There are several parts to the exam:

Visual acuity test
This uses an eye chart to measure how well you can distinguish object details and shape at various distances. Perfect visual acuity is 20/20 or better. Legal blindness is defined as worse than or equal to 20/200 in both eyes.  

Slit-lamp examinationSlit-lamp exam
A type of microscope is used to examine the front part of the eye, including the eyelids, conjunctiva, sclera, cornea, iris, anterior chamber, lens, and also parts of the retina and optic nerve.  

Dilated exam
Drops are placed in your eyes to widen, or dilate, the pupil, enabling your Eye M.D. to examine more thoroughly the retina and optic nerve for signs of damage.




It is important that your blood sugar be consistently controlled for several days when you see your eye doctor for a routine exam. If your blood sugar is uneven, causing a change in your eye's focusing power, it will interfere with the measurements your doctor needs to make when prescribing new eyeglasses. Glasses that work well when your blood sugar is out of control will not work well when your blood sugar level is stable.

Your Eye M.D. may find the following additional tests useful to help determine why vision is blurred, whether laser treatment should be started, and, if so, where to apply laser treatment.  

Fluorescein angiography
Your doctor may order fluorescein angiography to further evaluate your retina or to guide laser treatment if it is necessary. This is a diagnostic procedure that uses a special camera to take a series of photographs of the retina after a small amount of yellow dye (fluorescein) is injected into a vein in your arm. The photographs of fluorescein dye traveling throughout the retinal vessels show:
•   Which blood vessels are leaking fluid;
•   How much fluid is leaking;
•   How many blood vessels are closed;
•   Whether neovascularization is beginning.  

Optical coherence tomography (OCT)
OCT is a non-invasive scanning laser that provides high-resolution images of the retina, helping your Eye M.D. evaluate its thickness. OCT can provide information about the presence and severity of macular edema (swelling).




If your ophthalmologist cannot see the retina because of vitreous hemorrhage, an ultrasound test may be done in the office. The ultrasound can "see" through the blood to determine if your retina has detached. If there is detachment near the macula, this often calls for prompt surgery.  

Doctor and PatientWhen your diabetic retinopathy screening is complete, your ophthalmologist will decide when you need to be treated or re-examined.  

If you have diabetes, you should see your ophthalmologist right away if you have any visual changes that affect only one eye, last more than a few days, and are not associated with a change in blood sugar.  

When to schedule an eye examination

Diabetic retinopathy usually takes years to develop, which is why it is important to have regular eye exams. Because people with Type 2 diabetes may have been living with the disease for some time before they are diagnosed, it is important that they see an ophthalmologist (Eye M.D.) without delay.  

The American Academy of Ophthalmology recommends the following diabetic eye screening schedule for people with diabetes:  
Type 1 Diabetes: Within five years of being diagnosed and then yearly.
Type 2 Diabetes: At the time of diabetes diagnosis and then yearly.
During pregnancy: Pregnant women with diabetes should schedule an appointment with their ophthalmologist in the first trimester because retinopathy can progress quickly during pregnancy.  

Watch patients and an Eye M.D. talk about the importance of an annual diabetic eye exam.





Written by
Reviewed by Dr. Robert H. Janigian Jr. on Sept. 1, 2013

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