Changes in higher-order aberrations after central corneal regularization-a comparative two-year analysis of a semi-automated topography-guided photorefractive keratectomy combined with corneal cross-linking

Background:The optical quality in progressive keratoconus deteriorates due to ectasia and distortion of the corneal shape and optics.While corneal cross-linking(CXL)aims at stopping disease progression,"CXL-Plus"combines CXL with excimer laser ablation to improve visual function.Central corneal regularization(CCR)represents a therapeutic excimer laser modality specifically designed to smoothen the ectatic corneal shape and to reduce higher-order aberrations(HOA).We set out to compare CXL-Plus,consisting of CXL combined with CCR,with CXL by itself for patients with progressive keratoconus.Methods:Retrospective 2-year matched group analysis of patients who either underwent CXL-Plus{n=28)or CXL as a sole procedure(n=28)for progressive keratoconus.Main outcome parameters were HOA,visual function and tomographic results 12 and 24 months postoperatively.Results:After 12 months,the total HOA root mean square wavefront error was reduced from 0.79±0.30 to 0.40±0.19 pm(CXL-Plus;P<0.0001)and changed from 0.71±0.28 to 0.73±0.36 pm(CXL;P=0.814).Uncorrected distance visual acuity improved from 0.70±0.35 to 0.36±0.29 logMAR(CXL-Plus;P=0.0002)and from 0.65±0.39 to 0.46±0.37 logMAR(CXL;P=0.067),translating to gains of three or more lines in 50%(CXL-Plus)and 36%(CXL)of patients.The steepest keratometry value(Kmax)regressed by 5.84 D(CXL-Plus;P<0.0001)and 0.66 D(CXL;P=0752).For none of the investigated parameters a statistically significant change could be shown between 12 and 24 months.Conclusions:CXL-Plus in the form of a CCR reduces HOA and Kmax more effectively than CXL as a sole procedure.

Changes in higher order aberrations after central corneal regularization-a comparative two-year analysis of a semiautomated topography-guided photorefractive keratectomy combined with corneal cross-linking

Background:The optical quality in progressive keratoconus deteriorates due to ectasia and distortion of the corneal shape and optics.While corneal cross-linking(CXL)aims at stopping disease progression,“CXL-Plus”combines CXL with excimer laser ablation to improve visual function.Central Corneal Regularization(CCR)represents a therapeutic excimer laser modality specifically designed to smoothen the ectatic corneal shape and to reduce higher order aberrations(HOA).We set out to compare CXL-Plus,consisting of CXL combined with CCR,with CXL by itself for patients with progressive keratoconus.Methods:Retrospective 2-year matched group analysis of patients who either underwent CXL-Plus(n=28)or CXL as a sole procedure(n=28)for progressive keratoconus.Main outcome parameters were HOA,visual function and tomographic results 12 and 24 months postoperatively.Results:After 12 months,the total HOA root mean square wavefront error was reduced from 0.79±0.30 to 0.40±0.19μm(CXL-Plus;p<0.0001)and changed from 0.71±0.28 to 0.73±0.36μm(CXL;p=0.814).Uncorrected distance visual acuity improved from 0.70±0.35 to 0.36±0.29 logMAR(CXL-Plus;p=0.0002)and from 0.65±0.39 to 0.46±0.37 logMAR(CXL;p=0.067),translating to gains of three or more lines in 50%(CXL-Plus)and 36%(CXL)of patients.The steepest keratometry value(Kmax)regressed by 5.84 D(CXL-Plus;p<0.0001)and 0.66 D(CXL;p=0.752).For none of the investigated parameters a statistically significant change could be shown between 12 and 24 months.Conclusions:CXL-Plus in the form of a CCR reduces HOA and Kmax more effectively than CXL as a sole procedure.