Regular monitoring of the vision and opthalmalogical examinations will help to identify diabetic retinopathy in the early stages. However, many diabetics only seek treatment once the visual disturbance is significant and affecting daily functioning. Blurred vision is more commonly reported as a reason for seeking medical attention than the other diabetic retinopathy symptoms. If left untreated, diabetic retinopathy can lead to blindness.
Screening for Diabetic Retinopathy
The most widespread method of screening is via opthalmoscopy. This involves examination of the retina with an opthalmoscope and is described in detail below. In the hands of an experienced practitioner, non-proliferative diabetic retinopathy can be detected at an early stage. Retinal imaging through measures like fluoroscein angiography and digital photography depends on the availability of facilities. If available, these screening measures should be considered. Both type 1 and type 2 diabetics should be screened annually even if the diabetes is well controlled.
Diabetic patients should be made aware of the seriousness of diabetic retinopathy and the possibility of blindness. Tight diabetic control with medication, dietary and lifestyle measures are essential for life in order to limit or prevent diabetic complications. Patients should report to the supervising doctor immediately if any change of vision is noticed despite the routine annual screening.
Diagnosing Diabetic Retinopathy
The most important tests employed in ophthalmologic evaluations are ophthalmoscopy (fundoscopy), and fluorescein angiography. Other tests that may also be considered slit-lamp biomicroscopy, B scan ultrasonography, optical coherence tomography, tonometry and digital retinal screening.
Glucose testing with fasting glucose and hemoglobin A1c (HbA1c) are other lab investigations that are also essential in diagnosis, management and follow up of diabetes mellitus as a whole as well as complications like diabetic retinopathy.
Examination of the eye with an ophthalmoscope is the most important clinical examination which is necessary for screening. Ophthalmoscopy involves visualizing the retina through a magnifying lens which a provides clear view of the retinal surface and capillaries. The findings of ophthalmoscopy can be confirmed with a slit-lamp biomicroscopy.
Ophthalmoscopic examination of the eye (fundoscopy) may show :
- microaneurysms (seen as small red dots in retina)
- dot and blot hemorrhages (round shaped with blurred edges)
- splinter hemorrhages (flame shaped hemorrhages)
- hard exudates (yellowish and sharply edges)
- cotton-wool spots (round whitish or grayish swellings)
- venous beading
- retinal edema
- intraretinal microvascular abnormalities (non-leaky collateral vessels found along the borders of the ischemic retina)
- macular edema
- neovascularization (usually seen near the optic disc) – new capillaries and extensive capillary network
- vitreous hemorrhage (may appear as a haze or as clumps of blood clots
- retinal detachment
Fluorescein angiography is another important diagnostic test that is useful in identifying and managing diabetic retinopathy. It will help the practitioner to conclusively identify and distinguish between the different defects mentioned above.