Sensitivity and specificity of structural optic disc parameters in chronic glaucoma

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Research

Background:

• Glaucoma diagnosis relies on detecting optic nerve head damage.
• Accurate discrimination between normal and glaucomatous optic discs is essential for timely intervention.
• Computerized raster tomography offers advanced imaging for optic disc analysis.

Purpose of the Study:

• To evaluate the efficacy of various structural optic disc parameters in differentiating normal eyes from those with glaucoma.
• To compare the diagnostic performance of localized versus global optic disc parameters.

Main Methods:

• Two hundred seventy-six normal eyes and 146 glaucoma eyes were analyzed using a raster tomographic imaging system.
• Optic disc parameters including minimum rim width (60° and 90° sectors), vertical and horizontal cup-disc ratio, and rim/cup area were calculated.
• Receiver operating characteristic (ROC) curves were used to compare the diagnostic accuracy of different parameters.

Main Results:

• Minimum rim width within 60° and 90° sectors demonstrated the highest diagnostic accuracy, achieving 91% sensitivity at 90% specificity.
• Vertical cup-disc ratio showed good separating characteristics.
• Global indices such as cup/rim area and horizontal cup-disc ratio exhibited the poorest performance, especially in early to moderate glaucoma cases.

Conclusions:

• Localized optic disc parameters, particularly minimum rim width, are superior to global parameters for discriminating between normal and glaucomatous eyes.
• Global parameters are less effective in detecting early, focal glaucomatous optic nerve head damage.