Corneal densitometry changes post-CXL for keratoconus: Comparative evaluation of epithelium-off, contact lens-assisted, and transepithelial techniques.

To evaluate changes in corneal backscattering after collagen cross-linking (CXL) for progressive keratoconus and compare its course with different techniques - standard epithelium-off CXL (SCXL), contact lens-assisted CXL (CACXL), and transepithelial CXL (TECXL). Advanced Eye Center, Post Graduate Institute of Medical Education and Research, Chandigarh, India. Retrospective comparative study. Ninety-four eyes (SCXL: 47, CACXL: 30, and TECXL: 17) were compared. Corneal haze was quantified using Scheimpflug tomography, pre- and post-CXL at 1, 3, 6, and 12 months. The baseline mean density score of the central anterior stromal layer was 16.14 ± 7.07, 15.85 ± 7.89 and 15.89 ± 7.21 in SCXL, CACXL, and TECXL groups, respectively (P 0.93). After SCXL, the score increased to 28.83 and 31.34 at 1 and 3 months, respectively (both P < 0.001) and dropped at 6 months (28.66, P < 0.001) and 12 months (23.72, P 0.003). Post-CACXL, the mean densitometry peaked at 3 months (20.35, P 0.14) and returned toward baseline at 6 months (18.82, P 0.15). After TECXL, it increased slightly at 1 month (18.47, P 0.17), decreased at 3 months (14.88, P 0.7), and plateaued over 1 year. No correlation with visual acuity was seen. Corneal haze increased significantly after SCXL, peaking at 3 months, declining over 6-12 months, and returning to baseline at 12 months. In contrast, post-TECXL and -CACXL, there was an insignificant increase in anterior corneal haze, which returned to baseline within 3-6 months.

Gupta B ，Malhotra C ，Dhar S ，Abhyapal K ，Jain AK ，Gupta A ... -  《-》

Epithelium-on versus epithelium-off corneal collagen crosslinking for keratoconus: a systematic review and meta-analysis.

Corneal collagen crosslinking (CXL) is the primary treatment for progressive keratoconus which has a significant impact on vision and quality of life. Our study aimed to compare the efficacy and safety of epithelium-on versus epithelium-off CXL to treat keratoconus. We searched PubMed, Medline, Embase, Web of Science, and Scopus databases. We included studies that compared standard epithelium-off with epithelium-on CXL. The primary outcome measures were changes in corrected distance visual acuity (CDVA) and maximum keratometry (Kmax), and the secondary outcomes were uncorrected distance visual acuity (UDVA), central corneal thickness (CCT), and adverse events. A meta-analysis was performed on the primary and secondary outcomes based on the weighted mean differences between baseline to 12-month follow-up. The search retrieved 887 publications with 27 included in the systematic review. A total of 1622 eyes (1399 patients; age 25.51 ± 4.02 years) were included in comparisons of epithelium-off to epithelium-on CXL in keratoconus. Epithelium-off CXL treated 800 eyes and epithelium-on CXL for 822 eyes. At 12-month follow-up, CDVA and Kmax showed no significant difference between the epithelium-off and epithelium-on CXL. The secondary outcomes showed that UDVA was better in epithelium-off CXL (- 0.11D, 95% CI - 0.12, - 0.1; p < 0.001) and there was more thinning in CCT in epithelium-off CXL (- 3.23 μm, 95% CI - 4.64, - 1.81; p <0.001). Epithelium-off and epithelium-on CXL were both effective to treat progressive keratoconus. Further research is needed to compare the long-term outcomes and safety of both CXL protocols for adaptation into clinical practice.

Borchert GA ，Kandel H ，Watson SL 《-》

Biomechanical changes following corneal crosslinking in keratoconus patients.

To evaluate the biomechanical and tomographic outcomes of keratoconus patients up to four years after corneal crosslinking (CXL). In this longitudinal retrospective-prospective single-center case series, the preoperative tomographic and biomechanical results from 200 keratoconus eyes of 161 patients undergoing CXL were compared to follow-up examinations at three-months, six-months, one-year, two-years, three-years, and four-years after CXL. Primary outcomes included the Corvis Biomechanical Factor (CBiF) and five biomechanical response parameters obtained from the Corvis ST. Tomographically, the Belin-Ambrósio deviation index (BAD-D) and the maximal keratometry (Kmax) measured by the Pentacam were analyzed. Additionally, Corvis E-staging, the thinnest corneal thickness (TCT), and the best-corrected visual acuity (BCVA) were obtained. Primary outcomes were compared using a paired t-test. The CBiF decreased significantly at the six-month (p < 0.001) and one-year (p < 0.001) follow-ups when compared to preoperative values. E-staging behaved accordingly to the CBiF. Within the two- to four-year follow-ups, the biomechanical outcomes showed no significant differences when compared to preoperative. Tomographically, the BAD-D increased significantly during the first year after CXL with a maximum at six-months (p < 0.001), while Kmax decreased significantly (p < 0.001) and continuously up to four years after CXL. The TCT was lower at all postoperative follow-up visits compared to preoperative, and the BCVA improved. In the first year after CXL, there was a temporary progression in both the biomechanical CBiF and E-staging, as well as in the tomographic analysis. CXL contributes to the stabilization of both the tomographic and biomechanical properties of the cornea up to four years postoperatively.

Felter E ，Khoramnia R ，Friedrich M ，Son HS ，Auffarth GU ，Augustin VA ... -  《-》

Comparison of contact lens-assisted and transepithelial corneal crosslinking with standard epithelium-off crosslinking for progressive keratoconus: 24-month clinical results.

To compare the outcomes of contact lens-assisted corneal crosslinking (CACXL) and transepithelial CXL (TECXL) with standard epithelium-off (epi-off) CXL for progressive keratoconus. Advanced Eye Center, Postgraduate Institute of Medical Education and Research, Chandigarh, India. Retrospective, comparative study. Patients with progressive keratoconus undergoing CXL with a minimum follow-up of 24 months were included. CACXL and TECXL were performed in patients with epithelium-on minimal pachymetry between 350 μm and 450 μm. The main outcome measures included change in maximum keratometry (Kmax), corrected distance visual acuity (CDVA), and efficacy in halting progression (increase in Kmax ≥1 diopter [D]). Standard epi-off CXL, CACXL, and TECXL were performed in 34, 14, and 10 eyes, respectively. Baseline Kmax and CDVA were comparable for all groups. Kmax reduced significantly by -2.83 ± 3.35 D, -3.18 ± 2.74 D, and -2.02 ± 1.66 D in the standard epi-off CXL (P < .01), CACXL (P = .001), and TECXL (P = .004) groups, respectively; the reduction was comparable for all groups (P = .63). CDVA improved by -0.14 ± 0.24, -0.04 ± 0.19, and -0.12 ± 0.17 logMAR in the standard epi-off CXL (P = .006), CACXL (P = .42), and TECXL (P = .05) groups, respectively; the reduction was comparable for all groups (P = .46). Progression was documented in 2 eyes (6%) in the standard epi-off CXL group and in 0 eyes of the CACXL and TECXL groups (P = .61). CACXL and TECXL were comparable with the standard epi-off CXL for progressive keratoconus.

Malhotra C ，Gupta B ，Jain AK ，Dhar S ，Gupta A ，Balyan M ... -  《-》

Comparative Evaluation of Anterior Segment Optical Coherence Tomography Findings Following Accelerated Corneal Crosslinking Protocols Using Different Riboflavin Formulations and Soaking Durations.

Celik-Buyuktepe T ，Ucakhan OO 《-》