while staring at a large target, such as a big "E," or the doctor may use an automated machine (refractor) for the same purpose. By checking the way light reflects from your eyes, the doctor gets an approximate idea of the lens prescription you need now.
Refraction testing: For your exact lens prescription, the eye doctor may use the results of the computerized refractor, or he or she may fine-tune the prescription manually by asking you to respond to questions such as, "Which is better, this or that?" while flipping back and forth between different lenses. If you don't need corrective lenses, you won't have this test.
Slit lamp (biomicroscope): The slit lamp magnifies and lights up the front of your eye. The eye doctor uses it to detect several eye diseases and disorders by examining your cornea, iris, lens, and anterior chamber.
Retinal examination (ophthalmoscopy): Using an ophthalmoscope and pupil dilation, the eye doctor examines the back of your eyes: retina, retinal blood vessels, vitreous, and optic nerve head.
Glaucoma testing: This tests whether the fluid pressure inside your eyes is within a normal range. Painless and taking just a few seconds, the test can be done several ways.
- The tonometer test: This is the most accurate. With drops numbing your eyes, you stare directly ahead. The eye doctor barely touches the front surface of each eye with an instrument called an applanation tonometer or Tonopen to measure the pressure.
- The "puff of air" or non-contact tonometer test: While you focus on a target, you get a small "puff" of air in each eye. Resistance to the air puff indicates the pressure.
Pachymetry: This test uses ultrasound to measure corneal thickness. Thin corneas can lead to falsely low pressure readings and thick corneas can lead to falsely high pressure readings. This test is done just once to create a baseline for future testing. Pachymetry may be needed if you are being considered for corneal surgery.
Pupil dilation (enlargement): With your pupils fully enlarged, the eye doctor will examine the inside of your eyes with different instruments and lights. The pupil-enlarging drops for this part of your eye exam start to work after about 20-30 minutes, making your eyes more sensitive to light and blurring your vision. These effects may last for several hours or longer so it's important to bring a pair of sunglasses to your exam for the ride home.
Visual field test (perimetry): Your visual field is the area you can see in front of you without moving your eyes. Using one of three tests, the eye doctor "maps" what you see at the edges (periphery) of your visual field, using this map in diagnosing your eye condition.