Cup-to-Disc Ratio and Glaucoma Risk

Introduction to Cup-to-Disc Ratio

• An increased cup-to-disc ratio indicates progressive loss of optic nerve fibers and is a major risk factor for glaucoma, signaling either early glaucomatous damage or increased risk of developing primary open-angle glaucoma (POAG) 1, 2
• A larger cup-to-disc ratio is an established independent risk factor for developing POAG in patients who are glaucoma suspects 1, 2

Diagnostic Considerations

• Progressive enlargement over time with elevated intraocular pressure suggests glaucomatous cupping 1, 4
• Associated findings such as disc hemorrhages, retinal nerve fiber layer defects, or visual field changes consistent with glaucoma also suggest glaucomatous cupping 2, 4

Clinical Action Required

• Immediate assessment should include intraocular pressure measurement, gonioscopy to assess anterior chamber angle 3, and assessment for disc hemorrhages 4
• Central corneal thickness measurement is also recommended 4
• Follow-up frequency depends on risk stratification, with high-risk patients requiring follow-up every 6-12 months 4
• Any documented progression should be managed with target IOP reduction of at least 20% from baseline 5

Risk Assessment

• Risk calculators are available to quantify 5-year risk of conversion to glaucoma using cup-to-disc ratio combined with age, pattern standard deviation, central corneal thickness, and IOP 5