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What To Expect From an Eye Examination – Part II

Posted: Wednesday, May 05, 2004

In Part I, we considered some core elements of a professional eye examination, including case history, visual acuity, ocular motility, color vision and pupil reactions. Here are some additional fundamental components.

A test of peripheral vision may be given, which may be as simple as detecting the number of fingers the examiner is holding up, or as sophisticated as a computerized ’visual field’ test that more precisely determines the extent and sensitivity of a patient’s peripheral vision in relationship to thousands of other patients (a normative database). integrity of the entire visual pathway (from eye to brain) and uncovering much serious neurological disease.

No part of an eye examination is probably more frustrating to patients than this test: Oftentimes, neither of the two choices is clear, or both choices look identical. Take heart - this is entirely normal; the test intentionally forces the patient to pick between ‘crummy choices’ or choices that look virtually the same. Also, no one answer counts very much at all. The examiner is looking for consistency and will show the same choices repeatedly (even though you may not be aware of it!) When the test is completed, the prescription almost always is correct, and vision will be as clear as the patient is capable of seeing. If the doctor is a sub-specialist, such as a retina or glaucoma sub-specialist to whom your regular eye doctor has referred you, refraction may or may not be done.

Several points about ‘refraction’ should be of particular interest to diabetic patients. Changes in blood sugar can have a dramatic impact upon your prescription, so it is important that you and the doctor know if your overall blood sugar control is good (as reflected by recent HbA1c testing), and if your blood sugar level the day of the eye exam is high, low or relatively normal (as reflected by home blood glucose testing that day). Dramatic prescription changes may be the result of poor glycemic control, which should be corrected before getting a new eyeglass or contact lens prescription.

Diabetics sometimes have more difficulty than usual discriminating between the various choices presented during refraction. This may be due to loss of contrast sensitivity from keratopathy, cataract, or retinopathy (I personally prefer to perform a specialized test of contrast sensitivity on all diabetics.) Decreases in nearsightedness, or increases in farsightedness, especially in one eye more than the other, are often signs that the patient has diabetic macular edema and should alert the patient and doctor to this possibility.

The patient places her chin on a chinrest, and a bright (slit of) light is shined on various parts of the eye, including the cornea and conjunctiva, the iris, the lens, the anterior vitreous, the tear ducts and the eyelids. This allows the doctor to detect any sign of diabetic cataract, keratopathy, abnormal blood vessel growth on the iris (the cause of ’neovascular glaucoma’) or blood cells that might signal vitreous hemorrhage. A fluorescent dye may be dabbed into the eyes, which is especially useful for detecting keratopathy of the corneal epithelium. Measurement of intraocular pressure (tonometry) also may be performed with this instrument, a similar hand held device, or a machine that blows a ‘puff’ of air at the cornea. Examination of the eye’s internal drainage canal, with a specialized, mirrored contact lens, may also be performed at the slit lamp microscope.

Eye drops should be placed into the eyes that dilate the pupils. Drops typically take 15 to 30 minutes to work, cause blurred vision and make patients more sensitive to light. Once the pupils are dilated, the internal eye is examined once again with the slit lamp microscope, very powerful hand held lenses or other instruments which allow the doctor to visualize the posterior vitreous, optic nerve and retina in considerable detail. A combination of techniques and instruments is often used to ensure completeness. Use of the slit lamp microscope to view the retina and optic nerve is very important, because the doctor is able to use both of her eyes to examine the patient in stereo (3-D), a feature which is critical for assessing diabetic macular edema, as well as optic nerve cupping from glaucoma.

The eye doctor may recommend other tests depending upon the patient’s particular diagnosis, including retinal or optic nerve photographs to document baseline findings and subsequent changes, more sophisticated visual field testing, or a retinal dye test called “fluorescein angiography” (a fluorescent dye is injected into the vein of a patient’s arm, and travels to the blood vessels of the retina which are photographed, allowing the doctor to evaluate retinal circulation.) After all tests have been completed, the eye doctor should explain her findings and treatment recommendations to the patient in understandable detail, and ensure the patient’s questions are answered. Sometimes, the patient may be referred to an ophthalmic sub-specialist for further evaluation.

At the conclusion of the eye exam, every patient should know her diagnosis, be informed of various available treatment options as well as the doctor’s recommended treatment plan, the prognosis for her condition, and exactly when she should have an eye examination again. For the diabetic patient, special emphasis is placed on those findings pertaining to ‘diabetic eye disease.’ The doctor should discuss the need for prescription lenses, including any changes in prescription, particularly as those changes relate to diabetic cataract or retinopathy. The patient should be advised as to the presence or absence of any eye muscle abnormalities due to diabetic cranial neuropathy, as well as the presence or absence of diabetic keratopathy, cataract, glaucoma or other optic neuropathy, and retinopathy or other retinal abnormality.

If diabetic eye disease (or any eye disease) is detected, the doctor’s recommendations and treatment plan should be explained in detail (written instructions are ideal), the next appointment date should be established (always one year or less) and a letter describing the patient’s eye exam findings should be sent promptly to each of her doctors. All of the patient’s questions should be encouraged and answered, and the doctor’s availability to answer future questions firmly established.

It is the eye doctor’s professional and ethical responsibility to be thorough, knowledgeable, and caring, and to know her limits if there is some aspect of a given patient’s care with which she is not totally familiar and comfortable. Consulting with a diabetic patient’s other health care providers, or referring that patient to another eye doctor who has more experience with a particularly unusual or difficult problem, are not signs of inexperience, but of excellent professional judgment.

I will close this discussion with some key questions that I believe every patient with diabetes should ask her eye doctor:

Questions to Ask Your Eye Doctor

1. Do you have a lot of experience with diabetes and its various effects on the eyes?
2. Do you (or do other doctors in your practice) have any special interest in diabetic eye disease?
3. Do I have any signs of diabetic eye disease? Do I have any cataract, glaucoma, corneal problems, retina problems or eye muscle problems that are being caused by diabetes?
4. Has my eyeglass prescription changed significantly? If it has, is it likely caused by poor blood sugar control?
5. If I don’t have any diabetic eye disease, when do you want to see me again?
6. If I do have diabetic eye disease, how do you recommend we manage or treat it? When do you want to check my condition again? Are you experienced with the surgical or laser treatment of diabetic eye disease? If my condition worsens, will you refer me to a sub-specialist?
7. Do you have any recommendations on how to avoid or reduce eye complications from diabetes?
8. Will you send a report of your diagnosis and recommendations to my other doctors? Would you like me to ask my diabetes doctor to send you a report of her findings and recommendations?

Lessons from a Diabetic Eye Doctor: How to Avoid Blindne ss and Get Great Eye

Dr. Paul Chous received his undergraduate education at Brown University and the University of California at Irvine, where he was elected to Phi Beta Kappa in 1985. He received his Masters Degree in 1986 and his Doctorate of Optometry in 1991, both with highest honors from the University of California at Berkeley. Dr. Chous was selected as the Outstanding Graduating Optometrist in 1991. He has practiced in Renton, Kent, Auburn and Tacoma, Washington for the last 12 years, emphasizing diabetic eye disease and diabetes education. Dr. Chous has been a Type 1 diabetic since 1968. He lives in Maple Valley, Washington with his wife and son.