Optical bench evaluation of the effect of pupil size in new generation monofocal intraocular lenses.

BACKGROUND: A new generation of enhanced monofocal IOLs has been introduced to slightly increase the depth of focus as compared to standard monofocal IOLs. The purpose of this study is to evaluate the effect of pupil size on the through-focus optical performance of three new enhanced monofocal IOLs, designed to improve the range of vision as compared to standard monofocal IOLs. METHODS: Optical bench testing in white light was performed for different pupils, using an average cornea eye. Distance image quality was evaluated using Modulation Transfer Function (MTF) measurements. Through-focus Visual Acuity (VA) was simulated from these measurements (sVA). Three enhanced monofocal IOLs (ICB00, ISOPure, and RayOne-EMV) and three standard monofocal IOLs: two aspheric (ZCB00 and SN60WF) and one spherical (AAB00) were included. RESULTS: The enhanced monofocal IOLs provided an improvement in the intermediate sVA as compared to standard monofocal IOLs. For ICB00, the improvement was independent of the pupil size, while for the ISOPure and RayOne-EMV, the intermediate sVA improved with increased pupil size. Similar to the spherical monofocal IOL, the ISOPure and RayOne-EMV showed a strong correlation between improvement in intermediate sVA and reduction of distance sVA and MTF, and increasing pupil size. ICB00 provided the same distance sVA as the aspheric monofocal IOLs and the lowest variability in MTF with pupil size. CONCLUSION: Optical bench results showed that the ISOPure and RayOne-EMV provide similar performance to a spherical monofocal IOL, with a strong pupil dependency for distance and intermediate vision. The other enhanced monofocal IOL, ICB00, provided a sustained improvement in simulated intermediate VA and maintained distance image quality comparable to that of the standard aspheric monofocal IOLs, even for larger pupils.

Results of the United States Food and Drug Administration Clinical Trial of the CustomFlex Artificial Iris.

PURPOSE: To evaluate safety and efficacy of a custom-manufactured artificial iris device (CustomFlex Artificial Iris; HumanOptics AG) for the treatment of congenital and acquired iris defects. DESIGN: Multicenter, prospective, unmasked, nonrandomized, interventional clinical trial. PARTICIPANTS: Patients with photophobia, sensitivity secondary to partial or complete congenital or acquired iris defects, or both. METHODS: Eyes were implanted from November 26, 2013, to December 1, 2017, with a custom, foldable artificial iris by 1 of 4 different surgical techniques. Patients were evaluated 1 day, 1 week, and 1, 3, 6, and 12 months after surgery. At each examination, slit-lamp findings, intraocular pressure, implant position, subjective visual symptoms, and complications were recorded. Corrected distance visual acuity (CDVA) and endothelial cell density (ECD) were measured at 3, 6, or 12 months as additional safety evaluations. The 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) was used to assess health-related quality of life affected by vision. The Global Aesthetic Improvement Scale was used to assess cosmetic results. MAIN OUTCOME MEASURES: Photosensitivity, glare, visual symptoms, NEI VFQ-25 score, Global Aesthetic Improvement Scale rating, prosthesis-related adverse events, intraocular lens (IOL)-related adverse events, and surgery-related adverse events 12 months after surgery. RESULTS: At the 12-month postoperative examination, a 59.7% reduction in marked to severe daytime light sensitivity (P < 0.0001), a 41.5% reduction in marked to severe nighttime light sensitivity (P < 0.0001), a 53.1% reduction in marked to severe daytime glare (P < 0.0001), and a 48.5% reduction in severe nighttime glare (P < 0.0001) were found. A 15.4-point improvement (P < 0.0001) in the NEI VFQ-25 total score was found, and 93.8% of patients reported an improvement in cosmesis as measured by the Global Aesthetic Improvement Scale 12 months after surgery. No loss of CDVA of > 2 lines related to the device was found. Median ECD loss was 5.3% at 6 months after surgery and 7.2% at 12 months after surgery. CONCLUSIONS: The artificial iris surpassed all key safety end points for adverse events related to the device, IOL, or implant surgery and met all key efficacy end points, including decreased light and glare sensitivity, improved health-related quality of life, and satisfaction with cosmesis. The device is safe and effective for the treatment of symptoms and an unacceptable cosmetic appearance created by congenital or acquired iris defects.

Intraocular Lens Power Calculations in Eyes with Previous Corneal Refractive Surgery: Review and Expert Opinion.

Intraocular lens (IOL) power calculations are less accurate in eyes that have undergone corneal refractive surgery. A wide range of methods have been proposed. We reviewed the methods and outcomes of IOL power calculations in eyes with previous LASIK, excimer laser photorefractive keratectomy (PRK), or radial keratotomy (RK). The PubMed database was searched for articles that (1) discuss methods and outcomes of IOL power calculation in eyes with previous corneal refractive surgery and (2) evaluate the outcomes of toric, multifocal, or extended depth-of-focus (EDOF) IOLs in these eyes. We excluded review articles, case reports or case studies, and non-English reports. Seventy full-text articles were included in this review. Three categories of methods exist based on whether and how they use historical data acquired before the corneal refractive surgery. The American Society of Cataract and Refractive Surgery (ASCRS) postrefractive IOL calculator incorporates many commonly used methods. In eyes with previous myopic LASIK or PRK, hyperopic LASIK or PRK, and RK, 0% to 85%, 38.1% to 71.9%, and 29% to 87.5% of eyes, respectively, showed refractive prediction errors within ±0.5 diopter (D); in eyes with toric IOL implantation that met certain inclusion criteria, 80%, 84%, and 69% of eyes, respectively, achieved postoperative astigmatism of 0.50 D or less. Intraocular lenses with negative spherical aberration (SA) will reduce the positive corneal spherical aberration induced in eyes by myopic LASIK or PRK or by RK. Intraocular lenses with 0 SA on average best match corneal SA in eyes with prior hyperopic LASIK or PRK. Studies have reported excellent outcomes of postrefractive eyes implanted with multifocal or EDOF IOLs; however, corneal topographic enrollment criteria were not specified. Despite availability of new measurement technologies and development of new IOL calculation formulas, further advances are needed to improve outcomes of cataract surgery in eyes that have undergone corneal refractive surgery. Tools like the ASCRS postrefractive IOL calculator are useful for the clinician by incorporating a variety of formulas. Toric, EDOF, and multifocal IOLs may provide excellent outcomes in selected cases that meet certain corneal topographic criteria.

Cost-Effectiveness of Preoperative OCT in Cataract Evaluation for Multifocal Intraocular Lens.

PURPOSE: To determine the cost effectiveness of an adjunctive screening OCT during the preoperative evaluation of a patient considering cataract surgery with a multifocal intraocular lens (IOL) implantation. DESIGN: Cost-effectiveness analysis. PARTICIPANTS: A 67-year-old man with 20/60 vision undergoing evaluation for first-eye cataract surgery. METHODS: The cost-effectiveness analysis of the reference patient undergoing a preoperative cataract examination with and without a screening OCT was performed, evaluating for vitreoretinal diseases including an epiretinal membrane, age-related macular degeneration, vitreomacular traction, and cystoid macular edema. It was assumed that patients with macular pathologies detected before surgery would receive a monofocal IOL and be referred to a retina specialist for evaluation and management. The Medicare reimbursable cost of an OCT was $41.81. All costs and benefits were adjusted for inflation to 2019 United States dollars and discounted 3% per annum over a 16-year time horizon. Probability sensitivity analyses and 1-way deterministic sensitivity analyses were performed to assess for uncertainty. MAIN OUTCOME MEASURES: Incremental cost-effectiveness ratio and incremental cost-utility ratio (ICUR) measured in quality-adjusted life years (QALYs). RESULTS: Approximately 20.5% of patients undergoing cataract surgery may have macular pathologies, of which 11% may not be detected on the initial clinical examination. In the base case, an adjunctive preoperative OCT was cost effective from a third-party payer and societal perspective in the United States. In the probability sensitivity analyses, the ICURs were within the societal willingness-to-pay threshold of $50 000/QALY in approximately 64.4% of the clinical scenarios. CONCLUSIONS: A preoperative screening OCT during the evaluation of a patient considering a multifocal IOL added to the costs of the cataract surgery, but the OCT increased the detection of macular pathologies and improved the QALYs over time. An adjunctive screening OCT can be cost effective from a third-party payer and societal perspective.

Calculation of Axial Length Using a Single Group Refractive Index versus Using Different Refractive Indices for Each Ocular Segment: Theoretical Study and Refractive Outcomes.

PURPOSE: To investigate the difference between the segmented axial length (AL) and the displayed AL on an optical low-coherence reflectometry (OLCR) biometer and to compare the refractive prediction errors calculated using the segmented and displayed ALs. DESIGN: Retrospective case series. PARTICIPANTS: Four thousand nine hundred ninety-two eyes from 4992 patients in the theoretical study and 1758 eyes from 1758 patients in the refractive prediction error comparison. METHODS: First, we calculated the segmented AL as the sum of geometrical ocular segments converted from the optical path length (OPL) in each medium. To convert the OPL to a geometrical distance in each medium, we used 4 sets of group refractive indices. Then, the mean absolute prediction error (MAE) was calculated with the displayed AL and segmented AL using 6 intraocular lens power formulas: Olsen, Barrett Universal II (Barrett), Haigis, Hoffer Q, Holladay 1, and Sanders-Retzlaff-Kraff trial (SRK/T). MAIN OUTCOME MEASURES: Segmented AL, difference in AL (segmented AL minus displayed AL), MAE, and percentage of eyes within 0.5 diopter (D) of error. RESULTS: The segmented ALs were up to 0.29 mm longer in short eyes and 0.50 mm shorter in long eyes. The differences in ALs were correlated negatively with the displayed ALs (r values, -0.941 to -0.913; P < 0.001). The MAEs were significantly lower using segmented ALs for all formulas except the Olsen in both the entire group and the long eye subgroup (AL, ≥26 mm) and for the Holladay 1 and Hoffer Q in the short eye subgroup (AL, ≤ 22 mm). Use of segmented ALs produced a greater percentage of eyes within 0.5 D of error for all formulas except the Olsen and Haigis for the entire group, for long eyes, and for the Holladay 1 in short eyes. CONCLUSIONS: The segmented ALs were longer in short eyes and shorter in long eyes compared with the displayed ALs calculated with a single group refractive index for the entire eye. The refractive accuracy with segmented ALs was improved in short eyes with the Hoffer Q and Holladay 1 formulas and in long eyes with all formulas except the Olsen formula.

Evaluation of Femtosecond Laser Intrastromal Incision Location Using Optical Coherence Tomography.

PURPOSE: To use optical coherence tomography (OCT) to evaluate the femtosecond laser intrastromal incisions made during cataract surgery to reduce corneal astigmatism. DESIGN: Retrospective case series. PARTICIPANTS: Seventy-seven eyes of 77 patients. METHODS: Paired intrastromal incisions were created using the Catalys femtosecond laser (Abbott Medical Optics, Inc., Santa Ana, CA). The planned intrastromal incision parameters were 20% uncut anterior, 20% uncut posterior, midpoint depth of 50%, and 90° side cut angle. Optical coherence tomography scans were obtained 3 weeks or more after surgery to assess these 4 parameters, and actual values were compared with intended values. MAIN OUTCOME MEASURES: Percentages of uncut anterior and posterior tissue, midpoint depth, and degrees of side cut angle. RESULTS: The mean values were 17.2±5.8% (range, 7.2%-36.9%) for uncut anterior, 32.5±8.8% (range, 6.0%-57.9%) for uncut posterior, and 42.3±6.6% (range, 25.5%-65.4%) for midpoint depth, which all were significantly different from the planned parameters (all P < 0.05). The mean side cut angle was 88.5°±5.6° (range, 71°-114°) and was significantly different from the planned side cut angle of 90° (P < 0.05). In 50 eyes that had paired intrastromal incisions scanned by the OCT, there was no correlation between the paired incisions for midpoint depth and side cut angle (correlation coefficient, r = -0.063 and -0.067, respectively; P > 0.05). CONCLUSIONS: The intrastromal incision midpoint depth was significantly more anterior than the planned depth of 50%. The locations of paired intrastromal incisions in each eye were not correlated. Further improvements are needed to ensure the precise location of the intrastromal incisions made with this device.

Outcomes of femtosecond laser-assisted cataract surgery performed by surgeons-in-training.

PURPOSE: To compare intraoperative factors and post-operative outcomes of femtosecond laser-assisted cataract surgery (FLACS) and manual cataract surgery performed by resident surgeons. METHODS: All cases of FLACS performed by resident surgeons during the 2013-2014 academic year were compared to a control group of manual cataract surgery cases with regards to pre-operative patient data, operative complications, cumulative dissipated energy (CDE), postoperative corrected distance visual acuity (CDVA), refractive prediction error (RPE), and corneal edema. RESULTS: There were no significant preoperative differences in the FLACS (n = 57) and manual (n = 68) groups. Operative complication rates were similar in cases with sufficient data and follow-up with a higher rate of posterior capsule tear in the manual group. CDE (percent-seconds) was lower in the FLACS group (FLACS: 14.5 ± 7.5; manual: 21.6 ± 11.5; p < 0.01). CDVA (LogMAR) was comparable at 1 month postoperatively (FLACS: 0.004 ± 0.08; manual: 0.024 ± 0.11; p = 0.24) and 1 year postoperatively (FLACS: 0.013 ± 0.06; manual: 0.032 ± 0.09; p = 0.37). No difference in RPE was found at 1 month postoperatively (FLACS: 0.38 ± 0.24 D; manual: 0.41 ± 0.49 D; p = 0.66) and 1 year postoperatively (FLACS: 0.49 ± 0.63 D; manual: 0.34 ± 0.26 D; p = 0.31). CONCLUSIONS: Femtosecond laser-assisted cataract surgery is safe and effective compared to manual cataract surgery when performed by resident surgeons. Both 1-month and 1-year outcomes show no difference in refractive predictive error in FLACS compared to manual cataract surgery in surgeons in training.

Treatment of Presbyopia in Emmetropes Using a Shape-Changing Corneal Inlay: One-Year Clinical Outcomes.

PURPOSE: To report 1-year safety and efficacy clinical outcomes of a shape-changing corneal inlay for the treatment of presbyopia. DESIGN: Prospective, nonrandomized, multicenter United States Food and Drug Administration Investigational Device Exemption clinical trial (clinicaltrials.gov identifier, NCT01373580). PARTICIPANTS: Nondominant eyes (N = 373) of emmetropic presbyopic subjects were implanted at 11 sites with the Raindrop Near Vision Inlay (ReVision Optics, Lake Forest, CA); 340 eyes underwent the 1-year follow-up visit. METHODS: The corneal inlay was implanted under a corneal flap at the center of the light-constricted pupil created with a femtosecond laser. MAIN OUTCOME MEASURES: For subjects completing the 1-year follow-up, monocular and binocular uncorrected and corrected visual acuity, refractive stability, contrast sensitivity (CS; photopic and mesopic), symptom and satisfaction questionnaire results, and adverse events. RESULTS: At 1 year in the treated eye, on average, uncorrected near visual acuity (UNVA) improved by 5.1 lines, uncorrected intermediate visual acuity (UIVA) improved by 2.5 lines, and uncorrected distance visual acuity (UDVA) decreased by 1.2 lines. From 3 months through 1 year, 93% of subjects achieved UNVA of 20/25 or better, 97% achieve UIVA of 20/32 or better, and 95% achieved UDVA of 20/40 or better. Binocularly, the mean UDVA exceeded 20/20 from 3 months through 1 year. Contrast sensitivity loss occurred only at the highest spatial frequencies, with no loss binocularly. Absent or mild scores were reported in 96% of subjects for visual symptoms (glare, halos, double vision, and fluctuations in vision), in 99% for ocular symptoms (pain, light sensitivity, and discomfort), and in 95% for dryness. Adverse events were treatable and resolved. Eighteen inlays were replaced, usually soon after implantation because of decentration, but UNVA was little affected in this group thereafter. In the 11 cases requiring inlay explantations, 100% achieved a corrected distance visual acuity of 20/25 or better by 3 months after explant. CONCLUSIONS: The Raindrop Near Vision Inlay provides significant improvement in near and intermediate visual performance, with no significant change in binocular distance vision or CS. Subject satisfaction is improved significantly with minimal ocular or visual symptoms.

Comparison of Newer Intraocular Lens Power Calculation Methods for Eyes after Corneal Refractive Surgery.

PURPOSE: To compare the newer formulae, the optical coherence tomography (OCT)-based intraocular lens (IOL) power formula (OCT formula) and the Barrett True-K formula (True-K), with the methods on the American Society of Cataract and Refractive Surgery (ASCRS) calculator in eyes with previous myopic LASIK/photorefractive keratectomy (PRK). DESIGN: Prospective case series. PARTICIPANTS: A total of 104 eyes of 80 patients who had previous myopic LASIK/PRK and subsequent cataract surgery and IOL implantation. METHODS: By using the actual refraction after cataract surgery as target refraction, predicted IOL power for each method was calculated. The IOL prediction error (PE) was obtained by subtracting the predicted IOL power from the power of the IOL implanted. MAIN OUTCOME MEASURES: Arithmetic IOL PEs, variances of mean arithmetic IOL PE, median refractive PE, and percent of eyes within 0.5 diopters (D) and 1.0 D of refractive PE. RESULTS: Optical coherence tomography produced smaller variance of IOL PE than did Wang-Koch-Maloney (WKM) and Shammas (P < 0.05). With the OCT, True-K No History, WKM, Shammas, Haigis-L, and Average of these 5 formulas, the median refractive PEs were 0.35 D, 0.42 D, 0.51 D, 0.48 D, 0.39 D, and 0.35 D, respectively, the percentage of eyes within 0.5 D of refractive PE were 68.3%, 58.7%, 50.0%, 52.9%, 55.8%, and 67.3%, respectively, and the percentage of eyes within 1.0 D of refractive PE were 92.3%, 90.4%, 86.9%, 88.5%, 90.4%, and 94.2%, respectively. The OCT formula had smaller refractive PE compared with the WKM and Shammas, and the Average approach produced significantly smaller refractive PE than all methods except OCT (all P < 0.05). CONCLUSIONS: The OCT and True-K No History are promising formulas. The ASCRS IOL calculator has been updated to include the OCT and Barrett True K formulas. TRIAL REGISTRATION: Intraocular Lens Power Calculation After Laser Refractive Surgery Based on Optical Coherence Tomography (OCT IOL); Identifier: NCT00532051; www.ClinicalTrials.gov.

Astigmatic equivalence of 2.2-mm and 1.8-mm superior clear corneal cataract incision.

PURPOSE: To evaluate the astigmatic effects of 2.2-mm and 1.8-mm cataract incisions. METHODS: A randomized prospective study of 190 eyes of 151 patients undergoing superior clear corneal incision (SCCI) was divided into three groups: 61 eyes with a control 3.2-mm SCCI; 66 eyes with a 2.2-mm SCCI; and 63 eyes with a 1.8-mm SCCI. The corneal astigmatism was measured with an autokeratometer preoperatively and 1 month after surgery. The with-the-wound (WTW), against the-wound (ATW), and WTW-ATW changes were calculated using the Holladay-Cravy-Koch formula. RESULTS: The WTW, ATW, and WTW-ATW changes were significantly higher for the control 3.2-mm SCCI than for the 2.2- and 1.8-mm SCCI (all p < 0.001), and no difference was found between the 2.2- and 1.8-mm SCCI incision groups. CONCLUSION: In our study, the astigmatic effects were the same for the 2.2 mm and 1.8 mm incisions and as expected, were significantly lower than the control 3.2 mm incision group.

Effect of spherical aberration on visual acuity and depth of focus in pseudophakic eyes.

PURPOSE: To assess the performance of 4 intraocular lenses (IOLs) in various spherical aberration (SA) conditions, using the VAO adaptive optics simulator. SETTING: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas. DESIGN: Prospective case series. METHODS: Distance-corrected visual acuities at distance (CDVA), intermediate (DCIVA), and near (DCNVA) were measured in 42 dilated pseudophakic eyes at baseline and with ocular SA ranging from -0.4 to +0.4 µm in increments of 0.2 µm (6.0-mm pupil). 4 IOL types were assessed: monofocal IOLs with zero-SA, enhanced-monofocal, extended depth-of-focus (EDOF), and continuous range-of-vision. RESULTS: Compared with SA = 0 µm, significant changes (all P < .05) were: (1) zero-SA monofocal IOLs' DCNVA at high contrast improved by 0.13 logMAR with SA = -0.4 µm and worsened by 0.09 and 0.10 logMAR with SA = +0.2 and +0.4 µm, respectively. DCNVA at low contrast worsened by 0.09 logMAR with SA = +0.4 µm; and (2) with SA = -0.4 µm, the enhanced monofocal IOL lost 0.06 logMAR of CDVA at high contrast and gained 0.09 logMAR of DCNVA at low contrast. There were no significant changes from SA = 0 µm for EDOF and continuous range-of-vision IOLs. CONCLUSIONS: Zero-SA and EDOF IOLs were the most and least sensitive to SA modulation, respectively. In perfect optical systems where all the optical elements are aligned, induction of targeted amounts of negative SA improved the depth of focus of some IOL types. No benefit was found with positive SA.

Performance of IOL calculation formulas that use measured posterior corneal power in eyes following myopic laser vision correction.

PURPOSE: To compare the predictive accuracy of the biometer-embedded Barrett True-K TK and new total corneal power methods of intraocular lens (IOL) power calculation in eyes with prior laser vision correction (LVC) for myopia. SETTING: Academic clinical practice. DESIGN: Retrospective case series. METHODS: IOL power formulas were assessed using measurements from a swept-source optical coherence biometer. Refractive prediction errors were calculated for the Barrett True-K TK, EVO 2.0, Pearl-DGS, and HofferQST, which use both anterior and posterior corneal curvature measurements. These were compared with the Shammas, Haigis-L, Barrett True-K No History (NH), optical coherence tomography, and 4-formula average (AVG-4) on the ASCRS postrefractive calculator, and to the Holladay 1 and 2 with non linear axial length regressions (H1- and H2-NLR). RESULTS: The study comprised 85 eyes from 85 patients. Only the Barrett True-K TK and EVO 2.0 had mean numerical errors that were not significantly different from 0. The EVO 2.0, Barrett True-K TK, Pearl-DGS, AVG-4, H2-NLR, and Barrett True-K NH were selected for further pairwise analysis. The Barrett True-K TK and EVO 2.0 demonstrated smaller root-mean-square absolute error compared with the Pearl-DGS, and the Barrett True-K TK also had a smaller mean absolute error than the Pearl-DGS. CONCLUSIONS: The Barrett True-K TK and EVO 2.0 formulas had comparable performance to existing formulas in eyes with prior myopic LVC.

Comparison of accuracy of a toric calculator with predicted vs measured posterior corneal astigmatism.

PURPOSE: To compare the accuracy of postoperative residual astigmatism prediction using the Barrett toric calculator with predicted vs measured posterior corneal astigmatism (PCA). SETTING: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas. DESIGN: Retrospective case series. METHODS: We included 602 eyes with monofocal nontoric intraocular lens implantation. Biometry and PCA were obtained from the IOLMaster 700. Anticipated postoperative refractive astigmatism was calculated with the Barrett toric calculator for predicted and measured PCA, and the astigmatism prediction errors (PEs) for each were calculated using vector analysis. The vector PE magnitudes and percentage of eyes within certain amounts of vector PEs were compared between 2 methods. RESULTS: Compared with the Barrett toric calculator with predicted PCA, the Barrett toric calculator with measured PCA produced significantly smaller mean vector PE (0.54 diopter [D] vs 0.57 D) and higher percentage of eyes with vector PE of ≤0.5 D (57.6% [347/602] vs 52.5% [316/602]) (both P < .05). In eyes with predicted residual astigmatism of ≥0.5 D, the Barrett toric calculator with measured PCA again yielded a significantly higher percentage of eyes with vector PE of ≤0.5 D (51.2% [226/441] vs 44.7% [197/441], P < .05). CONCLUSIONS: Accuracy of residual astigmatism prediction is improved using the Barrett toric calculator with measured PCA rather than predicted PCA.

Outcomes of peripheral corneal relaxing incisions for residual astigmatism in patients after cataract surgery.

PURPOSE: To evaluate the outcomes of peripheral corneal relaxing incisions (PCRIs) for correcting residual astigmatism in eyes after cataract surgery. SETTING: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas. DESIGN: Retrospective case series. METHODS: Retrospectively, we reviewed all consecutive cases that had previous cataract surgery and subsequent PCRIs by 1 surgeon. The PCRI length was determined according to a nomogram based on age and manifest refractive astigmatism. Visual acuity and manifest refractive astigmatism before and after the PCRIs were compared. Vector analysis was performed, and net refractive changes along the incision meridian were calculated. RESULTS: Criteria were met by 111 eyes. After the PCRIs, mean uncorrected visual acuity was significantly improved, and the percentage of eyes with uncorrected distance visual acuity of ≥20/20 increased significantly by 36%; the mean refractive astigmatism magnitude decreased significantly, and the percentages of eyes with refractive cylinder of ≤0.25 diopters (D) and ≤0.50 D increased significantly by 63% and 75%, respectively (all P < .05). The vector magnitude difference between pre- and post-operative refractive astigmatism was 0.88 ± 0.38 D. The postoperative refractive astigmatism had significantly smaller centroid and variance values than the preoperative refractive astigmatism ( P < .05). CONCLUSIONS: PCRIs are an effective approach for correcting low amounts of residual astigmatism in patients after cataract surgery.

A Mouse Model for Corneal Neovascularization by Alkali Burn.

Corneal neovascularization (CoNV), a pathological form of angiogenesis, involves the growth of blood and lymph vessels into the avascular cornea from the limbus and adversely affects transparency and vision. Alkali burn is one of the most common forms of ocular trauma that leads to CoNV. In this protocol, CoNV is experimentally induced using sodium hydroxide solution in a controlled manner to ensure reproducibility. The alkali burn model is useful for understanding the pathology of CoNV and can be extended to study angiogenesis in general because of the avascularity, transparency, and accessibility of the cornea. In this work, CoNV was analyzed by direct examination under a dissecting microscope and by immunostaining flat-mount corneas using anti-CD31 mAb. Lymphangiogenesis was detected on flat-mount corneas by immunostaining using anti-LYVE-1 mAb. Corneal edema was visualized and quantified using optical coherence tomography (OCT). In summary, this model will help to advance existing neovascularization assays and discover new treatment strategies for pathologic ocular and extraocular angiogenesis.

Efficacy of segmented axial length and artificial intelligence approaches to intraocular lens power calculation in short eyes.

PURPOSE: In short eyes, to compare the predictive accuracy of newer intraocular lens (IOL) power calculation formulas using traditional and segmented axial length (AL) measurements. SETTING: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas and East Valley Ophthalmology, Mesa, Arizona. DESIGN: Multi-center retrospective case series. METHODS: Measurements from an optical biometer were collected in eyes with AL <22 mm. IOL power calculations were performed with 15 formulas using 2 AL values: (1) machine-reported traditional AL (Td-AL) and (2) segmented AL calculated with the Cooke-modified AL nomogram (CMAL). 1 AL method and 7 formulas were selected for pairwise analysis of mean absolute error (MAE) and root mean square absolute error (RMSAE). RESULTS: The study comprised 278 eyes. Compared with the Td-AL, the CMAL produced hyperopic shifts without differences in RMSAE. The ZEISS AI IOL Calculator (ZEISS AI), K6, Kane, Hill-RBF, Pearl-DGS, EVO, and Barrett Universal II (Barrett) formulas with Td-AL were compared pairwise. The ZEISS AI demonstrated smaller MAE and RMSAE than the Barrett, Pearl-DGS, and Kane. K6 had a smaller RMSAE than the Barrett formula. In 73 eyes with shallow anterior chamber depth, the ZEISS AI and Kane had a smaller RMSAE than the Barrett. CONCLUSIONS: ZEISS AI outperformed Barrett, Pearl-DGS, and Kane. The K6 formula outperformed some formulas in selected parameters. Across all formulas, use of a segmented AL did not improve refractive predictions.

Comparison of Keratoconus Specific to Standard IOL Formulas in Patients With Keratoconus Undergoing Cataract Surgery.

PURPOSE: To assess the performance of multiple intraocular lens (IOL) formulas in eyes with keratoconus. METHODS: Eyes with stable keratoconus scheduled for cataract surgery with biometry measurements on the Lenstar LS900 (Haag-Streit) were included. Prediction errors were calculated using 11 different formulas, including two with keratoconus modifiers. Primary outcomes compared standard deviations, mean and median numerical errors, and percentage of eyes within diopter (D) ranges across all eyes with subgroup analysis according to anterior keratometric values. RESULTS: Sixty-eight eyes from 44 patients were identified. In eyes with keratometric values less than 50.00 D, prediction error standard deviations ranged from 0.680 to 0.857 D. Percentages of eyes within ±0.50 D of target ranged from 57.89% to 73.68% with no statistical differences among formulas. In eyes with a keratometric value of more than 50.00 D, prediction error standard deviations ranged from 1.849 to 2.349 D and were not statistically different with heteroscedastic analysis; percentages of eyes within ±0.50 D of target ranged from 0% to 18.18% with no statistical differences among formulas. Only keratoconus-specific formulas (Barrett-KC and Kane-KC) and the Wang-Koch axial length adjustment version of SRK/T resulted in median numerical errors not significantly different than 0, regardless of keratometric values. CONCLUSIONS: In keratoconic eyes, IOL formulas are less accurate than in normal eyes and result in hyperopic refractive outcomes that increase with steeper keratometric values. Using keratoconus-specific formulas and the Wang-Koch axial length adjustment version of SRK/T for axial lengths of 25.2 mm or greater improved IOL power prediction accuracy compared to other formulas. [J Refract Surg. 2023;39(4):242-248.].

Intraocular lens power calculations in eyes with previous corneal refractive surgery: Challenges, approaches, and outcomes.

In eyes with previous corneal refractive surgery, difficulties in accurately determining corneal refractive power and in predicting the effective lens position create challenges in intraocular lens (IOL) power calculations. There are three categories of methods proposed based on the use of historical data acquired prior to the corneal refractive surgery. The American Society of Cataract and Refractive Surgery postrefractive IOL calculator incorporates many commonly used methods. Accuracy of refractive prediction errors within ± 0.5 D is achieved in 0% to 85% of eyes with previous myopic LASIK/photorefractive keratectomy (PRK), 38.1% to 71.9% of eyes with prior hyperopic LASIK/PRK, and 29% to 87.5% of eyes with previous radial keratotomy. IOLs with negative spherical aberration (SA) may reduce the positive corneal SA induced by myopic correction, and IOLs with zero SA best match corneal SA in eyes with prior hyperopic correction. Toric, extended-depth-of-focus, and multifocal IOLs may provide excellent outcomes in selected cases that meet certain corneal topographic criteria. Further advances are needed to improve the accuracy of IOL power calculation in eyes with previous corneal refractive surgery.

Astigmatism analysis and reporting of surgically induced astigmatism and prediction error.

PURPOSE: To provide a method for determining the vector that, when added to the preoperative astigmatism, results in no prediction error (PE) and to specify statistical methods for evaluating astigmatism and determining the 95% confidence convex polygon. SETTING: Baylor College of Medicine, Houston, Texas, and University of Southern California, Los Angeles, California. DESIGN: Retrospective consecutive case series. METHODS: An analysis of 3 clinical trials involving toric intraocular lenses was performed. 3 formulas were evaluated (generic vergence formula with zero surgically induced astigmatism, the Barrett toric formula, and the Holladay toric formula). Scalar and vector analyses were performed on each dataset with each formula and the results compared. Since the PE was not a Gaussian distribution, a 95% convex polygon was used to determine the spread of the data. RESULTS: The mean values for the vector absolute astigmatism PEs were not different for the 3 formulas and 3 datasets. The Barrett and Holladay toric calculators were statistically superior to the zero formula for 3 intervals (0.75, 1.0, and 1.25) in the high astigmatism dataset. CONCLUSIONS: Residual astigmatism and vector absolute astigmatism PE mean values and SDs are useful but require extremely large datasets to demonstrate a statistical difference, whereas examining percentages in 0.25 diopters (D) steps from 0.25 to 2.0 D reveals differences with far fewer cases using the McNemar test for a P value. Double-angle plots are especially useful to visualize astigmatic vector PEs, and a 95% confidence convex polygon should be used when distributions are not Gaussian.