Accelerated Epithelium-off Corneal Cross-linking With High Ultraviolet Energy Dose (7.2 J/cm ² ) for Progressive Keratoconus: 2-Year Results in a Chinese Population

Abstract

PURPOSE: To evaluate the results of epithelium-off continuous light accelerated corneal cross-linking (CXL) with a total dose of 7.2 J/cm 2 for treating progressive keratoconus in a Chinese population during 24 months of follow-up. METHODS: In this retrospective, interventional case series, 45 eyes of 31 consecutive patients with progressive keratoconus were evaluated. All patients underwent accelerated CXL with settings of 30 mW/cm 2 for 4 minutes, corresponding to a total dose of 7.2 J/cm 2 . Visual acuity, manifest refraction, epithelial thickness, topography, tomography, aberrometry, endothelial cell count, and intraocular pressure were evaluated at baseline and at 1, 3, 6, 12, 18, and 24 months postoperatively. RESULTS: Progressive keratoconus was stabilized in 91.11% and 93.33% of the patients at 12 and 24 months, respectively. The improvement in corrected distance visual acuity was significant throughout the postoperative follow-up period ( P < .05), excluding month 1. A significant decrease in the maximum keratometric values (0.67 ± 1.68, 0.92 ± 1.78, and 0.97 ± 1.73 D) was observed at months 12, 18, and 24, respectively ( P < .05 for all). Corneal irregularity improved, particularly total root mean square and higher order aberrations at 12 to 24 months after CXL. In bilateral CXL, the progression of the first eye was highly predictive of the outcome of the second eye. CONCLUSIONS: CXL with a total dose of 7.2 J/cm 2 maintains long-term results in halting the progression of keratoconus, with significant improvement in the corrected distance visual acuity and stability of keratometric values. Further clinical studies with longer follow-up periods and larger samples are necessary to confirm these results. [ J Refract Surg . 2020;36(11):731–739.]

Resultados queratométricos y refractivos tempranos en pacientes con queratocono operados con anillos intracorneales

“…Actualmente, la tendencia en el manejo del queratocono es detener su progresión lo más temprano posible para no tener que llegar a un trasplante de córnea. En los últimos años han surgido técnicas con esa finalidad, entre ellas el cross-linking, que con sus diferentes variantes [15][16][17] busca estabilizar el queratocono mediante la impregnación de riboflavina, seguida de la aplicación de radiación ultravioleta para que así el estroma de la córnea reaccione y genere puentes entrecruzados en las fibras de colágena de este [18][19][20][21] . En cuanto a la reducción del poder de las queratometrías, así como de la refracción, la técnica de cross-linking ha mostrado poco efecto 17 .…”

Comparative Results Between “Epi-Off” Accelerated and “Epi-Off” Standard Corneal Collagen Crosslinking-UVA in Progressive Keratoconus – 7 Years of Follow-Up

“…Our findings showed that RMS total was not statistically significantly different between the two groups at all time points. Kang et al 58 demonstrated that, after A-CXL with high UVA energy dose (7.2 J/cm 2 ) particularly, total root mean square and higher order aberrations improved at 12 to 24 months after CXL.…”

Long-term outcomes of corneal crosslinking

“…Five of the seven studies (71.4%) that evaluated UDVA noted statistically significant improvements [20,22,23,26,33], while eight of the 10 studies (80.0%) had a statistically significant improvement in CDVA post-CXL [20,22,26,28 && , 30,31,33,35]. Kmax significantly improved in all but one study [25] through the follow-up period.…”

“…We evaluated 10 studies exploring long term outcomes of accelerated, epithelium-off CXL for progressive KCN [20,22,23,25,26,28 && , 30,31,33,35]. Compared to the standard of 3 mW/cm 2 for a total of 30 min, studies had irradiation protocols of 9 mW/cm 2 for 10 min, 18 mW/cm 2 for 5 min, or 30 mW/cm 2 for 4 min.…”