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.

Accommodation response and spherical aberration during orthokeratology.

PURPOSE: To evaluate the changes in the accommodative response and in the corneal and internal spherical aberration during 3 months of wear of orthokeratology lenses from the baseline. METHODS: Fifty children aged 8 to 17 were recruited for a prospective study and were fitted with orthokeratology lenses. Refraction without cycloplegia, high and low uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), accommodation lag, horizontal near phoria without correction, corneal topography, corneal, and total wavefront aberration were performed at baseline, 1 day, 1 week, 1 month, and 3 months. Data were analyzed by Student's t test for related samples, repeated measures ANOVA test, and Pearson correlation test. RESULTS: The spherical equivalent (SE) before and after 3 months was - 3.33 ± 1.60 D and - 0.30 ± 0.46 D, respectively. Accommodation lag was 0.53 ± 0.38 D and 0.20 ± 0.33 D at baseline and at 3 months, respectively. A moderate correlation between lag at the baseline and its change between baseline and the 3-month visit was found (P < 0.05; R = 0.748). The spherical aberration (SA) increased for anterior corneal and total measurement, being statistically significant for all visits (P < 0.05). The internal SA decreased: - 0.105 ± 0.006 at baseline and - 0.196 ± 0.203 at 1 week (P < 0.05). No difference between baseline and the follow-up visits in posterior corneal SA was found (P > 0.05) CONCLUSION: The negative SA of the lens increases during OK treatment compensated for the increase of the anterior corneal surface positive SA, in addition to increasing the accommodative response.

Prospective, randomized, eye-to-eye comparison of a new silicone corneal shield versus conventional bandage contact lens after photorefractive keratectomy.

PURPOSE: To compare uncorrected distance visual acuity (UDVA) and patient-reported outcomes with a new silicone corneal shield and a conventional bandage contact lens (BCL) after photorefractive keratectomy (PRK). SETTING: Stanford Eye Laser Center (Palo Alto, California) and Slade & Baker Vision (Houston, Texas). DESIGN: Prospective randomized cohort study. METHODS: Standardized bilateral wavefront-guided or wavefront-optimized PRK was performed in 25 patients with myopia. Each patient's dominant eye was randomized to either a silicone corneal shield or a conventional BCL, which was placed at the conclusion of surgery. The contralateral eye was assigned the other intervention. The UDVA and patient-reported outcomes were measured preoperatively, 1 hour after surgery, and at 1, 2, 3, 4, and 7 days postoperatively. RESULTS: At 1 day postoperatively, the mean logarithm of the minimum angle of resolution (logMAR) UDVA was 0.04 ± 0.16 (SD) in the silicone corneal shield group and 0.29 ± 0.22 in the BCL group (P < 0.01). At 7 days postoperatively, the mean logMAR UDVA was 0.09 ± 0.17 in the silicone corneal shield group and 0.23 ± 0.24 in the BCL group (P = .01). At 1 day through 3 days postoperatively, the patients reported greater pain, discomfort, foreign body sensation, and heavy eyelid in the eye with the silicone corneal shield. There was no statistically significant difference in the survey outcomes between the two groups at 4 days and 7 days postoperatively. CONCLUSIONS: The new silicone corneal shield was safe and effective, with faster visual recovery and a trend toward quicker epithelialization; however, it might be less comfortable than a conventional BCL.

Multifocal contact lenses: towards customisation?

PURPOSE: Firstly, to determine if eyes with spherical aberration (SA) that deviates significantly from the average level underperform when fitted with a simultaneous-imaging contact lens (CL) with a power profile calculated for an 'average eye'. Secondly, to determine if CL customisation can improve image quality in these eyes after fitting with a bifocal CL. METHODS: A statistical model of the wavefront aberration function of normal eyes was used to generate a vector of Zernike fourth-order SA coefficients from 100 synthetic eyes. Four bifocal power profiles were modelled: centre-near (CN) or centre-distance (CD), and two-zone or four-zone. All designs had 0.1-mm-wide transition zones. Different levels of distance and add powers were modelled, using well-established computational wave-optics methods. Zone widths were optimised to obtain maximal multifocal efficiency (MFE), a metric based on the visual Strehl that synthesises the through-focus curve in one number. The MFE was calculated for each synthetic eye coupled with each bifocal power profile. RESULTS: For an 'average eye', the mean MFE values were 0.33 vs 0.25 and 0.32 vs 0.29, for CN vs CD and two vs four zone designs, respectively. When the four power profiles were assessed in eyes with non-average levels of ocular SA, the MFE decreased with higher levels of SA (eye and CL combined) for all designs. Some of this reduction in MFE could be prevented by adjusting the nominal distance and add power of the bifocal profiles to compensate for the increased or decreased level of combined SA. The four-zone CN profile showed better tolerance for different levels of ocular SA than the two-zone designs, but this was not true for the four-zone CD design. CONCLUSION: Eyes with SA levels differing significantly from the average level underperform when fitted with simultaneous-imaging CLs with power profiles calculated for average eyes. Our findings suggest that visual performance at distance and near when wearing bifocal CLs can be improved by using a semi-customised approach.

A novel method in correcting aberropia using pin hole soft contact lenses: A case report.

Aberropia leads to decrease in image quality due to higher order aberrations (HOA). Correction of these HOA poses a great challenge to clinicians. A case report is presented here where a 30 year old male visited with complaints of cloudy vision, diplopia in reduced illumination along with inferior vertical elongation of light during night time in the right eye since 6 years. The unaided visual acuity was found to be 0.0 Log MAR units and near acuity was N6. The patient did not accept any correction in subjective refraction. The aberrometry findings revealed vertical trefoil and vertical coma of -0.33 µm and 0.53 µm in the right eye and -0.07 µm and 0.12 µm in the left eye. Orbscan revealed a difference of 30 µm and 25 µm between the anterior and posterior float for the right and left eye respectively. Due to the significant increase in irregular astigmatism, vertical coma and vertical trefoil in the right eye, rigid gas permeable lenses and Rose K lenses were tried, but the symptoms did not reduce. This was due to the increase in posterior corneal astigmatism as the posterior float was more than 25 µm in the right eye which led to a diagnosis of early keratoconus. As the decrease in pupil size reduces HOA, a pin hole (2.5 mm pupil) soft contact lens was tried which reduced the symptoms. Hence a novel method is proposed to eliminate HOA which corrects aberropia by using pin hole soft contact lenses.

Corneal Configurations and High-order Aberrations in Primary Congenital Glaucoma.

PURPOSE: Corneal changes are prevalent in eyes with primary congenital glaucoma (PCG). This study aimed to describe corneal irregularity and high-order aberrations (HOAs) in PCG eyes. MATERIALS AND METHODS: The study consecutively enrolled 61 PCG eyes (of 39 participants with PCG) and 61 age-matched control eyes (of 61 healthy participants). Participants underwent corneal topography, best spectacle-corrected visual acuity (BSCVA), and fundus photography. Corneal irregularity and HOAs were derived from topographic data and evaluated over central 4 and 6 mm diameter zones. Variables were compared between PCG and control eyes. Percentages of PCG eyes with abnormal corneal irregularity and HOAs were calculated. RESULTS: The median ages of PCG and control participants were 8.8 and 8.6 years, respectively. Irregularity and total HOAs across both 4 and 6 mm zones were greater in PCG than in control eyes. The median irregularity of PCG eyes was 2 to 5 times that of the controls, whereas, their median total HOAs were approximately twice those of the controls. Thirty-nine (64%), 53 (87%), and 40 (66%) PCG eyes had abnormal (either 4 or 6 mm zone) anterior irregularity, posterior irregularity, and total HOAs. Similar percentages were observed among eyes with a cup-to-disc ratio <0.6 (n=28). Among 13 eyes with cup-to-disc ratio <0.6 but abnormal 4 mm total corneal HOAs, 9 (69%) had BSCVA<20/25, whereas only 1 of 7 (14%) had BSCVA<20/25 among eyes with normal HOAs. CONCLUSIONS: Abnormal corneal irregularity and HOAs are common in PCG eyes, even in those with limited optic nerve damage. These abnormalities relate to compromised visual outcomes.

Effects of tear film dynamics on quality of vision.

The precorneal tear film is maintained by blinking and exhibits different phases in the tear cycle. The tear film serves as the most anterior surface of the eye and plays an important role as a first refractive component of the eye. Alterations in tear film dynamics may cause both vision-related and ocular surface-related symptoms. Although the optical quality associated with the tear film dynamics previously received little attention, objective measurements of optical quality using wavefront sensors have enabled us to quantify optical aberrations induced by the tear film. This has provided an objective method for assessing reduced optical quality in dry eye; thus, visual disturbances were included in the definition of dry eye disease in the 2007 Dry Eye Workshop report. In addition, sequential measurements of wavefront aberrations have provided us with valuable insights into the dynamic optical changes associated with tear film dynamics. This review will focus on the current knowledge of the mechanisms of wavefront variations that are caused by different aspects of tear film dynamics: specifically, quality, quantity and properties of the tear film, demonstrating the respective effects of dry eye, epiphora and instillation of eye drops on the quality of vision.

Influence of Sodium Hyaluronate Concentration on Corneal Aberrations in Soft Contact Lens Wearers.

PURPOSE: This study aimed to evaluate the influence of varying concentrations of sodium hyaluronate (SH) eye drops on corneal aberrations in normal individuals wearing silicone hydrogel contact lenses. METHODS: Normal individuals wearing silicone hydrogel contact lenses were enrolled in this study. Subjects were classified into two groups depending on the concentration of the preservative-free SH used (group 1, 0.1% SH; group 2, 0.3% SH). All subjects were asked to blink five times after instillation of the SH eye drop and before the Galilei measurements. Corneal aberrations were measured over the contact lenses before and after SH eye drop instillation. Visual acuity (VA) over the contact lenses was also measured both before instillation of the SH eye drop and after the subjects completed the five blinks. RESULTS: There was no change in VA after SH instillation in group 1; however, group 2's VA significantly deteriorated after SH instillation. Changes in VA after SH instillation compared to baseline were significantly higher in group 2 than in group 1. Similarly, the increase in corneal aberrations after SH instillation was significant in group 2 but not significant in group 1. Among the significantly increased corneal aberration parameters, defocus was the main type in group 2. Changes in corneal aberrations after SH instillation compared to baseline were significantly higher in group 2 than in group 1. CONCLUSIONS: A 0.3%-concentration of SH increases corneal aberration and decreases VA in soft contact lens wearers. Defocus is the main type of aberration that increased in the 0.3% SH instillation group.

Extended depth of focus contact lenses vs. two commercial multifocals: Part 1. Optical performance evaluation via computed through-focus retinal image quality metrics / Lentes de contacto de profundidad de foco extendido vs. dos lentes multifocales comerciales: Parte 1. Evaluación del rendimiento óptico del enfoque computarizado mediante métricas de calidad de imagen retinianas

Purpose: To compare the computed optical performance of prototype lenses designed using deliberate manipulation of higher-order spherical aberrations to extend depth-of-focus (EDOF) with two commercial multifocals. Methods: Emmetropic, presbyopic, schematic eyes were coupled with prototype EDOF and commercial multifocal lenses (Acuvue Oasys for presbyopia, AOP, Johnson & Johnson & Air Optix Aqua multifocal, AOMF, Alcon). For each test configuration, the through-focus retinal image quality (TFRIQ) values were computed over 21 vergences, ranging from -0.50 to 2.00 D, in 0.125 D steps. Analysis was performed considering eyes with three different inherent aberration profiles: five different pupils and five different lens decentration levels. Results: Except the LOW design, the AOP lenses offered ‘bifocal’ like TFRIQ performance. Lens performance was relatively independent to pupil and aberrations but not centration. Contrastingly, AOMF demonstrated distance centric performance, most dominant in LOW followed by MED and HIGH designs. AOMF lenses were the most sensitive to pupil, aberrations and centration. The prototypes demonstrated a ‘lift-off’ in the TFRIQ performance, particularly at intermediate and near, without trading performance at distance. When compared with AOP and AOMF, EDOF lenses demonstrated reduced sensitivity to pupil, aberrations and centration. Conclusion: With the through focus retinal image quality as the gauge of optical performance, we demonstrated that the prototype EDOF designs were less susceptible to variations in pupil, inherent ocular aberrations and decentration, compared to the commercial designs. To ascertain whether these incremental improvements translate to a clinically palpable outcome requires investigation through human trials (AU)

Objetivo: Comparar el rendimiento óptico computado de los prototipos de lentes de contacto diseñadas mediante manipulación deliberada de aberraciones esféricas de alto orden para conseguir la profundidad de foco extendida (EDOF) con dos lentes multifocales comerciales. Métodos: Se adaptaron lentes de contacto con prototipo EDOF, y lentes multifocales comerciales a ojos esquemáticos présbitas emétropes (Acuvue Oasys para presbicia, AOP, Johnson & Johnson & Air Optix Aqua multifocal, AOMF, Alcon). Para cada configuración de la prueba se obtuvieron los valores de la calidad de imagen de la retina a través del foco (TFRIQ) en 21 vergencias, que oscilaron entre -0,5 y 2D, en pasos de 0,125D. Se llevó a cabo el análisis considerando los ojos con tres perfiles de aberración diferentes: cinco pupilas diferentes y cinco niveles de descentramiento de lentes distintos. Resultados: Exceptuando el diseño LOW, las lentes AOP aportaron un rendimiento TFRIQ de tipo ‘bifocal’. El desempeño de las lentes fue relativamente independiente de la pupila y aberraciones, pero no del descentramiento. Por contra, AOMF demostró un rendimiento céntrico en visión lejana, más dominante en el diseño LOW, seguido de los diseños MED y HIGH. Las lentes AOMF fueron más sensibles a la pupila, aberraciones y centrado. Los prototipos demostraron un efecto de mejora en el rendimiento TFRIQ, particularmente en visión intermedia y próxima, sin pérdida de rendimiento en visión lejana. Al compararlas con las lentes AOP y AOMF, las lentes EDOF demostraron una reducción de la sensibilidad al factor pupila, las aberraciones y el centrado. Conclusión: Con la calidad de imagen de la retina a través del foco, como medida del rendimiento óptico, demostramos que los diseños del prototipo EDOF fueron menos susceptibles a las variaciones de la pupila, las aberraciones oculares inherentes, y al descentramiento, en comparación a los diseños comerciales. Se precisa más investigación futura, mediante ensayos en humanos, para verificar si estas mejoras incrementales se trasladan a resultados clínicamente evaluables (AU)

Visual Performance and Optical Quality of Standardized Asymmetric Soft Contact Lenses in Patients With Keratoconus.

Purpose: To evaluate the visual performance and optical quality of a standardized asymmetric soft contact lens (SCL) used for correction of higher-order aberrations (HOAs) in eyes with keratoconus. Methods: We included 30 eyes (26 patients) with keratoconus (average K: 45.7 ± 2.3 diopters [D]). The patients were subjected to corneal tomography, aberrometry, measurements of manifest refraction and visual acuity (VA), and visual analog scale (VAS) assessments. The study lenses were made using a molding method and consisted of six standardized types, in which an asymmetric power distribution of approximately 2 to 12 D (2-D step) was used to correct HOAs. The lens type suitable for each eye was selected based on the corneal tomography and aberrometry data. The on-eye performance of the lens was evaluated using aberrometry (4-mm pupil), over refraction, VA, and VAS. Results: The standardized asymmetric SCL improved the best spectacle-corrected VA from -0.07 ± 0.09 to -0.11 ± 0.08 logMAR (P < 0.05) and the mean VAS score from 66.2 ± 21.8 to 75.4 ± 20.5 (P < 0.05). Vertical coma decreased significantly (-0.50 ± 0.36 µm without SCL; -0.36 ± 0.34 µm with SCL; P < 0.01). In subgroup analysis, subjects in the high VAS group (score ≥ 75) accounted for 70% of all subjects, and this was the group in which the vertical coma decreased significantly from the level without the lens. Conclusions: A standardized asymmetric SCL can reduce HOAs and improve vision quality when compared with spectacles in patients with keratoconus who wear rigid gas-permeable lenses.

Post-LASIK Visual Quality With a Corneoscleral Contact Lens to Treat Irregular Corneas.

OBJECTIVE: To evaluate the visual quality results of fitting a corneoscleral contact lens with multiaspheric geometry design (MAGD CScL) in subjects with irregular corneas after laser-assisted in situ keratomileusis (LASIK) surgery. METHODS: From a database of patients evaluated for scleral contact lenses, we identified those with irregular corneas and visual problems after they underwent LASIK surgery for correcting myopia. They manifested unsatisfactory visual quality with their current contact lenses or glasses. Therefore, a MAGD CScL was fitted and monitored according to standardized fitting methodology. A diagnostic trial set was used in the fitting process. Visual acuity (VA), subjective visual quality (SVQ), and ocular aberrations were evaluated. A new re-evaluation of these parameters was performed after 1 year wearing MAGD CScL. RESULTS: Eighteen eyes of 18 patients (10 male and 8 female) with irregular cornea after LASIK surgery participated in this study; their ages ranged from 27 to 39 years (mean±SD, 32.6±3.8 years). All patients showed good fitting characteristics: optimal values were seen for lens position and lens movement. Statistically significant differences were found between before and after fitting MAGD CScL in the VA (mean±SD, 0.14±0.03 logMAR and 0.01±0.06 logMAR, respectively; P<0.001); ocular aberrations of second-order, coma, spherical; and the total higher-order aberrations (HOAs) (all P<0.001). The total HOAs decreased by approximately 78% to normal levels after fitting MAGD CScL. In addition, SVQ was also significantly improved after fitting MAGD CScL (16 eyes were favorable or very favorable). After 1 year wearing MAGD CScL, no statistically significant differences were found in the total HOAs and VA in regard to the initial fitting. CONCLUSIONS: Corneoscleral contact lens with multiaspheric geometry design is proposed as an effective procedure, providing a good VA and an optimal visual quality on irregular corneas after LASIK surgery in myopic subjects.

Use of Wavefront Imaging Technology to Demonstrate Improvement in Corneal Aberrations Using Piggyback Contact Lens in a Keratoconus Eye With Intrastromal Corneal Ring Segment Implantation: A Case Report.

OBJECTIVE: To quantify short-term changes in corneal high-order aberrations (HOA) with piggyback contact lens use in an eye with keratoconus that had undergone intrastromal ring segment (Intacs) implantation. METHODS: A patient with keratoconus reporting of distorted images after Intacs surgery was found to have HOA (trefoil, point spread function [PSF], and modulation transfer function [MTF]) as measured using wavefront technology (Nidek OPD-Scan III) and evidenced by her cylindrical correction. She underwent piggyback contact lens (silicone hydrogel and fluoroperm rigid gas-permeable lenses) fitting in an attempt to improve the HOA. RESULTS: After piggyback contact lens fitting, her visual acuity improved and all her visual symptoms resolved. High-order aberrations reduced from 3.152 to 0.490 after the lens fitting and was noted to be 0.447 at 6 months; trefoil also significantly improved (0.360-0.096; it was 0.031 at 6 months). The cylinder decreased from -4.50 to -0.75 and was stable at 6 months (-1.00). There was also significant improvement in PSF and MTF. CONCLUSIONS: Visual acuity and symptoms along with HOA and cylinder improved after fitting of piggyback contact lens in our patient with keratoconus who had undergone Intacs.

A Comparison of Three Methods to Increase Scleral Contact Lens On-Eye Stability.

PURPOSE: To quantify on-eye rotational and translational stability of three scleral contact lens stabilization methods and to model the variation in visual acuity when these movements occur in a wavefront-guided correction for highly aberrated eyes. METHODS: Three lens stabilization methods were integrated into the posterior periphery of a scleral contact lens designed at the Visual Optics Institute. For comparison, a lens with no stabilization method (rotationally symmetric posterior periphery) was designed. The lenses were manufactured and lens movements were quantified on 8 eyes as the average SD of the observed translations and rotations over 60 min of wear. In addition, the predicted changes in acuity for five eyes with keratoconus wearing a simulated wavefront-guided correction (full correction through the fifth order) were modeled using the measured movements. RESULTS: For each lens design, no significant differences in the translation and rotation were found between left and right eyes, and lenses behaved similarly on all subjects. All three designs with peripheral stability modifications exhibited no statistically significant differences in translation and rotation distributions of lens movement and were statistically more stable than the spherical lens in rotation. When the measured movements were used to simulate variation in visual performance, the 3 lenses with integrated stability methods showed a predicted average loss in acuity from the perfectly aligned condition of approximately 0.06 logMAR (3 letters), compared with the loss of over 0.14 logMAR (7 letters) for the lens with the spherical periphery. CONCLUSION: All three stabilization methods provided superior stability, as compared with the spherical lens design. Simulations of the optical and visual performance suggest that all three stabilization designs can provide desirable results when used in the delivery of a wavefront-guided correction for a highly aberrated eye.

Effects of optical blur reduction on equivalent intrinsic blur.

PURPOSE: To determine the effect of optical blur reduction on equivalent intrinsic blur, an estimate of the blur within the visual system, by comparing optical and equivalent intrinsic blur before and after adaptive optics (AO) correction of wavefront error. METHODS: Twelve visually normal subjects (mean [±SD] age, 31 [±12] years) participated in this study. Equivalent intrinsic blur (σint) was derived using a previously described model. Optical blur (σopt) caused by high-order aberrations was quantified by Shack-Hartmann aberrometry and minimized using AO correction of wavefront error. RESULTS: σopt and σint were significantly reduced and visual acuity was significantly improved after AO correction (p ≤ 0.004). Reductions in σopt and σint were linearly dependent on the values before AO correction (r ≥ 0.94, p ≤ 0.002). The reduction in σint was greater than the reduction in σopt, although it was marginally significant (p = 0.05). σint after AO correlated significantly with σint before AO (r = 0.92, p < 0.001), and the two parameters were related linearly with a slope of 0.46. CONCLUSIONS: Reduction in equivalent intrinsic blur was greater than the reduction in optical blur after AO correction of wavefront error. This finding implies that visual acuity in subjects with high equivalent intrinsic blur can be improved beyond that expected from the reduction in optical blur alone.

Wavefront-guided scleral lens correction in keratoconus.

PURPOSE: To examine the performance of state-of-the-art wavefront-guided scleral contact lenses (wfgSCLs) on a sample of keratoconic eyes, with emphasis on performance quantified with visual quality metrics, and to provide a detailed discussion of the process used to design, manufacture, and evaluate wfgSCLs. METHODS: Fourteen eyes of seven subjects with keratoconus were enrolled and a wfgSCL was designed for each eye. High-contrast visual acuity and visual quality metrics were used to assess the on-eye performance of the lenses. RESULTS: The wfgSCL provided statistically lower levels of both lower-order root mean square (RMS) (p < 0.001) and higher-order RMS (HORMS) (p < 0.02) than an intermediate spherical equivalent scleral contact lens. The wfgSCL provided lower levels of lower-order RMS than a normal group of well-corrected observers (p << 0.001). However, the wfgSCL does not provide less HORMS than the normal group (p = 0.41). Of the 14 eyes studied, 10 successfully reached the exit criteria, achieving residual HORMS wavefront error less than or within 1 SD of the levels experienced by normal, age-matched subjects. In addition, measures of visual image quality (logVSX, logNS, and logLIB) for the 10 eyes were well distributed within the range of values seen in normal eyes. However, visual performance as measured by high-contrast acuity did not reach normal, age-matched levels, which is in agreement with prior results associated with the acute application of wavefront correction to keratoconic eyes. CONCLUSIONS: Wavefront-guided scleral contact lenses are capable of optically compensating for the deleterious effects of higher-order aberration concomitant with the disease and can provide visual image quality equivalent to that seen in normal eyes. Longer-duration studies are needed to assess whether the visual system of the highly aberrated eye wearing a wfgSCL is capable of producing visual performance levels typical of the normal population.

Corneal reshaping and wavefront aberrations during overnight orthokeratology.

PURPOSE: To investigate changes of corneal thickness at the vertical and horizontal meridians and of wavefront aberrations (WA) over a 30-day period of overnight myopia orthokeratology (OK) lens wear. METHODS: Sixteen subjects (11 women, 5 men, 26.3±3.2 years) were enrolled and fitted for OK lenses. Long scan depth optical coherence tomography was used to measure corneal thickness profiles at both horizontal and vertical meridians at baseline and on days 1, 7, and 30 days. Corneal and ocular WA of a 6-mm pupil were measured and the root-mean-square (RMS) of the astigmatism, coma, spherical aberration (SA), and total higher-order aberrations (HOAs) were determined. RESULTS: During the 30-day period, the central cornea thinned in the horizontal and vertical meridians, whereas corneal thickening occurred in the temporal, nasal, and inferior mid-peripheries. In contrast, the cornea thinned in the mid-peripheral superior. There were significant increases in RMS for astigmatism, SA, coma, and positive horizontal coma during the study period. After OK, there were significant positive correlations between the midperipheral-central thickness change difference and the changes in corneal and ocular RMS of total HOAs and SA (r range: 0.281 to 0.492, P<0.05). Only the change of corneal coma RMS was correlated with midperipheral-central thickness change difference (r=0.270, P<0.05). The change in corneal horizontal coma was correlated with the temporal-nasal thickness change difference (r=-0.289, P<0.05). CONCLUSIONS: Overnight OK caused unique changes in corneal thickness profiles at the vertical and horizontal meridians and increased corneal and ocular HOAs related to corneal reshaping.

Contrast sensitivity function after correcting residual wavefront aberrations during RGP lens wear.

PURPOSE: To investigate the effect on the contrast sensitivity function (CSF) of correcting the residual wavefront aberrations in myopic and keratoconic subjects wearing rigid gas permeable (RGP) contact lenses. METHODS: Seventeen eyes of 16 myopic subjects and 20 eyes of 19 keratoconic subjects were included in this study. All eyes were habitually corrected with RGP lenses. The residual aberrations of the RGP lens-wearing eyes were compensated by an adaptive optics (AO) system. The contrast sensitivities were measured through a 4-mm artificial pupil at spatial frequencies of 2, 4, 8, 16, and 32 cycles per degree (cpd) during RGP lens wear for the myopic and keratoconic groups, respectively. The CSF measurements were repeated with and without AO correction. Comparisons of contrast sensitivity at all spatial frequencies with and without AO correction were performed respectively for the myopic and keratoconic groups during RGP lens wear. RESULTS: In the myopic RGP lens-wearing group, the differences in contrast sensitivity at each spatial frequency, with and without AO correction, were not significant (all p values > 0.05). In the keratoconic RGP lens-wearing group, the contrast sensitivities at all spatial frequencies with AO correction were higher than those without AO correction, but differences only at the low (2 cpd) and intermediate (4, 8, and 16 cpd) spatial frequencies were significant (p = 0.039, 0.005, 0.001, and 0.007). CONCLUSIONS: The residual aberrations significantly reduced the contrast sensitivities at low and intermediate spatial frequencies for keratoconic RGP lens-wearing eyes but did not have any effect on the CSF for the myopic RGP lens-wearing eyes. Developing techniques that could more completely correct the wavefront aberrations may improve visual performance in keratoconus.

Wavefront error correction with adaptive optics in diabetic retinopathy.

PURPOSE: To determine the effects of diabetic retinopathy (DR), increased foveal thickness (FT), and adaptive optics (AO) on wavefront aberrations and Shack-Hartmann (SH) image quality. METHODS: Shack-Hartmann aberrometry and wavefront error correction were performed with a bench-top AO retinal imaging system in 10 healthy control and 19 DR subjects. Spectral domain optical coherence tomography was performed and central FT was measured. Based on the FT data in the control group, subjects in the DR group were categorized into two subgroups: those with normal FT and those with increased FT. Shack-Hartmann image quality was assessed based on spot areas, and high-order (HO) root mean square (RMS) and total RMS were calculated. RESULTS: There was a significant effect of DR on HO and total RMS (p = 0.01), and RMS decreased significantly after AO correction (p < 0.001). Shack-Hartmann spot area was significantly affected by DR (p < 0.001), but it did not change after AO correction (p = 0.6). High-order RMS, total RMS, and SH spot area were higher in DR subjects both before and after AO correction. In DR subgroups, HO and total RMS decreased significantly after AO correction (p < 0.001), whereas the effect of increased FT on HO and total RMS was not significant (p ≥ 0.7). There were no significant effects of increased FT and AO on SH spot area (p = 0.9). CONCLUSIONS: Diabetic retinopathy subjects had higher wavefront aberrations and less compact SH spots, likely attributable to pathological changes in the ocular optics. Wavefront aberrations were significantly reduced by AO, although AO performance was suboptimal in DR subjects as compared with control subjects.