Impact Of Patients’ Baseline Parameters On Refractive, Visual And Quality Of Vision Outcomes Of Corneal Lenticule Extraction For Advanced Refractive Correction (Clear) Procedure.

The purpose of the study was to assess how, and to what extent, patients’ baseline parameters may affect refractive, visual and quality of vision outcomes of CLEAR treatment in myopic (with or without astigmatism) patients.

A retrospective, single-surgeon, consecutive case-series study. All patients underwent CLEAR surgery in Silmäsairaala Pilke eye clinic in Vaasa and Tampere, Finland.

214 eyes (108 patients) with mean preoperative sphere of −3.77 ± 1.78 diopters (D) (range: -0.50 to -9.25 D) and cylinder of −0.72 ± 0.73 D (range: -0.25 to -3.50 D) underwent CLEAR surgery using FEMTO LDV Z8 laser (Ziemer Ophthalmic Systems AG). At 1 month after the treatment, the impact of patients’ preoperative parameters on surgical outcomes was assessed. The impact of age, gender, eye side, corneal thickness, asphericity, curvature, manifest cylinder and magnitude of the attempted refractive correction on postoperative manifest sphere, cylinder, correction index, visual acuity (both uncorrected and corrected), and objective scatter index were assessed.

Patients postoperative outcomes at 1 month indicated very high spherical equivalent refraction accuracy with 78% of eyes within ±0.25 D and 94% within ±0.50 D. In addition, 86% of eyes had a residual cylindrical error of not higher than ±0.50 D, and 100% were within ±1.00 D. Patients characterized by high target refractive correction, and with high corneal curvature values, tended to be slightly undercorrected. Furthermore, despite achieving high accuracy of refraction and astigmatism correction throughout patients’ age groups, uncorrected and corrected distance visual acuity (UDVA and CDVA), and objective scatter index (OSI) were affected by a patient age above 40 years.

In our study, CLEAR showed highly predictable correction of myopia and astigmatism, affected by high corrections and corneal curvature. Additionally, a patient age above 40 years showed to affect visual and quality of vision outcomes at 1 month. This could be attributed to CLEAR requiring tissue reshaping to achieve desired outcomes. Younger (elastic) corneas have a better ability to remodel, than older (stiffer) ones, which may prompt to an overall slightly slower visual recovery. We conclude that refractive error magnitude, along with corneal curvature and patient’s age should be taken into consideration, in order to assure optimal CLEAR outcomes on individual case basis.