Optical power profiles and aberrations of a non-diffractive wavefront-shaping extended depth of focus intraocular lens.

PURPOSE: This study is to evaluate the optical characteristics of a non-diffractive wavefront-shaping intraocular lens which incorporates surface refractive modifications for shaping the wavefront in order to achieve extended depth of focus (EDoF) and to assess whether the nominal power of this IOL influences the attainable add power. METHODS: A commercially available optical bench NIMO TR1504 device (LAMBDA-X, Nivelles, Belgium) was employed to obtain full optical characterization of three non-diffractive EDoF intraocular lenses with + 10 D, + 20 D, and + 30 D powers. After NIMO measurements, data were computed using a custom-made MATLAB program (Mathworks, Inc., Natick, MA, USA) to evaluate the optical quality functions, such as the point spread function (PSF), wavefront profiles, and modulation transfer function (MTF) for two pupil sizes: 3 mm and 4.0 mm. RESULTS: The non-diffractive EDoF intraocular lens showed a central serrated power profile behavior with additions of + 2.00 to + 2.50 D over the nominal power. Higher order aberrations were found to be driven mainly by the spherical aberration, with almost null comatic influence. Optical quality metrics showed good values, better for a 3 mm pupil compared to a 4.5 mm one, as expected. The three IOL powers tested showed a very similar behavior in terms of power and aberrometric profiles, with minimal to null differences related to the nominal power. CONCLUSION: The non-diffractive wavefront-shaping EDoF intraocular lens achieves a near addition up to + 2.50 D aiming for an extended range of vision, almost independently of the base power.

Corneal aberrations are associated with low-energy meniscus injuries.

BACKGROUND: Visual impairment can cause balance problems. Therefore, visual impairment caused by an increase in corneal deviations can lead to sudden and unstable loads in the lower extremities. We aimed to investigate the possible relationship between low-energy meniscal injuries and corneal structural measures. METHODS: This prospective, observational study included individuals aged between 18-40 years with a normal body-mass index. The study group consisted of 54 patients with grade 2 or 3 meniscus injuries after low-energy activity. The control group consisted of 54 healthy individuals without any complaints in the knee joint. The corneal parameters of all participants were evaluated with a Scheimpflug corneal topography and specular microscopy device. Simulated keratometry (SimK), minimum central corneal thickness (MCCT), cylindrical diopter (ClyD), corneal volume (CVol) spheric aberrations (SphAbb), high-order aberration (HOA), coma values, and endothelial parameters were recorded. RESULTS: The research and control groups were similar in terms of age, body mass index, and gender distribution. There was no significant difference between the groups in the corneal SimK and CylD, parameters. However, HOA, Coma, SphAbb, and cell variability (Cv) values were significantly higher in the study group, and contrarily MCCT, CVol, and endothelial count (Cd) values were significantly lower. CONCLUSIONS: Our findings suggest that individuals with relatively lower MCCT values tend to develop meniscal damage after low-energy activity. Hence, the loss of corneal strength in these patients may be a sign of possible weakness in the meniscus. The HOA value above 0.26, the coma value above 0.16, and the SphAbb value above 0.1 may significantly increase the possible meniscus injury.

Association of myopia and astigmatism with postoperative ocular high order aberration after small incision lenticule extraction.

OBJECTIVE: To investigate the correlation between higher-order aberrations (HOA) after small incision lenticule extraction (SMILE) and the severity of myopia and astigmatism, along with the relevant factors. These findings will provide valuable insights for decreasing the occurrence of HOA after SMILE and enhancing visual quality. METHODS: A total of 75 patients (150 eyes) with myopia and astigmatism who underwent SMILE were categorized into four groups based on the severity of myopia and astigmatism: Myopia Group 1 (Group M1, spherical diopter ranged from -1.00 D to -4.00 D), Myopia Group 2 (Group M2, spherical diopter ranged from -4.10 D to -10.00 D), Astigmatism Group 1 (Group A1, cylindrical diopter ranged from 0 D to -1.00 D), and Astigmatism Group 2 (Group A2, cylindrical diopter ranged from -1.10 D to -3.00 D). A comprehensive assessment was performed to examine the association between HOA and various relevant factors, including a detailed analysis of the subgroups. RESULTS: Group M1 had significantly lower levels of total eye coma aberration (CA), corneal total HOA (tHOA), internal tHOA, and vertical CA ( Z 3 - 1 ) after SMILE than Group M2 (P < 0.05). Similarly, Group A1 had significantly lower levels of total eye tHOA, CA, trefoil aberration (TA), corneal tHOA, TA, and vertical TA ( Z 3 - 3 ) after SMILE than Group A2 (P < 0.05). Pearson correlation analysis indicated a statistically significant positive relationship between the severity of myopia/astigmatism and most HOA (P < 0.05). Subgroup evaluations demonstrated a notable increase in postoperative HOA associated with myopia and astigmatism in Groups M2 and A2 compared with the control group. Lenticule thickness, postoperative central corneal thickness (CCT), postoperative uncorrected distance visual acuity (UDVA), and postoperative corneal Km and Cyl were strongly correlated with most HOA. Age, eyes, and postoperative intraocular pressure (IOP) were only associated with specific HOA. CONCLUSION: HOA positively correlated with the severity of myopia and astigmatism after SMILE. However, this relationship was not linear. HOA after SMILE was influenced by various factors, and additional specialized investigations are required to establish its clinical importance.

Comparison of long-term changes in the effective optical zone following SMILE and FS-LASIK for moderate and high myopia.

BACKGROUND: Visual quality after corneal refractive surgery is linked to the postoperative effective optical zone (EOZ). This study aims to compare long-term changes in the EOZ following small incision lenticule extraction (SMILE) and femtosecond laser-assisted in-situ keratomileusis (FS-LASIK) for moderate and high myopia. METHODS: This study included 42 patients (72 eyes) who underwent either SMILE (36 eyes) or FS-LASIK (36 eyes). A custom software program based on the tangential curvature difference map of the Pentacam HR (Oculus Optikgeräte GmbH) was used to define the EOZ at 3 and 7 years postoperatively. The EOZ, its chronological changes compared to the programmed optical zone (POZ), and the corneal wavefront aberrations following SMILE and FS-LASIK were analyzed. Correlations between the EOZ changes and relevant parameters were evaluated. RESULTS: Three years postoperatively, EOZ following SMILE and FS-LASIK were 5.13 ± 0.27 mm and 4.70 ± 0.24 mm (P < 0.001), respectively. Seven years postoperatively, EOZ following SMILE and FS-LASIK decreased to 5.03 ± 0.28 mm and 4.63 ± 0.23 mm (P < 0.001), respectively. At postoperative 7 years, the percentages of EOZ/POZ were negatively correlated with Q-value changes (ß = -5.120, P = 0.009) following SMILE and positively correlated with the cylinder correction (ß = 1.184, P = 0.004) following FS-LASIK. The induced spherical aberrations in the SMILE group were less than those in the FS-LASIK group (P < 0.05) and were negatively correlated with the EOZ/POZ (ß = -16.653, P < 0.001). CONCLUSIONS: The EOZ following SMILE was larger than that following FS-LASIK in the long postoperative term for moderate and high myopia. Furthermore, a continual reduction in the EOZ was noted after both surgical modalities.

Allowable movement of wavefront-guided contact lens corrections in normal and keratoconic eyes.

PURPOSE: The goal was to use SyntEyes modelling to estimate the allowable alignment error of wavefront-guided rigid contact lens corrections for a range of normal and keratoconic eye aberration structures to keep objectively measured visual image quality at or above average levels of well-corrected normal eyes. Secondary purposes included determining the required radial order of correction, whether increased radial order of the corrections further constrained the allowable alignment error and how alignment constraints vary with keratoconus severity. METHODS: Building on previous work, 20 normal SyntEyes and 20 keratoconic SyntEyes were fitted with optimised wavefront-guided rigid contact lens corrections targeting between three and eight radial orders that drove visual image quality, as measured objectively by the visual Strehl ratio, to near 1 (best possible) over a 5-mm pupil for the aligned position. The resulting wavefront-guided contact lens was then allowed to translate up to ±1 mm in the x- and y-directions and rotate up ±15°. RESULTS: Allowable alignment error changed as a function of the magnitude of aberration structure to be corrected, which depends on keratoconus severity. This alignment error varied only slightly with the radial order of correction above the fourth radial order. To return the keratoconic SyntEyes to average levels of visual image quality depended on maximum anterior corneal curvature (Kmax). Acceptable tolerances for misalignment that returned keratoconic visual image quality to average normal levels varied between 0.29 and 0.63 mm for translation and approximately ±6.5° for rotation, depending on the magnitude of the aberration structure being corrected. CONCLUSIONS: Allowable alignment errors vary as a function of the aberration structure being corrected, the desired goal for visual image quality and as a function of keratoconus severity.

Wavefront Changes during a Sustained Reading Task in Presbyopic Eyes.

The objective of this study was to assess the effect of sustained reading on the temporal changes in the wavefront error in the presbyopic eye. The wavefront aberration of the eyes was measured using an IRX3 Shack-Hartmann aberrometer before and after (immediately, 5 min, and 10 min after) a reading task. Temporal changes in C20, C40, and C3-1 coefficient values of the eyes were plotted, showing a predominant number of V-shaped patterns (for C40 and C3-1) and inverse V-shaped patterns (for C20) among the study group, and the percentages (between 27 and 73%) were reported. The median of the total RMS of aberrations and the RMS of HOA (higher-order aberrations), which included comatic (3rd order) and spherical-like aberrations (4th and 6th order), increased immediately after finishing the near-vision reading task and then decreased. The median of RMS of comatic aberrations had a similar pattern of variations, while the median of RMS of spherical-like aberrations displayed an opposite pattern. Simulating the aberration changes due to lens decentration caused by relaxed zonules during 4 D accommodation in an eye model demonstrated that the expected range of changes for the vertical coma and spherical aberrations are in the order of 0.001 and 0.01 µm, respectively, which could justify why the observed changes were not statistically significant. The observed dynamic changes in HOA might be linked to the biomechanical characteristics and alterations in the displacement of the crystalline lens following prolonged near-vision tasks in presbyopic people. Although some predominant patterns under some conditions were shown, they exhibit considerable inter-subject and inter-ocular variability. This might be due to slight misalignments while fixating on the internal extended object in the aberrometer.

Statistical optimal parameters obtained by using clinical human ocular aberrations for high-precision aberration measurement.

PURPOSE: Compared to Shack-Hartmann wavefront sensor (SHWS), the parameters of virtual SHWS (vSHWS) can be easily adjusted to obtain the optimal performance of aberration measurement. Its current optimal parameters are obtained with only a set of statistical aberrations and not statistically significant. Whether the above parameters are consistent with the statistical results of the optimal parameters corresponding to each set of aberrations, and which performance is better if not? The purpose of this study was to answer these questions. METHODS: The optimal parameters to reconstruct 624 sets of clinical ocular aberrations in the highest accuracy, including the numbers of sub-apertures (NSAs) and the expansion ratios (ERs) of electric field zero-padding, were determined sequentially in this work. By using wavefront-reconstruction accuracy as an evaluation index, the statistical optimal parameter configuration was selected from some possible configurations determined by the optimal NSAs and ERs. RESULTS: The statistical optimal parameters are consistent for normal and abnormal eyes. They are different from the optimal parameters obtained with a set of statistical aberrations from the same 624 sets of aberrations, and the performance using the former is better than that using the latter. The performance using a fixed set of statistical optimal parameters is even close to that using the respective optimal parameters corresponding to each set of aberrations. CONCLUSION: The vSHWS configured with a fixed set of statistical optimal parameters can be used for high-precision aberration measurement of both normal and abnormal eyes. The statistical optimal parameters are more suitable for vSHWS than the parameters obtained with a set of statistical aberrations. These conclusions are significant for the designs of vSHWS and also SHWS.

Comparison of clinical outcomes of a corneal wavefront- and topography-guided platforms for laser in situ keratomileusis on virgin eyes: an expanded cohort study.

PURPOSE: To compare the clinical outcomes of myopiacorrected with corneal-wavefront-guided (CWG) laser in situ keratomileusis (LASIK) with AMARIS 1050S (SCHWIND eye-tech-solutions GmbH & Co. KG) and corneal-topography-guided (CTG) LASIK with WaveLight EX500 (Alcon Laboratories, Fort Worth, TX). METHODS: In this prospective, pseudo-randomized expanded cohort study, a total of 266 patients were subjected to binocular LASIK surgery, either with WaveLight EX500 (WaveLight group) or Amaris 1050S (AMARIS group) platforms. Data related to right eyes were selected for analysis. Corneal higher-order aberration (HOA) was selected as the primary endpoint; while visual acuity and refraction were the secondary endpoints. All the endpoints were assessed at 3 months postoperatively. RESULTS: There were 134 eyes in the AMARIS group and 132 eyes in the WaveLight group. After 3 months of postoperative follow-up, spherical and coma aberrations were significantly lower (P < 0.05) in the WaveLight group (spherical aberration: - 0.104 ± 0.199 µm; coma aberration: - 0.117 ± 0.202 µm) in comparison with the AMARIS group (spherical aberrations: 0.254 ± 0.146 µm; coma aberrations: 0.316 ± 0.297 µm). In the AMARIS group, 96.3% of the eyes achieved an uncorrected distance visual acuity (UDVA) of 20/20 while in the WaveLight group, 96.2% of the eyes achieved an UDVA of 20/20. Furthermore, the mean postoperative manifest refraction spherical equivalent (MRSE) was - 0.02 ± 0.28 in the AMARIS group and - 0.05 ± 0.21 in the WaveLight group (P = 0.34). CONCLUSIONS: Both WaveLight EX500 and Amaris 1050S LASIK showed excellent refractive and visual outcomes. In addition, the WaveLight group showed minimal spherical and coma aberrations when compared to the AMARIS group.

[Wavefront characteristics in amblyopia of different etiologies in children]. / Osobennosti volnovogo fronta pri ambliopii razlichnogo geneza u detei.

Purpose. The study investigates corneal and higher-order internal aberrations in patients with amblyopia of different etiologies and their relationship with visual acuity, refraction, axial length, and fixation parameters. MATERIAL AND METHODS: Forty-five patients (90 eyes) were examined. All patients were divided into five groups: 1 - with dysbinocular amblyopia; 2 - with refractive amblyopia; 3 - with anisometropic amblyopia; 4 - with relative amblyopia due to congenital myopia; 5 (control) - fellow eyes without amblyopia. Aberrometry was performed using the OPD-Scan III device (Nidek, Japan). Fixation parameters were studied on the MP-3 microperimeter (Nidek, Japan). Correlation analysis was performed using Pearson's linear correlation coefficient (r). RESULTS: In amblyopia associated with congenital myopia, a significant increase in corneal and internal aberrations RMS, Total HOA, astigmatism (V) (0.65±0.26; 1.01±0.31; 4.22±1.17; -2.17±0.72; 0.86±0.3, respectively; control group - 0.44±0.19; 0.58±0.27; 1.0±0.75; -0.94±0.89; 0.47±0.65) and internal spherical aberration (0.06±0.02; control group - 0.04±0.03) was found. In dysbinocular amblyopia, a significant increase in internal aberrations Trefoil (V) and Coma (H) (0.75±0.52 and 0.17±0.35, respectively; control group - 0.05±0.28 and -0.07±0.21) was found, which correlated with a decrease in fixation density in the 2° ring (r= -0.40, r= -0.41). CONCLUSIONS: The increased level of higher-order aberrations in amblyopia associated with congenital myopia is due to the anatomical and optical features of the eyes. The increase in internal aberrations Trefoil (V) and Coma (H) in dysbinocular amblyopia is associated with a mismatch of the optical elements of the eye due to impaired fixation, i.e., it is not the cause, but the consequence of amblyopia.

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.

Randomized Clinical Trial Comparing Femtosecond LASIK and Small-Incision Lenticule Extraction.

PURPOSE: To compare femtosecond LASIK with small-incision lenticule extraction (SMILE) for the treatment of myopia and myopic astigmatism. DESIGN: Prospective, randomized, paired-eye, single-masked clinical trial. PARTICIPANTS: Consecutive eligible patients were randomized to undergo SMILE and LASIK in either eye at a single tertiary referral eye center. METHODS: Patients were treated in each eye using the VisuMax (Carl Zeiss Meditec, Jena, Germany) 500-kHz femtosecond laser system. Excimer ablation was subsequently performed using the WaveLight EX500 excimer laser (Alcon Laboratories, Inc, Fort Worth, TX) in the eye for LASIK. MAIN OUTCOME MEASURE: Refractive predictability at 3 months. Secondary outcomes were refractive outcomes, that is, efficacy and safety at 3 and 12 months. RESULTS: We recruited 70 consecutive patients (mean age, 28±5 years; 64% women; all Asian) with no difference in preoperative spherical equivalent (SE) between eyes (-5.3±1.8 diopters [D] vs. -5.2±1.7 D; P = 0.87). At 3 months, 99% of SMILE eyes and 97% of LASIK eyes achieved SE within ±1.0 D of attempted correction (P = 1.0). Small-incision lenticule extraction achieved similar results as LASIK in terms of efficacy index (0.97±0.20 vs. 0.99±0.20; P = 0.56), uncorrected distance visual acuity (UDVA) of 20/40 or better (100% vs. 100%; P = 1.0), and UDVA of 20/20 or better (84% vs. 87%; P = 0.63). Safety index (1.1±0.2 vs. 1.1±0.2; P = 0.57) was similar between SMILE and LASIK eyes at 3 months. At 12 months, SMILE was similar to LASIK in terms of efficacy (85% vs. 83% UDVA ≥20/20; P = 0.81), predictability (99% vs. 99% ±1.0 D of attempted correction SE; P = 1.0), and safety (1.15±0.20 vs. 1.15±0.20; P = 0.93). CONCLUSIONS: The results from this randomized trial suggest that SMILE produced promising refractive outcomes in terms of predictability, efficacy, and safety at 3 and 12 months of follow-up.

Redefining vision assessment.

PURPOSE OF REVIEW: This review outlines ophthalmic diagnostic systems, which objectively evaluates the human visual system and its potential beyond that of Snellen acuity. RECENT FINDINGS: Advances in ophthalmic diagnostic systems have allowed for a deeper understanding of the optical principles of the human eye and have created the opportunity to evolve our current standards of vision assessment beyond Snellen acuity charts. Definitive comparative and validation trials will continue to be necessary in order for these advanced diagnostics to gain more widespread acceptance in the specialty, in addition to providing the guidance on the specific indications and utilities. SUMMARY: Advancements in wavefront analysis, light scatter measurements, and adaptive optics technologies can provide greater insight into an individual optical system's potential and irregularities. Modalities that test for anterior corneal surface and whole eye aberrations, light scatter and contrast sensitivity can be an excellent educational tool for our patients to help them better understand their visual dysfunction and can prove useful for medical or surgical decision-making.

Relating wavefront error to visual acuity in pre- and post-LASIK eyes: a comparison of methods.

Contrast threshold and visual Strehl ratio methods are used to predict visual acuity from wavefront error for a sample population of pre- and post-LASIK patients. Relative error (in logMAR) between predicted and measured visual acuity values are computed for each method and compared using paired t-tests. Differences in aberration data between pre- and post-LASIK eyes are then evaluated. The visual acuity prediction using visual Strehl proved to be more accurate for pre-LASIK patients than contrast threshold. However, both methods are comparable for post-LASIK patients.

HIGHER-ORDER ABERRATIONS IN EYES WITH SILICONE OIL TAMPONADE.

PURPOSE: To investigate the changes in higher-order aberrations (HOAs) after silicone oil removal and to evaluate their associations with visual acuity. METHODS: Fifty-nine eyes of 58 patients who underwent SO removal were included. Total, corneal, and internal optic HOAs, and best-corrected visual acuity were measured before and 1 month after SO removal, and changes were compared between phakic and pseudophakic eyes. RESULTS: Total ocular and internal optic HOAs decreased significantly after SO removal both in pseudophakic (n = 40, all P < 0.001) and phakic eyes (n = 19, P = 0.017, P = 0.004). Preoperative HOAs (P < 0.001) and changes in HOAs (P = 0.006) were greater in pseudophakic eyes than in phakic eyes. Best-corrected visual acuity was significantly improved after SO removal, from 20/105 to 20/78 (P < 0.001) in pseudophakic eyes, whereas there was no difference in phakic eyes (P = 0.714). Preoperative HOAs and the reduction in HOAs after SO removal were greater in best-corrected visual acuity-improved eyes than best-corrected visual acuity-unchanged eyes (P < 0.001). CONCLUSION: Silicone oil tamponade induced an increase in HOAs, and these increases were greater in pseudophakic eyes than in phakic eyes. Silicone oil may cause additional visual impairments because of HOAs, beyond those caused by retinal diseases, particularly in pseudophakic eyes.

Do Polymer Coatings Change the Aberrations of Conventional and Wavefront-guided Scleral Lenses?

SIGNIFICANCE: The findings of this study indicate that patients could simultaneously be offered the individualized optical correction of wavefront-guided (WFG) lenses and the superior comfort afforded by polymer coatings. This could be helpful to patients with ectasia suffering ocular dryness or dependent on scleral lenses for lengthy periods of wear. PURPOSE: Wavefront-guided scleral lenses target lower- and higher-order aberrations of individual eyes using submicrometer-level contours in the anterior lens surface. Hydrophilic polyethylene glycol (PEG) polymer coatings applied to lens surfaces improve comfort and wettability. This study aimed to quantify aberration changes (e.g., masking) when applying polymer coatings to WFG and conventional scleral lenses. METHODS: Two control lenses (remained uncoated) and 14 experimental lenses (two repeated builds of seven aberration designs: one spherical, two coma, four full WFG [second- to fifth-order aberrations]) were manufactured, and aberrations were measured (mean of three) by two operators before and after coating. Root mean square (RMS) and visual image quality (logVSX) differences were calculated for 6-mm diameters. RESULTS: Median RMS aberration change due to coating was 0.012 µm (range, 0.008 to 0.057 µm). Maximum logVSX change due to coating was 0.073, predicting an approximately one letter change in acuity. Instrument sensitivity was 0.002 µm. Acute instrument and operator variabilities (standard deviations of individual [second- to fifth-order Zernikes] were all <0.027 µm). Longitudinal variability (control lenses) was low: all less than 0.017 µm. Although RMS of differences between repeated builds of all lenses was less than 0.25 D and not statistically significant, relatively, manufacture constituted the major variability, and RMS difference between repeated builds was at least four times greater than the effect of coating (median, 0.167 µm; range, 0.088 to 0.312 µm). CONCLUSIONS: Application of polymer coatings caused measurable changes in aberrations of WFG and conventional scleral lenses; however, these were clinically and statistically insignificant and within variability of repeated lens manufacture. In their current states, WFG lenses and polymer coatings could be used simultaneously.

Effect of Simulated and Real Spherical and Astigmatism Defocus on Visual Acuity and Image Quality Score.

SIGNIFICANCE: Image simulation is a useful and efficient tool to explore the impact of spherical and astigmatic blur on visual acuity (VA) and image gradation. It could help to design new optical corrections more efficiently and rapidly. PURPOSE: The purpose of this study was to compare the effects of simulated (convolution by an artificial eye) and real spherical and astigmatic defocus on VA and image gradation. METHODS: Experiments were performed under highly controlled conditions: dynamic correction of the subjects' aberrations at 1 Hz and application of an artificial pupil. In experiment 1, Landolt C VA was measured in various conditions of spherical and astigmatism defocus. The amounts of spherical or positive astigmatic defocus oriented at 45° that gives a Landolt C VA of 0.0, 0.2, and 0.5 logMAR were measured in experiment 2. In experiment 3, the subjects scored the quality of the perceived image (three high-contrast 0.4 logMAR letters) with a five-item continuous grading scale. RESULTS: Simulated blur was always more detrimental than optical blur. We measured a difference of 0.08 ± 0.03 and 0.11 ± 0.05 logMAR between both conditions, respectively, in presence of spherical and astigmatism defocus. An average ± standard deviation difference of 0.16 ± 0.06 D (i.e., spherical defocus) and 0.24 ± 0.15 D (i.e., astigmatism defocus) was observed between simulated and real optics blur to provide a given VA. The differences of image quality score between both conditions were, respectively, 15.13 ± 9.63 and 13.33 ± 4.83 for spherical and astigmatism defocus. Most of the differences were statistically significant. CONCLUSIONS: We observed a difference of about 20 and 35% between simulated and real optics blur, respectively, in presence of spherical and astigmatism blur. However, the difference between both methods remains equal to or below the clinically significant difference.

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.

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.