Corneal Higher-Order Aberrations and Posterior Segment Changes in Keratoconus: A Multimodal OCT and OCTA Study

Area of Science:

• Ophthalmology
• Corneal Diseases
• Retinal Imaging

Background:

• Keratoconus is a progressive corneal ectasia characterized by topographic irregularity and higher-order aberrations (HOAs).
• The posterior segment's structural and microvascular status in keratoconus remains incompletely understood.

Purpose of the Study:

• To investigate associations between anterior segment parameters (corneal irregularity, HOAs) and posterior segment (retinal, choroidal) features in keratoconus.
• Utilize advanced imaging techniques like optical coherence tomography (OCT) and OCT angiography (OCTA).

Main Methods:

• Cross-sectional study involving 81 keratoconus eyes and 60 controls.
• Corneal topography, wavefront analysis, spectral-domain OCT, and OCTA were performed.
• Analysis included retinal layer thickness, choroidal metrics, choroidal vascularity index (CVI), and vascular parameters, with FDR correction.

Main Results:

• Keratoconus eyes exhibited increased corneal curvature, irregularity, and HOAs.
• Reduced outer nuclear layer thickness and increased outer retinal layer thickness were observed.
• Increased choroidal thickness and area, but unchanged CVI.
• Reduced superficial capillary plexus density, while deep capillary plexus was preserved.
• Weak, non-significant correlations between corneal and posterior segment parameters after FDR correction.

Conclusions:

• Posterior segment structural and microvascular alterations in keratoconus are minimal and poorly correlated with anterior segment disease severity.
• Findings suggest a predominantly anterior segment-centered pathophysiology for keratoconus.
• Emphasizes the need for rigorous statistical control in multimodal imaging studies.