Factors Affecting Outcomes of Corneal Collagen Crosslinking Treatment

I Toprak; V Yaylalı; C Yildirim


Eye. 2014;28(1):41-46. 

In This Article

Abstract and Introduction


Purpose To assess the effects of preoperative patient characteristics on clinical outcomes of corneal crosslinking (CXL) treatment in patients with progressive keratoconus.

Methods This retrospective study comprised 96 eyes of 96 patients who had unilateral CXL treatment for progressive keratoconus. All patients underwent a complete ophthalmological examination and corneal topography at baseline and 1 year. Subgroup analyses were performed according to the age (<30 and≥30 years), gender, preoperative corrected distance visual acuity (CDVA, <0.3 and ≥0.3 logMAR (log of the minimum angle of resolution)), preoperative maximum keratometry (K, <54 and ≥54 D), baseline topographic cone location (central, paracentral, and peripheral), and preoperative thinnest pachymetry (<450 and ≥450 μm) to determine the associations between preoperative patient characteristics and outcomes (changes in visual acuity and maximum keratometry) of CXL treatment.

Results In the entire study population, mean CDVA and maximum K significantly improved after CXL treatment (P<0.001). Patients with a preoperative CDVA of 20/40 Snellen equivalent or worse (≥0.3 logMAR) experienced more visual improvement after CXL treatment (P<0.001). However, an age ≥30 years and a baseline thinnest pachymetry less than 450 μm were found significantly associated with more flattening in maximum keratometry (P=0.024, P=0.005 respectively). Gender, preoperative maximum K, and baseline topographic cone location did not show significant effect on postoperative visual acuity and maximum keratometry (P>0.05).

Conclusions In patients with progressive keratoconus, age, baseline visual acuity, and baseline thinnest pachymetry seem to affect the success of the CXL treatment.


Keratoconus is a non-inflammatory ectatic corneal disorder.[1] Major clinical findings are progressive stromal thinning and visual deterioration secondary to irregular astigmatism, myopia, and central corneal scarring.[1,2] Conservative treatment modalities such as spectacles and gas permeable rigid contact lenses become insufficient for visual rehabilitation in advanced stages of keratoconus and 10–20% of the patients need corneal transplantation.[2]

Wollensak et al[3,4] introduced corneal collagen crosslinking (CXL) using riboflavin and ultraviolet A (UVA) as a new hope for treatment of progressive keratoconus. Studies concluded that CXL is an effective procedure to arrest the progression of keratoconus by increasing biomechanical stability of the cornea.[4,5,6] Moreover, significant improvements in visual acuity and keratometry (K) readings after CXL treatment could be considered as a regression in disease severity.[7,8,9,10]

Although the efficacy of CXL treatment has been shown in many studies, there is little evidence about the influence of preoperative patient characteristics on clinical outcomes of CXL treatment.[8,9,10] In this study, we aimed to assess the effects of initial demographic and topographic properties on outcomes of CXL treatment in patients with progressive keratoconus at 1-year follow-up.