title: Theoretical model and design of a device to reduce the influence of environmental factors on refractive surgery outcomes.
abstract: Recently many different groups show that environmental temperature and relative humidity affects the outcomes of refractive surgery performed by excimer lasers in an unpredictable fashion. A theoretical model of the water vapor absorption at 193 nm wavelength is presented and discussed in order to quantitatively assess the influence of environmental parameters on the laser energy that actually reaches the corneal surface. Model simulations show that laser energy absorption (up to 7% of the available energy) occurs along the path of laser beam, into the existent space between the laser beam source and the patient's eye, and is caused by environmental temperature and relative humidity (respectively 35 degrees C and 95%). Our findings suggest that this energy loss reduces the ablation rate, producing a significant under-correction of the treated corneas. A cost effective device which keeps thermo hygrometric parameters constant along the laser beam path, is also provided.
authors.affiliation: Faculty of Biomedical Engineering, University Campus Bio-Medico of Rome, Italy.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Schena
authors.forename: Sergio
authors.initials: S
authors.lastname: Silvestri
authors.forename: Giovanni Talei
authors.initials: GT
authors.lastname: Franzesi
authors.forename: Gaetano
authors.initials: G
authors.lastname: Cupo
authors.forename: Pino
authors.initials: P
authors.lastname: Carito
authors.forename: Emiliano
authors.initials: E
authors.lastname: Ghinelli
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D003315:Cornea / Q000503:physiopathology* / Q000601:surgery*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006361:Heating / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000295:instrumentation* / Q000379:methods*; D008954:Models, Biological; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D016896:Treatment Outcome