Measurement of Optic Disc Cup Surface Depth Using Cirrus HD-OCT

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Research

Background:

• Glaucoma is a progressive optic neuropathy characterized by damage to the optic nerve.
• Monitoring glaucoma progression is crucial for timely intervention and vision preservation.
• Current methods for assessing glaucoma progression have limitations.

Purpose of the Study:

• To introduce a novel method for measuring optic disc cup surface depth using spectral-domain optical coherence tomography (SD-OCT).
• To evaluate the rate of cup surface depression at different stages of glaucoma.
• To compare the rate of cup surface depth change with retinal nerve fiber layer (RNFL) thinning.

Main Methods:

• Retrospective identification of 52 eyes with preperimetric glaucoma, 56 with mild-to-moderate glaucoma, and 50 with severe glaucoma.
• Annual SD-OCT imaging over at least 48 months.
• Calculation of mean cup surface depth using a specific formula: Cup volume/(disc area×average cup-to-disc ratio)-200 μm.

Main Results:

• Mean cup surface depression rates (μm/y) were significantly higher in mild-to-moderate glaucoma (-7.96±1.03) compared to preperimetric (-3.11±0.61) and severe glaucoma (-0.70±0.12).
• Percentile rates of cup surface depression (%/y) exceeded RNFL thinning rates in preperimetric and mild-to-moderate glaucoma.
• In severe glaucoma, cup surface depth changed slower than RNFL thickness.

Conclusions:

• Optic disc cup surface depth measured by SD-OCT changes more rapidly than RNFL thickness in early-to-moderate glaucoma.
• SD-OCT-based estimation of cup surface depth shows potential as a tool for monitoring glaucoma development and progression.
• This method may offer a more sensitive indicator of early glaucomatous changes.