Changes In Optical Quality Research Articles

Optical quality changes of the eye during peak SARS-CoV-2 pandemic in young adults

IntroductionTo determine whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection affects corneal morphology and optical quality. MethodsIn this cross-sectional study, ophthalmological indicators were examined during the peak of SARS-CoV-2 infection after adjusting for public health control measures. Participants were divided into control (remained uninfected), A (infected during follow-up), and B (infected prior to the first consultation) groups. Effects of varying SARS-CoV-2 infection levels were determined using reverse transcription polymerase chain reaction. Changes in corneal morphology, backscatter, and aberrations were measured. Corneal parameters, such as flat keratometry, steep keratometry, and surface variance, vertical asymmetry, height asymmetry, and height decentration indices were considered. ResultsOverall, 110 participants (208 eyes, 42.7% male; age 17–31 years) were enrolled. Eighteen (16.3%) were infection-free during the outbreak with unchanged corneal morphology, backscatter, and aberration. In group A, 34.73 ± 9.30 days after infection, the backscatter of the anterior corneal layer and central layer (both p=0.000) decreased. Total low-order aberration, defocus, horizontal coma, and spherical aberration of the cornea increased (p<0.05), while corneal morphology after infection did not change (p>0.05). In group B, a decrease in backscattering in the corneal middle layer and an increase in horizontal coma (p<0.05) were noted. ConclusionBackscattering of the anterior and intermediate layers of the cornea decreased and corneal aberrations increased after SARS-CoV-2 infection, which affected corneal optical quality. However, corneal morphology and thickness remained unchanged. Ophthalmological indicators and optical quality should be monitored during SARS-CoV-2 infection.

Suprathreshold contrast perception of resolvable high spatial frequencies remain intact in keratoconus

Contrast detection thresholds are elevated with optical quality loss in keratoconus. This study hypothesized that suprathreshold contrast perception is also impaired in keratoconus, with the impairment being predictable from the pattern of loss in threshold-level performance. Contrast detection thresholds were determined across a range of spatial frequencies in 12 cases with mild to severe keratoconus and 12 age-similar controls. These values were used to predict the contrast needed to achieve perceptual matches between reference and test spatial frequency pairs (peak of CSF Vs. 0.3x, 0.5x, 2x or 3x spatial frequency from the peak) for stimuli at 10% and 50% suprathreshold contrast. Contrast thresholds predicted a 1.5 to 6.7-fold increase in the test pattern’s contrast to obtain a perceptual match with the reference pattern in keratoconus, relative to controls. Contrary to predictions, the empirical data of contrast matches between test and reference patterns were similar for higher than peak spatial frequencies at both contrast levels. However, as predicted, test patterns required higher contrast than the reference pattern for a perceptual match for lower than peak spatial frequencies. These results were similar to controls and invariant of disease severity, interocular asymmetry and short-term changes in optical quality. Unlike thresholds, suprathreshold contrast perception of resolvable high spatial frequencies appears immune to optical quality losses in keratoconus. These results are discussed in the context of the prevailing models of contrast constancy in healthy humans. Breakdown of contrast constancy at lower than peak spatial frequencies may reflect the properties of the testing paradigm employed here.

The effect of orthokeratology lenses on optical quality and visual function in children.

To assess changes in optical quality and visual function in children after 3 months of wearing orthokeratology (OK) lenses. A total of 25 myopic children aged 8-12 years were recruited and completed the follow-up study. Optical quality, visual function and corneal morphology were assessed at baseline and at follow-ups 1 and 3 months after wearing OK lenses. Optical quality parameters mainly included the modulation transfer function (MTF) cutoff, objective scattering index (OSI), Strehl ratio (SR) and the predicted visual acuities (PVAs). Visual function was assessed by visual acuity, monocular contrast sensitivity function (CSF) across five spatial frequencies and the area under the log contrast sensitivity function (AULCSF) that was also computed as an index for overall CSF. The MTF cutoff and SR values both increased after 1 month of wearing the OK lenses (baseline vs. 1 month: P MTF = 0.008 and P SR = 0.049); this improvement plateaued after 3 months of lens wear (1 month vs. 3 months: P MTF = 0.626, P SR = 0.428). The corneal morphology also showed the similar change trend. The OSI showed the opposite change trend (baseline vs. 1 month: P OSI < 0.001; 1 month vs. 3 months: P OSI = 0.720). The mean CSF at 1.5 cpd decreased significantly after 1 month of wearing the lenses (baseline vs. 1 month: p = 0.001) and recovered after 3 months of lens wear (baseline vs. 3 months: p = 0.076). CSF at spatial frequencies of 3, 6, 12 and 18 cpd as well as the AULCSF did not significantly differ between any two timepoints (all Ps > 0.05). After 3 months of wearing OK lenses, the subjects exhibited a decrease in optical quality, similar to corneal morphology, whereas their visual function remained largely unchanged. Thus, the optical quality was more susceptible to OK lenses than visual function in children. The initial month of OK treatment of children is a key period to be paid close attention to deterioration of optical quality and visual function.

Optical Quality Variation of Different Intraocular Lens Designs in a Model Eye: Lens Placed Correctly and in an Upside-Down Position

Introduction: Intraocular lenses (IOLs) may lose their optical quality if they are not correctly placed inside the capsular bag once implanted. One possible malpositioning of the IOL could be the implantation in an upside-down position. In this work, three aspheric IOLs with different spherical aberration (SA) have been designed and numerically tested to analyse the optical quality variation with the IOL flip, and misalignments, using a theoretical model eye. Methods: Using the commercial optical design software OSLO, the effect of decentration and tilt was evaluated by numerical ray tracing in two conditions: in their designed position and flipped with respect to the planned position (IOL is implanted upside down). The theoretical model eye used was the Atchison model eye. Seven IOL designs of +27.00 diopters were used: a lens with negative SA to correct the corneal SA, a lens to partially correct the corneal SA, and a lens to not add any SA to the cornea (aberration-free IOL). These lenses were designed with the aspherical surface located on the anterior and posterior IOL surface. A lens with no aspherical surfaces was also included. For the optical quality analysis, the modulation transfer function (MTF) was used, together with the Zernike wavefront aberration coefficients of defocus, astigmatism, and primary coma. Results: Off-centring and tilting the IOL reduced overall MTF values and increased wavefront aberration errors. With the IOL correctly positioned within the capsular bag, an aberration-free IOL is the best choice for maintaining optical quality. When the IOL is flipped inside the capsular bag, the optical quality changes, with the aberration-free IOL and the IOL without aspheric surfaces providing the worst results. With the lens in an upside-down position, an IOL design to partially correct corneal SA shows the best optical quality results in decentration and tilt, in terms of MTF and wavefront aberrations. Conclusion: The aberration-free IOL is the best choice when minimal postoperative errors of decentration or tilt are predicted. With IOL flip, the negative SA lens design is the best choice, regarding the root mean square wavefront aberrations. However, in a proper IOL implantation, the IOL designed to partially compensate the corneal SA including asphericity on its posterior surface is the better possible option, even in the presence of decentration or tilt.

Physiological Mechanisms Regulating Lens Transport.

The transparency and refractive properties of the lens are maintained by the cellular physiology provided by an internal microcirculation system that utilizes spatial differences in ion channels, transporters and gap junctions to establish standing electrochemical and hydrostatic pressure gradients that drive the transport of ions, water and nutrients through this avascular tissue. Aging has negative effects on lens transport, degrading ion and water homeostasis, and producing changes in lens water content. This alters the properties of the lens, causing changes in optical quality and accommodative amplitude that initially result in presbyopia in middle age and ultimately manifest as cataract in the elderly. Recent advances have highlighted that the lens hydrostatic pressure gradient responds to tension transmitted to the lens through the Zonules of Zinn through a mechanism utilizing mechanosensitive channels, multiple sodium transporters respond to changes in hydrostatic pressure to restore equilibrium, and that connexin hemichannels and diverse intracellular signaling cascades play a critical role in these responses. The mechanistic insight gained from these studies has advanced our understanding of lens transport and how it responds and adapts to different inputs both from within the lens, and from surrounding ocular structures.

Five-Year Follow-Up of Visual Outcomes and Optical Quality After Small Incision Lenticule Extraction for Moderate and High Myopia.

IntroductionThis study investigated the long-term visual and optical quality changes after small incision lenticule extraction (SMILE) for the correction of moderate to high myopia.MethodsForty-one eyes of 41 patients with a mean spherical equivalent (SE) of − 6.74 ± 1.45 D undergoing SMILE were enrolled. Preoperative and 1-month, 3-month, 1-year and 5-year postoperative follow-up examinations were performed including visual acuity, manifest refraction, corneal aberrations and contrast sensitivity. An optical quality analysis system was used to measure objective scatter index (OSI), Strehl ratio (SR) and modulation transfer function cutoff frequency (MTFcutoff).ResultsThe safety and efficacy indices were 1.09 ± 0.12 and 1.03 ± 0.17, respectively, at the 5-year follow-up. No significant changes in SE from 1 month to 5 years postoperatively were found. The OSI significantly increased at 1 and 3 months postoperatively (p < 0.01 and p < 0.01) and declined at 1 and 5 years (p = 0.81 and p = 0.87). MTFcutoff and SR showed similar trends. Coma, spherical aberration and total higher-order aberration significantly increased after SMILE (p < 0.01) and remained stable from 1 month to 5 years after surgery (p > 0.05). Contrast sensitivity in the photopic and mesopic condition showed no significant changes during 5-year follow-up (p > 0.05).ConclusionThe SMILE procedure is satisfactory in terms of optical quality for correcting moderate and high myopia in the long-term period.Trial RegistrationChiCTR-ONRC-13003114.

Time Course of Perceived Visual Distortion and Axial Length Growth in Myopic Children Undergoing Orthokeratology

Purpose: To establish the time course of the subjective visual function changes during the first month of orthokeratology treatment in myopic children, and to investigate how the time course variations are associated with the objective optical quality changes and the axial length growth (ALG) after 1 year of treatment.Methods: A total of 58 myopic children aged from 8 to 16 years participated in this self-controlled prospective study. All subjects were fitted with designed spherical four-zone orthokeratology lenses. Subjective visual function was evaluated with orientation discrimination threshold (ODT), and objective optical quality was quantified with the high-order aberration root-mean-square (HOA-RMS) and the changing speed of HOA. The measurements were done before the lens fitting and 1 day, 1-, 2-, and 4-weeks after lens wear. Axial length was obtained at baseline and 1-year follow-up, and ALG was defined as the difference. One-way ANOVA was conducted to compare the difference for statistical analysis.Results: After lens fitting, the ODT time courses peaked on day 1 in 28 children, 1 week in 15 children, 2 weeks in 11 children, and 4 weeks in 4 children. In contrast, the HOA-RMS steadily rose during the first month, and the changing speed of HOA was only transiently elevated on day 1 after the initial lens wear. The ALG was 0.12 ± 0.20 mm in subjects whose ODT peaked at day 1, 0.08 ± 0.09 mm in subjects whose ODT peaked on 1-week, and 0.12 ± 0.15 mm in subjects whose ODT peaked on 2-week or later. There was no difference in axial growth among the subjects whose ODT peaked at different days (P = 0.734).Conclusion: While half ODT time course resembled the changing speed of HOA with a transient elevation on day 1, about a quarter of the ODT time course resemble the steadily rising of HOA-RMS, and the rest was located in the middle. The ALGs in children with different types of ODT time courses were similar.

Changes in Optical Quality Induced by Tilt and Decentration of a Trifocal IOL and a Novel Extended Depth of Focus IOL in Eyes With Corneal Myopic Ablations.

To assess the effect of decentration and tilt combined with prior myopic ablations on the optical performance of a trifocal intraocular lens (IOL) and a novel IOL with an extended depth of focus (EDOF) design. The XACT Mono-EDOF ME4 (Santen Pharmaceutical Co Ltd) and the trifocal FineVision (PhysIOL) IOLs were analyzed with and without simulated previous myopic ablations. The optical quality of the IOLs was evaluated with the PMTF optical bench (LAMBDA-X). The through-focus modulation transfer function (MTF) curves were recorded. Measurements were done for three situations: centered, 0.4 mm decentered, and 4 degrees tilted. The trifocal IOL showed three peaks of vision and the EDOF IOL showed a far distance peak with intermediate addition. When decentration or tilt were induced, the trifocal IOL showed negligible changes but the EDOF IOL showed a -0.50 diopters (D) shift of the overall curve. With simulated myopic ablation, the trifocal IOL showed a -0.50 D shift of the curve. When tilt or decentration were also induced, the better optical results were found at -1.00 D. With myopic ablations, the EDOF IOL showed a -0.50 D shift of the optical quality and when decentration or tilt were then induced, negative shifts over -1.00 D were found. The trifocal IOL was less affected by mis-alignments. When myopic ablations were induced, both lenses decreased their optical quality and the effects of misalignments were higher. In patients who have undergone corneal myopic ablation procedures, proper alignment of the implanted IOL and obtaining effective emmetropia becomes even more critical. [J Refract Surg. 2021;37(8):532-537.].

Structural and Optical Properties of InAsSbBi Grown by Molecular Beam Epitaxy on Offcut GaSb Substrates

Three InAsSbBi samples are grown by molecular beam epitaxy at 400 °C on GaSb substrates with three different offcuts: (100) on-axis, (100) offcut 1° toward [011], and (100) offcut 4° toward [011]. The samples are investigated using X-ray diffraction, Nomarski optical microscopy, atomic force microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The InAsSbBi layers are 210 nm thick, coherently strained, and show no observable defects. The substrate offcut is not observed to influence the structural and interface quality of the samples. Each sample exhibits small lateral variations in the Bi mole fraction, with the largest variation observed in the on-axis growth. Bismuth rich surface droplet features are observed on all samples. The surface droplets are isotropic on the on-axis sample and elongated along the [011¯] step edges on the 1° and 4° offcut samples. No significant change in optical quality with offcut angle is observed.

Optical quality in patients with dry eye before and after treatment

ABSTRACT Clinical relevance Dry eye disease could result in vision‐related subjective symptoms even in patients with good best‐corrected visual acuity. The standard deviation of corneal power and the surface asymmetry index could be indicators of treatment efficacy in dry eye. Background Few studies have examined changes in optical quality before and after dry eye treatment. Here, we evaluated changes in optical quality in patients with dry eye before and after treatment and identified potential indicators of dry eye‐treatment efficacy. Methods Twenty‐five right eyes of 25 untreated patients with dry eye were included. The same ocular‐surface and optical‐quality examinations were performed before and after two-weeks of treatment with hyaluronate in conjunction with fluorometholone eye drops. The Ocular Surface Disease Index, tear film break‐up time, and corneal fluorescein staining were measured. Contrast sensitivity was used to measure resolution capability, the double‐pass Optical Quality Analysis System to examine the modulation transfer function, Strehl ratio, and objective scattering index, and OPD Scan III to measure anterior corneal aberrations over 4-mm analytical zones including total corneal and high‐order aberrations. The standard deviation of corneal power, surface regularity index, and surface asymmetry index were also measured. Paired sample t‐tests and Spearman’s correlations were used for the analyses. Results The Ocular Surface Disease Index, tear film break‐up time, and corneal fluorescein staining improved after two weeks of treatment. Contrast sensitivity in photopic, photopic with glare, scotopic, and scotopic with glare conditions all improved (p < 0.05), as did the modulation transfer function, Strehl ratio, and objective scattering index (p = 0.001, p = 0.008, and p = 0.001, respectively). Total corneal aberrations and the surface regularity index did not significantly differ before and after treatment; corneal high‐order aberrations, standard deviation of corneal power, and the surface asymmetry index significantly improved after treatment (p = 0.045, p = 0.019, and p = 0.049, respectively). Changes in standard deviation of corneal power and in surface asymmetry index correlated with change in corneal fluorescein staining (p = 0.006 and p = 0.007, respectively). Conclusion Optical quality in patients with dry eye improved after treatment. The standard deviation of corneal power and surface asymmetry index could be indicators of treatment efficacy in dry eye.

Longitudinal Changes in Optical Quality, Spatial Vision, and Depth Vision after Laser Refractive Surgery for Myopia.

Laser refractive surgery procedures are efficacious at correcting myopia, but they result in long-term deterioration of optical quality that affects monocular and binocular visual performance. The study shows that the optical quality of the two eyes needs to be similar to optimize binocular visual performance after surgery. This study aimed to systematically analyze longitudinal changes in optical quality, high- and low-contrast logMAR acuity and random-dot stereoacuity before and after three refractive surgery procedures for correcting myopia. A total of 106 subjects (laser-assisted in situ keratomileusis, 40; photorefractive keratectomy, 26; small-incision lenticule extraction, 40) with myopia and astigmatism ≤1.5 D participated in this prospective cohort-based study. All aforementioned outcome variables were measured in both eyes pre-operatively and 1 week and 1, 3, and 6 months post-operatively. Pre-operative myopic spherical equivalent of refraction (median [25th to 75th interquartile range], -6.4 D [-8.0 to -4.2 D] for laser-assisted in situ keratomileusis, -4.3 D [-5.0 to -3.5 D] for photorefractive keratectomy, -5.5 D [-6.5 to -4.3 D] for small-incision lenticule extraction) was corrected to within ±0.75 D of emmetropia in all cohorts up to 6 months post-operatively (P < .001). Higher-order wavefront aberrations, uncorrected high- and low-contrast logMAR acuity, and stereoacuity all worsened and remained so up to 6 months post-operatively, relative to pre-operative values (P < .001). Stereoacuity worsened with both interocular average and difference in the magnitude of higher-order aberrations, whereas logMAR acuities worsened only with interocular average of these aberrations (r ≥ 0.40; P < .01 for all). Although the refractive surgery procedures tested here correct myopia, they result in a sustained (up to 6 months) loss of optical quality and spatial and depth-related visual functions post-operatively. Both interocular average and difference in the eye's optical quality seem to impair binocular visual functions after refractive surgery for myopia.

Objective optical assessment of tear-film quality dynamics in patients with meibomian gland dysfunction and aqueous-deficient dry eye optical quality changes in different dry eye subtypes.

Purpose:To evaluate the optical quality and tear-film dynamics in patients with aqueous-deficient or evaporative subtype of dry eye disease (DED).Methods:Twenty-five aqueous-deficient dry eye (ADDE) patients, 25 DED patients with meibomian gland dysfunction (MGD), and 25 healthy subjects were included in this study. Vision-related health-targeted quality of life was evaluated using the Ocular Surface Disease Index (OSDI) questionnaire. Dynamic recording with a double-pass system (Optical Quality Analysis System [OQAS]) was performed in right eyes. Scattered light was measured as the objective scatter index (OSI) at 0.5-second intervals over 20 seconds without blinking. Then, we recorded OSI every 0.5 seconds within a 20-second period with the subjects asked to blink freely. Several parameters were established to evaluate the dynamic alterations of optical quality and the effects of blinks: OSI, OSI standard deviation (SD), ΔOSI, ΔOSI/time, blinking change (BC), and blinking frequency (BF). Additional clinical examination included tear film break-up time (BUT), Schirmer I test (SIT), fluorescein staining grade (FL), meibomian gland quality, meibomian gland expressibility, and meibomian gland drop-out.Results:The OSI, SD, ΔOSI, ΔOSI/time, BC, and BF were significantly higher in DED patients than controls (P < 0.01, respectively). The OSI, SD, ΔOSI, ΔOSI/time, BC, and BF were significantly higher in patients with MGD than patients with ADDE (P < 0.01). In the MGD group, BUT, FL staining score, lid abnormality, meibomian gland expressibility, and meibomian gland drop-out were correlated with Δ OSI and Δ OSI/time.Conclusion:Dry eye patients with MGD had significant alterations of optical quality compared with ADDE patients. The double-pass system has potential to be a useful quantitative method to evaluate the optical quality and tear-film dynamics in patients with dry eye.

Long-Term Changes in Backscattered Light Measurements in Keratoconus Corneas Treated with Collagen Cross-Linking

ABSTRACTPurpose: Our aim was to compare densitometry data between keratoconus and normal corneas and to assess the long-term changes in corneal backscattered light values after corneal collagen cross-linking (CXL) treatment.Material and methods: Retrospective analysis was performed on 26 eyes of normal patients (age: 32.71 ± 12.68 years) and 39 eyes of keratoconus patients (28.93 ± 7.59 years) using the Pentacam HR corneal densitometry module before CXL and during the postoperative period, which lasted a mean of 2.53 years (range: 1–4 years). Corneal backscattered light values in grey scale unit (GSU) were recorded for the anterior 120 µm, the center layer, and the posterior 60 µm of the cornea in four concentric, central rings. An additional calculation was performed with converting GSU values to GSU/cubic millimeters (mm3) with surface area calculations and using corneal thickness data.Results: Statistically significant differences were observed between normal and keratoconus group densitometry values (in GSU/mm3) in all annuli of the center layer; all, but anterior layer of the 10–12 annuli; all annuli of the total thickness and in all values of the total diameter. In all these cases, the normal cornea showed higher GSU/mm3 values compared to keratoconus corneas (p < 0.05). One month after the CXL treatment, the GSU/mm3 data increased significantly in the anterior, the center, and the posterior zone (p < 0.05), followed by its slow decrease. At the end of the follow-up period, the GSU/mm3 values were significantly higher in all three zones compared to those before the CXL treatment (p < 0.01).Conclusion: Densitometry measurements can reflect the changes of optical quality of the cornea. These measurements may play a valuable role in assessing keratoconus and optical changes of the corneas after CXL treatment.

Overview of Objective Methods for Assessing Dynamic Changes in Optical Quality.

Quality of vision has been emphasized in ophthalmologic clinical practice in recent years. The optical or visual performance of the human eye is not static and fluctuates over time. Considering the major origins of temporal fluctuations in optical or visual performance, quantitative assessment of the dynamic changes in the optical quality of the entire eye is important. This review provides an overview of the clinical application of the objective methods for assessing dynamic changes in optical quality, particularly those associated with accommodation, the precorneal tear film, the prelens tear film, and contact lens movement and fitting.

Objective optical quality analysis using double-pass technique in pterygium surgery.

To analyze objective optical quality changes after pterygium surgical excision using the Optical Quality Analysis System. Forty eyes with primary pterygium suitable for surgical treatment were included. Uncorrected distance visual acuity, corrected distance visual acuity (CDVA), objective scattering index (OSI), and cutoff frequency of the modulation transfer function (MTFcutoff) were recorded preoperatively and at 1 and 6 months postoperatively. Slit-lamp measurement of pterygium size was performed to classify them: small in group 1 and medium size/large in group 2. A paired comparative study of all data that included preoperative with 1-month results (comparison A), preoperative with 6-month results (comparison B), and 1 month with sixth-month results (comparison C) was performed. In global analysis, uncorrected distance visual acuity and OSI showed significant changes in comparison A, all parameters in comparison B, and CDVA, OSI, and MTFcutoff in comparison C. When subdividing into groups, in group 1, there was significant improvement between preoperative uncorrected distance visual acuity value and those at 1 and 6 months. Significant improvement in CDVA, OSI, and MTFcutoff values were observed in comparisons B and C. In group 2, MTFcutoff values significantly improved in comparisons B and C. The comparison of mean values between each group at each evaluation showed a lower value for MTFcutoff at 1 month after surgery. A comparative analysis of the evolution between both groups based on pterygium size did not reveal significant differences. Pterygium can undermine visual quality, and its excision provides significant improvement even at 6 months after surgery. Optical Quality Analysis System proved useful for postoperative outcomes.

Longitudinal Assessment of Optical Quality and Intraocular Scattering Using the Double-Pass Instrument in Normal Eyes and Eyes with Short Tear Breakup Time

PurposeTo assess the longitudinal changes in optical quality including intraocular scattering in normal eyes and eyes with short tear breakup time (TBUT).MethodsWe prospectively examined twenty eyes of 20 healthy subjects, and age-matched twenty eyes of 20 short TBUT subjects. The modulation transfer function (MTF) cutoff frequency, the Strehl ratio, and the objective scattering index (OSI) were quantitatively assessed using an Optical Quality Analysis System. We investigated the changes in these variables measured consecutively at the initial examination, 5, and 10 seconds without blinking. We also compared these variables in eyes with short TBUT with those in normal eyes.ResultsNo significant differences in the MTF cutoff frequency, Strehl ratio, or OSI were detected over a 10-second period in normal eyes. These variables also became significantly degraded even over a 5-second period in eyes with short TBUT (p<0.01). We found significant differences in these variables at 5 and 10 seconds (p<0.05), but none immediately after the blink between normal and short TBUT eyes.ConclusionsOptical quality including intraocular scattering deteriorated significantly with time in eyes with short TBUT, whereas we found significant differences over a 10-second period in normal eyes. Eyes with short TBUT showed greater deterioration in optical quality after the blink than normal eyes. The longitudinal assessment of optical quality may be effective in distinguishing eyes with short TBUT from normal eyes.

Change in visual acuity is well correlated with change in image-quality metrics for both normal and keratoconic wavefront errors.

We determined the degree to which change in visual acuity (VA) correlates with change in optical quality using image-quality (IQ) metrics for both normal and keratoconic wavefront errors (WFEs). VA was recorded for five normal subjects reading simulated, logMAR acuity charts generated from the scaled WFEs of 15 normal and seven keratoconic eyes. We examined the correlations over a large range of acuity loss (up to 11 lines) and a smaller, more clinically relevant range (up to four lines). Nine IQ metrics were well correlated for both ranges. Over the smaller range of primary interest, eight were also accurate and precise in estimating the variations in logMAR acuity in both normal and keratoconic WFEs. The accuracy for these eight best metrics in estimating the mean change in logMAR acuity ranged between ±0.0065 to ±0.017 logMAR (all less than one letter), and the precision ranged between ±0.10 to ±0.14 logMAR (all less than seven letters).

The 2012 Charles Prentice medal lecture: wavefront measurement of refractive state.

Modern efforts to define and measure the refractive state of aberrated eyes have led to new insights about the nature of refractive error, the quality of the retinal image, the interplay of the crystalline lens, and the eye's pupil during accommodation. Our change in mind-set engendered by wavefront concepts has the power to alter our way of thinking about many clinical issues that are fundamentally optical in nature, such as dynamic changes in optical quality of eyes caused by tear film deterioration, outcome assessment of refractive therapies, and myopia progression. The aim of this lecture is to help make advances in these areas of optometric science broadly accessible to educators, clinicians, and patients by explaining in simple terms the underlying optical concepts of wavefront aberrometry.

Factors Accounting for the 4-Year Change in Acuity in Patients Between 50 and 80 Years

It is well known that acuity slowly decreases in the later decades of life. We wish to determine the extent by which 4-year longitudinal acuity changes can be accounted for by changes in optical quality, or combination of optical quality metrics and of age between 50 and 80 years. High-contrast logMAR acuity, 35 image quality metrics, 4 intraocular scatter metrics, and 4 Lens Opacification Classification System III metrics and entry age were measured on one eye of each of the 148 subjects. Acuity change between baseline and the last visit was regressed against change in each metric for all eyes and a faster changing subset of 50 eyes with a gain or loss of four or more letters. Average change across 148 subjects was a 1.6 ± 4 letter loss (t148 = 4.31, p < 0.001) and loss for the faster changing subset was 3.4 ± 6.1 letters (t50 = 2.73, p = 0.008). The multiple-regression model for faster changing eyes included change in point spread function entropy, posterior subcapsular cataract, and trefoil and baseline age (sequential r adjusted values of 0.19, 0.27, 0.32, and 0.34, respectively; p = 1.48 × 10 for the full four-factor model). The same variables entered the multiple-regression model for the full 148 data set where most of the acuity measurements were within test-retest error and accounted for less of the variance (r adjusted = 0.15, p = 2.37 × 10). Despite being near noise levels for the measurement of acuity, change in optical quality metrics was the most important factor in eyes that lost or gained four or more letters of acuity. These findings should be generalizable given that our 4-year acuity change is essentially identical to other studies and indicate that these optical quality markers can be used to help identify those on a faster track to an acuity change.

Changes in Optical Quality of Cataract Patients' Corrected Visual Acuity before and after Phacoemulsification

Changes in Optical Quality of Cataract Patients' Corrected Visual Acuity before and after Phacoemulsification