Conventional automated keratometry is better at measuring refractive outcomes after cataract surgery than pupil-based Scheimpflug keratometry, according to a study published in the Journal of Cataract and Refractive Surgery.

Dr Sheridan Lam et al., DuPage Ophthalmology, Lombard, Illinois, USA, conducted a comparative case series on 110 eyes of 76 virgin cornea patients (Group 1) and 137 eyes of 94 control group participants also with virgin corneas (Group 2). Each group underwent phacoemulsification with implantation of a posterior chamber intraocular lens (IOL) and ultrasound biometry.

Group 1 underwent Scheimpflug keratometry based on pupil size and group 2 had conventional automated keratometry. The Holladay 2 formula was used to evaluate IOL power. Refractive outcomes and keratometry (K) readings were assessed by statistical analysis.

In group 1 the mean K reading and mean absolute refractive error was 43.45 D and 0.480 D, respectively. In group 2 it was 43.51 D and 0.252 D, respectively— meaning the absolute refractive error between the two groups was statistically significant.

Of the 110 eyes studied in group 1, 77 were within ±0.50 D of the intended postoperative refraction, 28 were between ±0.50 D and ±1.00 D, 4 were between ±1.00 D and ±1.50 D, and 1 was between ±1.50 D and ±2.00 D. Group 2 saw 131 eyes within ±0.50 D, 3 were between ±0.50 D and ±1.00 D, and 3 were between ±1.00 D and ±1.50 D. The findings were described as statistically significant between the 2 groups.