Correction: Efficacy of toric intraocular lens implantation with high corneal astigmatism within the United Kingdom's National Health Service.

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Efficacy of toric intraocular lens implantation with high corneal astigmatism within the United Kingdom's National Health Service.

OBJECTIVES: To determine the efficacy of toric intraocular lens (TIOL) implantation in cataract surgery patients with high levels of pre-operative corneal astigmatism and ocular co-morbidities in a state funded, National Health Service (NHS) hospital. METHODS: Retrospective cohort study involving consecutive cases of TIOL implantation in cataract surgery with over 3.00DC of pre-operative corneal astigmatism. Subjects were implanted with the Tecnis TIOL (Abbot Medical Optics) with capsular tension ring stabilisation using the Callisto system (Carl Zeiss Meditec). Visual acuity and refraction were assessed at 4-6 weeks post-operatively. Vector analysis was used to calculate the intended refractive correction, surgically induced refractive correction (SIRC), correction ratio (CR), error of magnitude (EM) and error vector (EV). RESULTS: Sixty-six eyes of forty-seven subjects aged 73.8 ± 11.9 were included. Eyes with ocular co-morbidities included dry age-related macular degeneration (n = 13), amblyopia (n = 7), high myopia (n = 7), glaucoma (n = 6), previous corneal transplantation (n = 2), nanophthalmos (n = 2) and corneal scarring (n = 1). Pre-operative corneal astigmatism was 4.25 ± 1.69DC (range 3.00-12.00), post-operative refractive astigmatism was 1.31 ± 1.05DC (range 0.00-6.50DC) and post-operative unaided visual acuity was 0.25 ± 0.19 LogMAR. Vector analysis demonstrated an SIRC of 4.08 ± 1.39DC, CR = 1.1 ± 0.3, EM -0.4 ± 1.0 and EV of 1.23 ± 0.72. CONCLUSIONS: The results demonstrate the efficacy of TIOL implantation in patients with high corneal astigmatism and provide strong evidence advocating their use in cataract surgery within a state funded hospital eye service. Refractive astigmatism was significantly lower than the pre-operative corneal astigmatism and a low error vector was achieved relative to the magnitude of correction.

Comparison of reliability and repeatability of corneal curvature assessment with six keratometers.

BACKGROUND: Keratometric methodology varies between instruments and the differences may have a clinical impact. We investigated the agreement and reproducibility of six keratometers. METHODS: Keratometry was performed on 100 subjects at two separate sessions with IOLMaster 500, Pentacam, OPD scanner, Medmont E300, Javal-Schiøtz and TMS-5. A second observer assessed 30 subjects to determine inter-observer variability. A single individual was assessed on 10 separate sessions to determine intra-observer variability. Data were analysed using coefficient of variation (CV) and intra-class correlation coefficient (ICCC) for intra-observer variation. Inter-observer concordance was evaluated by the ICCC. Bland-Altman plots, Pearson's correlation coefficient and repeated measures analysis of variance were used to assess agreement of data produced by the instruments. RESULTS: OPD scanner and Javal-Schiøtz mean spherical equivalent (MSE) results were systematically different (p < 0.001) from other instruments (flatter and steeper, respectively). J0 /J45 were similar for all instruments (p < 0.05). Bland-Altman comparison plots indicated that Pentacam and IOLMaster demonstrated greatest level of agreement (ICC results MSE = 0.992, J0 = 0.934 and J45 = 0.890). Agreement (ICC) between observers for MSE ranged from 0.955 to 0.995 for all instruments; lower levels of agreement were found for J0 /J45 (0.289 to 0.901). IOLMaster showed greatest correlation and Medmont the lowest. All instruments showed high intra-observer repeatability of MSE (CV 0.1 to 0.3 per cent). The J0 /J45 readings showed greater variability (CV range 8.8 to 57.6 per cent). CONCLUSION: When considering MSE alone IOLMaster, Pentacam, OPD scan and Medmont may be considered interchangeable; however, assessment of astigmatism shows greater variability between instruments, sessions and observers.