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Corneal ectasia after excimer surgery and the mandelbrot B. fractal theory in ophthalmology
Author(s) -
KACHANOV ANDRE,
NIKULIN SERGE,
BAUER SVETA,
ZIMIN BORIS
Publication year - 2012
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2012.t099.x
Subject(s) - lasik , medicine , ophthalmology , ectasia , cornea , keratoconus , refractive surgery , surgery
Purpose To investigate corneal ectasia after LASIK surgery by using the Mandelbrot B. fractal theory in ophthalmology. Methods We reviewed our consecutive 55012 cases of excimer‐laser surgery including LASIK (48910 eyes) and PRK (6102 eyes). We used MEL‐60, MEL‐70 and MEL‐80 excimer laser (“Carl Zeiss Meditec”) and microkeratomes LSK‐Evolution 1, 2 and 3 (“Moria”) for LASIK. Follow‐up period was up to 14 years. The age of all patients was from 18 to 74 years. Some of them had hyperopia with sphere‐equivalence (SE) up to 6,5D, and the others had myopia with SE from –1,0D to –18,0D. Results There was NO corneal ectasia in the PRK and the hyperopic LASIK groups. 38 eyes (0,08%) had corneal ectasia after myopic LASIK (46294 eyes). There were 8 eyes with previous radial keratotomy, 8 eyes with subclinical keratoconus and 22 eyes with normal cornea (0,048% of all myopic LASIK) among the eyes . Pre‐op parameters of these eyes were the followings: central K ‐ 44,37±1,09D, CCT ‐ 530,4±34,4 microns, SE – 5,90±3,36D. Fractal theory allows to explain post‐op corneal ectasia phenomenon. Conclusion There are NO optical methods to predict corneal ectasia after LASIK surgery. But the risk factors of this complication were the followings: steep cornea (more than 44,0 D), corneal scars after previous corneal surgery (e.g. anterior radial keratotomy etc.), corneal topography irregularity and probably very thin residual corneal thickness. Myopic LASIK surgery can provoke post‐op corneal ectasia development in the long follow‐up period. We described post‐op myopic LASIK cornea as a “odd” (“curious”) attractor according to the Mandelbrot B. fractal theory.