Visual Threshold Research Articles

Long-term Recovery Patterns of Olfactory Function after Trans-sphenoidal Approach with Nasoseptal Flap Elevation.

Introduction Nasoseptal flap is widely used in reconstruction of the skull base to prevent cerebrospinal fluid leakage after surgery for skull base lesions. There has been a debate on whether more severe olfactory dysfunction occurs after nasoseptal flap elevation than the conventional trans-sphenoidal approach. Objective To compare the long-term recovery patterns associated with nasoseptal flap and the conventional trans-sphenoidal approach. Methods The subjects were divided into the conventional trans-sphenoidal approach group and the nasoseptal flap elevation group. We followed up self-reported olfactory score using the visual analogue scale and threshold discrimination identification (TDI) score of the Korean Version of the Sniffin Stick test II for 12 months, with olfactory training. Results The study included 31 patients who underwent the trans-sphenoidal approach. Compared with preoperative status, the mean visual analogue scale and TDI scores in the conventional trans-sphenoidal approach group recovered 2 months postoperatively, while in the nasoseptal flap elevation group the visual analogue scale and TDI scores recovered 6 months and 3 months after surgery, respectively. Twelve months after surgery, the visual analogue scale and TDI scores in the conventional trans-sphenoidal approach group were 9.3 ± 0.5 and 28.5 ± 4.3, while those from the nasoseptal flap elevation group were 8.9 ± 1.5 and 27.2 ± 4.7 ( p = 0.326; 0.473). Only one of the patients in the nasoseptal flap elevation group had permanent olfactory dysfunction. Conclusion The olfactory function recovered more gradually in the nasoseptal flap elevation group than in the conventional trans-sphenoidal approach group, but there was no difference between the two groups after 6 months.

Research on the Inscriptions on Ancient Bronze Objects and Related Issues under the Visual Threshold of Calligraphy National Exhibition

In recent years, the selected rate continues to rise in the calligraphy works taking as the model of inscriptions on ancient bronze objects in national calligraphy exhibitions, which reflects the current situation of taking as seal characters’ models in the calligraphy circle and the aesthetic orientation of calligraphers. Based on the analysis of the relevant data of seal characters in the calligraphy national Exhibition, this paper reveals the status and development trend of works taking as the model of inscriptions, and further discusses the gains, losses and prospects of calligraphy creation taking as the model of inscriptions in the national exhibition.

Psychomusic-clomipramine therapy on students’ anxiety disorders based on the perspective of the Civics program

BackgroundAt present, students’ learning pressure is increasing, and many schools have introduced psychomusical therapy from the perspective of ideological and political courses to relieve students’ mental anxiety.Subjects and Methods In this study, 100 students with mental anxiety disorder in a high school were selected as research objects and randomly divided into a control group and a study group. The control group was treated with clomipramine only. The study group was treated with ideological and political curriculum visual threshold psychomusic therapy based on clomipramine therapy and the self-rating Anxiety Scale (SAS) was used for comparative analysis. Finally, Minitab was used for statistical analysis.ResultsAfter 3 months of the experiment, the anxiety scale score of middle school students in the control group changed from 65 points to 54 points; The anxiety scale scores of middle school students in the study group changed from 64 to 46. In the study group, the psychological pressure of students before and after the experiment was significantly different (P<0.05). The experimental results show that the combination of ideological and political curriculum visual psychomusical therapy with drug therapy can alleviate students’ mental anxiety.ConclusionsIn this study, the introduction of visual psychomusic in ideological and political courses into drug therapy has a positive impact on student’s mental anxiety caused by study pressure, and can also arouse other schools’ attention to mental health, provide new ideas for the popularization of psychological counselling, and promote the development of student’s mental health.

Reliability of gaze-contingent perimetry.

Standard automated perimetry, a psychophysical task performed routinely in eyecare clinics, requires observers to maintain fixation for several minutes at a time in order to measure visual field sensitivity. Detection of visual field damage is confounded by eye movements, making the technique unreliable in poorly attentive individuals and those with pathologically unstable fixation, such as nystagmus. Microperimetry, which utilizes 'partial gaze-contingency' (PGC), aims to counteract eye movements but only corrects for gaze position errors prior to each stimulus onset. Here, we present a novel method of visual field examination in which stimulus position is updated during presentation, which we refer to as 'continuous gaze-contingency' (CGC). In the first part of this study, we present three case examples that demonstrate the ability of CGC to measure the edges of the physiological blind spot in infantile nystagmus with greater accuracy than PGC and standard 'no gaze-contingency' (NoGC), as initial proof-of-concept for the utility of the paradigm in measurements of absolute scotomas in these individuals. The second part of this study focused on healthy observers, in which we demonstrate that CGC has the lowest stimulus positional error (gaze-contingent precision: CGC = ± 0.29°, PGC = ± 0.54°, NoGC = ± 0.81°). CGC test-retest variability was shown to be at least as good as both PGC and NoGC. Overall, CGC is supported as a reliable method of visual field examination in healthy observers. Preliminary findings demonstrate the spatially accurate estimation of visual field thresholds related to retinal structure using CGC in individuals with infantile nystagmus.

A new static visual field test algorithm: the Ambient Interactive ZEST (AIZE)

Visual field (VF) test is one of the most vital tests in the diagnosis of glaucoma and to monitor the disease worsening. In the past couple of decades, the standard automated perimetry (SAP) test takes a major role in VF test for glaucoma patients. The SAP has been demanded to finish a test in short time without sacrificing accuracy. In this study, we developed and evaluated the performance of a new perimetric algorithm (ambient interactive zippy estimation by sequential testing (ZEST): AIZE) by computer simulation. AIZE is a modification of the ZEST procedure that utilizes the spatial information (weighted likelihood: WL) of neighboring test locations, which varies from the distance to the tested location, to estimate a visual threshold. Ten glaucomatous and 10 normal empirical visual field (VF) test results were simulated with five error conditions [(3% false positives (FP), 3% false negatives (FN)), (9% FP, 9% FN), (15% FP, 15% FN), (3% FP, 15% FN), (15% FP, 3% FN)]. The total number of test presentations and the root mean square error (RMSE) of the estimated visual sensitivities were compared among AIZE, the non-weighted test (WL = 0) and the fixed-weighted test (WL = 0.33). In both glaucomatous (G) and normal (N) VFs, the fixed-weighted test had the lowest number of test presentations (median G 256, N 139), followed by the AIZE (G 285, N 174) and the non-weighted test (G 303, N 195). The RMSE of the fixed-weighted test was lower (median 1.7 dB) than that of the AIZE (1.9 dB) and the non-weighted test (1.9 dB) for normal VFs, whereas the AIZE had a lower RMSE (3.2 dB) than the fixed-weighted test (4.5 dB) and the non-weighted test (4.0 dB) for glaucomatous VFs. Simulation results showed that AIZE had fewer test presentations than the non-weighted test strategy without affecting the accuracy for glaucomatous VFs. The AIZE is a useful time saving test algorithm in clinical settings.

Development and application of lateral flow strip with three test lines for detection of deoxynivalenol in wheat.

Lateral flow strip was widely used and their qualitative and quantitative performance was in continuous improvement. However, the traditional strip was in a single-test-line format, which restricted operators to making a semi-quantitative judgment around a desired threshold concentration. Herein, a single strip with three test lines (TTLS) was developed for the semi-quantitative and quantitative determination of deoxynivalenol (DON). Four visual detection thresholds were obtained under optimized conditions and 35 wheat samples with DON content from 45µg/kg to 2841µg/kg were used to verify the method. The detection results were compared with that of the traditional strip and UPLC-MS/MS. In a three-test-line format, TTLS could reveal at least 200, 500, 1000, and 2000µg/kg DON existed in different samples by the naked eye. The agreement analysis and statistical results indicated the new TTLS can be used as a useful tool for quantitative detection of DON with wide dynamic range.

Illuminant metamerism between natural teeth and zirconia restorations evaluated with a chromatic adaptation transform

Little is known about the effect of illuminant metamerism between natural teeth and zirconia restorations, despite their increasing clinical popularity. The purpose of this in vitro study was to compare illuminant metamerism between pairs of natural teeth and layered zirconia restorations and pairs of natural teeth and monolithic zirconia restorations under 10 different illuminants and analyze their metameric potential. Spectral reflectance factors were obtained from 10 pairs of extracted natural teeth and layered zirconia restorations and 28 pairs of extracted natural teeth and monolithic multilayer zirconia restorations. Each pair showed a color match that was within the visual threshold for clinical acceptability (CIEDE2000≤1.8). A special index of metamerism for the change of illuminant (Milm) was calculated from the CIEDE2000 color difference equation. Descriptive statistics and the one-sample t test were used to analyze the results for the Milm and for both groups of layered and monolithic zirconia restorations (α=.05). Layered zirconia restorations reached a mean ±standard deviation value for Milm=0.3 ±0.2 and Milm=0.5 ±0.4 for monolithic zirconia restorations (P<.01). The effect of illuminant metamerism between natural teeth and zirconia crowns was weak and generally within the clinical acceptability limit.

Dim-light colour vision in the facultatively nocturnal Asian giant honeybee, Apis dorsata.

We discovered nocturnal colour vision in the Asian giant honeybee Apis dorsata-a facultatively nocturnal species-at mesopic light intensities, down to half-moon light levels (approx. 10-2 cd m-2). The visual threshold of nocturnality aligns with their reported nocturnal activity down to the same light levels. Nocturnal colour vision in A. dorsata is interesting because, despite being primarily diurnal, its colour vision capabilities extend into dim light, while the 'model' European honeybee Apis mellifera is reported to be colour-blind at twilight. By employing behavioural experiments with naturally nesting A. dorsata colonies, we show discrimination of the trained colour from other stimuli during the day, and significantly, even at night. Nocturnal colour vision in bees has so far only been reported in the obligately nocturnal carpenter bee Xylocopa tranquebarica. The discovery of colour vision in these two bee species, despite differences in the extent of their nocturnality and the limitations of their apposition compound eye optics, opens avenues for future studies on visual adaptations for dim-light colour vision, their role in pollination of flowers at night, and the effect of light pollution on nocturnal activity in A. dorsata, a ubiquitous pollinator in natural, agricultural and urban habitats in the Asian tropics and sub-tropics.

Keep your finger on the pulse: Better rate perception and gap detection with vibrotactile compared to visual stimuli

Important characteristics of the environment can be represented in the temporal pattern of sensory stimulation. In two experiments, we compared accuracy of temporal processing by different modalities. Experiment 1 examined binary categorization of rate for visual (V) or vibrotactile (T) stimulus pulses presented at either 4 or 6 Hz. Inter-pulse intervals were either constant or variable, perturbed by random Gaussian variates. Subjects categorized the rate of T pulse sequences more accurately than V sequences. In V conditions only, subjects disproportionately tended to mis-categorize 4-Hz pulse rates, for all but the most variable sequences. In Experiment 2, we compared gap detection thresholds across modalities, using the same V and T pulses from Experiment 1, as well as with bimodal (VT) pulses. Visual gap detection thresholds were larger (3times ) than tactile thresholds. Additionally, performance with VT stimuli seemed to be nearly completely dominated by their T components. Together, these results suggest (i) that vibrotactile temporal acuity surpasses visual temporal acuity, and (ii) that vibrotactile stimulation has considerable, untapped potential to convey temporal information like that needed for eyes-free alerting signals.

Long-term trifocal toric intraocular lens outcomes in Asian eyes after cataract surgery.

To determine the visual and refractive outcomes of trifocal toric intraocular lens (IOL) implantation in Asian eyes with cataract and astigmatism. Asian Eye Institute, Makati City, Philippines. Prospective study. 187 eyes were implanted with the FineVision POD FT IOL and followed for 2 years. The measurements included subjective refraction, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), distance-corrected intermediate visual acuity (DCIVA), uncorrected near visual acuity (UNVA), distance-corrected near visual acuity (DCNVA), defocus curve, photopic and mesopic contrast sensitivity, and rotational stability. The mean spherical equivalent and cylinder values were, respectively, -0.07 ± 0.34 diopters (D) and -0.48 ± 0.31 D at the 2-year follow-up. At this same follow-up, 69.4% of patients had monocular CDVA and 79.3% had binocular UDVA ≤0.0 logMAR. For intermediate vision, monocular DCIVA reached 74.1%, while binocular UIVA was 86.2% ≤ 0.1 logMAR. Near vision showed 63% for monocular DCNVA and 70.7% for binocular UNVA ≤0.1 logMAR. The mean values at this follow-up were 0.02 ± 0.08, 0.08 ± 0.10, and 0.10 ± 0.12 logMAR for CDVA, DCIVA, and DCNVA, respectively. At the visual acuity threshold of ≤0.20 logMAR, the binocular defocus curve extended up to -3.75 D. Stable contrast sensitivity values were obtained at the different follow-ups. The mean IOL rotation was ≤2 degrees. The FineVision POD FT IOL yielded good visual outcomes at far, near, and intermediate distances with accurate refractive outcomes and good rotational stability in Asian eyes.

Soybean Tolerance to ultra-low doses of dicamba: Hormesis or not

The widespread use of dicamba across the soybean growing regions of the United States resulted in increased off-target movement of this herbicide to susceptible vegetations. There are speculations that a drift of sublethal (ultra-low) doses of dicamba can enhance soybean growth and yield through a phenomenon called hormesis. Field studies were conducted during 2018 and 2019 to determine whether soybean growth and yield can be enhanced with ultra-low doses (0.0112–56 g ae ha−1) of dicamba, applied at three growth stages (V2, R1 and R2). There was no evidence that the ultra-low doses of dicamba (0.0112–56 g ae ha−1) increased any of the observed parameters, irrespective of the application timing. Doses of 0.56 g ae ha−1 and lower did not have a negative impact on plant dry matter, height and grain yield, even if causing visible symptomology. The estimated effective doses for 50% reduction in various growth parameters and yield (ED50) indicate that soybean is more sensitive at the R1 compared to the V2 or R2 stages. The estimated visual injury threshold that caused 5% yield loss were 53, 36 and 21% for V2, R1 and R2 stage of dicamba exposure, respectively. The proposed “No Observed Adverse Effect Level” (NOAEL), which is a safe exposure threshold, ranged from 0.0003 to 0.033 g ae ha−1. However, efforts should be made to avoid dicamba drift to susceptible soybean as there is no evidence of enhanced growth and yield with the ultra-low doses.

Contrast detection is enhanced by deterministic, high-frequency transcranial alternating current stimulation with triangle and sine waveform.

Stochastic resonance (SR) describes a phenomenon where an additive noise (stochastic carrier-wave) enhances the signal transmission in a nonlinear system. In the nervous system, nonlinear properties are present from the level of single ion channels all the way to perception and appear to support the emergence of SR. For example, SR has been repeatedly demonstrated for visual detection tasks, also by adding noise directly to cortical areas via transcranial random noise stimulation (tRNS). When dealing with nonlinear physical systems, it has been suggested that resonance can be induced not only by adding stochastic signals (i.e., noise) but also by adding a large class of signals that are not stochastic in nature that cause "deterministic amplitude resonance" (DAR). Here, we mathematically show that high-frequency, deterministic, periodic signals can yield resonance-like effects with linear transfer and infinite signal-to-noise ratio at the output. We tested this prediction empirically and investigated whether nonrandom, high-frequency, transcranial alternating current stimulation (tACS) applied to the visual cortex could induce resonance-like effects and enhance the performance of a visual detection task. We demonstrated in 28 participants that applying 80-Hz triangular-waves or sine-waves with tACS reduced the visual contrast detection threshold for optimal brain stimulation intensities. The influence of tACS on contrast sensitivity was equally effective to tRNS-induced modulation, demonstrating that both tACS and tRNS can reduce contrast detection thresholds. Our findings suggest that a resonance-like mechanism can also emerge when deterministic electrical waveforms are applied via tACS.NEW & NOTEWORTHY Our findings extend our understanding of neuromodulation induced by noninvasive electrical stimulation. We provide the first evidence showing acute online benefits of transcranial alternating current stimulation (tACS)triangle and tACSsine targeting the primary visual cortex (V1) on visual contrast detection in accordance with the resonance-like phenomenon. The "deterministic" tACS and "stochastic" high-frequency-transcranial random noise stimulation (tRNS) are equally effective in enhancing visual contrast detection.

Does the use of antioxidant agents after dental bleaching compromise the aesthetic results of ceramic laminate veneers?

PurposeThis in vitro study aimed to evaluate the aesthetic compromise generated in adhesive interface of ceramic laminate veneer luted after tooth bleaching and the use of antioxidant agents. Thus, the chromatic coordinates and whitening index (WID) were evaluated, comparing whiteness changes (ΔWID) results to perceptibility and acceptability thresholds. Material and methodsIn total, 88 bovine enamel samples (7 × 8 × 4 mm; n = 8) were submitted to the ceramic laminate veneer luting protocol according to surface treatment (unbleached and bleached enamel), antioxidant agents (control; 10% ascorbic acid and 10% α-tocopherol), and luting periods (after 24 h and after 14 days). To lute IPS e.max ceramic restorations (7 × 8 × 0.6 mm), Tetric N-Bond Universal adhesive system and Variolink Aesthetic LC resin cement were used. An ultraviolet–visible spectrophotometer (UV–VIS) was utilized to measure CIE L*a*b* coordinates prior to and after UV-B artificial accelerated aging for 252, 504, and 756 h. L*, a*, and b* axes were evaluated separately, and the whitening stability (ΔWID) effect was assessed by varying the whiteness index for dentistry (WID). The 50:50% visual threshold was used to evaluate ΔWID values (whiteness perceptibility [WPT] and whiteness acceptability [WAT]). Color parameters changes (ΔL*Δa*Δb*), WID, and ΔWID data were subjected to 2-way repeated measures ANOVA followed by Tukey's test (α = 0.05). ResultsDifferent UV-aging periods influenced the chromatic coordinates, WID, and ΔWID of the ceramic restorations regardless of the bleaching treatment, antioxidant solutions and luting periods (P < .05). In general, ΔWID values after UV-aging periods were above perceptibility and acceptability thresholds (WPT = 0.72 and WAT = 2.62, respectively) for all experimental groups (P < .05). Unbleached and 10% ascorbic acid-treated enamels luted after 14 days of the antioxidant action exhibited lower ΔL* and Δb* values, while control group showed lower Δa* values. All experimental groups showed similar performance on ΔWID compared to the control group, regardless of the UV-aging period analyzed (P > .05). Conclusionα-tocopherol is a suitable antioxidant solution to be used 24 h post enamel bleaching not compromising clinical acceptability of ceramic laminate veneers. Clinical relevanceThe adhesive interface of ceramic laminate veneers may appear darker after the use of antioxidant agents affecting the clinical acceptability of the restorations.

ID: 203988 Spinal ECAP Thresholds Relative to Evoked Muscle Activation in Rats With Clinically Translatable Paradigms

Rats are commonly used as a translational model of pain and spinal cord stimulation (SCS), with stimulation amplitudes often programmed relative to visual motor threshold (vMT). Recent work1 explored both vMTs and spinal evoked compound action potentials (ECAPs)—a sensed measured of neural activation—in rats using SCS with a 2 Hz rate and a 20 μs pulse width (PW). However, this rate and PW are slower and narrower, respectively, than those typically used clinically. In this study2, we used clinically relevant SCS traditional parameters to characterize the relationship between ECAP thresholds (ECAPTs) and evoked muscle activity as measured both by evoked compound muscle action potential thresholds (ECMAPTs) and vMTs.

Modulation of Visual Contrast Sensitivity with tRNS across the Visual System, Evidence from Stimulation and Simulation

Transcranial random noise stimulation (tRNS) has been shown to significantly improve visual perception. Previous studies demonstrated that tRNS delivered over cortical areas acutely enhances visual contrast detection of weak stimuli. However, it is currently unknown whether tRNS-induced signal enhancement could be achieved within different neural substrates along the retino-cortical pathway.In 3 experimental sessions, we tested whether tRNS applied to the primary visual cortex(V1) and/or to the retina improves visual contrast detection. We first measured visual contrast detection threshold (VCT; N=24, 16females) during tRNS delivery separately over V1 and over the retina, determined the optimal tRNS intensities for each individual(ind-tRNS), and retested the effects of ind-tRNS within the sessions. We further investigated whether we could reproduce the ind-tRNS-induced modulation on a different session (N=19, 14females). Finally, we tested whether the simultaneous application of ind-tRNS to the retina and V1 causes additive effects. Moreover, we present detailed simulations of the induced electric field across the visual system.We found that at the group level tRNS decreases VCT compared to baseline when delivered to the V1. Beneficial effects of ind-tRNS could be replicated when retested within the same experimental session but not when retested in a separate session. Applying tRNS to the retina did not cause a systematic reduction of VCT, irrespective of whether the individually optimized intensity was considered or not. We also did not observe consistent additive effects of V1 and retina stimulation.Our findings demonstrate significant tRNS-induced modulation of visual contrast processing in V1, but not in the retina.Significance statementOur findings confirm previous evidence showing acute online benefits of tRNS of V1 on visual contrast detection in accordance with the stochastic resonance phenomenon. We further extend it, demonstrating that the optimal tRNS intensity varies among participants, but when individually tailored it can improve visual processing when re-tested within the experimental session. The tRNS-induced enhancement in visual sensitivity was observed for cortical contrast processing, but stimulation of the retina did not lead to systematic effects.

Reduction of Pain After Laparoscopic Bariatric Surgery by Personalized Checkpoint Acupuncture—Data of a STRICTA Conform Pilot Study

BackgroundItremains challenging in clinical practice to perform optimal pain management following bariatric surgeries. Acupuncture (AC) is an effective method of postoperative pain management, but its clinical efficacy depends on the rationale used to select AC points.MethodsWe developed a method to identify individual patterns of pain and a corresponding set of acupoints (corrAC) based on the relative pressure sensitivity of six abdominal visceral pressure points, i.e., the gastrointestinal (GI) checkpoints (G1–G6). Patients with moderate to severe pain were included and received a single AC treatment following surgery. The visual analog scale (VAS) score, pain threshold, and skin temperature were assessed before AC and at 5 min, 1 h, and 24 h following AC. AC was performed with 1-mm-deep permanent needles.ResultsFrom April 2021 to March 2022, 72 patients were included in the analysis. Fifty-nine patients received corrAC, whereas 13 received a noncorresponding AC (nonAC) as an internal control. Patients receiving corrAC showed a significant reduction (74%) in pain at 5 min after treatment (p < 0.0001) and a significant increase (37%) in the pain threshold (p < 0.0001). In this group, a significant increase in skin temperature above G1, G3, G4, and G5 was observed. Patients receiving nonAC showed neither significant pain reduction nor significant changes in pain threshold. The skin above G3 and G4 did not reveal temperature changes.ConclusionCheckpoint AC may be an effective tool in postoperative pain therapy after bariatric surgery. Vegetative functional involvement might be associated with pain relief.Graphical

Laser pulse train parameters determine the brightness of a two-photon stimulus.

This report presents the results of measurements of the two-photon vision threshold for various pulse trains. We employed three pulsed near-infrared lasers and pulse stretchers to obtain variations of the pulse duty cycle parameter over three orders of magnitude. We proposed and extensively described a mathematical model that combines the laser parameters with the visual threshold value. The presented methodology enables one to predict the visual threshold value for a two-photon stimulus for a healthy subject while using a laser source of known parameters. Our findings would be of value to laser engineers and the community interested in nonlinear visual perception.

New Insights into Wine Color Analysis: A Comparison of Analytical Methods to Sensory Perception for Red and White Varietal Wines.

The Glories method and CIE L*a*b* color space are poorly correlated in the light red high-saturation color area. Non-uniformities in the CIE L*a*b* color space have led to the CIEDE2000 formula, while the Euclidean color distance is still used in wine research. In this study, 112 white and red wines were examined to compare the Glories method, CIE L*a*b, and human perception using monovarietal wines from different grape varieties. The objective of this study was to investigate which of the two methods and which parameter of each method better aligned with human perception. The visual color threshold was re-evaluated with the CIEDE2000 formula and triangle testing. CIE L*a*b* more closely matched the human perception, elevating the use of CIE L*a*b* over the use of the Glories method. Visual color thresholds were better expressed with CIEDE2000 but still varied depending upon the color area in the CIE L*a*b* color space.

Effects of induced aniseikonia on binocular visual acuity

ABSTRACT Clinical relevance Binocular visual acuity is an important index of functional performance. Optometrists need to know how binocular visual acuity is affected by aniseikonia, and whether reduced binocular visual acuity is a marker for aniseikonia. Background Aniseikonia, the perception of unequal image sizes between the eyes, can occur spontaneously or can be induced after different types of eye surgery, or trauma. It is known to affect binocular vision, but there are no prior studies about how it affects visual acuity. Methods Visual acuity was measured for 10 healthy well-corrected participants aged 18–21 years of age. Aniseikonia of up to 20% was induced in one of two ways: (1) size lenses, which provided minification of field of view in one eye of each participant and (2) polaroid filters, which allowed vectographic viewing of optotypes on a 3D computer monitor. The best corrected acuity was measured on conventional logarithmic progression format vision charts and isolated optotypes, under both induced aniseikonia conditions. Results Induced aniseikonia caused binocular visual acuity thresholds to increase by small but statistically significant amounts, with the largest deficit being 0.06 logMAR for 20% size differences between the eyes. Binocular visual acuity was worse than monocular visual acuity for aniseikonia of 9% and greater. Acuity measured with the vectographic presentation gave slightly higher thresholds (by 0.01 logMAR) than for those viewed with size lenses. Acuity measured with charts gave slightly higher thresholds (by 0.02 logMAR) than with isolated letters. Conclusion An acuity change of 0.06 logMAR is small and may be missed in a clinical examination. Therefore, visual acuity cannot be used as a marker of aniseikonia in clinical settings. Even with very marked induced aniseikonia, binocular visual acuity remained well within standards for licen*c*sing of drivers.

Low Level Laser Versus Transcutaneous Electrical Nerve Stimulationon Post Herpetic Neuralgia

Background: Post herpetic neuralgia (PHN), a common neuropathic pain syndrome, usually occurs in patients with acute herpes zoster after resolving skin eruption. Persistent severe pain has a huge impact on a patient's physical function, mental health, and social communication ability, and also places a heavy burden on patients' families and on society. Objective: The current study was conducted to compare the efficacy of low level laser therapy (LLLT) versus transcutaneous electrical nerve stimulation (TENS) in the treatment of post-herpetic neuralgia Subjects and Methods: Fifty patients suffering from pain post herpetic neuralgia .Their ages ranged from 40 to 80 years.They were selected randomly from outpatient clinic in Deraya university referred by dermatologist then divided into two equal groups. Group (A) composed of 25 patients with post herpetic neuralgia and they received low level laser therapy LLLT in addition to traditional medical treatment and Group (B) composed of 25 patients with post herpetic neuralgia and they received Transcutaneous electrical nerve stimulation in addition to traditional medical treatment .Both modalities were applied once daily, 3 times a week for 20 minutes for 4 successive weeks. Visual analog scale (VAS) and pain pressure threshold (PPT) had been assessed before and after interventions. Results: There was a significant decrease in VAS and a significant increase in PPT post treatment compared with that pre treatment in group A and B (p &gt; 0.001). The percent of change in VAS and PPT in group A was 88.97 and 522.22% respectively, while that in group B was 82.39 and 462.79% respectively. Conclusion: Both LLLT and TENS were effective improving the post-herpetic neuralgia but LLLT was more effective. Keywords: Low level laser therapy, transcutaneous electrical nerve stimulation, post herpetic neuralgia, visual analog scale and pain pressure threshold