Influence of decentration and tilt of Tecnis ZCB00 on visual acuity and higher order aberrations.

BACKGROUND/OBJECTIVES: To determine the influence of decentration and tilt of a pseudophakic aspheric intraocular lens (IOL) on visual acuity (VA) and higher-order aberrations (HOAs), and to analyze the agreement between pupil center/axis and iridocorneal angles center/axis when assessing IOL decentration and tilt. SUBJECTS/METHODS: A prospective interventional case series study including thirty-three patients undergoing Tecnis ZCB00 (Abbott Medical Optics) implantation. IOL decentration and tilt with respect to two reference systems (pupil and iridocorneal angles centers/axes), in cartesian (X,Y) and polar (radius/tilt, polar angle/azimuth) coordinates, were assessed with optical coherence tomography. VA and internal and ocular HOAs were evaluated. Multiple linear regression models and intraclass correlation coefficient (ICC) were computed. RESULTS: IOL decentration only showed a significant effect on internal HOAs for [Formula: see text] (R2 = 0.20, P = 0.04). IOL decentration with respect to the pupil center showed a significant effect on ocular [Formula: see text] (R2 = 0.18, P = 0.05), [Formula: see text] (R2 = 0.36, P = 0.001) and [Formula: see text] (R2 = 0.24, P = 0.02); and with respect to the center of iridocorneal angles, on ocular [Formula: see text] (R2 = 0.21, P = 0.03), [Formula: see text] (R2 = 0.32, P = 0.003), primary coma (R2 = 0.41, P < 0.001), and coma-like (R2 = 0.40, P = 0.001). Poor agreement between both reference systems was found for IOL decentration measurements (ICC ≤ 0.41), except for the polar angle coordinate (ICC = 0.83). Tilt measurements showed good agreement (ICC ≥ 0.75). CONCLUSIONS: Tecnis ZCB00 decentration and tilt values after uneventful implantation appear not to have influence on VA, and their effect on HOAs are not high enough to clinically affect quality of vision. Pupil and iridocorneal angles used as reference systems may be interchangeable for IOL tilt measurements, but not for decentration.

Efficacy of a One-Piece Aberration Neutral Hydrophobic Acrylic Toric Intraocular Lens.

Purpose: To assess the refractive outcomes, intraocular centration and rotational stability of the enVista toric intraocular lens (IOL). Patients and Methods: This study was a prospective, multi-centre, double-masked, partially randomized and partially controlled clinical trial. A total of 191 participants were implanted with toric IOL (1.25, 2.00, or 2.75D) or non-toric IOL (control). The lowest range of corneal astigmatic eyes were randomized to 1.25D toric or control. Higher astigmatic powers were allocated to the treatment arm. Subjects were assessed immediately postoperatively, 1-2 (V1), 7-14 (V2), 30-60 (V3) and 120-180 (V4) days postoperatively. Unaided (UDVA) and distance corrected visual acuity (CDVA), manifest refraction and corneal curvature were assessed. Vector analysis was used to calculate surgically induced refractive correction (SIRC), correction ratio (CR), error magnitude (EM) and error vector (EV). Slit-lamp photography was used to measure centration and rotational stability. Results: UDVA was better in the low toric IOL group in comparison with the control group at V4 (p<0.001). There was an undercorrection in the control group, whereas the average CR for all toric subjects was 1.00 ± 0.32: V2, 0.98 ± 0.34: V3 and 0.98 ± 0.35: V4. The absolute IOL rotational stability in comparison to the position of the IOL at V1 was 1.35° ± 0.97°: V2, 1.35° ± 1.07°: V3 and 1.38° ± 1.25°: V4. Decentration was generally inferior (V1: 0.04 ± 0.22mm, V2: 0.05± 0.20mm, V3: 0.08 ± 0.22mm, V4: 0.04 ± 0.21mm) and nasal (V1: 0.19 ± 0.23mm, V2: 0.20 ± 0.20mm, V3: 0.20 ± 0.21mm, V4: 0.17 ± 0.22mm). Conclusion: Participants with low levels of corneal astigmatism achieved superior vision and refractive outcomes in the low toric group over the control. Moderate and high levels of astigmatism achieved excellent refractive outcomes. The toric IOL demonstrated high levels of both rotational and centrational stability.

Optimising curve fitting techniques to look for standardisation of the analysis of defocus curves derived from multifocal intraocular lenses.

INTRODUCTION: To establish the most appropriate curve fitting method to allow accurate comparison of defocus curves derived from intraocular lenses (IOLs). METHODS: Defocus curves were plotted in five IOL groups (monofocal, extended depth of focus, refractive bifocal, diffractive bifocal and trifocal). Polynomial curves from 2nd to 11th order and cubic splines were fitted. Goodness of fit (GOF) was assessed using five methods: least squares, coefficient of determination (R2adj ), Akaike information criteria (AIC), visual inspection and Snedecor and Cochran. Additional defocus steps at -2.25 D and -2.75 D were measured and compared to the calculated visual acuity (VA) values. Area under the defocus curve and range of focus were also compared. RESULTS: Goodness of fit demonstrated variable results, with more lenient methods such as R2adj leading to overfitting and conservative methods such as AIC resulting in underfitting. Furthermore, conservative methods diminished the inflection points resulting in an underestimation of VA. Polynomial of at least 8th order was required for comparison of area methods, but overfitted the EDoF and monofocal groups; the spline curve was consistent for all IOLs and methods. CONCLUSIONS: This study demonstrates the inherent difficulty of selecting a single polynomial function. The R2 method can be used cautiously along with visual inspection to guard against overfitting. Spline curves are suitable for all IOLs, guarding against the issues of overfitting. Therefore, for analysis of the defocus profile of IOLs, the fitting of a spline curves is advocated and should be used wherever possible.

Visual function and subjective perception of vision after bilateral implantation of monofocal and multifocal IOLs: a randomized controlled trial.

PURPOSE: To examine monocular and binocular visual function and patient-reported outcomes after implantation of multifocal IOLs (mIOLs) or monofocal IOLs, using a rigorous series of clinical assessments. SETTING: BMI Southend Hospital, United Kingdom. DESIGN: Prospective, randomized, double-masked clinical trial. METHODS: One hundred patients were randomized for bilateral implantation of either a Bi-Flex 677MY mIOL or a Bi-Flex 677AB IOL and were assessed at 3 to 6 months (V1) and 12 to 18 months (V2). Primary outcomes included distance, intermediate, and near logarithm of the minimum angle of resolution (logMAR) visual acuities (VAs) and defocus curve profile assessment. Secondary outcomes included reading speed, contrast sensitivity (CS), and the subjective perception of quality of vision. RESULTS: Forty-seven subjects with monofocal IOL and 43 mIOL subjects completed the study. Uncorrected (mIOL: 0.10 ± 0.09 logMAR; IOL: 0.09 ± 0.11 logMAR) and corrected (mIOL: 0.04 ± 0.06 logMAR; IOL: 0.01 ± 0.07 logMAR) distance VAs were comparable (P > .05). Uncorrected near VA (mIOL: 0.23 ± 0.13 logMAR; IOL: 0.55 ± 0.20 logMAR, P < .001) and distance-corrected near VA (mIOL: 0.24 ± 0.13 logMAR; IOL: 0.54 ± 0.17 logMAR, P < .001) were significantly improved with mIOLs. There was no significant difference in distance-corrected intermediate VA (mIOL: 0.38 ± 0.13 logMAR; IOL: 0.39 ± 0.13 logMAR, P = .431). Defocus curves demonstrated an increased range-of-focus among mIOLs (mIOL: 4.14 ± 1.10 diopter [D]; IOL: 2.57 ± 0.77 D). Pelli-Robson CS was different at V1 (P < .001) but similar by V2 (P = .059). Overall satisfaction was high (>90%) in both groups for distance tasks whereas significantly different for near tasks (mIOL, 18.45 ± 16.53 logUnits; IOL, 55.59 ± 22.52 logUnits). CONCLUSIONS: Uncorrected near visual acuity was demonstrably better with mIOLs and there was greater subjective satisfaction with quality of near vision. Halos reported by the mIOL group were significant compared with the IOL group but did not show an adverse effect on overall satisfaction.

Long-term Outcomes After LASIK Using a Hybrid Bi-aspheric Micro-monovision Ablation Profile for Presbyopia Correction.

PURPOSE: To evaluate visual outcomes 6 years after hybrid bi-aspheric multifocal central laser in situ keratomileusis for presbyopia correction (PresbyLASIK) treatments. METHODS: Thirty-eight eyes of 19 patients consecutively treated with central PresbyLASIK were assessed. The mean age of the patients was 51 ± 3 years at the time of treatment with a mean spherical equivalent refraction of -0.57 ± 1.98 diopters (D) and mean astigmatism of 0.58 ± 0.57 D. Monocular corrected distance visual acuity (CDVA), corrected near visual acuity (CNVA), and distance-corrected near visual acuity (DCNVA), uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), distance-corrected intermediate visual acuity (DCIVA), and uncorrected near visual acuity (UNVA) were assessed preoperatively and postoperatively for the dominant eye, non-dominant eye, and binocularly. Subjective quality of vision and near vision were assessed using the 10-item, Rasch-scaled, Quality of Vision (QoV) Questionnaire and Near Activity Visual Questionnaire (NAVQ), respectively. RESULTS: At 6 years postoperatively, mean binocular UDVA was 20/18 ± 4 and mean binocular UNVA and UIVA were 0.11 ± 0.13 and -0.08 ± 0.08 logRAD, respectively. Spherical equivalent showed a slow hyperopic drift of +0.10 D per year with refractive astigmatism stable from 6 weeks postoperatively. Defocus curves showed an improvement of 0.4 Snellen lines at best focus from 1 to 6 years of follow-up, reaching preoperative levels. Compared to the preoperative status, the corneal and ocular spherical aberrations (at a 6-mm diameter) decreased and were stable from 3 months of follow-up. Questionnaires revealed a postoperative unaided QoV score comparable to preoperative scores and with an improved postoperative unaided NAVQ score compared to preoperative scores with best correction. CONCLUSIONS: Presbyopic treatment using a hybrid bi-aspheric micro-monovision ablation profile is safe and efficacious even after 6 years postoperatively. The postoperative outcomes indicate improvements in binocular vision at far, intermediate, and near distances. An 8% re-treatment rate should be considered to increase satisfaction levels, including a 3% reversal rate. [J Refract Surg. 2020;36(2):89-96.].

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

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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.

Evaluation of clinical outcomes following implantation of a sub-2-mm hydrophilic acrylic MICS intraocular lens.

PURPOSE: To evaluate clinical outcomes following sub-2-mm microincision cataract surgery (MICS) and intraocular lens (IOL) implantation. SETTING: Five EU clinical sites. DESIGN: Prospective, multicenter, open-label, single-arm, non-randomized. METHODS: Preoperative assessment involved visual acuity (VA), intraocular pressure and biometry measurements. 1.4-mm wound-assisted or 1.8-mm MICS was performed. Follow-up visits were made 1 day, 1-2 weeks, 1-2 and 4-6 months after surgery. The incision size, corrected distance VA (CDVA), uncorrected distance VA, manifest refraction spherical equivalent (MRSE), refraction predictability/stability and IOL decentration were assessed. At 12-, 18-, and 24-month, long-term centration, posterior capsular opacification (PCO) and Nd:YAG capsulotomy rates were investigated. RESULTS: A total of 103 eyes were implanted with the study IOL (INCISE, Bausch & Lomb), 96 of which were included in visual outcome analysis. A mean 6-month CDVA of - 0.02 logMAR (20/20 + 1) was observed and 75 eyes (79.8%) and 93 eyes (98.3%) achieved a visual acuity of at least 20/20 or 20/40. Mean MRSE was - 0.20 ± 0.60 D. Mean absolute predictive error was 0.44 ± 0.36 D, with 90.4% within 1.00 D of target. Mean total decentration was 0.35 ± 0.36 mm at 6 months and 0.32 ± 0.14 mm at 24 months (p > 0.05). 24-month evaluation of posterior capsular opacification score was 0.03 for the central area. A Nd:YAG rate of 3.4% was observed at 24 months. CONCLUSIONS: The new MICS IOL provided excellent visual outcomes and was safe and effective for the sub-2-mm procedure. The MICS IOL demonstrated long-term centration, stability and a low rate of PCO development.

Assessment of dysphotopsia in pseudophakic subjects with multifocal intraocular lenses.

AIM: To better understand the phenomenon of dysphotopsia in patients implanted with multifocal intraocular lenses (IOLs). METHODS: Forty-five patients (aged 61.8±8.9 years) implanted bilaterally with Tecnis ZM900 (diffractive multifocal), Lentis Mplus MF30 (segmented refractive multifocal) or Softec-1 (monofocal) IOLs (each n=15) 4-6 months previously and who had achieved a good surgical outcome were examined. Each reported their dysphotopsia symptoms subjectively, identified its form (EyeVisPod illustrations), quantified retinal straylight (C-Quant) and halo perception (Aston halometer). Retinal straylight and halometry was repeated by a second masked clinician to determine interobserver repeatability. RESULTS: Subjective dysphotopsia ratings were able to differentiate Tecnis ZM900 from Lentis Mplus MF30 (p<0.001), but not Lentis Mplus MF30 from groups implanted with Softec-1 (p=0.290). Straylight was similar between the monofocal and multifocal IOL designs (p=0.664). ZM900 IOLs demonstrated a uniform increase in dysphotopsia in comparison with the monofocal IOL (p<0.001) as measured with the halometer, whereas sectorial refractive multifocal IOLs demonstrated a localised increase in dysphotopsia over the inferior visual field. Intraobserver repeatability was good for the straylight (intraclass correlation coefficients (ICC)=0.77) and halometry (ICC=0.89). There was no significant correlation between the subjective dysphotopsia severity and the straylight (p=0.503) or halometry (p>0.10) quantification or between straylight and the halo area (p>0.30). CONCLUSIONS: Multifocal IOLs induce symptoms of dysphotopsia. Straylight did not differentiate between IOL designs, however halometry identified clear differences in light scatter due to the IOL optics. Whereas, subjective rating of overall dysphotopsia are not strongly associated with straylight or halo perception, the halometry polar diagram reflected the subjective descriptions of dysphotopsia.

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.

Tablet App halometer for the assessment of dysphotopsia.

PURPOSE: To assess the validity and repeatability of the Aston Halometer. SETTING: University clinic, United Kingdom. DESIGN: Prospective, repeated-measures experimental study. METHODS: The halometer comprises a bright light-emitting-diode (LED) glare source in the center of an iPad4. Letters subtending 0.21° (~0.3 logMAR) were moved centrifugally from the LED in 0.05 degree steps in 8 orientations separated by 45 degrees for each of 4 contrast levels (1000, 500, 100, and 25 Weber contrast units [Cw]) in random order. Bangerter occlusion foils were inserted in front of the right eye to simulate monocular glare conditions in 20 subjects (mean age 27.7 ± 3.1 years). Subjects were positioned 2 meters from the screen in a dark room with the iPad controlled from an iPhone via Bluetooth operated by the researcher. The C-Quant straylight meter was also used with each of the foils to measure the level of straylight over the retina. Halometry and straylight repeatability was assessed at a second visit. RESULTS: Halo size increased with the different occlusion foils and target contrasts (F = 29.564, P < .001) as expected and in a pattern similar to straylight measures (F = 80.655, P < 0.001). Lower contrast letters showed better sensitivity but larger glare-obscured areas, resulting in ceiling effects caused by the screen's field-of-view, with 500 Cw being the best compromise. Intraobserver and interobserver repeatability of the Aston Halometer was good (500Cw: 0.84 to 0.93 and 0.53 to 0.73) and similar to the straylight meter. CONCLUSION: The halometer provides a sensitive, repeatable way of quantifying a patient-recognized form of disability glare in multiple orientations to add objectivity to subjectively reported discomfort glare.

Safety and effectiveness of a new toric presbyopia-correcting posterior chamber silicone intraocular lens.

PURPOSE: To evaluate the safety and effectiveness of the Trulign toric intraocular lens (IOL) in adults with cataract. SETTING: Eight private practices in the United States and 1 in Canada. DESIGN: Prospective randomized single-masked multicenter study. METHODS: A toric IOL (1.25 D, 2.00 D, or 2.75 D, determined by a toric calculator) was implanted in eligible patients with age-related cataract requiring a 16.00 to 27.00 diopter (D) spherical IOL power and with a predicted postoperative astigmatism of 0.83 to 2.50 D. Eyes within the lowest cylinder range (predicted postoperative astigmatism 0.83 to 1.32 D) were randomized in a 1:1 ratio between the 1.25 D toric IOL group and the nontoric accommodating IOL (Crystalens) control group. RESULTS: The toric 1.25 D group had a statistically significantly greater percentage reduction in absolute cylinder (P < .001) and uncorrected distance visual acuity (P = .002) than the control group at the 120- to 180-day visit. The mean monocular uncorrected vision at distance, intermediate, and near was 20/25, 20/22, and 20/39, respectively, with the 1.25 D, 2.00 D, and 2.75 D toric IOLs in aggregate (toric group). In addition, 96.1% of patients (123/128) had 5.0 degrees or less absolute IOL rotation postoperatively. Regarding safety, the endpoints for preservation of corrected visual acuity and the incidence of complications and adverse events were met. CONCLUSION: The toric IOL was safe and effective in reducing the effects of preoperative corneal astigmatism and provided excellent uncorrected distance and intermediate vision and functional near vision. FINANCIAL DISCLOSURES: Dr. Pepose is a consultant to Bausch & Lomb and was medical monitor of this study. Drs. Buckhurst, Whitman, Feinerman, Hovanesian, Davies, Labor, and Carter are consultants to Bausch & Lomb. At the time of the study, Drs. Hayashida, and Khodai were employees of Bausch & Lomb. Drs. Colvard and Mittleman have financial or proprietary interest in any material or method mentioned.

Multifocal intraocular lens differentiation using defocus curves.

PURPOSE: To determine the most appropriate analysis technique for the differentiation of multifocal intraocular lens (MIOL) designs by using defocus curve assessment of visual capability. METHODS: Four groups of 15 subjects were implanted bilaterally with either monofocal intraocular lenses, refractive MIOLs, diffractive MIOLs, or a combination of refractive and diffractive MIOLs. Defocus curves between -5.0 D and +1.5 D were evaluated by using an absolute and relative depth-of-focus method, the direct comparison method, and a new "area-of-focus" metric. The results were correlated with a subjective perception of near and intermediate vision. RESULTS: Neither depth-of-focus method of analysis was sensitive enough to differentiate between MIOL groups (P > 0.05). The direct comparison method indicated that the refractive MIOL group performed better at +1.00 diopter (D), -1.00 D, and -1.50 D and worse at -3.00 D, -3.50 D, -4.00 D, and -5.00 D than did the diffractive MIOL group (P < 0.05). The area-of-focus intermediate zone was greater with the refractive than with the diffractive MIOL group (P = 0.005) and the near zone was better with the diffractive (P = 0.020) and "mix and match" (P = 0.039) groups than with the refractive MIOL group. The subjective perception of intermediate and near vision agreed best with the area-of-focus metric for the intermediate (r(s) = 0.408, P = 0.010) and near zone (r(s) = 0.484, P < 0.001). CONCLUSIONS: Conventional depth-of-focus metrics provide a single value to quantify the useful range of vision; however, they fail to provide sufficient detail to differentiate between MIOL designs. The direct comparison method provides a large amount of information, although the results can be complex to interpret. The proposed area-of-focus metric provides a simple, but differentiating method of evaluating MIOL defocus curves.

Refractive outcomes of laser-assisted subepithelial keratectomy for myopia, hyperopia, and astigmatism using a 213 nm wavelength solid-state laser.

PURPOSE: To study the visual and refractive outcomes after laser-assisted subepithelial keratectomy (LASEK) performed with a 213 nm solid-state laser for a broad range of refractive errors. SETTING: Private practice, Jersey, United Kingdom. DESIGN: Case series. METHODS: The LASEK was performed using a Pulzar Z1 213 nm solid-state laser. Manifest refraction and uncorrected (UDVA) and corrected (CDVA) distance visual acuities were measured preoperatively and 2 and 6 months postoperatively. Accuracy, safety, efficacy, and stability were assessed at 6 months. RESULTS: The study enrolled 245 eyes (134 patients). The preoperative spherical equivalent (SE) refractive errors ranged from -9.50 to +6.50 diopters (D); 24 eyes had more than 2.50 D of astigmatism. At 6 months, 60.4% of eyes were within ±0.25 D of the intended SE, 89.4% were within ±0.50 D, and 97.9% were within ±1.00 D. No eye lost 2 or more lines of CDVA; 95.5% of eyes were unchanged or gained 1 line. The mean cylinder power decreased from -0.98 ± 1.17 D to -0.14 ± 0.28 DC at 6 months. The mean SE was unchanged over the follow-up period; -0.01 ± 0.57 D and -0.01 ± 0.55 D at 2 months and 6 months, respectively. CONCLUSION: Laser-assisted subepithelial keratectomy performed using the 213 nm wavelength solid-state laser was safe, accurate, and effective for the treatment of myopia, hyperopia, and astigmatism. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Development of a questionnaire to assess the relative subjective benefits of presbyopia correction.

PURPOSE: To develop a standardized questionnaire of near visual function and satisfaction to complement visual function evaluations of presbyopic corrections. SETTING: Eye Clinic, School of Life and Health Sciences, Aston University, Midland Eye Institute and Solihull Hospital, Birmingham, United Kingdom. DESIGN: Questionnaire development. METHODS: A preliminary 26-item questionnaire of previously used near visual function items was completed by patients with monofocal intraocular lenses (IOLs), multifocal IOLs, accommodating IOLs, multifocal contact lenses, or varifocal spectacles. Rasch analysis was used for item reduction, after which internal and test-retest reliabilities were determined. Construct validity was determined by correlating the resulting Near Activity Visual Questionnaire (NAVQ) scores with near visual acuity and critical print size (CPS), which was measured using the Minnesota Low Vision Reading Test chart. Discrimination ability was assessed through receiver-operating characteristic (ROC) curve analysis. RESULTS: One hundred fifty patients completed the questionnaire. Item reduction resulted in a 10-item NAVQ with excellent separation (2.92), internal consistency (Cronbach α = 0.95), and test-retest reliability (intraclass correlation coefficient = 0.72). Correlations of questionnaire scores with near visual acuity (r = 0.32) and CPS (r = 0.27) provided evidence of validity, and discrimination ability was excellent (area under ROC curve = 0.91). CONCLUSION: Results show the NAVQ is a reliable, valid instrument that can be incorporated into the evaluation of presbyopic corrections.

Rotational and centration stability of an aspheric intraocular lens with a simulated toric design.

PURPOSE: To assess the stability of the Akreos AO intraocular lens (IOL) platform with a simulated toric design using objective image analysis. SETTING: Six hospital eye clinics across Europe. METHODS: After implantation in 1 eye of patients, IOLs with orientation marks were imaged at 1 to 2 days, 7 to 14 days, 30 to 60 days, and 120 to 180 days. The axis of rotation and IOL centration were objectively assessed using validated image analysis. RESULTS: The study enrolled 107 patients with a mean age of 69.9 years +/- 7.7 (SD). The image quality was sufficient for IOL rotation analysis in 91% of eyes. The mean rotation between the first day postoperatively and 120 to 180 days was 1.93 +/- 2.33 degrees, with 96% of IOLs rotating fewer than 5 degrees and 99% rotating fewer than 10 degrees. There was no significant rotation between visits and no clear bias in the direction of rotation. In 71% of eyes, the dilation and image quality was sufficient for image analysis of centration. The mean change in centration between 1 day and 120 to 180 days was 0.21 +/- 0.11 mm, with all IOLs decentering less than 0.5 mm. There was no significant decentration between visits and no clear bias in the direction of the decentration. CONCLUSION: Objective analysis of digital retroillumination images taken at different postoperative periods shows the aspheric IOL platform was stable in the eye and is therefore suitable for the application of a toric surface to correct corneal astigmatism.

Surgical correction of astigmatism during cataract surgery.

High levels of corneal astigmatism are prevalent in a significant proportion of the population. During cataract surgery pre-existing astigmatism can be corrected using single or paired incisions on the steep axis of the cornea, using relaxing incisions or with the use of a toric intraocular lens. This review provides an overview of the conventional methods of astigmatic correction during cataract surgery and in particular, discusses the various types of toric lenses presently available and the techniques used in determining the correct axis for the placement of such lenses. Furthermore, the potential causes of rotation in toric lenses are identified, along with techniques for assessing and quantifying the amount of rotation and subsequent management options for addressing post-operative rotation.

Objective analysis of toric intraocular lens rotation and centration.

PURPOSE: To assess the repeatability of an objective image-analysis technique to determine intraocular lens (IOL) rotation and centration. SETTING: Six European ophthalmology clinics. METHODS: Eyes with an Akreos AO aspheric IOL with orientation marks were imaged. A masked observer rated image quality. The axis of rotation was determined from a line bisecting the IOL orientation marks. This was normalized for rotation of the eye between visits using the axis bisecting 2 consistent conjunctival vessels or iris features. The center of ovals overlaid to circumscribe the IOL optic edge and the pupil or limbus were compared to determine IOL centration. Intrasession repeatability was assessed in a subgroup of eyes and the variability of repeated analysis examined. RESULTS: The SD of intrasession repeatability was +/-0.79 degrees for IOL rotational stability, +/-0.10 mm for horizontal centration, and +/-0.10 mm for vertical centration. The SD of repeated-analysis variability of the same image was +/-0.70 degrees, +/-0.20 mm, and +/-0.31 mm, respectively. The mean eye rotation (absolute) between visits was 2.23 degrees +/- 1.84 (SD) (10% >5 degrees rotation) using 1 set of consistent conjunctival vessels or iris features and 2.03 +/- 1.66 degrees (7%>5 degrees rotation) using the mean of 2 sets (P = .13). Poorer image quality resulted in larger apparent absolute IOL rotation (r = -0.45, P<.001). CONCLUSIONS: Objective analysis of digital retroillumination images allowed sensitive assessment of IOL rotation and centration stability. Eye rotation between images can lead to significant errors if not taken into account. Image quality is important to analysis accuracy.