Can an Eye Exam Detect Diabetes?

Some patients have heard that eye doctors can "spot diabetes" and want to know if that is really true, especially if diabetes runs in their family. Others already have diabetes and want to understand why they are told to come in every year even when their vision seems fine. Both are getting at the same point: the retina is a place where the effects of diabetes show up early and clearly.

The retina is packed with fine blood vessels, and elevated blood sugar gradually weakens their walls. They begin to bulge, leak fluid and blood, and eventually can close off, starving areas of the retina of oxygen.

This is diabetic retinopathy. In its early stages it usually causes no symptoms, but it can progress to swelling of the central retina or to fragile new vessels that bleed, both of which threaten vision. Finding it early is what allows treatment before sight is lost.

Diabetic retinopathy typically begins as nonproliferative changes: microaneurysms (tiny outpouchings of vessels), dot-and-blot hemorrhages, hard exudates from leaking fluid, and cotton-wool spots. Many people at this stage see perfectly well, which is exactly why screening matters. If leakage collects in the central macula, diabetic macular edema develops and can blur central vision.

As the disease advances, blocked vessels leave parts of the retina starved for oxygen, prompting the growth of fragile new blood vessels, called proliferative diabetic retinopathy. These vessels can bleed into the eye or pull on the retina and cause a detachment, leading to severe vision loss if untreated.

The risk rises with how long a person has had diabetes and how well blood sugar and blood pressure are controlled. Because the earliest and most treatable stages are silent, guidelines call for regular dilated exams, generally yearly for people with diabetes and more often if retinopathy is present or during pregnancy.

Diabetic eye changes are often painless until they are advanced. Seek prompt care if you have diabetes and notice sudden blurring, a shower of new floaters or dark spots (which can mean bleeding inside the eye), a shadow or curtain in your vision, or sudden vision loss. These can signal advanced retinopathy, a vitreous hemorrhage, or a retinal detachment. Even without symptoms, missing your regular dilated exams is risky, because sight-threatening disease can be well underway before you feel anything.

A dilated exam is the core evaluation, allowing the doctor to inspect the retina for microaneurysms, hemorrhages, exudates, swelling, and new vessels. OCT imaging measures whether the macula is swollen and guides treatment of diabetic macular edema. When needed, fluorescein angiography, a dye study, maps areas of leakage and poor blood flow, and wide-field retinal photography documents the periphery. If diabetes has not been diagnosed but the retina suggests it, the doctor will refer you for blood testing to confirm it.

The foundation is controlling blood sugar, blood pressure, and cholesterol, which slows retinopathy and is managed with your primary doctor. For diabetic macular edema and proliferative disease, ophthalmologists use anti-VEGF injections that reduce leakage and abnormal vessel growth, laser treatment to seal leaking areas or treat the ischemic retina, and, in advanced cases with bleeding or detachment, surgery called vitrectomy. Early detection through regular exams greatly improves how well these treatments preserve vision.

• Do not skip your yearly dilated exam because your vision feels fine; early diabetic retinopathy is silent.
• Do not treat the eye exam as a blood-sugar test; confirm suspected diabetes with proper blood work.
• Do not ignore new floaters, blurring, or a shadow in your vision if you have diabetes; these can be serious.
• Do not assume good vision means good control; check your numbers with your primary doctor.
• Do not delay recommended injections or laser if retinopathy is found; timing affects the outcome.

Call to schedule a dilated exam if you have diabetes and are due for your yearly check, if diabetes runs in your family, or if you have noticed any change in your vision. Patients in the Hanover area can have their retina evaluated and monitored as part of ongoing diabetic eye care. If you develop sudden vision loss, a burst of floaters, or a curtain over your sight, seek urgent care right away.

An eye exam can uncover the retinal effects of diabetes, sometimes before diagnosis, and is essential for monitoring known diabetes; pair regular dilated exams at May Eye Care Center with blood-sugar control and confirmatory testing from your primary doctor.