Differences in Axial Length and Anterior Chamber Depth among Keratoconic, Myopic and Emmetropic Eyes

Abstract

Purpose: To report variation of the axial length (AL) and anterior chamber depth (ACD) among keratoconic (KC) eyes compared to myopic and emmetropic eyes in an African population sample. Study Design: Cross sectional observational. Place and Duration of Study: Al-Faisal Eye Hospital at Khartoum state of Sudanfrom January 2022 to September 2022. Methods: One-hundred and twenty-four eyes of 62 patients were divided into KC group (n =17, eyes=34), myopic group (n=28, eyes=56), and an age/gender matched emmetropic group (n=17, eyes =34). Central corneal thickness (CCT) was measured using ultrasonic pachymeter, AL, ACD and keratometry readings (K-reading) were recorded for each patient using non-contact partial coherence interferometry with an IOL Master. Results: Mean age of the sample population was 22.27± 6.05 (range; 10 – 40 years). KC patients had the highest spherical equivalent of refraction (SER) (-6.19±3.91 dioptres), highest k-reading (48.98±5.68 dioptres) and the thinnest CCT. Myopic participants had a longer AL compared to other refractive error groups (AL=24.99±2.39, p<0.001). KC patients exhibited a larger ACD in comparison to emmetropes and myopes (ACD=3.6?9±0.26, p<0.001). Among all participants, SER exhibited the highest correlation with AL (r=-0.71, p<0.001) followed by a weaker correlation with ACD (r=-0.26, p=0.003). However, among KC patients, SER exhibited a weaker correlation with AL compared to myopes (r=-0.55, p=0.001), and a higher correlation with ACD compared to myopes (r=-0.38, p=0.03). Conclusion: ACD and corneal curvature were the most significantly detrimental parameters in KC. KC participants demonstrated a lower correlation between SER and AL and higher correlation between SER and ACD.