Axial length measurements in same sized DALK grafts – new insights

Introduction: At the Sri Jayawardenapura General Hospital (SJGH), Deep Anterior Lamellar Keratoplasty (DALK) for keratoconus is performed by a single surgeon with graft sizing done on vertical corneal height and same-sized grafting done for all patients.
Method: A single centre cross-sectional descriptive study was conducted from 01. 01. 2020 to 01. 04. 2020 at the SJGH. Patients who had completed two years of follow up after DALK for keratoconus had refraction, topography and biometry on a planned hospital visit.
Results: The study included 71 patients (97 eyes). Mean age at surgery was 23.9 years; standard deviation (SD) – 6.9 years. The mean, postsurgical duration was 63.1 months (SD=23.4) and refractive SE was – 1.18 D (SD=1. 88). Hyperopic SE was seen in 21.5% of eyes. Mean axial length (AXL) was 23.50 mm (SD=1.16) and mean anterior chamber depth (ACD) was 3.578 mm (SD=0.36 mm). Mean AXL had significant negative correlation with SE (r= -0.676, P=0.000). ACD was correlated with average topographic keratometry (P=0.048). Mean topographic cylinder was -3.237 D (SD=1.85).
Conclusion: Axial length measurements should be performed in pre operative work up in DALK. Patients with short eyes need to be counseled for postoperative hyperopia. Vitreous length may be a better measurement than axial length as it may not be affected by changes in ACD in keratoconus.