Measuring visual acuity and spherical refraction with smartphone screens emitting blue light

Introduction A periodical self-monitoring of spherical refraction using smartphones may potentially allow a quicker intervention by eye care professionals to reduce myopia progression. Unfortunately, at low levels of myopia, the far point (FP) can be located far away from the eye which can make interactions with the device difficult. To partially remedy this issue, a novel method is proposed and tested wherein the longitudinal chromatic aberration (LCA) of blue light is leveraged to optically bring the FP closer to the eye. Methods Firstly, LCA was obtained by measuring spherical refraction subjectively using blue pixels in stimuli shown on organic light-emitting diode (OLED) screens and also grey stimuli with matching luminance. Secondly, the visual acuity (VA) measured with a smartphone located at 1.0 m and 1.5 m and displaying blue optotypes was compared with that obtained clinically standard measurements. Finally, the spherical over refraction obtained in blue light with a smartphone was compared with clinical over-refraction with black and white (B&W) optotypes placed at 6 m. Results Mean LCA of blue OLED smartphone screens was −0.67 ± 0.11 D. No significant differences (p > 0.05) were found between the VA measured with blue optotypes on a smartphone screen and an eye chart. Mean difference between spherical over-refraction measured subjectively by experienced subjects with smartphones and the one obtained clinically was 0.08 ± 0.34 D. Conclusions Smartphones using blue light can be used as a tool to detect changes in visual acuity and spherical refraction and facilitate monitoring of myopia progression. (AU)

Measuring visual acuity and spherical refraction with smartphone screens emitting blue light.

INTRODUCTION: A periodical self-monitoring of spherical refraction using smartphones may potentially allow a quicker intervention by eye care professionals to reduce myopia progression. Unfortunately, at low levels of myopia, the far point (FP) can be located far away from the eye which can make interactions with the device difficult. To partially remedy this issue, a novel method is proposed and tested wherein the longitudinal chromatic aberration (LCA) of blue light is leveraged to optically bring the FP closer to the eye. METHODS: Firstly, LCA was obtained by measuring spherical refraction subjectively using blue pixels in stimuli shown on organic light-emitting diode (OLED) screens and also grey stimuli with matching luminance. Secondly, the visual acuity (VA) measured with a smartphone located at 1.0 m and 1.5 m and displaying blue optotypes was compared with that obtained clinically standard measurements. Finally, the spherical over refraction obtained in blue light with a smartphone was compared with clinical over-refraction with black and white (B&W) optotypes placed at 6 m. RESULTS: Mean LCA of blue OLED smartphone screens was -0.67 ± 0.11 D. No significant differences (p > 0.05) were found between the VA measured with blue optotypes on a smartphone screen and an eye chart. Mean difference between spherical over-refraction measured subjectively by experienced subjects with smartphones and the one obtained clinically was 0.08 ± 0.34 D. CONCLUSIONS: Smartphones using blue light can be used as a tool to detect changes in visual acuity and spherical refraction and facilitate monitoring of myopia progression.

Clinical validation of a novel smartphone application for measuring best corrected visual acuity

Purpose Personal mobile devices such as smartphones are proving their usefulness in ever more applications in tele-eyecare. An inconvenience and potential source of error in these past approaches stemmed from the requirement for the subjects to situate their devices at a distance. The present study aims to clinically validate best corrected visual acuity (BCVA) measures carried out by a novel smartphone application “vision.app” (VisionApp Solutions S.L.) using comparative statistics against clinical measurements. Materials and methods BCVA was measured in both eyes of 40 subjects using vision.app which displayed a black Landolt-C optotype with crowding on a white background, and utilized a 4 forced-choice procedure for the subjects to find (by means of swiping in either of four directions) the smallest optotype size they could resolve. Results were compared to BCVA measurements taken using a standard Snellen chart placed at 20 feet (6 m). Results The t-test revealed no significant differences between the app- and clinically-measured VA (p = 0.478 (OD) and 0.608 (OS)), with a mean difference between clinical and app measurements of less than one line of the eye chart (-0.009 logMAR (OD) and -0.005 logMAR (OS)). A limit of agreement for a 95% confidence interval of ± 0.08 logMAR for OD and OS was found. Conclusions The results show the potential use of a smartphone to measure BCVA at a handheld distance. The newly validated study results can hold major future advancements in tele-eyecare and provide eye care professionals with a reliable and accessible method to measure BCVA. (AU)

Clinical validation of a novel smartphone application for measuring best corrected visual acuity.

PURPOSE: Personal mobile devices such as smartphones are proving their usefulness in ever more applications in tele-eyecare. An inconvenience and potential source of error in these past approaches stemmed from the requirement for the subjects to situate their devices at a distance. The present study aims to clinically validate best corrected visual acuity (BCVA) measures carried out by a novel smartphone application "vision.app" (VisionApp Solutions S.L.) using comparative statistics against clinical measurements. MATERIALS AND METHODS: BCVA was measured in both eyes of 40 subjects using vision.app which displayed a black Landolt-C optotype with crowding on a white background, and utilized a 4 forced-choice procedure for the subjects to find (by means of swiping in either of four directions) the smallest optotype size they could resolve. Results were compared to BCVA measurements taken using a standard Snellen chart placed at 20 feet (6 m). RESULTS: The t-test revealed no significant differences between the app- and clinically-measured VA (p = 0.478 (OD) and 0.608 (OS)), with a mean difference between clinical and app measurements of less than one line of the eye chart (-0.009 logMAR (OD) and -0.005 logMAR (OS)). A limit of agreement for a 95% confidence interval of ± 0.08 logMAR for OD and OS was found. CONCLUSIONS: The results show the potential use of a smartphone to measure BCVA at a handheld distance. The newly validated study results can hold major future advancements in tele-eyecare and provide eye care professionals with a reliable and accessible method to measure BCVA.

The impact of amphotericin B-fortified preservation media on donor rim cultures and posttransplant infection.

Purpose: To determine the impact of amphotericin B supplementation to donor cornea preservation solutions on the rates of positive donor rim fungal cultures and postkeratoplasty fungal infections. Methods: This was a retrospective analysis of cases undergoing corneal transplantations at a single tertiary referral center from 2016 to 2021. Patients undergoing corneal transplantations with and without amphotericin B supplementation to the storage media were reviewed for donor rim culture results and postoperative infection. The primary outcome measures were positive donor rim fungal culture results and postkeratoplasty fungal infection. Results: A total of 1238 corneal transplants were analyzed. Of these, 849 were stored in preservation solution without amphotericin B, while 389 had amphotericin B included. There was a lower incidence of positive donor rim fungal cultures in cases with amphotericin B supplementation (1.8%) compared to the cases without amphotericin B (2.9%), although this difference was not statistically significant (P = 0.24). Of the 389 cases with amphotericin B supplementation, one (0.25%) went on to develop clinically significant infection, while three of 849 (0.35%) cases without amphotericin B developed infection. The sample size was too small to determine the effect of amphotericin B on the incidence of postkeratoplasty fungal infection. Conclusion: The addition of amphotericin B to donor cornea preservation solution resulted in a downward trend of positive donor rim fungal cultures and postkeratoplasty fungal infections, although these differences did not reach statistical significance. Further studies with larger sample sizes are necessary to appropriately determine the impact of amphotericin B supplementation in the storage solution on positive donor rims and postkeratoplasty fungal infections.

Oculofacial plastic surgeon distribution by county in the United States, 2021.

PURPOSE: To characterize the number of oculofacial plastic surgeons (OPS) per county in the United States (U.S.). METHODS: The 2021 public databases of the American Society of Ophthalmic Plastic and Reconstructive Surgery and the American Academy of Ophthalmology were used to identify all OPS in the U.S. Surgeon practice location was used to determine per capita physician density by county. RESULTS: A total of 1184 OPS in the U.S. were identified. Three hundred forty-eight counties were served by at least one OPS whereas 2795 counties (89%), and two states, North Dakota and Wyoming, had no OPS. The average ratio of OPS to 100,000 population was 0.3572 (1 per 279,955). Of the counties with at least one OPS, the average was 0.5860 surgeons per 100,000 population (1 per 170,648), ranging from 0.0705 (1 per 1,418,440) to 11.26 (1 per 8,881) per 100,000. The counties with the greatest OPS density were Pitkin County, CO (1 per 8,881), San Juan County, WA (1 per 17,580), and Montour County, PA (1 per 18,231). Counties with the lowest density of those with at least one OPS were Bronx County, NY (1 per 1,418,238), San Bernardino County, Ca (1 per 1,090,037), and Gwinnett County, GA (1 per 936,329). The counties with the most OPS were Los Angeles County, CA (46), New York County, NY (38), and Cook County, IL (25). CONCLUSIONS: Geographic disparities in OPS distribution exist in the U.S. Future investigations of OPS supply according to population and other characteristics for demand may be useful.

Two-Photon Microperimetry: A Media Opacity-Independent Retinal Function Assay.

Purpose: Compare results obtained using infrared two-photon microperimetry (2PM-IR) with conventional visual function tests in healthy subjects of varying ages with and without simulated media opacities. Methods: Subjects from two separate cohort studies completed cone contrast threshold (CCT) testing, conventional microperimetry, visible light microperimetry from a novel device (2PM-Vis), and infrared two-photon microperimetry. The first cohort study, which consisted of six healthy volunteers (23 to 29 years of age), evaluated the effects of simulated media opacities on visual performance testing. Subjects underwent testing on four visual function devices nine separate times under the following conditions: no filter, red filter, green filter, blue filter, light brown filter, dark brown filter, polarized black filter (0° rotation), and polarized black filter (90° rotation). Subjects subsequently performed 2PM-IR and 2PM-Vis testing without a filter in the mydriatic state. The second cohort study evaluated the effect of age on visual test performance in 42 healthy subjects split between two groups (ages 20-40 years and 60-80 years). Results: Retinal sensitivity measured by 2PM-IR demonstrated lower variability than all other devices relying on visible spectrum stimuli. Retinal sensitivity decreased proportionally with the transmittance of light through each filter. CCT scores and retinal sensitivity decreased with age in all testing modalities. Visible spectrum testing modalities demonstrated larger test result differences between young and old patient cohorts; this difference was inversely proportional to the wavelength of the visual function test. Conclusions: 2PM-IR mitigates media opacities that may mask small differences in retinal sensitivity when tested with conventional visual function testing devices. Translational Relevance: Conventional visual function tests that emit visible light may not detect differences in retinal function during the early stages of age-related diseases due to the confounding effects of cataracts. Infrared light, which has greater transmittance through ocular tissue, may reliably quantify retinal sensitivity and thereby detect degenerative changes early on.

Native paraneurial tissue and paraneurial adhesions alter nerve strain distribution in rat sciatic nerves.

Paraneurial adhesions have been implicated in the pathological progression of entrapment neuropathies. Surgical decompression of adhesions is often performed, with the intent of restoring nerve kinematics. The normal counterpart of adhesions, native paraneurium, is also thought to influence nerve deformation and mobility. However, influences of native or abnormal paraneurial structures on nerve kinematics have not been investigated. We measured regional strains in rat sciatic nerves before and immediately after decompression of native paraneurial tissue, and before and after decompression of abnormal paraneurial adhesions, which formed within 6 weeks of the initial decompression. Strain was significantly higher in the distal-femoral than in the mid-femoral region of the nerve before either decompression. Decompression of native and abnormal paraneurial tissue removed this regional strain difference. Paraneurial tissues appear to play a major role in distributing peripheral nerve strain. Normal nerve strain distributions may be reconstituted following decompression, even in the presence of paraneurial adhesions.