Monday, 23 July 2012

An ophthalmic exam

An ophthalmic exam is a series of tests done to check your vision and the health of your eyes.

How is performed

First, you will be asked by the eye doctor if you are having any eye problems. You will be asked to describe these problems, how long you have had them, and any factors that have made them better or worse.

If you wear, your history of glasses or contact lenses will also be reviewed. The eye doctor will then ask questions about your overall health, including any medications you take and your family's medical history so he’ll see if you may have a condition that’s triggering your vision problems.

Next, the doctor will check your visual acuity using a Snellen chart:

  • You will be asked to read random letters that become smaller line by line as your eyes move down the chart. Newer electronic devices have been developed that check vision in a way similar to a Snellen chart.
  • To see if you need glasses, the doctor will place several lenses in front of your eye, one at a time, and ask you when the letters on the Snellen chart become easier to see.

Other parts of the exam include tests to:

  • See if you have proper 3D vision (stereopsis)
  • Check your peripheral vision
  • Check the eye muscles by asking you to look in different directions at small object
  • Examine the pupils with a penlight to see if they respond properly to light

To see inside your eye, the doctor looks through an ophthalmoscope. The device allows the doctor to see the retina and nearby blood vessels, the back of the eye (fundus) and the optic nerve area.

Often, you'll be given eye drops to dilate your pupils so that the doctor can view better the structures in the back of the eye.

Another magnifying device called a slit lamp is used to:

  • See the clear surface of the eye (eyelids, cornea, conjunctiva, sclera, and iris)
  • Check for glaucoma using a method called tonometry
  • Color blindness is tested using multicolored dots that form numbers.

How to Prepare for the Test

Make an appointment with an eye doctor (some take walk-in patients). Avoid eye strain on the day of the test. You may need someone to drive you home if the doctor uses eye drops to dilate your pupils. The tests cause no pain or discomfort.

All children should have vision screening in a pediatrician office around the time they learn the alphabet and then every 1 to 2 years. Screening should begin sooner if any eye problems are suspected. Between ages 20 and 39 a complete eye exam should be done every 5 to 10 years and adults who wear contact lenses often need early eye exams. Also, certain eye symptoms or disorders may require more frequent exams. Adults over age 40 who have no risk factors or ongoing eye conditions should be screened every 2 to 4 years (ages 40 - 54), every 1 to 3 years (ages 55 - 64) or every 1 to 2 years (age 65 and older)

Various eye and medical problems can be found by a routine eye test, including cataracts, diabetes, glaucoma, high blood pressure or macular degeneration.

Results - what is normal and what not

Normal Results

  • 20/20 vision
  • Ability to identify different colors
  • Full visual field
  • Proper eye muscle coordination
  • Normal eye pressure
  • Normal eye structures (cornea, iris, lens, etc.)

Abnormal Results may be due to:

  • Age-related macular degeneration
  • Astigmatism
  • Blocked tear duct
  • Cataract or glaucoma
  • Color blindness
  • Corneal abrasion, ulcers and infections
  • Damaged nerves or blood vessels in the eye
  • Diabetic retinopathy
  • Hyperopia, myopia, presbyopia
  • Lazy eye (amblyopia)
  • Strabismus
  • Trauma

If you received drops to dilate your eyes your vision will be blurred and the sunlight can damage your vision. So wear dark glasses or shade your eyes to avoid discomfort until the dilation wears off, usually in several hours. Because of this you won’t be able to drive for a couple of hours so you should not come alone at the eye doctor.

No comments:

Post a Comment