How Is Diabetic Retinopathy Diagnosed?
Diabetic retinopathy is diagnosed through an eye examination. Your eye care specialist, or ophthalmologist, checks your retina for early signs of the disease, including:
- Leaking blood vessels.
- Retinal swelling (macular edema).
- Pale, fatty deposits on the retina–signs of leaking blood vessels.
- Damaged nerve tissue.
- Any changes to the blood vessels.
Diabetic retinopathy and macular edema are detected during a comprehensive eye examination that includes:
- Fluorescein angiography. Patients with diabetic retinopathy may undergo fluorescein angiography to assess blood flow in the retina or to assess for leakage or bleeding that may lead to vision loss. It is performed by injecting sodium fluorescein dye into a peripheral vein with a small needle; this dye then goes through the body and eyes, as well as the retina to assess blood flow and to determine where areas of leakage are located.
- OCT imaging. OCT imaging is a non-invasive optical coherence tomogram examination of the macula; an OCT uses low energy laser to scan the macula and determine whether there is leakage or swelling within the macula, potentially signifying diabetic retinopathy. This can help assess the status of the macula and retina in patients with diabetic retinopathy. It can monitor swelling in the macula that can lead to vision loss and can also identify areas of attachment of the vitreous gel to the retina (the vitreous gel is a semi-solid transparent jelly-like substance that lies in front of the retina and occupies most of the eye cavity). OCT imaging may be performed to monitor treatment for diabetic macular leakage or to evaluate the attachment of the vitreous gel to the retina over time.
- Visual acuity test. This test uses an eye chart to measure how well a person sees at various distances. In addition, it is used to measure accurate vision without correction as well as best corrected vision confirmed by refraction.
- Pupil dilation. The eye care professional places drops into the eye to widen the pupil. This allows the doctor to see more of the retina and look for signs of diabetic retinopathy. After the examination, close-up vision may remain blurred for several hours.
- Ophthalmoscopy. This is an examination of the retina in which the eye care professional looks through a special magnifying lens that provides a narrow view of the retina. Alternatively, he/she can wear an indirect ophthalmoscope with a bright light and looks through a special magnifying glass to gain a wide view of the retina.
- Tonometry. This is a standard test that determines the fluid pressure inside the eye. The elevated pressure is a possible sign of secondary glaucoma, another common eye problem in people with diabetes.
- Digital Retinal Screening Programs. This is a systematic programs for the early detection of eye disease including diabetic retinopathy are becoming more common, such as in the UK, where all people with diabetes mellitus are offered retinal screening at least annually. This involves digital image capture and transmission of the images to a digital reading center for evaluation and treatment referral.
