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Health Encylopedia

 
Standard ophthalmic exam
 
SubjectContents
Definition A series of tests performed by an ophthalmologist or optometrist (eye doctor) that measure the refraction and visual acuity of the eye and test for disease. (See also Refraction test .)
Alternative Names Routine eye examination; Eye exam - standard
How the test is performed The eye doctor will start by asking a series of questions about your medical and ocular history and any noticeable eye problems. Visual acuity (vision) is determined in each eye using the Snellen Chart. This chart consists of random letters of different sizes. The letters for normal vision (20/20) are 3/8-inch tall when viewed at 20 feet. People with normal vision can read these letters. A refraction test may also be performed where the doctor puts several lenses in front of the eyes to determine if glasses are needed. Eye movement (see extraocular muscle function ) and peripheral vision (see visual fields ) are tested by moving a light or object through the field of vision. The eye's reaction to light (pupillary response) is also measured. Color blindness is tested using multicolored dots that form numbers (see color vision test ). Color blind people are not able to detect certain numbers or may see a different number than people who are not color blind. Glaucoma testing ( tonometry ) is performed with a puff of air directed at the eye or using a blue circle of light that comes very close to the eye. Evaluation of the cornea and the front part of the eye is performed while seated at a slit lamp, a device which magnifies the doctors view. The retina , fundus (back of the eye), retinal vessels, and optic nerve head (optic disc) are viewed with an ophthalmoscope (a device made up of a light and magnifier). This procedure is known as an ophthalmoscopy . Drops that dilate the pupil are usually used to allow more of the fundus to be viewed.
How to prepare for the test Make an appointment with the eye doctor (some take walk-in patients). Avoid eye strain the day of the test. Arrange transportation, since your pupils will be dilated. Infants and children: The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
  • preschooler test or procedure preparation
  • (3 to 6 years)
  • schoolage test or procedure preparation
  • (6 to 12 years)
  • adolescent test or procedure preparation
  • (12 to 18 years)
  • How the test will feel The tests cause no pain or discomfort.
    Why the test is performed This test should be performed on a regular basis to detect eye problems early and help determine the cause of noticeable changes in vision . Some professions (such as pilots, military, personnel, and professional drivers) require eye tests. Various eye and medical problems can be found by a routine eye test. People with diabetes should have their eyes examined at least once a year.
    Normal Values
  • 20/20 (normal) vision
  • able to differentiate colors
  • no signs of
  • glaucoma
  • normal optic nerve, retinal vessels, and fundus
  • What abnormal results mean
  • glaucoma
  • myopia
  • hyperopia
  • damaged optic nerves, vessels, or fundus
  • astigmatism
  • presbyopia
  • corneal abrasion
  • (or dystrophy)
  • color blindness
  • strabismus
  • (motility disturbance between eyes)
  • eye diseases
  • cataracts
  • trauma
  • corneal ulcers and infections
  • blocked tear duct
  • amblyopia
  • (
  • lazy eye )
  • age related macular degeneration (ARMD)
  • diabetic retinopathy
  • What the risks are If your pupils are dilated during the ophthalmoscopy , vision will be blurred and sunlight can damage your eye. Wear dark glasses or shade your eyes to avoid discomfort.
    Special considerations Many eye diseases, if detected early, are curable or can be treated.