What To Expect From an Eye Examination
– Part II
Paul Chous, M.A., O.D. Doctor of Optometry
Type 1 diabetic since 1968
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).
All patients, diabetics included, should have their visual field checked
by professional examination regularly, as visual field loss can be very
subtle until severe damage has occurred (as in glaucoma). Such testing
also represents the least expensive and invasive technique for assessing
the integrity of the entire visual pathway (from eye to brain) and uncovering
much serious neurological disease.
At some point, the patient will be “refracted,” the process
through which a new eyeglass prescription is determined (‘tell
me which lens choice is better, choice #1 or choice #2’). 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.
All patients should have their eyes examined by a ‘slit lamp,’
a specialized microscope that gives the examiner a highly magnified
view of the eyes. 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?
Read Part One
Lessons
from a Diabetic Eye Doctor: How to Avoid Blindness and Get Great Eye
More Info:
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.
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