title: [Application of corrective formula for intraocular pressure changes in patients that underwent LASIK].
abstract: OBJECTIVE
  To compare the intraocular pressure (IOP) pre and post LASIK, correlating it to changes in central corneal thickness (CCT) and average simulated keratometry (K), as well as verifying the results of a corrective formula previously proposed.
  
  
  METHODS
  Longitudinal prospective study conducted in outpatients that underwent to LASIK. Patients underwent complete ophthalmic examination, previously and 2 months after the surgery. Intraocular pressure was evaluated with Goldmann applanation tonometer between 9 am and 11 am, average simulated keratometry was evaluated using corneal topography and central corneal thickness was measured with ultrasound pachymetry, been considered the average of three measurements. Two patients were excluded due to surgery or eye disease, and previous use of topical steroids over the past three months. The surgeries were performed according to standard procedures. The formula [real IOP = IOP measured + (540 - ECC)/71 + (43 - K)/2.7 + 0.75 mmHg] proposed for correcting intraocular pressure was used.
  
  
  RESULTS
  Fifteen eyes of eight patients were evaluated, age ranged from 24 to 46 years (mean: 31.37 ± 7.27). There was a statistically significant difference between the measurements of intraocular pressure, central corneal thickness and average simulated keratometry pre and post-LASIK. (p=0.0001). It was observed that each 1D corrected underestimated the IOP 1.06 ± 0.59 mmHg (0.11 a 1.89 mmHg). The use of the corrective formula lead to 80% of eyes within 2.50 mmHg of preoperative intraocular pressure. Although, the two sets of data are statistically different (p=0.0266).
  
  
  CONCLUSIONS
  Post LASIK eyes presented lower intraocular pressure than preoperatively. Intraocular pressure was moderately correlated to central corneal thickness and weakly correlated to average simulated keratometry. With the use of the corrective formula, we were able to determine that 80% were within 2.50 mmHg of the preoperative intraocular pressure.
authors.affiliation: Hospital do Servidor Público Estadual de São Paulo, SP, Brasil. thiagogeorge@hotmail.com
authors.forename: Thiago George Cabral
authors.initials: TG
authors.lastname: Silva
authors.forename: Júlia Gomes Fernandes
authors.initials: JG
authors.lastname: Polido
authors.forename: Maurício Vieira
authors.initials: MV
authors.lastname: Pinheiro
authors.forename: André Luís de Freitas
authors.initials: AL
authors.lastname: Silva
authors.forename: Laerte
authors.initials: L
authors.lastname: Goldbach
authors.forename: Vera Lúcia Degaspare Monte
authors.initials: VL
authors.lastname: Mascaro
authors.forename: Pedro Durães
authors.initials: PD
authors.lastname: Serracarbassa
authors.forename: Maria Emília Xavier dos Santos
authors.initials: ME
authors.lastname: Araújo
mesh_terms: D000328:Adult; D000465:Algorithms; D001251:Astigmatism / Q000601:surgery; D003315:Cornea / Q000473:pathology; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D020731:Keratomileusis, Laser In Situ; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D009929:Organ Size; D011184:Postoperative Period; D011446:Prospective Studies; D014065:Tonometry, Ocular; D016896:Treatment Outcome; D055815:Young Adult