title: Visual outcome after correcting the refractive error of large pupil patients with wavefront-guided ablation.
abstract: OBJECTIVE
  To investigate the efficacy and predictability of wavefront-guided laser in situ keratomileusis (LASIK) treatments using the iris registration (IR) technology for the correction of refractive errors in patients with large pupils.
  
  
  METHODS
  Horus Vision Correction Center, Alexandria, Egypt.
  
  
  METHODS
  Prospective noncomparative study including a total of 52 eyes of 30 consecutive laser refractive correction candidates with large mesopic pupil diameters and myopia or myopic astigmatism. Wavefront-guided LASIK was performed in all cases using the VISX STAR S4 IR excimer laser platform. Visual, refractive, aberrometric and mesopic contrast sensitivity (CS) outcomes were evaluated during a 6-month follow-up.
  
  
  RESULTS
  Mean mesopic pupil diameter ranged from 8.0 mm to 9.4 mm. A significant improvement in uncorrected distance visual acuity (UCDVA) (P < 0.01) was found postoperatively, which was consistent with a significant refractive correction (P < 0.01). No significant change was detected in corrected distance visual acuity (CDVA) (P = 0.11). Efficacy index (the ratio of postoperative UCDVA to preoperative CDVA) and safety index (the ratio of postoperative CDVA to preoperative CDVA) were calculated. Mean efficacy and safety indices were 1.06 ± 0.33 and 1.05 ± 0.18, respectively, and 92.31% of eyes had a postoperative spherical equivalent within ±0.50 diopters (D). Manifest refractive spherical equivalent improved significantly (P < 0.05) from a preoperative level of -3.1 ± 1.6 D (range -6.6 to 0 D) to -0.1 ± 0.2 D (range -1.3 to 0.1 D) at 6 months postoperative. No significant changes were found in mesopic CS (P ≥ 0.08), except CS for three cycles/degree, which improved significantly (P = 0.02). Magnitudes of primary coma and trefoil did not change significantly (P ≥ 0.34), with a small but statistically significant increase in primary spherical aberration.
  
  
  CONCLUSIONS
  Wavefront-guided LASIK provides an effective correction of low to moderate myopia or myopic astigmatism in large pupil patients without deterioration of visual quality.
authors.affiliation: Ophthalmology Department, Tanta University Eye Hospital, Tanta, Egypt ; Horus Vision Correction Center, Alexandria, Egypt.
authors.forename: Mounir A
authors.initials: MA
authors.lastname: Khalifa
authors.forename: Waleed A
authors.initials: WA
authors.lastname: Allam
authors.forename: Mohamed S
authors.initials: MS
authors.lastname: Shaheen