title: Predicting the refractive outcome after cataract surgery: the comparison of different IOLs and SRK-II v SRK-T.
abstract: OBJECTIVE
  To determine any differences between the predictive abilities of the IOL calculation formulas of SRK-II and SRK-T and to compare these using two different IOL types.
  
  
  METHODS
  A prospective, consecutive, single surgeon clinical trial was conducted on 400 consecutive patients who received routine, standardised phacoemulsification cataract surgery. 200 had cataract surgery and had the Alcon MZ30BD, a 5.5 mm one piece PMMA IOL, and another 200 cases used the Chiron C11UB, a silicone plate haptic IOL. The data used optimised A-constants. The measures were preoperative axial length and keratometry, IOL implanted, and refractive error at 4-6 weeks postoperatively.
  
  
  RESULTS
  There was no significant difference between the predictive abilities of SRK-II or SRK-T. For the Alcon and Chiron lens respectively, prediction errors using SRK-II were <0.5 dioptres in 58% and 70% and for <1.0 dioptres in 84% and 92%. These differences were statistically significant (chi(2), p=0.02).
  
  
  CONCLUSIONS
  There are differences in the predictability of refractive outcomes between intraocular lens styles.
authors.forename: M J
authors.initials: MJ
authors.lastname: Elder
mesh_terms: D001699:Biometry; D003315:Cornea / Q000473:pathology; D005123:Eye / Q000473:pathology; D006801:Humans; D007910:Lenses, Intraocular; D009907:Optometry; D018918:Phacoemulsification; D011183:Postoperative Complications; D011300:Preoperative Care; D011446:Prospective Studies; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000209:etiology; D016896:Treatment Outcome