Abstract
Purpose: :
Corneal power measurements prior to surgery are essential for a successful outcome especially with toric intraocular (TIOL) lenses designed to reduce astigmatism. We sought to evaluate the visual outcomes of TIOL placement in a teaching institution using a Nidek ARK-760A Autorefractor (AUTO) versus the IOLMaster (IOLM) for keratometry measurements.
Methods: :
A retrospective case series of cataract extractions with AcrySof Toric IOL implantation from October 2009 to October 2011 were reviewed. In a training facility with multiple surgeons operating on different dates, corresponding time periods both before and following the acquisition of the IOLM were chosen. Similar months of the year were selected in order to reflect similar training levels of surgeons. The AUTO group time period was slightly extended to increase the number of cases to make the groups comparable. The Ellex immersion A-scan was used in conjunction with the AUTO group to compete pre-operative measurements. Patients with visually significant ocular conditions and limited visual potential were excluded including advanced glaucoma and age related macular degeneration. Surgical procedures with significant complications such as anterior vitrectomy were also excluded.
Results: :
The AUTO group included 20 patients, 23 eyes with 24 procedures, including one lens rotation. Using the IOLM, cases from 28 patients with 31 eyes were reviewed. Following surgery, the mean uncorrected visual acuity (UCVA) was good in the AUTO group (20/34) and significantly improved with the IOLM (20/28) with a P-value of 0.014. Also 37.5% had an UCVA of 20/25 or better with the AUTO and 64% with the IOLM. Including 20/30 vision, this increased to 54% with the AUTO and 87% with the IOLM. The amount of remaining cylinder post surgery was minimal, less than 0.75D, and not significantly different with a P-value of 0.283. The mean spherical equivalent using the AUTO was -0.28 and with the IOLM -0.018 with significant difference and P-value of 0.043.
Conclusions: :
While surgical outcomes by resident surgeons with TIOL resulted in good UCVA, the IOLM was better at predicting the final refractive result. Both groups significantly reduced the amount of residual astigmatism with comparable outcomes. UCVA in the AUTO group may have been limited by myopic outcomes due to compression with the immersion A-scan. Further comparison of corneal measurements between the two machines is warranted.
Keywords: cataract • intraocular lens • treatment outcomes of cataract surgery