Abstract
Purpose: :
Optic capture through an intact capsulorhexis is an established technique which improves centration and stability of a sulcus fixated IOL. The effect of this manoeuvre on refractive outcome as compared to sulcus fixation alone, which is known to produce a myopic shift in refraction is unknown. This study aims to assess the effect of optic capture on the achieved refractive outcome after complicated cataract surgery with a sulcus fixated IOL.
Methods: :
Retrospective case note review of patients undergoing either vitrectomy for retained lens matter following phacoemulsification or phacoemulsification with posterior capsule rupture and undergoing sulcus fixated posterior chamber IOL insertion by one surgeon. IOL power was adjusted as per published nomograms for sulcus fixated IOL powers. (http://doctor-hill.com/iol-main/bag-sulcus.htm) Patients were divided into two groups - those in whom the optic of the IOL implant was captured through the anterior capsulorhexis and those in whom it was not. Pre and post operative refractive data was collected to allow calculation of refractive accuracy. The same three piece IOL was used in all cases.
Results: :
Data on 40 patients was collected with 19 in the optic capture (OC) group and 21 in the without optic capture (WOC) group. The mean age was 75 in the OC group and 72 in the WOC group. The mean IOL power and mean axial length was 22 dioptres (D) and 23.24mm in the OC group and 20 D and 23.94mm respectively in the WOC group. The mean error between the aimed and achieved refraction was 0.40D (SEM 0.16) in the OC and -0.03D (SEM 0.10) in the WOC group. The mean refractive shift (between the achieved refraction and the refraction that was predicted if the IOL used had been placed in the capsular bag) was 0.59D in the OC group and 0.76D in the WOC group. Dividing the groups in two halves based on the median preoperative anterior chamber depth (3.1mm) the group with the largest mean error was the OC group with AC depth greater than 3.1mm at 0.59D (compared to approximately 0.1D in other three groups)
Conclusions: :
Optic capture effects the refractive outcome with a mean lower myopic shift in refraction than sulcus fixation alone but not equivalent to bag fixation. However the greatest reduction was in eyes with deeper anterior chambers where the optic captured power approached those of a bag fixated IOL. A nomogram for IOL power selection when optic capture is used will be presented.
Keywords: refractive error development • intraocular lens • cataract