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Computer-based colour perception tests permit clinical assessment of cone-specific pathways, proving valuable for both identifying type and severity of hereditary colour vision deficiency and enhanced detection and monitoring of acquired colour deficiency from disease. Understanding the parameters that affect computer-based colour perception tests may enhance their veracity and clinical utility. Testing contrast sensitivity separately for the three cone systems enables a quantification of colour perception that can be clinically useful. This study evaluated the effects of pupil diameter and stimulus size on cone contrast sensitivity (CCS) assessed with the ColorDx (Konan Medical, Incorporated). Forty subjects, aged 21–31 years, who met the inclusion criteria participated. The tested eye was randomised. Two Landolt C sizes (2.68 degrees, 6/194, "small"; 8.58 degrees, 6/619, "large") were used, with one size and three chromaticities presented per block of trials. Stimulus presentation used the adaptive screening mode, sequentially determining contrast sensitivity for long-, medium-, and short-wavelength stimuli. Subjects were tested with their natural pupil size (range 4–5 mm diameter), then while viewing through a 2.5-mm artificial pupil. Parametric statistical tests were used for comparisons of performance across pupil size and stimulus size. Two-way within-subjects ANOVA indicates no interaction between pupil size and stimulus size for any of the three stimulus chromaticities. The main effect of stimulus size was significant for M-cone (F = 6.506, 2-tailed P =.015) and S-cone (F = 67.728, 2-tailed P <.001) stimuli. The main effect of pupil size was significant for all three stimulus chromaticities (L-cone: F = 227.161, M-cone: F = 249.979, S-cone: F = 89.371, 2-tailed P <.001 for all). Although CCS was reduced for all three chromaticities and both stimulus sizes with lower retinal illuminance, only S-wavelength cone contrast sensitivity was significantly different for the small versus large stimuli under the 2.5-mm pupil condition in this cohort. Whether CCS in older patients with naturally small pupils changes with an enlarged stimulus or dilated pupils remains to be explored. [ABSTRACT FROM AUTHOR]

Background: Whether a history of mild traumatic brain injury (mTBI) affects pupil dynamics that could confound the interpretation of pupil data in other causes of visual dysfunction is unknown. We investigated the relationship between history of mTBI and pupil dynamics recorded with highdefinition pupillography. Methods:Subjects (n = 137) aged 19 to 81 years were enrolled from attendees of an optometric meeting in 2016. The data collected included: ocular and systemic health histories, current medications, history of TBI, and pupil dynamics using the automated afferent pupillary defect protocol of the RAPDx (Konan Medical). Multiple regressions with backward analysis were used to identify factors that predicted pupil dynamics. Results: Thirty-five subjects reported positive history of mTBI (15 reported more than 1 mTBI). None of the pupil parameters assessed for either eye were predicted by history of mTBI. Time from most recent head injury to pupil testing predicted only latency of constriction onset of each eye (right eye: P = 0.02, R2 = 0.214; left eye: P = 0.02, R2 = 0.187). Age and time from most recent head injury to pupil testing predicted latency of constriction onset for each eye in those reporting head injury (right eye: adjusted R2 = 0.23, P = 0.02; left eye: adjusted R2 = 0.26, P = 0.01). Conclusions: Dynamic pupil parameters elicited with a bright white stimulus were not predicted by history of mTBI. Time from most recent mTBI to date of pupil testing may partially predict latency of pupil constriction, and longer times from most recent mTBI to date of pupil testing may be associated with slower redilation velocities. However, the influence of age on the association between time from most recent mTBI and velocity of redilation in this study sample is unknown. [ABSTRACT FROM AUTHOR]

We explored the relationship between self-regulated test duration and test performance in first-year optometry students using test administration software. The scores for two midterms (MT1 and MT2) and the final exam for a single course (Visual Sensation and Perception) and time from password submission to exam upload were obtained for 132 students in spring 2019. Statistical analysis suggests that the relationship between self-regulated test duration and test performance is inconsistent across the semester for this group. Exploration of self-regulated test duration and test performance for other courses and throughout the optometric program may provide additional insight. [ABSTRACT FROM AUTHOR]

Background: Adverse visual symptoms with electronic devices have been reported, but causes have yet to be clearly defined. Previous studies have neither equated stimulus luminance across devices nor studied subjects with verified normal accommodation prior to testing. Pupil size during device use also has not been explored. We compared pupil sizes and accommodative responses to targets of similar size displayed with ink on paper, an e-ink reader, and an LCD device in young, healthy adults with normal accommodation. Methods: Subjects were 42 healthy adults, aged 22 to 33 years, with near acuity 20/20 (6/6) or better in the tested eye. Normal accommodation was verified with accommodative amplitude and facility (+/-2.00 flippers) tests. The reading text was presented at 40 cm, and text size and device luminance were matched across devices. While the subject read the passage aloud, pupil size was measured. Accommodative responses were obtained twice with near retinoscopy and twice with an open-field autorefractor for each device. Results: One-way ANOVA for correlated samples and Tukey's HSD test were used to compare mean pupil size and mean accommodative response across devices. The differences in mean pupil size for paper versus e-ink (5.1 ± 0.9 vs. 5.5 ± 0.8, p<0.01) and LCD versus e-ink (5.1 ± 0.9 vs 5.5 ± 0.8, p<0.01) were significant. By retinoscopy, the difference in mean accommodative response was significant only for e-ink and LCD (1.48 ± 0.76 D vs. 1.78 ± 1.26 D, p<0.01). By autorefraction, no significant differences in mean accommodative response were found across device type. Linear regression showed that accommodative response was not predicted by pupil size for any of the devices. Conclusions: In this group of young adults with normal accommodation, accommodative response was not significantly different for ink on paper, e-ink, or LCD devices of matched luminance. Pupil size did not predict accommodative response for any device. [ABSTRACT FROM AUTHOR]

Objective During the current pandemic, COVID-19 has been detected in patients using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) that confirms the presence of SARS-CoV-2 RNA. The demand for increased testing, particularly for asymptomatic individuals required alternative approaches to single-patient RT-PCR testing, such as pooling. Methods This study explored the impact of dilution on the detectability of SARS-CoV-2 in asymptomatic patients using RT-PCR and demonstrated that pooling can be effective in low prevalence populations. Results The RT-PCR results for the 3:1, 5:1, and 7:1 aliquot samples showed little differences in CT values, confirming detection capability at these dilutions. Conclusion Based on the results of the present study, a pooled approach with up to 5:1 sample aliquots and using the current RT-PCR methodology likely will detect SARS CoV2 RNA among asymptomatic patients. [ABSTRACT FROM AUTHOR]

Despite motion of the entire retinal image that results from fixational eye-movements, the visual scene is perceived as stationary. One hypothesis to account for this observation is that normal motion sensitivity is limited by the variability of fixational eye velocity. The present experiments tested this hypothesis by comparing motion sensitivity and the variability of fixational eye velocity in corresponding meridians. Speed thresholds to detect horizontal, vertical, and rotary motion in a set of eight random-dot patches were measured, while normal observers monocularly viewed the stimulus with gaze either straight-ahead or deviated to the left by 45°. Eye-movement recordings using the search-coil technique were used to estimate the variability of eye velocity in the horizontal, vertical, and torsional meridians during fixation. As reported previously by Murakami (), the averaged thresholds for horizontal and vertical motion correlated with the averaged variability of eye velocity in the horizontal and vertical meridians when observers looked straight-ahead. However, no relationship existed between the threshold for rotary motion and the variability of eye velocity in the torsional meridian. Furthermore, no relationship existed between the motion threshold and the variability of eye velocity in any meridian during fixation in lateral eccentric gaze. These results are only partly consistent with the hypothesis that fixation variability limits motion sensitivity. [ABSTRACT FROM AUTHOR]