Long-term follow-up of repeated corneal cross-linking for progressive keratoconus in young patients / Acompanhamento a longo prazo do retratamento com cross-linking corneano para ceratocone em progressão em pacientes jovens

ABSTRACT Objective: To evaluate the long-term safety and efficacy of repeated corneal cross-linking in eyes of children and adolescents with progressive keratoconus. Methods: This retrospective study included nine eyes of nine consecutive patients with progressive keratoconus who underwent repeated corneal cross-linking 3.9 (range of 1.6 to 5.6) years after a primary one. All patients were followed for a mean period of 9.11 (range of 6 to 11) years after first treatment and 5.44 (range of 4 to 9) years, after corneal cross-linking retreatment. Results: Nine eyes of nine patients (six male) with progressive keratoconus underwent primary corneal cross-linking from 2009 to 2011. Despite the stability achieved with the epi-off corneal cross-linking, keratoconus continued to progress after some time. Mean time to documented evidence of keratoconus progression after primary corneal cross-linking was 3.9 (range of 1.6 to 5.6) years. All eyes were retreated as soon as progression was noted. At the last follow-up visit, 5.44 (range of 4 to 9) years after repeated corneal cross-linking, there was a significant decrease of 2.02 D in mean maximum topographic K-value (p = 0.045) and 1.95D in mean topographic K-value (p = 0.007). Conclusion: Repeated corneal cross-linking seems to be a safe and effective procedure to halt keratoconus progression after a primary corneal cross-linking failure.

RESUMO Objetivo: Avaliar a segurança e a eficácia a longo prazo da repetição do cross-linking corneano em olhos de crianças e adolescentes com ceratocone progressivo. Métodos: Estudo retrospectivo que incluiu nove olhos de nove pacientes consecutivos com ceratocone progressivo, que foram submetidos a retratamento com cross-linking corneano de 3,9 (variação de 1,6 a 5,6) anos após tratamento primário com cross-linking corneano. Todos os pacientes foram acompanhados por um período médio de 9,11 (variação de 6 a 11) anos após o primeiro tratamento e 5,44 (variação de 4 a 9) anos após retratamento com cross-linking corneano. Resultados: Nove olhos de nove pacientes (seis homens) com progressão do ceratocone foram submetidos a cross-linking corneano primário de 2009 a 2011. Apesar da estabilidade alcançada com o epi-off cross-linking corneano, o ceratocone continuou a progredir após algum tempo. O tempo médio para evidência documentada de progressão do ceratocone após cross-linking corneano primário foi de 3,9 (intervalo de 1,6 a 5,6) anos. Todos os olhos foram retratados com cross-linking corneano, assim que a progressão foi observada. Na última consulta de acompanhamento, 5,44 (variação de 4 a 9) anos após a repetição do cross-linking corneano, houve diminuição significativa de 2,02 D na média da curvatura máxima (p = 0,045) e 1,95 D na média da curvatura média (p = 0,007). Conclusão: O retratamento com cross-linking corneano parece ser um procedimento seguro e eficaz para interromper a progressão do ceratocone após falha primária do cross-linking corneano.

Actualización sobre factores de riesgo asociados a daño corneal post Cross-Linking / Update on risk factors associated with corneal damage post Cross-Linking

El Cross-Linking corneal es un procedimiento utilizado en oftalmología principalmente para el tratamiento del queratocono, la ectasia corneal más frecuente. A pesar de su baja tasa de complicaciones, no es una técnica exenta de ellas. Entre las principales complicaciones se encuentran el haze y el melting corneal, ambas poseen una fisiopatología que no está totalmente esclarecida. Se realizó una revisión bibliográfica sobre la asociación entre el uso de quinolonas y el daño corneal frente a la exposición de luz UV. También se plantearon factores inherentes al paciente que se han relacionado al aumento de complicaciones. Se determinó que la radiación UV produce daños en aquellos tejidos sometidos previamente a tratamiento con quinolonas siendo de suma importancia la correcta anamnesis para seleccionar a los candidatos al procedimiento. (AU)

Corneal Cross-Linking is a procedure used in ophthalmology mainly for the treatment of keratoconus, the most frequent corneal ectasia. Despite its low complication rate, it is not an exempt technique. Among the main complications are haze and corneal melting, both have a pathophysiology that is not fully clarified. A bibliographic review of the association between the use of quinolones and corneal damage versus UV light exposure was performed. Inherent patient factors that have been related to increased complications were also raised. It was determined that UV radiation causes damage to these tissues, sometimes prior to quinolone treatment, with the correction of the anamnesis being of utmost importance to select the candidates for the procedure.

Effect of accelerated corneal crosslinking on ocular response analyzer waveform-derived parameters in progressive keratoconus / Efeito do crosslimking corneano acelerado nos parâmetros derivados da forma de onda do analisador de resposta ocular no ceratocone progressivo

ABSTRACT Purpose: To evaluate the effect of accelerated corneal crosslinking on corneal biomechanics with an ocular response analyzer in patients with progressive keratoconus. Methods: In this retrospective study, 50 eyes of 45 patients with progressive keratoconus who underwent accelerated corneal crosslinking were evaluated with ocular response analyzer waveform parameters before and one year after corneal crosslinking. Paired two-tailed Student's t-test was performed to compare the parameters before vs. after corneal crosslinking. Results: Mean patient age was 17.6 ± 3.6 (range 9-25) years. A significant increase was observed in p1 area, p2 area, h2, and dive2 values. No significant difference in corneal hysteresis, corneal resistance factor, or other waveform-derived parameters was observed at one year postoperatively. Conclusion: For estimating the effect of accelerated corneal crosslinking on corneal biomechanics, parameters such as p1 area, p2 area, h2, and dive2 are more sensitive than corneal hysteresis and corneal resistance factor. These results may help us to find out which corneal crosslinking method is most effective for stiffening the cornea.

RESUMO Objetivo: Avaliar o efeito do cross-linking corneano acelerado na biomecânica corneana com analisador de resposta ocular em pacientes com ceratocone progressivo. Métodos: Neste estudo retrospectivo, 50 olhos de 45 pacientes com ceratocone progressivo submetidos à cross-linking corneano acelerado foram avaliados com os parâmetros da forma de onda do analisador de resposta ocular antes e um ano após o tratamento com cross-linking corneano. O teste t de Student pareado bicaudal foi realizado para comparar os parâmetros antes e depois do cross-linking corneano. Resultados: A média de idade dos pacientes foi de 17,6 ± 3,6 (variação de 9 a 25) anos. Um aumento significativo foi observado nos valores de p1area, p2area, h2 e dive2. Nenhuma diferença significativa foi encontrada na histerese da córnea, fator de resistência da córnea ou outros parâmetros derivados da forma de onda foi observada em um ano de pós-operatório. Conclusão: Para estimar o efeito do cross-linking corneano acelerado na biomecânica corneana, parâmentros como p1area, p2area, h2 e dive2 são mais sensíveis que histerese da córnea e fator de resistência corneana. Esses resultados podem nos ajudar a descobrir qual método cross-linking corneano é mais eficaz no enrijecimento da córnea.

Two-year follow-up of corneal cross-linking and refractive surface ablation in patients with asymmetric corneal topography.

AIMS: To evaluate the safety and efficacy of corneal cross-linking (CXL) followed by photorefractive keratectomy (PRK) for refractive correction in patients with bilateral asymmetric topography. METHODS: Forty-four patients (88 eyes) were enrolled in this prospective randomised clinical trial. CXL with subsequent PRK after 6 months was performed in one eye (study group), and PRK alone was performed in contralateral eyes (control group). Patients were followed for 24 months after PRK. Outcome measures investigated included visual acuity (VA), refraction, aberrometry, topography, pachymetry and endothelial cell count. Groups were compared with linear mixed regression and repeated measures logistic regression. Multiple comparison adjustment with the Holm procedure was performed. RESULTS: At baseline, the logMAR VA (best spectacle corrected) in study and control groups was 0.12±0.13 (mean±SD) and 0.08D±0.14, respectively, and axial inferior-superior index (IS) (topographic IS) in study and control groups were 0.59D±0.31D and 0.58D±0.32D, respectively. After 24 months, a mean under correction of -0.50D was observed in both groups. Change from baseline in logMAR VA in study and control groups was 0.00D±0.08D and -0.02D±0.10D, respectively. Frequency of haze at 30 months in study and control group eyes was, respectively, 18.2% and 4.6% (p=0.05). There was no statistical difference between groups in spherical aberration and coma after adjustment for multiple comparisons. CONCLUSIONS: Non-simultaneous CXL followed by PRK may be performed safely, and refractive results over a 2-year follow-up are highly similar in virgin and previously cross-linked corneas. Despite using mitomycin C, corneal haze can be significantly higher in the first year after PRK in eyes pretreated with CXL.

Trans-epithelial accelerated corneal cross-linking for keratoconus in children.

The aim of the study is to evaluate the safety and efficacy of trans-epithelial accelerated corneal cross-linking (TE-ACXL) in children with progressive keratoconus. Retrospective, case-series of 23 eyes of 14 children who underwent TE-ACXL. Evaluations were performed at baseline and 1, 3, 6, 12 and 18mo postoperatively. Mean follow-up time of 23.82±3.15mo and mean age was 13.7±1.4y (range 11 to 16y). Mean preoperative uncorrected distance visual acuity changed from 0.92±0.45 logMAR (20/160) to 0.71±0.40 logMAR (20/100) (P=0.001). Mean keratometry (Km) changed from 53.87± 6.03 to 53.00±5.81 (P=0.001). Pachymetry did not have significant changes at last follow-up (P=0.30). The mean preoperative sphere was -5.58±2.48 and -4.89±4.66 D (P=0.11) at last follow-up; refractive cylinder from -5.58±2.48 to -5.02±2.23 (P=0.046). In conclusion, tomographic and refractive stability are shown in over 91% of eyes with pediatric progressive keratoconus who underwent TE-ACXL.

High-resolution wavefront-guided surface ablation with corneal cross-linking in ectatic corneas: a pilot study.

PURPOSE: A preliminary study to evaluate the outcomes of high-resolution wavefront-guided (HRWG) photorefractive keratectomy (PRK) with simultaneous corneal cross-linking (CXL) in ectasia eyes. METHODS: Sixteen eyes of 11 patients (mean age 31.9±9.8 years; range: 15-48 years) with keratoconus or post-laser-assisted in situ keratomileusis ectasia underwent HRWG PRK with simultaneous CXL. Manifest refraction, uncorrected (UDVA) and corrected distance visual acuity (CDVA), and keratometric and aberrometric outcomes are reported at 12 months. RESULTS: Significant improvement was observed postoperatively in visual acuity, refraction, and keratectomy in all eyes. At postoperative 12 months, 87.5% eyes were within ±1.0 D of attempted correction and 81.25% of eyes had a postoperative UDVA of 20/32 or better. A gain of 2 or more lines of CDVA was observed in 12.5% (2/16) of eyes and there was no change in CDVA lines in 25% (4/16) eyes. A substantial reduction in higher-order aberrations was observed in all eyes postoperatively; however, the improvement was not statistically significant. CONCLUSION: The outcomes of HRWG PRK in ectasia eyes with estimated residual stromal bed thickness of at least 350 µm (without epithelium) are promising at postoperative 1 year and provide surgeons with a valuable tool to improve vision with a high degree of refractive predictability.

Corneal Cross-Linking (with a Partial Deepithelization) in Keratoconus with Five Years of Follow-Up.

We performed a retrospective interventional case series including 80 eyes of 48 patients with keratoconus (KC) who were treated with modified corneal cross-linking (CXL) for KC (with a partial deepithelization in a pattern of stripes). The average follow-up was 5.8 years (with a minimum of 5 years). At the last follow-up visit, compared with preoperative values, there were no significant changes in spherical equivalent, average keratometry, corneal thickness, corneal hysteresis, or corneal resistance factor. The distance-corrected visual acuity was 20/39 preoperatively and 20/36 postoperatively (P = 0.3). The endothelial cell count decreased by 4.7% (P < 0.005). These findings suggest that this modified corneal CXL technique is a safe and effective alternative to halt the progression of KC up to five years after the procedure. However, some concerns remain as to whether this technique can affect in some degree the corneal endothelial cells.