Purpose: To evaluate the thinnest corneal thickness changes during and after corneal collagen cross-linking treatment with ultraviolet-A irradiation, using hypo-osmolar riboflavin solution in thin corneas. Methods: Eighteen eyes of 18 patients were included in this study. After epithelium removal, iso-osmolar 0.1% riboflavin solution was instilled to the cornea every 3 minutes for 30 minutes. Hypo-osmolar 0.1% riboflavin solution was then applied every 20 seconds for 5 minutes or until the thinnest corneal thickness reached 400 µm. Ultraviolet-A irradiation was performed for 30 minutes. During irradiation, iso-osmolar 0.1% riboflavin drops were applied every 5 minutes. Ultrasound pachymetry was performed at approximately the thinnest point of the cornea preoperatively, after epithelial removal, after iso-osmolar riboflavin instillation, after hypo-osmolar riboflavin instillation, after ultraviolet-A irradiation, and at 1, 6 and 12 months after treatment. Results: Mean preoperative thinnest corneal thickness was 380 ± 11 µm. After epithelial removal it decreased to 341 ± 11 µm, and after 30 minutes of iso-osmolar 0.1% riboflavin drops, to 330 ± 7.6 µm. After hypo-osmolar 0.1% riboflavin drops, mean thinnest corneal thickness increased to 418 ± 11 µm. After UVA irradiation, it was 384 ± 10 µm. At 1, 6 and 12 months after treatment, it was 372 ± 10 µm, 381 ± 12.7, and 379 ± 15 µm, respectively. No intraoperative, early postoperative, or late postoperative complications were noted. Conclusions: Hypo-osmolar 0.1% riboflavin solution seems to be effective for swelling thin corneas. The swelling effect is transient and short acting. Corneal thickness should be monitored throughout the procedure. Larger sample sizes and longer follow-up are required in order to make meaningful conclusions regarding safety.

Rev Bras Oftalmol. 2015; 74 (6): 400-3 RESUMOO melanocitoma do disco óptico é um tumor benigno, com pouca predisposição a transformação maligna para melanoma. Geralmente é assintomático, contudo deve ser avaliado periodicamente com exames, sendo um deles a campimetria computadorizada que se encontra alterada em 90% dos casos. Relatamos o caso de um homem de 61 anos sem diagnóstico prévio de melanocitoma do disco óptico. Discute-se a importância de um diagnóstico diferencial com melanoma e acompanhamento seriado do paciente.Descritores: Disco óptico/patologia; Neoplasias do nervo óptico/complicações; Melanoma/diagnóstico; Diagnóstico diferencial; Diagnóstico por imagem; Relatos de casos ABSTRACTThe optic disc melanocytoma is a benign tumor, with little predisposition to become a melanoma. It is usually asymptomatic, nonetheless should be evaluated periodically, most often by computerized perimetry, which in 9 out of 10 cases will show some alteration. In the following paper we report the case of 61 years old man without previous diagnosis of optic disc melanocytoma and discuss the importance of melanoma differential diagnosis and monitoring.