Новый взгляд на фотопротекцию и кросслинкинг в эксимерлазерной коррекции зрения

Abstract

Purpose. To develop approaches to excimer laser keratorefractive surgery based on a new view of the photoprotective function of the cornea, ablation-induced secondary radiation, photoprotective and side effects of crosslinking. Material and methods. The literature data and our own 32-year clinical observations of complications in excimer laser vision correction, methods of their treatment and prevention have been analyzed. Particular emphasis was placed on the analysis of works on photoprotection and crosslinking in photorefractive surgery. New approaches to excimer laser keratorefractive surgery are based on studies on the use of riboflavin for photoprotection and laser-induced crosslinking in corneal ablation (598 operations). Corneal crosslinking was assessed by computed keratotopography, optical coherence tomography, and corneal densitometry. Long-term results were followed up to 8 years. Results. Complications in excimer laser refractive surgery were associated with the development of dry eye syndrome, the formation of subepithelial or intrastromal fibroplasia. Ablation-induced secondary radiation played an important role in the development of complications of excimer laser refractive surgery. It negatively affected keratocytes, nerves and increased oxidative stress in the cornea. To protect against secondary radiation, a new technology of keratoablation with 0.25% isotonic riboflavin solution has been developed. This reduced oxidative stress and aseptic inflammatory response. According to OCT and densitometric studies, a decaying effect of crosslinking with the formation of a membrane structure on the ablation surface was revealed. Local photoprotection during ablation with riboflavin and the effect of crosslinking in combination with postoperative spectacle spectral UV photoprotection accelerated the stabilization of optical-refractive and visual results, increased the photoprotective and strength properties of the thinned cornea. This reduced the risks of keratoectasia and earlier development of cataracts. Conclusion. A new look at photoprotection and crosslinking in excimer laser refractive surgery provides for keratoablation with riboflavin in combination with postoperative spectacle spectral photoprotection from external UV radiation. Key words: excimer laser refractive surgery, dry eye, fibroplasia, keratoectasia, riboflavin, photoprotection, crosslinking.