IN NON-ECTATIC CORNEAL PATHOLOGIES, THE IMPACT OF DALK AND PKP SURGERIES ON HIGH-ORDER ABERRATIONS AND VISUAL FUNCTIONS

The aim of this study was to investigate the effect of high-order aberrations on visual acuity in patients undergoing penetrating keratoplasty (PKP) and deep anterior lamellar keratoplasty (DALK) due to non-ectatic corneal pathologies.

Clinical examination findings,surgery videos and topographic evaluations of patients who underwent PKP and DALK surgery(150 eyes of 135 patients)with non-ectatic corneal pathology.

Patients were followed up for at least 24 months between January 2019 and September 2023 at the Ankara Health Application and Research Center Cornea Unit of the University of Health Sciences were retrospectively analyzed.Statistical analyses were performed using SPSS version 22, with all statistical tests evaluated at a significance level of p <0.05 and 95% confidence interval.

In the study comprising 150 subjects,(47.7%)female and (52.3%) male (p=0.389).Predominant corneal pathologies necessitating surgical intervention were stromal dystrophies in the DALK group(65.3%) and corneal scars in the PKP group (44%). Following surgical intervention, the most frequent complication encountered in both group was cataract, with phacoemulsification being the predominant secondary surgical procedure in both groups(p=0.017).In terms of topographic findings, the K1and K-mean values were notably lower in the PKP group(p>0,05), whereas anterior chamber volume and posterior elevation values of DALK group was higher(p=0,009).While no difference was found in the posterior surface corneal RMS values (p>0,05), the mean anterior surface total corneal RMS value of DALK group (1,37) was found to be higher than that of the PKP group(-0,13)(p=0,018).When analyzing the impact of graft size on aberrations, it was observed that as the graft diameter increased, there was a reduction in posterior surface coma aberration, coupled with an increase in posterior surface RMS 4th order aberrations. Conversely, the anterior surface exhibited a decrease in spherical aberration and RMS 4th order aberrations. On the posterior surface, patients with scars demonstrated elevated values of secondary astigmatism and posterior surface quadrafoil aberration, while patients with dystrophies showed higher values of posterior surface total corneal RMS.Regarding postoperative outcomes,it was observed that best corrected visual acuities were lower in the scar group (0.79 logMAR) compared to the dystrophy group (0.55 logMAR), primarily attributable to the acquired aberrations (p=0.09).

DALK and PKP surgeries are not superior to each other in terms of high-order aberrations.The effect of each aberration on vision varies, and the presence of some high-order aberrations together may reduce their negative impact on vision.Corneal scars may not reach the potential visual acuity despite having transparent grafts due to their high-order aberrations postoperatively.