During Vision Health Month, CNIB has been promoting the need for people to have their eyes examined by an eye doctor as the best way to ensure their vision health. It is estimated that seventy five percent of vision loss can either be prevented or treated. Early diagnosis and treatment of eye diseases goes a long way toward mitigating vision loss as a result of eye disease.
So what actually happens when you go see an eye doctor?
Firstly, if you haven’t had your eyes examined recently, the eye doctor will ask you a lot of questions about your eyes and your lifestyle. It helps to be prepared. Make sure you have a list of things you want to discuss with the eye doctor either about your eyes or your general health. If your parents or siblings have an eye disease, make sure that you tell your doctor, as many eye diseases have a genetic component. It is important that your doctor know this. If you don’t know your family eye disease history, ask your family before you visit the doctor. If you are taking any medications for any reasons, bring the doctor either a list of the medications or all of the medications themselves, in their original containers. Some systemic medications may have ocular effects. Finally, if you have been treated for an eye disease in the past, let your eye doctor know when you have your initial discussion.
After talking with you, the doctor most likely will put your eyes in front of an instrument called a slit lamp microscope. This is an instrument that permits the doctor to have a close look at the surface and inside of your eye and will help him or her detect whether there is any eye disease present. By an attachment to the slit lamp, it is also possible for the doctor to measure the pressure within your eye, to see if you have elevated pressure within the eye - one of the major risk factors for glaucoma. Before the doctor does this, they will probably put a drop of anesthetic onto the surface of your eye. This will sting a bit. They will also put a drop of dye onto the eye that will fluoresce in the blue light of the slit lamp and enable the doctor to measure the pressure within your eye.
Based on the results of this test your eye doctor may recommend you have a visual field test which may be done at the same appointment, or you may be referred to another centre for this test. A visual field test checks whether there are any areas within your central or peripheral fields of vision where your vision may be reduced due to some type of damage.
To fully examine the back of your eye, the doctor will probably want to dilate your pupil. To do this they will also put a drop or two of a dilating eye drop onto the surface of your eye. It will take a few hours for the effect of the dilating drop to wear off, so make sure you bring sunglasses with you to your examination. A dilated pupil lets in a lot of light and this can be dazzling if you don’t have sunglasses. Also, try to arrange for someone to drive you home while your pupils are dilated, as your vision will be somewhat reduced for a few hours.
Some eye doctors may take “pictures” of the back of your eye using a variety of instruments. Feel free to ask the doctor what the instruments are and what they are being used for. One of these instruments provides a picture of the retina (the tissue at the back of the eye). Another is able to image the various layers within the retina itself. It can tell if there is damage to the retina long before it becomes obvious to either the patient or the doctor. Finally, some doctors may have an instrument that takes similar pictures of the head of the optic nerve, to see if there is any damage to the optic nerve as a result of glaucoma.
The tests I have discussed so far assess your eye health. Your eye doctor will, of course, also want to assess your vision. To do this they will first check you out for basic eye movement and for colour vision. Your visual acuity (your ability to see near or far) will also be assessed using an eye chart for distance and a different one for near vision. This is the same chart we all were asked to read when we were assessed at school or in our family doctor’s office. You will be asked to read letters on these charts, from which the doctor will be able to tell you what your visual acuity is. This reading is written as a fraction such as 20/20 or 20/40. The top number is the distance at which the test is done (20 feet). If you have 20/40 vision this means you will have to stand at 20 feet to see what someone with normal vision sees at 40 feet.
The eye doctor will then conduct what is called a refraction. This is done with an instrument called a phoropter which contains a number of different lenses. The doctor will place a series of lenses in front of your eyes and ask you which one of a pair of lenses looks clearer. By doing this the doctor will come up with your final eyeglasses prescription, which will tell if you are nearsighted, farsighted, have astigmatism or presbyopia.
Finally, make sure you ask your eye doctor when you should return for your next examination. Make an appointment even if it is a year or two away, and put it in your calendar. It is the most important thing you can do to take care of your vision health.