Differentiation Between Pellucid-Like Keratoconus and Pellucid Marginal Degeneration Using Swept-Source Optical...

Area of Science:

• Ophthalmology
• Corneal Imaging
• Biomechanical Analysis

Background:

• Pellucid-like keratoconus (PLK) and pellucid marginal corneal degeneration (PMD) are corneal ectasias with overlapping clinical presentations.
• Accurate differentiation is crucial for appropriate patient management and treatment planning.
• Current tomographic and biomechanical assessments often struggle to reliably distinguish between PLK and PMD.

Purpose of the Study:

• To evaluate the efficacy of swept-source optical coherence tomography (SS-OCT) in differentiating PLK from PMD.
• To compare corneal tomographic and biomechanical parameters between PLK and PMD groups classified by SS-OCT.

Main Methods:

• Patients were classified into PLK (n=30) and PMD (n=10) groups using SS-OCT imaging.
• Corneal thickness was measured at multiple positions using SS-OCT.
• Tomographic, densitometric, and biomechanical parameters were assessed using Scheimpflug-based methods.

Main Results:

• The PMD group was significantly older than the PLK group (P=0.002).
• Astigmatism was significantly higher in the PMD group compared to the PLK group (P<0.001).
• No significant differences were found in Kmax or biomechanical parameters (e.g., CBI) between the groups (P>0.05).
• Significant differences in corneal thickness ratios were observed inferiorly and at the 6 and 7 o'clock positions between PLK and PMD (P<0.001).

Conclusions:

• Scheimpflug-based tomographic and biomechanical parameters alone cannot reliably differentiate between PLK and PMD.
• SS-OCT is valuable for distinguishing PLK from PMD due to its ability to detect characteristic peripheral corneal thinning.
• Peripheral corneal pachymetry analysis using SS-OCT aids in the differential diagnosis of these conditions.