Diagnosis

Differential diagnosis

Differential diagnosis should consider the following conditions: branch retinal and central retinal vein occlusion, ocular ischemic syndrome, retinopathy, hemoglobinopathies. There are a range of common ocular and systemic conditions that can mimic DR in patients with diabetes: age-related macular degeneration, hypertensive retinopathy, radiation retinopathy, and other causes of retinopathy (such as retinal telangiectasias and various connective tissue diseases, including Bechet's disease, temporal arteritis, systemic lupus vasculitis, sarcoidosis, sickle cell retinopathy, Wegener's granulomatosis).

Diagnosis

Patient history should be carefully obtained in order to determine the vision difficulties experienced by the patient. Presence of diabetes and diseases or health conditions that may affect the vision should be considered. Comprehensive eye examination includes visual acuity measurements, refraction, evaluation of the ocular structures, including the evaluation of the retina through a dilated pupil, and measurement of the pressure within the eye.

DR is best diagnosed by funduscopy (dilated indirect ophthalmoscopy coupled with biomicroscopy and seven-standard field fundus photography). The diagnosis is based on the following findings: abnormal blood vessels, swelling, blood or fatty deposits in the retina, damaged nerve tissue, growth of new blood vessels and scar tissue, bleeding in the vitreous, retinal detachment.

Fluorescein angiography and optical coherence tomography (OCT) are used to confirm the diagnosis, determine the extent of damage, treatment planning and monitor the efficacy of the treatment.

On fluorescein angiography it is possible to detect and observe "leaky" blood vessels and compromised circulation in the retina. Microaneurysms appear as pinpoint hyperfluorescence that does not enlarge but rather fades in the later phases of the test. Blot and dot hemorrhages appear as hypofluorescent, thus they can be distinguished from microaneurysms. Areas of nonperfusion appear as homogenous dark patches bordered by occluded blood vessels. Intraretinal microvascular abnormalities are usually found in the borders of the nonperfused retina and are evidenced by collateral vessels that do not leak.

OCT is used to determine the thickness of the retina, the presence of retinal swelling, and vitreomacular traction. It is particularly useful for diagnosis and management of DME.