title: Effect of pupillary dilation on Haigis formula-calculated intraocular lens power measurement by using optical biometry.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of pupillary dilation on the Haigis formula-calculated intraocular lens (IOL) power and ocular biometry measurements by using IOLMaster(®).
  
  
  METHODS
  A prospective study was performed for biometry measurements of 373 eyes of 192 healthy subjects using the IOLMaster at the outpatient department of King Chulalongkorn Memorial Hospital from February 2013 to July 2013. The axial length (AL), anterior chamber depth (ACD), keratometry (K), and IOL power were measured before and after 1% tropicamide eye drop instillation. The Haigis formula was used in the IOL power calculation with the predicted target to emmetropia. Each parameter was compared by a paired t-test prior to and after pupillary dilation. Bland-Altman plots were also used to determine the agreement between each parameter.
  
  
  RESULTS
  The mean age of the subjects was 53.74±14.41 years (range 18-93 years). No differences in AL (P=0.03), steepest K (P=0.42), and flattest K (P=0.41) were obtained from the IOLMaster after pupillary dilation. However, ACD and IOL power were significantly different postdilation (P<0.01 and P<0.01, respectively). In ACD and IOL power measurements, the concordance rates were 93.03% and 97.05% within 95% limits of agreement (-0.48 to 0.26 mm and -1.09 to 0.88 D, respectively) in the Bland-Altman plots.
  
  
  CONCLUSIONS
  Biometry measurements in the cycloplegic stage should be considered in the IOL formulas that use parameters other than AL and K.
authors.affiliation: Department of Ophthalmology, King Chulalongkorn Memorial Hospital, Thai Red Cross Society.
authors.forename: Bharkbhum
authors.initials: B
authors.lastname: Khambhiphant
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University, Bangkok.
authors.forename: Suganlaya
authors.initials: S
authors.lastname: Sasiwilasagorn
authors.affiliation: Department of Ophthalmology, Samut Prakan Hospital, Samut Prakan, Thailand.
authors.forename: Nattida
authors.initials: N
authors.lastname: Chatbunchachai
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University, Bangkok; Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Krit
authors.initials: K
authors.lastname: Pongpirul
keywords: Haigis formula; IOLMaster; intraocular lens; optical biometry; pupillary dilation