Analyzing Effect of Waterclefts on Visual Functions Via Optical Simulations.

Purpose: To investigate the impact of the size and location of waterclefts (WC), which are one of several cataract subtypes, on visual function by optical simulation analysis. Methods: An optical simulation software (CODE V) was used to develop a schematic eye model and several sizes of WC central and peripheral types that were located below the anterior and posterior subcapsules of the crystalline lens, and analyses of refraction, higher-order aberrations (HOA), and the modulation transfer function (MTF) were performed. Results: An increase in the WC size increased the refraction and HOA and decreased the MTF. The impact of the WC below the posterior subcapsule on the visual function was more enhanced than that below the anterior subcapsule. Large WC demonstrated a remarkable hyperopic shift in refractive power as well as an increase in HOA. The MTF decreased slightly with increasing WC size at a spatial frequency of 20 cycles/mm, and it decreased remarkably at 60 cycles/mm. Conclusions: The impact on the visual function increased with increasing WC size. It was revealed that eyes with WC below the posterior subcapsule are more hyperopic than those with WC below the anterior subcapsule, and the former have a higher HOA and lower MTF than the latter.

Clinical Outcomes of a New Type of Continuous Intrastromal Corneal Ring for Treatment of Keratoconus.

PURPOSE: The purpose of this study was to evaluate the efficacy and safety of implantation of a new continuous corneal ring in keratoconic corneas of an Iranian population. METHODS: This study was conducted on 95 contact lens-intolerant keratoconic eyes with clear central corneas. A continuous corneal ring, annular intrastromal corneal inlay (AICI), was inserted using femtosecond laser in all cases. Patients were followed up for 1, 3, and 12 months postsurgery. Visual and subjective refractive outcomes were evaluated in each examination. Besides, keratometry and aberrometric values were recorded before and 12 months after surgery. Finally, vector analysis of refractive astigmatism was performed using the Alpins method. RESULTS: The uncorrected and corrected distance visual acuities improved significantly 12 months after surgery from 0.91 ± 0.39 to 0.38 ± 0.22 (P < 0 0.001) and 0.33 ± 0.21 to 0.13 ± 0.11 logMAR (P < 0.001), respectively. Moreover, spherical and cylindrical refractive components reduced from -2.52 ± 2.62 to -0.76 ± 1.78 D (P < 0.001) and -4.14 ± 1.64 to -1.91 ± 1.18 D (P < 0.001), respectively. The mean anterior keratometry had a significant reduction 12 months after AICI insertion (P< 0.001). Primary coma and spherical aberration values showed a significant increase (both, P < 0.05). Our results showed 100% safety (safety index: 1.8) and 45% efficacy (efficacy index: 1). CONCLUSIONS: AICI implantation seemed to be a safe and effective procedure for improving visual acuity and refractive outcomes in subjects with keratoconus.

Predictors of Vision-Related Quality of Life After Endothelial Keratoplasty in the Descemet Endothelial Thickness Comparison Trials.

PURPOSE: To determine which baseline characteristics are associated with vision-related quality of life (QOL) after endothelial keratoplasty. METHODS: A patient- and outcome-masked randomized clinical trial. Consecutive patients presenting with isolated endothelial disease requiring endothelial keratoplasty at Oregon Health Sciences University and Stanford University. Study eyes randomized to one of the 2 types of endothelial keratoplasty were given the national eye institute vision function questionnaire 25 at baseline and 12 months. In this prespecified secondary outcome, we assessed the role of recipient and donor characteristics as predictors of the 12-month national eye institute vision function questionnaire 25 change score. RESULTS: The mean vision function questionnaire (VFQ) score was 74 (SD 14) at baseline and increased to 82 (SD 12) at 3 months and 87 (SD 10) at 12 months. We were unable to find a difference in vision-related QOL in study participants who underwent Descemet membrane endothelial keratoplasty compared with ultrathin Descemet stripping endothelial keratoplasty [coef -0.98, 95% confidence interval (CI) -9.27 to 7.31; P = 0.82]. In multivariable analysis, patients who underwent endothelial keratoplasty in 2 eyes had approximately 8 points higher VFQ at 12 months after the second eye than those who had only one eye enrolled (95% CI 0.10-15.72; P = 0.047). Posterior densitometry produced an approximately 1-point increase each in the VFQ change score for each 1 grayscale unit increase at baseline (95% CI 0.26-1.81; P = 0.009). Although the sample size was small, a diagnosis of pseudophakic bullous keratopathy had approximately 19-points more improvement on average compared with Fuchs (95% CI 7.68-30.00; P = 0.001). CONCLUSIONS: Bilateral endothelial keratoplasty resulted in higher vision-related QOL compared with unilateral. Baseline densitometry, objective measure of corneal haze that predicts vision-related QOL, may play a role in monitoring disease progression.

Influence of angle Kappa on the optimal intraocular orientation of asymmetric multifocal intraocular lenses

PURPOSE: to evaluate the effects of kappa angle and intraocular orientation on the theoretical performance of asymmetric multifocal intraocular lenses (MIOL). METHODS: For a total of 21 corneal aberrations, a computational analysis simulated the implantation of a computationally designed MIOL. An image quality parameter (IQ) (visually modulated transfer function metric) was calculated for a 5.0-mm pupil and for three conditions: distance, intermediate, and near vision. The procedure was repeated for each eye after a rotation of the MIOL with respect to the cornea from 0º to 360º in 5º steps. Kappa angles from 0 to 900 microns, in 150 microns steps, combined with two two variants of MIOL centration were tested: in the corneal apex or in the center of the entrance pupil. A p-value ≤ 0.05 was considered significant. RESULTS: There were statistically significant differences of the IQ depending of the intraocular orientation of the MIOL. If kappa angle was increased, there was a statistically significant decrease of the IQ. The IQ maintained stable when the optimal intraocular orientation was re-calculated for each kappa angle. In general, the inter-variability of the results between subjects was very high. There were no strong evidences supporting that there exists a preferable centration point. CONCLUSIONS: Our results suggest that kappa angle theoretically affects significantly the performance of asymmetric MIOL implantation. However, its negative effect can be compensated if a customized intraocular orientation is calculated taking into account the presence of the kappa angle

No disponible

Evaluation of a Portable Wavefront Aberrometer for Community Screening Refraction in the Elderly.

SIGNIFICANCE: The SVOne may prove useful to quickly and easily assess refractive correction needs in community screenings and low-resource settings, but not all subjects were testable with the device. PURPOSE: This study aimed to compare the SVOne handheld, smartphone-based wavefront aberrometer with a tabletop autorefractor in identifying refractive errors in elderly subjects. METHODS: Participants 50 years or older at community eye screenings with visual acuity worse than 20/40 in either eye underwent autorefraction followed by two SVOne trials. Power vectors of right eye data were analyzed. RESULTS: Of 84 subjects who underwent autorefraction, 67 (79.8%) were successfully autorefracted with the SVOne, of whom 82.1% (55/67) had a successful repeat reading. Mean M (spherical equivalent) values from tabletop and handheld autorefraction were -0.21 D (95% confidence interval [CI], -0.71 to +0.29 D) and -0.29 D (95% CI, -0.79 to +0.21 D), respectively (P > .05). Mean astigmatism values from tabletop and handheld devices were +1.06 D (95% CI, 0.87 to 1.26 D) and +1.21 D (95% CI, 0.99 to 1.43 D), respectively (P > .05). Intraclass correlation coefficients between devices were 0.95 (95% CI, 0.93 to 0.97) for M, 0.78 (95% CI, 0.66 to 0.86) for J0, and 0.45 (95% CI, 0.24 to 0.63) for J45 (P < .05 for all). Excellent test-retest correlation between SVOne measurements was noted for M (Pearson correlation [r] = 0.96; P < .05), but a weaker correlation was noted for J0 and J45 (r = 0.67 and r = 0.63 [P < .05 for both], respectively). CONCLUSIONS: The SVOne provided strong agreement for M, with the majority of readings within ±1.00 D of each other, when compared with the tabletop autorefractor. A weaker but still good correlation was noted for astigmatism. Similar findings were noted when assessing repeatability.

Contrast Rivalry Paradigm Reveals Suppression of Monocular Input in Keratoconus.

Purpose: Keratoconus results in image quality loss in one or both eyes due to increased corneal distortion. This study quantified the depth of monocular suppression in keratoconus due to this image quality loss using a binocular contrast rivalry paradigm. Methods: Contrast rivalry was induced in 50 keratoconic cases (11-31 years) and 12 age-matched controls by dichoptically viewing orthogonal Gabor patches of 5 cycles per degree (cpd) and 1.5 cpd spatial frequency for 120 seconds with their best-corrected spectacles and rigid gas permeable (RGP) contact lenses. The dwell time on each eye's percept was determined at baseline (100% contrast bilaterally) and at varying contrast levels (80-2.5%) in the stronger eye of keratoconus or dominant eye of controls. The contrast reduction needed in the stronger eye to balance dwell times on both eyes was considered a measure of suppression depth. Results: At baseline with 5 cpd stimuli and spectacle correction, the rivalry switches were less frequent and biased toward the stronger eye of cases, all relative to controls (P < 0.001). The contrast balance point of cases (20.51% [10.7-61%]) was lower than the controls (99.80% [98.6-100%]; P < 0.001) and strongly associated with the overall and interocular difference in disease severity (r = 0.83, P < 0.001). The suppression depth reduced for 1.5 cpd (70.8% [21.7-94%]), relative to 5 cpd stimulus (P < 0.001) and with contact lenses (80.1% [49.5-91.7%]), relative to spectacles (P < 0.001). Conclusions: The eye with lesser disease severity dominates binocular viewing in keratoconus. The suppression depth of the poorer eye depends on the extent of bilateral disease severity, optical correction modality, and the target spatial frequency.

Recovery of Contrast Sensitivity After Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To study the change in contrast sensitivities in eyes with Fuchs endothelial dystrophy and bullous keratopathy after Descemet membrane endothelial keratoplasty (DMEK). METHODS: In this prospective study, 50 pseudophakic eyes of 50 patients who received DMEK surgery at the Charité-Universitätsmedizin Berlin were included. Visual acuity; contrast sensitivity using OPTEC 6500 at spatial frequencies of 1.5, 3, 6, 12, and 18 cycles/degree in photopic and mesopic light with and without glare; central corneal thickness (CCT); and anterior and posterior corneal aberrations were measured preoperatively and at 3 and 12 months postoperatively. RESULTS: Best-corrected visual acuity (preoperative 0.67 ± 0.46 and after 12 months 0.19 ± 0.16 LogMAR, P < 0.001) and photopic and mesopic contrast sensitivities with and without glare improved significantly, whereas CCT decreased significantly (preoperative 677 ± 114 µm, after 12 months 527 ± 29 µm, P < 0.001). Preoperative CCT correlates significantly with preoperative photopic contrast sensitivity (correlation coefficient -0.462, P = 0.002), and postoperative total anterior aberrations correlates with postoperative photopic contrast sensitivity (correlation coefficient -0.361, P = 0.006). CONCLUSIONS: Photopic and mesopic contrast sensitivities, especially with glare, are impaired in patients with Fuchs endothelial dystrophy and bullous keratopathy. The extent of the corneal thickening seems to mainly influence the contrast sensitivity preoperatively. DMEK surgery improves the contrast sensitivity significantly. However, higher postoperative anterior corneal aberrations limit the postoperative contrast sensitivities.

Pediatric Keratoconus: Topographic, Biomechanical and Aberrometric Characteristics.

PURPOSE: This study sought to evaluate the demographic profile, clinical features, topographic features, and biomechanical and aberrometric characteristics in pediatric keratoconus (KC). DESIGN: Cross-sectional study. METHODS: Pediatric KC cases <18 years of age were evaluated at a tertiary hospital. Main outcome measurements were demographic profile, clinical features, visual acuity, corneal topography, aberrometry, and biomechanical and confocal microscopy findings. RESULTS: A total of 116 eyes of 62 consecutive patients were recruited with a mean ± age of 14.7 ± 2.77 years (range: 8-18 years); 46 of 62 (88%) were males; 57 of 62 cases (92%) had bilateral disease; 53 of 116 eyes (46%) had progressive KC; and 9 of 116 eyes (8%) had acute hydrops. Systemic associations were found in 6 of 62 patients (9.7%) and ocular associations in 77 of 116 eyes (66.3%); 68 of 116 eyes (58.6%) had associated vernal keratoconjunctivitis (VKC). Among eyes with VKC, 29 of 68 eyes (46%) were in stage IV KC, versus 25% of eyes with no VKC (P = .004). The mean ± SD refractive spherical equivalent was -4.72 ± 3.32 diopters (D), and refractive astigmatism was 3.69 ± 3.09 D. The mean values of maximum keratometry, thinnest pachymetry, and corneal higher-order aberrations were 60.89 ± 10.9 D, 396.05 ± 95.03 µm, and 1.18 ± 1.2 µm, respectively. Values of corneal hysteresis and corneal resistance factor correlated with the stage of KC (r = -0.26; P = .007). CONCLUSIONS: Pediatric KC was commonly associated with VKC in this cohort. Eyes with VKC had more severe KC than those without VKC. Nearly half of the patients presented with progressive disease. Corneal biomechanical changes correlated well with stage of KC in this pediatric age group.

Comparative Analysis of Safety and Efficacy of Topography-Guided Customized Cross-linking and Standard Cross-linking in the Treatment of Progressive Keratoconus.

PURPOSE: To compare the safety and efficacy of topography-guided customized corneal cross-linking (PiXL) with standard cross-linking (CXL) for the treatment of progressive keratoconus. METHODS: In a prospective interventional analysis, the eyes of patients with progressive keratoconus underwent standard cross-linking (homogenous 9-mm ultraviolet-A irradiation of 9 mW/cm2 delivering a total fluence of 5.4J/cm2) versus topography-guided customized cross-linking (30 mW/cm2 pulsed irradiance with a total fluence ranging from 5.4 to 15 J/cm2, in concentric circles centered on the posterior float maximum). The following parameters were analyzed at the preoperative, 1-month, 6-month, and 1-year postoperative visits: corrected spectacle distance visual acuity, manifest refraction including sphere, cylinder and mean refractive spherical equivalent, corneal tomography, higher order aberration profile, and endothelial cell count. Anterior segment optical coherence tomography evaluation was performed at the 1-month postoperative visit to assess the depth of the demarcation line. RESULTS: Sixty-four eyes of 45 patients (32 eyes in each group) were included. There was a significant reduction in maximum keratometry and IS asymmetry in the PiXL group at both the 6-month and 1-year postoperative visits (P = 0.001 and 0.06). Corrected spectacle distance visual acuity improved significantly in the PiXL (0.05 ± 0.08 logarithm of the minimum angle of resolution, P = 0.02) versus the standard CXL (0.01 ± 0.025 logarithm of the minimum angle of resolution, P = 0.26) group. A greater depth of a stromal demarcation line was observed in the customized CXL group (P = 0.02). No significant complications were noted in either cohort. CONCLUSIONS: PiXL demonstrated similar safety with significantly greater keratometry flattening and corneal regularization vis-à-vis standard CXL. This resulted in significant improvement of spectacle corrected visual acuity for eyes with mild-to-moderate keratoconus.

Pediatric versus Adult Corneal Collagen Crosslinking: Long-term Visual, Refractive, Tomographic and Aberrometric Outcomes.

PURPOSE: To comparatively evaluate the long-term visual, refractive, topographic and aberrometric outcomes of conventional corneal collagen crosslinking (CXL) in the management of pediatric versus adult progressive keratoconus patients. MATERIALS AND METHODS: Retrospective, cross-sectional review of consecutive progressive keratoconus cases of corneal standard CXL using a standardized protocol for treatment and examinations was performed. Best spectacle-corrected distance visual acuity (CDVA), manifest refraction, slit lamp biomicroscopy, corneal tomography, corneal aberrometry and endothelial cell counts were evaluated at baseline and yearly at all postoperative follow-up examinations after month-12. The outcomes were analyzed by dividing the patients into 2 age groups; pediatric (≤18 years) versus adult (>18 years). RESULTS: Eighty-eight eyes (54 patients) in the pediatric and 104 eyes (68 patients) in the adult age groups completed 3 years follow-up. Compared to baseline, the mean CDVA, manifest refraction, keratometric readings, tomographic and aberrometric parameters improved statistically significantly in both groups at postoperative year-3 and year-4, without any statistically significant between-group differences. No change in the mean endothelial cell density (p > .05), or no sight threating complication was encountered in any patient eye in either group. In a subset of patients who were followed for 4 years (71 eyes in the pediatric and 70 eyes in the adult age groups), the outcome analyses were again similar between-groups. CONCLUSION: Conventional corneal CXL effectively halts the progression of keratoconus in both pediatric and adult age groups in long-term follow-up with similar visual, refractive, tomographic and aberrometric efficacy in both groups.

Optical Quality in Keratoconus Is Associated With Corneal Biomechanics.

PURPOSE: To evaluate the correlations between corneal biomechanical indices from dynamic Scheimpflug assessment and optical quality assessed as higher-order aberrations (HOAs) using a Hartmann-Shack ocular wavefront sensor in patients with keratoconus (KC). METHODS: In this prospective, observational case series, the eyes with KC or KC suspect (KCS) from Osaka University Hospital, Osaka, Japan, were analyzed. Corneal biomechanical assessment was performed using Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany), and ocular wavefront aberrations were measured using the KR-1W (Topcon Corp, Tokyo, Japan). Correlations between the biomechanical indices and ocular HOAs were assessed. Corneal biomechanical indices included the deformation amplitude ratio within 2 mm, integrated radius, stiffness parameter at the first applanation, and the linear Corvis Biomechanical Index. Wavefront data of the central 4-mm region were expanded up to the sixth order of Zernike polynomials. The magnitudes of trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were calculated by Zernike vector analysis and then used as ocular HOA parameters along with total HOAs. RESULTS: Thirty-four KC eyes and 37 KCS eyes were included. KC eyes showed significant correlations between ocular HOAs and biomechanics, whereas there were few significant correlations in KCS eyes. In KC eyes, deformation amplitude ratio within 2 mm, integrated radius, and Corvis Biomechanical Index beta showed stronger correlations with coma among the wavefront parameters. CONCLUSIONS: Corneal biomechanical indices correlated with ocular HOAs in patients with KC. In particular, there was a strong association with the increase in coma caused by inferosuperior asymmetry of the shape of the cornea in patients with KC.

Optical Quality and Visual Performance for One Year in a Sample of Scleral Lens Wearers.

SIGNIFICANCE: This study shows the optical and visual quality behavior of modern scleral lenses (SLs) in the medium and long term in patients with irregular cornea (IC) and regular cornea (RC). PURPOSE: The purpose of this study was to evaluate the 12-month optical quality outcomes with SL in patients with IC and RC. METHODS: Sixty-nine patients completed the 12 months of follow-up (99 eyes with IC and 27 with RC). LogMAR high- and low-contrast visual acuity, whole eye aberrometry, and the size (Light Disturbance Index, %) and shape (BFCIrregSD, mm) of night vision disturbances were measured at baseline with habitual correction (HC), best spectacle correction (BSC), and SL at all the follow-up visits (1, 3, 6, and 12 months). Subjective visual quality was measured with the Quality of Vision (QoV) questionnaire. RESULTS: After SL fitting, high-contrast visual acuity improved significantly compared with HC and BSC in the IC group (average improvement of +0.35 ± 0.32 and +0.29 ± 0.26 to +0.08 ± 0.14, P < .001) and RC group (+0.17 ± 0.23 and +0.12 ± 0.23 to +0.10 ± 0.23, P < .05). Light Disturbance Index decreased significantly with SL compared with HC and BSC from 13.85 ± 13.99% and 15.89 ± 13.38% to 5.75 ± 4.51% in the IC group (P < .001) and 6.16 ± 5.38 and 5.98 ± 5.39 to 3.99 ± 3.05 in the RC group (P < .05). BFCIrregSD also decreased significantly, namely, in the IC group (-51%). All subscales of the QoV questionnaire had a statistically significant decrease (improvement) with SL (P < .05). CONCLUSIONS: Scleral lenses promote a better subjective and objective visual quality, mainly in patients with IC. Additional measurements such as night vision disturbances, aberrometry, and subjective perceptions should be considered to characterize the visual enhancement promoted by SL in RC and IC patients.

Case Report: What Are We Doing for Our "20/20 Unhappy" Scleral Lens Patients?

SIGNIFICANCE: Scleral lenses (SLs) partially mask higher-order aberrations (HOAs) in highly aberrated eyes. Although visual acuity (VA) may show satisfactory quantitative clinical outcomes during SL wear, residual (uncorrected) HOAs can leave subjective visual quality goals unmet. PURPOSE: The purpose of this study was to report a case where a "20/20 unhappy" patient with SLs was able to meet visual goals with wavefront-guided SLs. CASE REPORT: A 40-year-old male with bilateral keratoconus, whose Snellen VA with SLs was 20/20 right eye (OD) 20/16 left eye (OS), reported halos and glare at night and perceptual smearing. When viewing a point of light, a "Ferris wheel" shadowing was observed OD and a U-shaped shadowing OS. Residual higher-order root mean square wavefront error was 0.49 µm OD and 0.39 µm OS; visual image quality measured by visual Strehl ratio was 0.067 OD and 0.092 OS (pupil size, 4.00 mm). Wavefront-guided SLs reduced residual higher-order root mean square to 0.19 µm OD and 0.25 µm OS, VA improved to 20/10 OD and 20/13 OS, and visual Strehl improved to 0.150 OD and 0.121 OS. The patient reported reduced smearing, shadowing, and night vision concerns, meeting his visual expectations and goals. CONCLUSIONS: Wavefront sensing quantifies both lower and HOAs, which can cause visual dissatisfaction in individuals with highly aberrated eyes, despite sometimes reaching typical levels of VA. As wavefront-guided SLs targeting these residual aberrations to improve visual image quality become more available, they should be considered for 20/20 unhappy patients when conventional clinical options are unsatisfactory.

Comparison of Corneal Higher-order Aberrations between Miniscleral and Hybrid Lenses in Keratoconus.

SIGNIFICANCE: Fitting specialty contact lenses (hybrid and miniscleral) can be a useful option in keratoconus patients to decrease higher-order aberrations (HOAs) and increase the quality of vision. PURPOSE: The aim of the present study was to compare corneal HOAs between miniscleral and hybrid lenses in keratoconus patients. METHODS: The target population of this study was 37 patients with bilateral keratoconus aged 20 to 35 years who were referred to a specialized contact lens clinic by a corneal specialist. Pre-fitting examinations included objective and subjective refraction, measurement of uncorrected and best spectacle-corrected visual acuity, and measurement of corneal HOAs. Lens fitting was performed in the next step. Finally, post-fitting measurements including contact lens-corrected visual acuity and corneal HOAs were performed. RESULTS: The root mean square of the total HOAs significantly decreased after fitting both miniscleral and hybrid lens designs. There was a significant change in the third-order vertical coma and spherical aberration after fitting the miniscleral lens. In the hybrid lens group, a significant change was found only in vertical coma after fitting. There was no significant difference in the post-fitting HOA change between the two groups. CONCLUSIONS: The results of this study showed the effectiveness of both miniscleral and hybrid lenses in decreasing HOAs in keratoconus patients. No significant difference was observed between these two lenses in this regard.

The Impact of Misaligned Wavefront-guided Correction in a Scleral Lens for the Highly Aberrated Eye.

SIGNIFICANCE: To achieve maximum visual benefit, wavefront-guided scleral lens corrections (WGCs) are aligned with the underlying wavefront error of each individual eye. This requirement adds complexity to the fitting process. With a view toward simplification in lens fitting, this study quantified the consequences of placing WGCs at two pre-defined locations. PURPOSE: This study aimed to quantify performance reduction accompanying the placement of the WGC at two locations: (1) the average decentered location (ADL; average decentration observed across individuals wearing scleral lenses) and (2) the geometric center (GC) of the lens. METHODS: Deidentified residual aberration and lens translation data from 36 conventional scleral lens-wearing eyes with corneal ectasia were used to simulate WGC correction in silico. The WGCs were decentered from the eye-specific pupil position to both the ADL and GC locations. The impact of these misalignments was assessed in terms of change (from the aligned, eye-specific pupil position) in higher-order root mean square (HORMS) wavefront error, change in log of the visual Strehl ratio (logVSX), and predicted change in logMAR visual acuity (VA). RESULTS: As expected, HORMS increased, logVSX decreased, and predicted VA was poorer at both ADL and GC compared with the aligned condition (P < .001). Thirty-four of 36 eyes had greater residual HORMS, and 33 of 36 eyes had worse logVSX values at the GC than at the ADL. In clinical terms, 19 of 36 eyes at the ADL and 35 of 36 eyes at the GC had a predicted loss in VA of three letters or greater. CONCLUSIONS: The placement of the WGC at either ADL or GC is predicted to lead to a noticeable reduction in VA for more than half of the eyes studied, suggesting the simplification of the fitting process is not worth the cost in performance.

The Relationship Between Preoperative Anterior Corneal Higher Order Aberrations and Topography-Guided Excimer Ablation Depth.

PURPOSE: To determine the correlation and relative contribution of preoperative anterior corneal Zernike coefficients to higher order aberration ablation depth (HOA-AD) with topography-guided excimer laser correction. METHODS: Retrospective study of 46,271 consecutive preoperative virgin eyes. Anterior corneal Zernike coefficients (C6 to C27) and HOA-AD data on a 6.5-mm optical zone were analyzed from the Contoura (Alcon Laboratories, Inc) treatment software. Pearson correlations were performed to assess the relationship between Zernike coefficients and HOA-AD. RESULTS: A strong direct relationship was found between the total root mean square (RMS) anterior corneal HOA and HOA-AD (R = 0.84; P < .001). The 3rd order HOAs (C6 to C9) accounted for most of the HOA-AD (R = 0.83; P < .001). Zernike orders 4, 5, and 6 had significantly weaker correlations (4th order: R = 0.30; 5th order: R = 0.38; 6th order: R = 0.29). Vertical coma was the individual HOA with the highest correlation (R = 0.59; P < .001). Combining vertical and horizontal coma as total RMS coma increased the correlation significantly (R = 0.76; P < .001). The average HOA-AD increased by 1.5 µm for each additional 0.1-µm increment of total RMS coma. CONCLUSIONS: Anterior corneal Zernike coefficients directly and strongly correlate to the HOA-AD, with anterior corneal coma having the greatest contribution to HOA-AD. [J Refract Surg. 2020;36(8):506-510.].

Higher Order Aberrations (HOA) Changes after Femto-LASIK in Topography and Wavefrontguided Treatments.

BACKGROUND: Publications have focused on comparing the effect of various methods of refractive surgery or ablation profiles on higher order aberrations (HOA), yet the effect of WG compared to TG ablation in femtosecond laser-assisted in-situ keratomileusis femto-LASIK on HOAs has not been studied adequately. MATERIALS AND METHODS: We reviewed the changes of HOAs before and after femto-LASIK for simple myopia or compound myopic astigmatism after topography-guided (TG) and wavefront-guided (WG) ablation profiles. In this retrospective study, 42 eyes underwent TG and 31 WG femto-LASIK. RESULTS: The total HOAs increased from 0.41±0.16 µm pre-operatively to 0.66±0.30 µm post-operatively in the TG group and from 0.42±0.13 µm pre-operatively to 0.59±0.27 µm post-operatively in the WG group without statistically significant difference between the two groups. However, the postoperative change of secondary astigmatism showed a statistically significant difference between the two groups [0.20 (0.0-0.53) vs. 0.0 (0.0-0.20) for TG and WG groups, respectively; p=0.009]. CONCLUSIONS: The total HOAs increased compared to pre-operative data, in both the TG and WG ablation profile groups. The extent of increase of secondary astigmatism was significantly lower in the WG group, which might favour the postoperative quality of vision.

Comparison of Higher-Order Aberrations After Single-Step Transepithelial and Conventional Alcohol-Assisted Photorefractive Keratectomy

Objectives: To compare the asphericity and higher-order aberration (HOA) outcomes of single-step transepithelial photorefractive keratectomy (tPRK) and conventional alcohol-assisted PRK (aaPRK) in patients with myopia and myopic astigmatism. Materials and Methods: Of the 108 eyes of 54 patients enrolled in the study, tPRK was performed on 54 (50%) eyes and aaPRK was performed on 54 (50%) eyes. The following parameters were compared: corrected distance visual acuity (CDVA), spherical equivalent (SE), flat and steep keratometry, intraocular pressure, central corneal thickness, asphericity, and HOAs including horizontal and vertical coma, horizontal and vertical trefoil, spherical aberration, second-order vertical coma, and aberration coefficient. Results: The demographic and baseline characteristics were similar between the two groups (p>0.05, for all). The aberration coefficient value was significantly lower in patients treated with aaPRK compared to patients treated with tPRK at postoperative 3 months, 6 months, and 1 year (p=0.022, p=0.019, and p=0.017, respectively). Differences in the other variables were statistically insignificant (p>0.05 for all). Conclusion: Both tPRK and aaPRK procedures obtain similar postoperative CDVA, SE, asphericity, and HOA outcomes, except the aberration coefficient value.

Lower Corneal Haze and Aberrations in Descemet Membrane Endothelial Keratoplasty Versus Descemet Stripping Automated Endothelial Keratoplasty in Fellow Eyes for Fuchs Endothelial Corneal Dystrophy.

PURPOSE: To investigate the long-term corneal changes in patients with Fuchs endothelial corneal dystrophy contributing to superior postoperative visual outcomes after Descemet membrane endothelial keratoplasty (DMEK) compared with Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: Using retrospective analysis, we evaluated 9 patients with Fuchs endothelial corneal dystrophy who underwent DSAEK in 1 eye and DMEK in the fellow eye. Patients were genotyped for the triplet repeat expansion in the TCF4 gene and imaged using optical coherence tomography, Scheimpflug imaging, and in vivo confocal microscopy through focusing. RESULTS: Eight of 9 subjects were genotyped, and all were found to harbor the triplet repeat expansion. The average time between endothelial keratoplasty and imaging was 76 ± 22 and 37 ± 9 months after DSAEK and DMEK, respectively. The mean best spectacle-corrected visual acuity (logMAR) was 0.04 ± 0.05 and 0.11 ± 0.03 in the DMEK eyes versus DSAEK eyes (P = 0.02), respectively. Posterior corneal higher order aberrations were less in the DMEK eyes compared with fellow DSAEK eyes (0.25 ± 0.06 and 0.66 ± 0.25, respectively, P ≤ 0.01). Using confocal microscopy through focusing, we found that the persistent anterior stromal haze was correlated between the right and left eyes (R = 0.73, P ≤ 0.05), but total stromal backscattering was higher for the DSAEK eyes (P ≤ 0.05). CONCLUSIONS: DSAEK inherently results in higher total stromal backscattering (haze) compared with DMEK because of the addition of stromal tissue. Lower higher order aberrations of the posterior cornea and lower total stromal backscattering (haze) may both contribute to superior visual outcomes after DMEK compared with DSAEK.

Clinical outcomes of topography-guided femtosecond laser-assisted in situ keratomileusis after multifocal intraocular lens implantation.

This retrospective study is to evaluate refractive and visual outcomes of topography-guided femtosecond laser-assisted in situ keratomileusis (TGL) for correcting corneal high-order aberrations (HoA) after multifocal intraocular lens (mIOL) implantation. Twenty-eight eyes of 28 patients with both corrected distance visual acuity (CDVA) under 20/25 and subjective visual discomfort at 3 months after mIOL implantation were included in the study. TGL was performed to correct corneal HoA. Visual acuity, manifest refraction, and corneal HoA were measured 3 months after TGL. CDVA was improved in 22 (78.57%) of 28 eyes after TGL. Uncorrected distance visual acuity (0.12 ± 0.16 logMAR) and uncorrected near visual acuity (0.081 ± 0.16 logMAR) were better than those before TGL (P < 0.001). Residual refractive astigmatism showed no difference compared to that before TGL. Root mean square (RMS) of HoA (P = 0.012), spherical aberration (P = 0.013), and RMS of coma (P = 0.001) were reduced relative to those before TGL. Amount of improvement in CDVA was correlated with amount of reduced coma RMS (R = 0.524; P = 0.005) and spherical aberration (R = 0.443; P = 0.021). TGL showed to improve both refractive and visual outcomes in patients with mIOL implantation by correcting corneal HoA.