title: Effect of pupil dilation on biometry measurements with partial coherence interferometry and its effect on IOL power formula calculation.
abstract: OBJECTIVE
  To determine if there are any differences between eye parameters measured by the IOLMaster (Carl Zeiss Meditec AG, Jena, Germany) biometer before and after dilating the pupil. The effect of those changes on intraocular lens (IOL) power calculation is also analyzed.
  
  
  METHODS
  A prospective observational study was carried out including 107 right eyes of 107 patients with cataract and no other ocular morbidity. An IOLMaster baseline measurement included axial length (AL), mean keratometry (K), and anterior chamber depth (ACD) (corneal epithelium to lens). A second measurement was taken 45 minutes after instillation of topical tropicamide and phenylephrine. Biometric variation was analyzed and prediction for IOL power based on the Haigis and the Sanders/Retzlaff/Kraff Theoretical (SRK/T) formulas was calculated for both measurements.
  
  
  RESULTS
  The ACD increased significantly after dilation (+0.12 ± 0.12 mm; p&lt;0.01). The AL and K variation was not significant: +0.00 ± 0.02 mm (p = 0.62) and +0.01 ± 0.22 D (p = 0.57), respectively. Pupil dilation did not affect IOL power calculation based on SRK/T formula either targeting emmetropia (-0.02 ± 0.26, p = 0.30) or the lowest myopic residual refraction (-0.03 ± 0.34, p = 0.30). However, using the Haigis formula significantly changed calculations for emmetropia (0.07 ± 0.34, p = 0.03) and for the lowest myopic refraction (0.10 ± 0.40, p = 0.01).
  
  
  CONCLUSIONS
  Pupil pharmacologic dilation produces a significant increase in ACD when measured by the IOLMaster. This change results in a different IOL power prediction according to the Haigis formula, which calculates the effective lens position taking into account the ACD.
authors: 1 San Eloy Hospital, Baracaldo, Vizcaya - Spain.
authors: Alvaro
authors: A
authors: Rodriguez-Raton
authors: Marianela
authors: M
authors: Jimenez-Alvarez
authors: Lucia
authors: L
authors: Arteche-Limousin
authors: Estibaliz
authors: E
authors: Mediavilla-Peña
authors: Iñaki
authors: I
authors: Larrucea-Martinez
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000867:Anterior Chamber / Q000473:pathology*; D058452:Axial Length, Eye; D001699:Biometry / Q000379:methods; D063171:Corneal Pachymetry; D004338:Drug Combinations; D005260:Female; D006801:Humans; D007368:Interferometry / Q000379:methods*; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008027:Light; D008297:Male; D008875:Middle Aged; D009184:Mydriatics / Q000008:administration & dosage*; D055095:Optics and Photonics; D010656:Phenylephrine / Q000008:administration & dosage; D011446:Prospective Studies; D011680:Pupil / Q000187:drug effects*; D014331:Tropicamide / Q000008:administration & dosage
chemical_list: D004338:Drug Combinations; D009184:Mydriatics; D010656:Phenylephrine; D014331:Tropicamide