anwar versus melles deep anterior lamellar keratoplasty for keratoconus: a randomized clinical trial

purpose: to compare outcomes of two techniques (anwar vs. melles) of deep anterior lamellar keratoplasty (dalk) in patients with keratoconus. methods: this randomized double-blind clinical trial was performed on 57 eyes of 57 patients with keratoconus. patients aged 20-35 years with a clinical diagnosis of keratoconus who were contact lens intolerant and had corrected distance visual acuity (cdva) of less than 20/80 were included. eligible eyes were randomly allocated into 2 groups: anwar (23 eyes) versus melles (25 eyes). the primary outcome measure was cdva; secondary outcome measures included spherical equivalent (se), contrast sensitivity, corneal aberrations, corneal biomechanical properties, endothelial cell count, and central corneal thickness. all outcomes were compared 15 months postoperatively. results: mean cdva was 0.17±0.09 vs 0.18±0.11 logmar in the anwar vs melles groups, respectively (p=0.803) and mean se was -1.82±2.7 and -2.69±3.94 d (p=0.155). overall, photopic and mesopic contrast sensitivity function was different between the two groups (p<0.05). there was no significant difference between the two groups in terms of total and higher order aberrations up to fifth order (p>0.05 for all parameters). corneal hysteresis was not significantly different between the two groups (9.9±0.8 vs 9.9±0.6; p=0.606). corneal resistance factor was 10.02±0.8 and 10.13±0.76 (p=0.509). there was no significant difference between the two groups regarding percentage of endothelial cell loss (1%±2 vs 1%±3; p=0.869). central corneal thickness was 525.56±47.87 µm versus 504.64±54.20 µm in the study groups, respectively (p=0.155). conclusion: anwar and melles techniques for dalk have comparable visual and refractive outcomes, aberrometric profile, biomechanical properties, corneal thickness and endothelial cell density. however, patients undergoing anwar technique show better contrast sensitivity.