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Neema Nayeb-Hashemi, Ronald Krueger, Minoru Tomita; Correlation of Temperature and Humidity to the Incidence of LASIK Flap Striae In A Very High Volume Refractive Surgery Center. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3119.
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© ARVO (1962-2015); The Authors (2016-present)
To correlate temperature and humidity to the monthly incidence of flap striae after LASIK performed by experienced surgeons at a single center between June 2007 and April 2012
Data on all LASIK cases performed at the Shinagawa LASIK Center in Tokyo between June 2007 and April 2012 was reviewed and organized by month for total LASIK cases as well as the total number of striae requiring flap realignments. Statistical analyses were then performed to determine any significant differences in incidence by month, season, and year. Using data from the Japan Meteorological Agency, average monthly humidities and temperatures for the same time were obtained and compared to monthly realignment rates.
A total of 614,340 eyes had LASIK surgery of which 5,244 developed striae requiring realignment, a cumulative incidence of 0.85%. The average number of LASIK cases per month ranged from 8,959 to 12,028, while the average flap striae per month ranged from 300 to 534. There was a significant decline in the total number of LASIK cases and macrostriae in 2011 (p<.05). Analysis of complete data for the years of 2008-2011 revealed a yearly incidence ranging between 0.803% and 0.877% (p>.05). Averaged for all years, the monthly incidence ranged from 0.657% to 1.006%. The lowest incidences were in the summer months (June-August). Subgroup analysis demonstrated no difference in the incidence of macrostriae between years, however there was a notable decline in the incidence of macrostriae for the summer season (p<.05). Comparison of the average monthly humidity and temperatures to the average monthly incidence of macrostriae from 2008 to 2011 revealed a strong inverse correlation for each (R = -.902,R = -.888).
This analysis represents the first large scale retrospective review on the incidence of macrostriae at a high volume practice. The 0.85% cumulative incidence represents a number that experienced surgeons can use as a metric to improve outcomes. The lower incidence during the summer months has not been previously reported. The strong inverse correlation with monthly/seasonal temperature and humidity may point to air moisture as providing a protective effect in the early post postoperative period, however pursuit of a detailed, geographically diverse multi-center longitudinal study incorporating both humid and arid climates is necessary.
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