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.

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.

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.].

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.

Surgeons need to know more about intraocular lens design for accurate power calculation.

Improvement in biometry and formulas has raised the bar for accurate intraocular lens (IOL) power calculation. However, when we look closely at the performance of a specific IOL model, we often find that the prediction error varies with the implant power. This phenomenon has no explanation other than that the optic design of the IOL has shifted over the power range, thereby disrupting the assumptions of the calculations. By this report, we call the industry to be more transparent and disclose the basic information about the IOL design that is important for accurate IOL power calculation. The relevant information concerns the refractive index, the central optic thickness, the anterior and posterior curvature radii, the toricity location, the spherical aberration, and haptic angulation. The goal is to predict possible shifts in principal planes or IOL position over the power range causing a refractive surprise if not corrected for.

Astigmatism Profile in a Large Series of Brazilian Patients.

PURPOSE: To assess anterior, posterior, and total corneal astigmatism in a large sample of Brazilian patients. METHODS: In this retrospective cross-sectional study, all patients whose corneas were imaged with the Galilei G6 (Ziemer Ophthalmology) between January 2017 and February 2019 at HOPE Eye Hospital, in Recife, Brazil, were eligible to participate. Anterior, posterior, and total corneal astigmatism values were collected and analyzed. RESULTS: The study included 3,253 eyes of 1,919 patients. The mean magnitude of the anterior, posterior, and total corneal astigmatism was 1.50 ± 1.11, 0.34 ± 0.15, and 1.29 ± 0.98 diopters (D), respectively. Corneal astigmatism was greater than 0.50 D in the anterior cornea of 86.3% of eyes (2,807 eyes) and in the posterior cornea of 13.2% of eyes (429 eyes). Vertical alignment of the steepest corneal meridian was observed in the anterior cornea of 74.5% of eyes (2,423 eyes) and in the posterior cornea of 93.1% of eyes (3,029 eyes). The correlation between the astigmatism magnitude of the anterior and posterior cornea was strong when the steep anterior meridian was aligned vertically (r = 0.720; P < .001), and absent when it was aligned horizontally (r = 0.102; P = .036). CONCLUSIONS: Corneal astigmatism values in the Brazilian population were similar to those found in other ethnicities, suggesting that toric calculators, nomograms, coefficients of adjustment, and formulas that were developed based on astigmatism values of other populations may be used in Brazilian patients with comparable accuracy. [J Refract Surg. 2023;39(1):56-60.].

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.

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.

Clinical outcomes in a U.S. registration study of a new EDOF intraocular lens with a nondiffractive design.

PURPOSE: To evaluate the effectiveness and safety of the DFT015 intraocular lens (IOL) (AcrySof IQ Vivity Extended Vision) compared with an aspheric monofocal control IOL (AcrySof IQ model SN60WF). SETTING: 11 investigation sites in the U.S. DESIGN: Prospective randomized controlled clinical study. METHODS: Patients aged 22 years or older with bilateral cataracts were randomized to receive bilateral implantation of DFT015 or SN60WF. The 4 coprimary effectiveness outcomes (6 months postoperatively) were monocular photopic distance-corrected intermediate visual acuity (DCIVA), monocular photopic corrected distance visual acuity (CDVA), monocular depth of focus (DoF), and the percentage of patients achieving a DCIVA of 0.2 logMAR or better. The mean monocular photopic distance-corrected near visual acuity (DCNVA) was a secondary effectiveness outcome. Safety and patient-reported visual disturbances were evaluated through questionnaires. RESULTS: 218 patients (435 eyes) completed the study. Compared with SN60WF, DFT015 demonstrated superior mean monocular photopic DCIVA ( P &lt; .001), noninferior mean monocular photopic CDVA, and superior mean monocular photopic DCNVA ( P &lt; .001) and provided an extended monocular DoF (increase of 0.54 diopters at 0.2 logMAR). With DFT015, 78 first eyes (72.9%) achieved a DCIVA of 0.2 logMAR or better at 6 months. Incidences of ocular serious adverse events and patient-reported most bothersome visual disturbances were low and consistent between groups. CONCLUSIONS: DFT015 is safe and effective for the visual correction of aphakia, exceeding American National Standards Institute criteria for an extended depth-of-focus IOL by providing superior DCIVA and DCNVA, with comparable CDVA and visual disturbances to the SN60WF monofocal IOL.

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.

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.

Outcome of astigmatism correction using femtosecond laser combined with cataract surgery: penetrating vs intrastromal incisions.

PURPOSE: To compare the effectiveness of penetrating vs intrastromal femtosecond laser corneal relaxing incisions (CRIs) in reducing corneal astigmatism during cataract surgery. SETTINGS: Baylor College of Medicine and Mercy Clinic Eye Specialists. DESIGN: Prospective randomized study. METHODS: 248 eyes from 248 patients were included. Patients were randomly assigned to undergo paired penetrating (8 mm optical zone [OZ] at 1 center and 9 mm OZ at the other) or intrastromal CRIs (8 mm OZ at both centers). The lengths of the CRIs were based on published nomograms but modified to take into account posterior corneal astigmatism. Vector analysis was performed, and net corneal changes along the CRI meridian were calculated. Multiple regression analysis was performed to assess factors contributing to net corneal changes. RESULTS: Preoperatively, 9% to 18% of eyes had corneal astigmatism of ≤0.5 diopters (D), and 76% to 93% of eyes had postoperative refractive astigmatism of ≤0.5 D ( P < .05). Both penetrating and intrastromal CRIs produced significant mean net corneal changes along the CRI meridian (-0.49 to -1.21 D), and 71% to 84% of eyes had postoperative astigmatism vector prediction errors of ≤0.50 D. The 8 mm penetrating CRIs induced greater net corneal changes but more eyes with overcorrection than did the intrastromal and 9 mm penetrating CRIs (all P < .05). Greater net corneal changes occurred with longer CRI length, higher preoperative corneal astigmatism magnitude, and preoperative against-the-rule corneal astigmatism. Nomograms based on anterior and total corneal astigmatism are proposed. CONCLUSIONS: Both penetrating and intrastromal CRIs were effective in reducing corneal astigmatism during cataract surgery.