Extended just-noticeable difference for ultralow-luminance displays used in diagnostic imaging.

This study investigates the just-noticeable difference (JND) in luminance below the 0.050c d/m 2 threshold not covered by the DICOM standard in medical imaging displays. A total of 21 healthy young adults were tested using an ultralow-luminance liquid crystal display at a viewing distance of 46 cm. The optotype featured a 4 cycle/deg rectangular wave-like stripe. The average percentage of correct responses for JND indices between -18 and 0 was 70.8%. Using the extended JND based on the Barten model that matches the current JND definition, we confirmed the JND at a very low luminance of 0.0500c d/m 2 or less. These findings suggest the feasibility of further refining the gradation differences in medical imaging displays.

Wavelength Characteristics and Visual Function of Photochromic Contact Lenses in Indoor and Outdoor Conditions.

PURPOSE: To examine the wavelength characteristics of photochromic contact lenses (CL) and evaluate the impact of tinting on visual function in indoor, outdoor, and glare environments. METHODS: A total of 33 healthy individuals with refractive errors were recruited and fully corrected for refractive errors. Three groups were established, including non-activated photochromic CL, activated photochromic CL, and lenses without photochromic properties, which replicated the dimming characteristics of CL. Visual acuity and contrast sensitivity were measured and compared among the three groups. RESULTS: Statistically significant differences were observed in the spatial frequency (6, 12 cpd) and contrast sensitivity outdoors, with improved values recorded in the activated photochromic-CL group. In subsequent comparisons, the activated-photochromic-CL group demonstrated significantly better contrast-sensitivity values than the non-photochromic-CL group, as well as significant improvement in contrast sensitivity compared to the non-activated-photochromic-CL group. No significant differences were observed in the indoor or outdoor visual acuity. CONCLUSION: Our results suggest that photochromic CL enhances visual function in outdoor environments, while maintaining visual function indoors and under glare, thereby improving the quality of vision (QOV) in severe light conditions where exposure to sunlight and ultraviolet light is anticipated.

Relationship of Low-luminance Visual Acuity with Ocular Aberrations in Older Participants.

SIGNIFICANCE: This study highlights the importance of twilight adaptation for reliable assessment of low-luminance visual acuity and understanding the relationship between low-luminance visual acuity and ocular aberrations. PURPOSE: The human eye experiences reduced visual acuity as luminance decreases owing to reduced retinal and optical resolutions; however, the details are unclear. This study aimed to quantify the effects of refraction, pupil diameter, and ocular aberrations on visual acuity during the transition from high- to low-light environments, thereby contributing to the standardization of low-luminance visual acuity measurements. METHODS: In total, 27 older participants with a mean age of 70.0 ± 4.1 years were included in this study. Visual acuity was measured according to the Early Treatment Diabetic Retinopathy Study (ETDRS) protocol with three luminance conditions: high luminance (300 cd/m 2 ), low luminance (10 cd/m 2 ), and low luminance with short-term (15-minute) twilight adaptation (10 cd/m 2 ). RESULTS: The mean logarithm of minimum angle of resolution values of visual acuity were -0.09 ± 0.09, 0.10 ± 0.13, and 0.03 ± 0.09 at 300, 10, and 10 cd/m 2 with twilight adaptation, respectively. Multiple regression analysis determined that spherical aberration ( P < .005) and tetrafoil ( P < .005) were significant factors associated with low-luminance visual acuity after twilight adaptation, with an adjusted R2 value of 0.35 for this model ( P < .005). CONCLUSIONS: Although the influence of ocular aberrations on low-luminance visual acuity may be relatively modest compared with neural effects, it remains a crucial factor that should not be overlooked. The absence of twilight (or dark) adaptation can cause ocular aberrations and neural effects, potentially leading to inaccuracies in the measurement of low-luminance visual acuity.

Cone contrast test-HD: sensitivity and specificity in red-green dichromacy and the impact of age.

We report normative cone contrast sensitivity values, right-left eye agreement, and sensitivity and specificity values for the cone contrast test-HD (CCT-HD). We included 100 phakic eyes with color vision normal (CVN) and 20 dichromatic eyes (10 with protanopia and 10 with deuteranopia). The CCT-HD was used to measure L, M, and S-CCT-HD scores, and the right and left eyes were evaluated for agreement using Lin's concordance correlation coefficient (CCC) and Bland-Altman analysis to investigate the sensitivity and specificity of the CCT-HD based on diagnosis with an anomaloscope device. All cone types were in moderate agreement with the CCC (L-cone: 0.92, 95% CI, 0.86-0.95; M-cone: 0.91, 95% CI, 0.84-0.94; S-cone: 0.93, 95% CI, 0.88-0.96), whereas the Bland-Altman plots showed that the majority of cases (L-cone: 94%; M-cone: 92%; S-cone: 92%) fell within the 95% limits of agreement and showed good agreement. The m e a n±s t a n d a r d error L, M, and S-CCT-HD scores for protanopia were 0.6±1.4, 74.7±2.7, and 94.6±2.4, respectively; for deuteranopia, these were 84.0±3.4, 40.8±3.3, and 93.0±5.8, respectively; and for age-matched CVN eyes (m e a n±s t a n d a r d deviation age, 53.1±5.8 years; age range, 45-64 years), these were 98.5±3.4, 94.8±3.8, and 92.3±3.4, respectively, with significant differences between the groups except for S-CCT-HD score (Bonferroni corrected α=0.0167, p<0.0167). The sensitivity and specificity of the CCT-HD were 100% for protan and deutan in diagnosing abnormal types in those aged 20 to 64 years; however, the specificity decreased to 65% for protan and 55% for deutan in those aged >65 years. The CCT-HD is comparable to the diagnostic performance of the anomaloscope in the 20-64-year-old age group. However, the results should be interpreted cautiously in those ≥65 years, as these patients are more susceptible to acquired color vision deficiencies due to yellowing of the crystalline lens and other factors.

Measurement of Aniseikonia Tolerance in Binocular Fusion.

SIGNIFICANCE: The determination of aniseikonia tolerance may aid in developing optimal treatment plans for cataract surgery, refractive surgery, and refractive correction with glasses and contact lenses. PURPOSE: This study aimed to measure aniseikonia tolerance. METHODS: We included 33 patients (mean age ± standard deviation, 28.9 ± 6.4 years; male/female, 12:21) with anisometropia ≤1.0 D and best spectacle-corrected visual acuity of 20/20 or more in both eyes, with no ophthalmologic disease other than refractive errors and no history of ocular surgery. The exclusion criteria were anisometropia >1.0 D, axial length difference >0.5 mm, corneal refractive power difference >0.5 D, astigmatism >3.0 D, stereoacuity threshold >100 arcsec according to the Titmus Stereo Test, and >0% aniseikonia according to the New Aniseikonia Test. Aniseikonia tolerance was assessed using Eyemark Hello, a haploscope using gaze detection technology. Although the optotype of one eye was enlarged or reduced at a speed of 2%/s, the patients were instructed to press a button on the controller to indicate blurring, flickering, and diplopia. The value at which the patient responded was considered the aniseikonia tolerance value and assessed thrice per eye, five times if the values were highly variable, and then averaged. RESULTS: The mean aniseikonia tolerance was approximately 3%; the median value was approximately 2% (range, 1.0 to 11.5%; dominant eye, 3.3 ± 2.6%; nondominant eye, 2.9 ± 1.8%). No significant difference in aniseikonia tolerance between the dominant and nondominant eyes was observed for the enlarged optotypes. No case showed changes in the ocular alignment before discomfort occurred. No significant correlation was observed between aniseikonia tolerance and anisometropia, axial length difference, corneal power difference, and ocular deviation. CONCLUSIONS: Aniseikonia should be maintained at <2% for a comfortable visual environment. Aniseikonia tolerance may be an important indicator for cataract surgery, refractive surgery, and spectacle correction.

Comparison of Amblyopia Treatment Effect with Dichoptic Method Using Polarizing Film and Occlusion Therapy Using an Eye Patch.

We developed a novel, low-cost, easily administered method that uses a polarizing film to enable dichoptic treatment for amblyopia. In this study, we compared its effects with occlusion therapy using an eye patch. Fifty-eight patients (aged 4.7 ± 1.0 years) diagnosed with anisometric amblyopia were included and instructed to wear complete refractive correction glasses with either occlusion therapy using an eye patch (eye patch group) or dichoptic treatment using polarizing film (polarizing film group) for 2 h per day. We examined the improvement in the visual acuity and compliance rate of the patients 2 months after treatment initiation. After treatment, the polarizing film group showed significant improvement in visual acuity compared with the eye patch group. Moreover, the compliance rate was significantly better in the polarizing film group than in the eye patch group. In both groups, there was a significant correlation between the improvement in visual acuity and compliance rate. This new dichoptic treatment using a polarizing film was shown to be effective for anisometropic amblyopia.

High visibility colored fabrics for normal trichromats and individuals with color vision defects in a sunset-simulated environment.

This study aimed to investigate the visibility of colors in congenitally color vision defect people using general and fluorescent colors in an environment simulating sunset to examine the standards for high-visibility safety clothing for general users. Twenty participants with normal trichromats, seven protanopes, and five deuteranopes were included, with mean ages (± standard deviation) of 21.0±1.0, 46,7±16.1, and 56.6±6.9 years, respectively. Dyed fabrics were used to evaluate visibility. We evaluated brightness and conspicuousness sensitivity by combining red, yellow-red, yellow, green, red-purple, blue, white, black, fluorescent yellow, and fluorescent orange. For brightness sensitivity, the combination of fluorescent yellow and white/yellow stripes was highly visible and significantly different from all other samples (p < 0.05). For conspicuousness sensitivity, the combinations of black/fluorescent yellow, black/yellow, black/white, black/yellow-red, and white/red-purple stripes were highly visible and significantly different from all the other samples (p < 0.05). Yellow light is most visible and even better when fluorescent. They are based on specific spectral sensitivity, and yellow is the most visible, even for congenitally colorblind individuals. Furthermore, with regard to color combinations, it was found that the contrast between two distinct light or dark colors, such as black, yellow, black, and white, is perceived to be equally noticeable by congenital color vision defect individuals. This suggests the possible further applications of safety clothing.

Comparison of the effectiveness of amblyopia treatment with eye-patch and binocular Occlu-tab for the same treatment duration.

Purpose: This study aimed to compare the conventional eye patch with Occlu-tab-a binocular open-type amblyopia training device-and evaluate their effectiveness in amblyopia treatment. Methods: In this prospective, multi-center study, 40 patients between ages 3 to 12 years, diagnosed with anisometropic amblyopia (refraction difference of both eyes ≥ 2 D, best-corrected visual acuity [BCVA] of the amblyopic eye ≤ 0.1 [logMAR]) were treated with Occlu-tab or conventional eye patch for 1 h per day thrice a week. We compared the visual acuity of both groups before and after 6, 7, and 8 weeks of amblyopia treatment. One-way repeated-measures analysis of variance and Tukey's test were used to compare the visual acuity of both groups pre- and post-treatment. Results: Both groups had significantly improved visual acuity at 6, 7, and 8 weeks compared to that before treatment (all P < 0.001). The improvement in BCVA of the Occlu-tab group (0.33 ± 0.25) was significantly greater than that of the eye patch group (0.16 ± 0.17) after 8 weeks of treatment (P = 0.02). Conclusion: Amblyopia treatment using binocular open game training with Occlu-tab led to greater improvement in visual acuity than that with a conventional eye patch for the same treatment duration.

Refractive and visual function changes in twilight conditions.

PURPOSE: We investigated the effect of luminance on refraction and visual function under twilight conditions. METHODS: Twenty young adults (mean age 20.5 ± 0.5 years) without ocular diseases and 20 eyes were included in the study. Subjective and objective spherical equivalent power (SE), logMAR, pupil diameter, ocular aberration, and ocular axial length were evaluated. Measurements were conducted in a light room with high luminance (300 cd/m2) targets (photopic), in a dark room with low luminance (10 cd/m2) targets (twilight), and a dark room after 15 min of adaptation to low luminance (10 cd/m2) targets (after adaptation: AA). Differences between the three conditions were analyzed using the Friedman test and Scheffe's multiple comparisons. RESULTS: The results of logMAR were -0.20 ± 0.07, -0.08 ± 0.08, and -0.11 ± 0.08 in photopic, twilight, and AA, respectively, with significant differences between photopic and twilight (p < 0.001) and between photopic and AA (p < 0.001). Then subjective SE were -3.58 ± 2.04 D, -3.75 ± 2.08 D, and -3.74 ± 2.04 D in photopic, twilight, and AA, respectively, with significant differences between photopic and twilight (p = 0.007) and photopic and AA (p = 0.023). However, none of the other objective SEs produced a significant difference (p = 0.63). The pupil diameter and ocular aberration changed significantly in all conditions (p < 0.001). CONCLUSIONS: Subjective myopic refraction increased and visual resolution decreased in younger subjects. However, this change in refraction is less than one level (±0.25 D) in clinical optometry, so fully corrected eyeglasses are important when assuming refraction in twilight, and there is no need for additional correction.

Intrasession and Intersession Variabilities of Intraocular Pressure Measured by Noncontact Tonometer in Normal Volunteers.

PURPOSE: Intraocular pressure (IOP) measured using a noncontact tonometer is evaluated by performing multiple measurements because IOP is affected by the ocular pulse. We investigated the relationship between value fluctuations in multiple measurements during noncontact tonometer measurements and cardiac rate. MATERIALS AND METHODS: Forty-two healthy subjects were included and IOP was measured using a noncontact tonometer. The measurement was performed three times each for the right eye and the left eye, for a total of six times. Blood pressure and cardiac rate were measured at the same time as the IOP measurement. Using repeated-measures analysis of variance, we examined whether the measured IOP and cardiac rate fluctuate throughout the day over the course of 4 days. RESULTS: There was a fluctuation in the IOP in a sequence only on day 1 of the four measurement days (P < 0.001). The IOP on day 1 tended to be high for the first and second measurements (P = 0.0111-0.0015). Systolic blood pressure and diastolic blood pressure did not fluctuate over the 4 days (P = 0.6247 and 0.7132), but cardiac rate was high only on day 1 (P = 0.0276). CONCLUSION: The IOP on day 1 tended to be high in the first and second measurements. The IOP measured on days 2-4 did not fluctuate during the sequence of measurements. The cardiac rate measured at the same time as the IOP was high only on the first day.

Objective measurement of nine gaze-directions using an eye-tracking device.

PURPOSE: To investigate the usefulness and efficacy of a novel eye-tracking device that can objectively measure nine gaze-directions. METHODS: We measured each of the nine gaze-directions subjectively, using a conventional Hess screen test, and objectively, using the nine gaze-direction measuring device, and de-termined the correlation, addition error, and proportional error. We obtained two consecu-tive measurements of the nine gaze-directions using the newly developed device in healthy young people with exophoria and investigated the reproducibility of the measurements. We further measured the nine gaze-directions using a Hess screen test and the newly developed device in three subjects with cover test-based strabismus and compared the results. RESULTS: We observed that the objective measurements obtained with the newly developed gaze-direction measuring device had significant correlation and addition error compared to the conventional subjective method, and we found no proportional error. These measure-ments had good reproducibility. CONCLUSION: The novel device can be used to observe delayed eye movement associated with limited eye movement in the affected eye, as well as the associated excessive movement of the healthy eye in patients with strabismus, similar to the Hess screen test. This is a useful device that can provide objective measurements of nine gaze-directions.

Comparison between Amblyopia Treatment with Glasses Only and Combination of Glasses and Open-Type Binocular "Occlu-Pad" Device.

We evaluated amblyopia treatment, comparing training with glasses only and training with glasses and the Occlu-pad, a binocular open-type amblyopia training device. Forty-six children (4.8 ± 1.1 years) diagnosed with anisometropic amblyopia, all wearing complete correction glasses, were treated either with glasses only, or with glasses in combination with the Occlu-pad (training time: 2 days a week, 30 minutes per day). We compared visual acuity scores at 3 and 6 months after treatment had started, and examined the compliance rate for the Occlu-pad training. Three months as well as 6 months after amblyopia treatment started, the "Occlu-pad treatment group" showed significantly improved visual acuity, compared to the "Glasses treatment group" (at both 3 and 6 months: p < 0.0001). The compliance rate for using the Occlu-pad was 88.4 ± 18.7% after 3 months and 69.6 ± 19.5%, after 6 months. There was no significant correlation between the training time using the Occlu-pad and improvement in visual acuity (3 months: p = 0.97; 6 months: p = 0.55). The compliance rate for months 4 to 6 was significantly lower than that for months 1 to 3 (p = 0.003). Amblyopia treatment using the Occlu-pad device in combination with glasses led to a better effect than treatment with glasses alone.

Evaluation of the Effects of the Occlu-Pad for the Management of Anisometropic Amblyopia in Children.

PURPOSE: In recent years, amblyopia treatment device that can be used with both eyes open have been reported. The Occlu-pad is a device that can present images of tablet terminals to one eye only under binocular open conditions. Till date, no study has reported the effectiveness of Occlu-pad training for anisometropic amblyopia in a series of cases. In the present study, we evaluated the effectiveness of the Occlu-pad for the management of anisometropic amblyopia without the use of occlusion therapy (eyepatch). MATERIALS AND METHODS: We implemented Occlu-pad training for 22 children (mean age ± standard deviation: 4.7 ± 1.2 years) with anisometropic amblyopia. The visual acuity before treatment initiation was 0.25 ± 0.08. The difference in refraction between the healthy and amblyopic eyes was 3.10 ± 0.58 D. RESULTS: The visual acuity at 3 months and 6 months after training initiation was 0.06 ± 0.09 and -0.04 ± 0.07, respectively; this indicates a significant improvement in vision. The compliance rates for Occlu-pad use during 0 - 3 months and 4 - 6 months after training initiation were 88.6% ± 18.9% and 73.2% ± 18.9%; these rates decreased significantly with time. CONCLUSIONS: Our findings suggest that the Occlu-pad is an effective tool for the management of anisometropic amblyopia in children.

Improvement of Adherence with Occlu-Pad Therapy for Pediatric Patients with Amblyopia.

We aimed to examine visual acuity improvement effect and adherence in amblyopia training using tablet type vision training equipment (Occlu-pad). The subjects were 138 patients with amblyopia (average age of 5.5 ± 1.6 years old); their amblyopic visual acuity at the start of training was logMAR 0.15 to 1.3. Occlu-pad is a device that processes images such that amblyopic eyes can only view the image as it passes through polarized glasses; this is achieved by peeling off the polarizing film layer in the liquid crystal display of an iPad (Apple). Amblyopia training comprised either the instructional training with Occlu-pad or the eye patch (Patching) as a family training, after wearing perfectly corrected glasses. Visual acuity improvement following amblyopia training by Occlu-pad and Patching was significantly different after 6 months in patients with anisometropic amblyopia (p <0.05). In patients with strabismic amblyopia, a significant difference between training methods was observed after 9 months (p <0.05). Use of the Occlu-pad resulted in better adherence for patients with either anisometropic amblyopia or strabismic amblyopia; a significant difference in adherence was observed after 3 months, compared with Patching (p <0.05). Amblyopia training with Occlu-pad supports greater visual acuity improvement and adherence than Patching.

Efficacy of an Amblyopia Treatment Program with Both Eyes Open: A Functional Near-Infrared Spectroscopy Study.

INTRODUCTION AND PURPOSE: To investigate the efficacy of an amblyopia treatment program with both eyes open. METHODS: Ten subjects (mean age 20.5 ± 1.5 years) were enrolled. All subjects had un-remarkable ophthalmic examinations, but several subjects had minor refractive errors. Vision function was evaluated using the 3-D visual function trainer-ORTe. Brain measurements were made using functional near-infrared spectroscopy (fNIRS) to examine the oxygenated hemoglobin (HbO2) concentration change upon visual stimulus presentation. The three conditions were as follows: both eyes open and both eyes stimulated, both eyes open and only one eye stimulated, and one eye open and one eye stimulated. RESULTS: Changes in HbO2 between the rest and stimulation phases were not statistically different between the unilateral and bilateral stimulation conditions with both eyes open. However, HbO2 change was significantly higher in subjects with both eyes open than in subjects with one eye closed (P < 0.001, all comparisons). CONCLUSION: Greater activation of the visual cortex is achieved when subjects are treated with both eyes open as compared to subjects with one eye occluded. From a perspective of functional brain activation, amblyopia treatment administered without occluding the healthy eye may provide the greatest therapeutic benefit.

Effects of Target Size and Test Distance on Stereoacuity.

Target size and test distance effects on stereoacuity were investigated in 24 subjects using a three-dimensional monitor. Examination 1: Target Size Effects. The test distance was 2.5 m for 0.1°, 0.2°, 0.5°, and 0.9° target sizes; crossed parallax was presented in 22-second units. Average stereoacuity values for 0.1°, 0.2°, 0.5°, and 0.9° target sizes were 59.58 ± 14.86, 47.66 ± 13.71, 41.25 ± 15.95, and 39.41 ± 15.52 seconds, respectively. Stereoacuity was significantly worse with a 0.1° target than with 0.2°, 0.5°, and 0.9° target sizes (P = 0.03, P < 0.0001, and P < 0.0001, resp.). Examination 2: Test Distance Effects. Test distances of 2.5, 5.0, and 7.5 m were investigated for a 0.5° target size; crossed parallax was presented in 22-second units. Average stereoacuity values at 2.5 m, 5.0 m, and 7.5 m test distances were 44.91 ± 16.16, 34.83 ± 10.84, and 24.75 ± 7.27 seconds, respectively. Stereoacuity at a 7.5 m distance was significantly better than at distances of 2.5 m and 5.0 m (P < 0.0001 and P = 0.02, resp.). Stereoacuity at a 5.0 m distance was significantly better than at 2.5 m (P = 0.04). Stereoacuity should be estimated by both parallax and other elements, including test distance and target size.

Modified iPad for treatment of amblyopia: a preliminary study.

We report the results of a new amblyopia treatment device used in 7 children with anisometropic amblyopia. The Occlu-pad was created by removing the polarizing film layer from the liquid crystal display screen of an iPad Air (Apple Inc, Cupertino, CA). Patients were asked to wear special glasses that contained a polarizing filter for their amblyopic eye and a light reduction filter for their normal eye and instructed to play an amblyopia training game displayed only to the amblyopic eye. In 5 patients corrected distance visual acuities in the amblyopic eyes improved after 2 months' treatment on average by 0.38 (logarithm of the minimum angle of resolution).

Evaluation of Sensory Dominance Using Binocular Rivalry as Related to Ocular Deviations.

INTRODUCTION AND PURPOSE: To investigate the relationship between sensory dominance and ocular deviations. PATIENTS AND METHODS: Sixty-three patients were evaluated with a new device for the measurement of exclusive visibility during binocular rivalry. The patients were consisted of twenty-three with exotropia (XT), twenty with intermittent exotropia [X(T)], twenty with exophoria (XP), respectively. Device is composed of two retinometers, their holders in which angle and position can be adjustable and a PC for data storage and analysis. In each of eyes, exclusive visibility of one stimulus during binocular rivalry was measured for 60 sec, and the strength of ocular dominance was evaluated by the difference of exclusive visibility between dominant and nondominant eye. RESULTS: The difference of exclusive visibility time between dominant and nondominant eye were 9.8±3.7 sec in the XT group, 6.1±4.1 sec in the X(T) group and 2.2±1.5 sec in the XP group, respectively. There were significant differences between XT and X(T) (P<0.01) as well as between XT and XP (P<0.001). CONCLUSIONS: The present result indicates that sensory dominance was obviously influenced by ocular deviations since exclusive visibility of dominant eye was prolonged with decreasing the opportunity of normal binocular vision such as XT or X(T).