Ask Dr. K: Regular eye exams can catch diseases early

DEAR DOCTOR K: How often should I have my eyes examined? What will the doctor check for during the exam?

DEAR READER: Routine examinations in people without known eye diseases, and who don’t have hereditary eye diseases in their families, usually are done by optometrists. You should have your eyes examined every two to four years between the ages of 40 and 64, and then every one to two years after that.

But this is just a general recommendation, as no one size fits all. You may need more-frequent eye exams depending on your personal or family medical history.

The exam usually starts with vision tests. First, you’re asked to look at rows of letters and numbers that keep getting smaller until you can no longer see them clearly. If you do not have optimal vision (20/20), the doctor will test whether different lenses can sharpen your vision and make it 20/20. That’s the basis for fitting you with corrective lenses (normal glasses or contact lenses).

After testing how well you see, the doctor will begin to examine your eyes themselves. First comes an examination of your outer eye. The doctor will look for signs of any underlying problems, such as infections, sties, cysts, tumors or lid muscle weakness.

Then comes an examination of the inside of your eye as seen through your pupil. The more wide open the pupil is, the easier it is to see inside the eye. For that reason, the doctor will apply eye drops to dilate your pupils.

First, the doctor examines the lens, which sits just behind the pupil. Is it crystal clear or does it have areas that are cloudy or opaque – called cataracts?

Next comes the retina, a flat layer of cells in the back of the eye. The image formed as light enters your eye is focused on the retina.

Finally, eye pressure is measured to detect signs of glaucoma. This can be done with an “air puff” test. Alternatively, after your eye is numbed with anesthetic drops, the doctor will gently touch your cornea with an instrument to measure the eye’s internal pressure.