Topographic differences between large and normal optic discs: a confocal scanning laser ophthalmoscopy study.

Area of Science:

• Ophthalmology
• Optic Nerve Head Imaging
• Glaucoma Research

Background:

• Macrodiscs, characterized by large optic disc areas (>2.82 mm²), present unique challenges in quantitative analysis.
• Establishing normative data for optic nerve head parameters in healthy macrodiscs is crucial for accurate diagnosis and monitoring.

Purpose of the Study:

• To investigate and establish standard optic nerve head (ONH) measurements for healthy macrodiscs.
• To provide a basis for future quantitative comparisons and diagnostic assessments of macrodiscs.

Main Methods:

• A comparative study involving 69 subjects with macrodiscs and 91 healthy controls.
• Confocal scanning laser ophthalmoscopy (CSLO) was performed to obtain stereometric parameters of the optic nerve head.
• Comparison of ONH parameters and Moorfield Regression Analysis classifications between the macrodisc and control groups.

Main Results:

• Significant differences were observed in multiple ONH parameters, including cup area, rim area, and various cup-to-disc ratios between macrodiscs and controls.
• Rim volume and height variation contour were the only ONH topographic parameters that did not differ significantly between the two groups.
• Moorfield Regression Analysis erroneously classified a substantially higher proportion of macrodiscs as abnormal (79.4% vs 15.1%).

Conclusions:

• Rim volume and height variation contour are potentially reliable parameters for evaluating optic nerve heads in individuals with macrodiscs.
• These parameters may serve as valuable tools for differentiating healthy macrodiscs from glaucomatous changes, overcoming limitations of standard analyses.