13.2 Diabetic Retinopathy & Systemic Diseases Affecting the Retina

Diabetic Retinopathy and Systemic Manifestations

The retina provides a view of neural tissue and microvasculature, so ocular findings can reflect both local disease and systemic health. Consistent documentation helps the clinician compare progression.

Diabetic retinopathy

Common nonproliferative findings include microaneurysms, dot-and-blot hemorrhages, hard exudates, cotton-wool spots, venous beading, and intraretinal microvascular abnormalities (IRMA). Proliferative disease is marked by neovascularization of the disc or elsewhere, or preretinal or vitreous hemorrhage associated with neovascular tissue.

The 4-2-1 rule supports recognition of severe NPDR:

• hemorrhages or microaneurysms meeting the reference severity in all four quadrants;
• definite venous beading in two or more quadrants;
• prominent IRMA in at least one quadrant.

One criterion supports severe NPDR; two or more support very severe NPDR. A scenario that meets all three is not merely severe. Formal grading uses examination or validated photographic standards and clinician interpretation.

Diabetic macular edema can occur at any stage. OCT may show retinal thickening, intraretinal cysts, subretinal fluid, hyperreflective foci, or traction. Inspect segmentation and compare the same scan protocol. Do not infer activity from central thickness alone.

History includes diabetes type and duration, recent glycemic information if known, renal disease, pregnancy, blood pressure, lipid and smoking history, medications, and prior retinal treatment. The technician records values without prescribing systemic targets.

Hypertension and vascular disease

Hypertensive retinal findings can include arteriolar narrowing, arteriovenous crossing changes, hemorrhages, cotton-wool spots, hard exudates, and disc swelling. A very high pressure reading with acute retinal end-organ findings, neurologic symptoms, chest pain, dyspnea, or renal symptoms requires immediate clinician notification and emergency evaluation.

Repeat an unexpected blood pressure with correct cuff size and technique if protocol permits, but do not delay emergency response when the patient is unstable. Optic-disc swelling in this setting should be described objectively; the clinician determines whether the term papilledema or another diagnosis applies.

Other systemic categories

• Autoimmune and inflammatory: lupus, sarcoidosis, vasculitis, and related disorders may produce vascular leakage, occlusion, uveitis, or choroidal findings.
• Infectious: HIV-associated infections, tuberculosis, syphilis, herpes viruses, and other pathogens can affect retina or choroid. Appearance alone does not establish the organism.
• Hematologic: sickle-cell disease, leukemia, anemia, hyperviscosity, and coagulopathy can alter perfusion or cause hemorrhage.
• Neurologic and cardiovascular: embolic disease, carotid disease, stroke, and intracranial pathology can produce retinal or field findings.
• Cancer: primary or metastatic tumors and treatment toxicity may involve choroid, retina, optic nerve, or orbit.
• Medication toxicity: hydroxychloroquine, tamoxifen, and other agents have distinct screening patterns and risk factors.

Use respectful, precise terms. Historical nicknames may be memorable but can be stigmatizing or imprecise; describe the actual lesions.

Documentation workflow

Record laterality, location, extent, size reference, hemorrhage layer, exudation, vascular change, neovascularization, vitreous status, macular findings, pupil response, visual acuity, and imaging quality. Note comparison with prior photographs or OCT. If the finding is outside the technician's certainty, document what is seen rather than guessing.

The exam tests recognition, but clinical practice requires objective reporting and supervised decisions.

Longitudinal documentation and systemic coordination

Record diabetes type and duration, recent glycated hemoglobin when available, blood pressure, renal disease, pregnancy status, medications, prior retinal treatment, and barriers to follow-up. These factors inform risk but do not let the technician grade disease from history alone. Imaging should be labeled by eye and field and should document artifacts or incomplete coverage. New vessels, hemorrhage, exudate, or edema are described objectively and routed for clinician interpretation.

The 4-2-1 rule applies to severe nonproliferative diabetic retinopathy: hemorrhages or microaneurysms in all four quadrants, venous beading in two or more quadrants, or prominent intraretinal microvascular abnormalities in at least one quadrant. Meeting any one criterion supports the severe category; meeting two or more is commonly termed very severe. Proliferative disease is defined by neovascularization or preretinal/vitreous hemorrhage, not simply by a high hemorrhage count. Sudden vision loss, new floaters, or a curtain needs urgent triage regardless of the last recorded grade.