What a thorough eye test will cover

Tuesday, September 29th, 2009 at 1:38 pm Post in Eye Exams and Vision Screening

A comprehensive eye exam contains several tests, from simple eye chart reading to tiny structure visualization. Some factors play a role in deciding the exam time, such as caseload and test complexity.

Retinoscopy is always used to get an approximation of your prescription. You will be required to fixate on a large target and receive a light shined by the doctor. By changing lenses in front of your eyes and interpret the light reflects from your eyes, the doctor can work out the general prescription of your eyes.

Refraction is for precise prescription, which uses a phoropter to switch different powered lenses. From your vision response to these lenses, the doctor can determine your final exact prescription for farsightedness, nearsightedness, astigmatism or presbyopia.

An autorefractor or aberrometer with wavefront technology can be used to evaluate the way your retina refracts light rays, and then your wavefront map can be formulated. This test is convenient since it only requires the people to rest their chin on the machine.

Amblyopia potential risks such as strabismus and turned-eye can be searched out by a cover test, which is the simplest and most common. The test requires you to focus on a distance object and alternately cover each of your eyes. The doctor can get useful information by observing the way your eye moves.

The slit lamp also uses a chin rest to stabilize the patient and shines its light at him. The doctor looks through a set of oculars to get the highly magnified images of the patient’s eye lids, cornea, conjunctiva and iris, in order to find any sign of infection or disease. With a high-powered lens, more complex eye diseases such as cataracts, macular degeneration, corneal ulcers and diabetic eye disease can be detected, by viewing retina, optic nerve and macula.

Glaucoma tests are used to measure your eye’s pressure. By puffing an air burst at your open eye and evaluate its resistance, the commonly used non-contact tonometer can calculate your intraocular pressure. The process is painless and you just need to rest your chin. Another machine used to measure the intraocular pressure is an applanation tonometer, which is always mounted on the slit lamp. Numbed by a yellow drop, each of your eyes will be touched by a bright-blue glowing instrument, which manually measures your intraocular pressure. Unlike non-contact tonometry, applanation tonometry may bring probe tickle on your eyelashes. Glaucoma tests are important for long-term eye health.

A visual field test screens your peripheral vision to find the presence of blind spots, which may be caused by glaucoma. Stroke or tumor caused brain damage can be located by analyzing blind spots.

For better viewing of your eyes inside structures, the doctor may put different strength dilating drops in your eyes. After 20 to 30 minutes, the drops will widen your pupils and make you sensitive to light. Within the following hours, the doctor can use instruments and light sources to examine your eye’s internal components, in order to find potential eye diseases. You need a pair of sunglasses to protect your weak eyes from sun light on your way home.

Besides the above common tests, contact lenses evaluation, LASIK work-ups and pediatric exams can be additional items, depending on your personal needs. For precise results, you should strictly follow your doctor’s instructions.