Binocular Measurements Research Articles

Visual quality following FS-LASIK with Q-value-guided optimized monovision in patients with myopia and presbyopia: Custom-Q in treating myopia and presbyopia

PurposeTo evaluate the objective and subjective visual quality 3 months after femtosecond laser‐assisted laser in situ keratomileusis (FS-LASIK) performed with Q-value–guided optimized monovision scheme (Custom-Q) for correction of myopia with or without astigmatism and compensate for age-related accommodation deficiency. DesignProspective before-and-after study. MethodsPatients who had Custom-Q FS-LASIK for myopia with age-related accommodation deficiency were included in this prospective study. Distance, intermediate, and near visual acuities; refraction; Q value; corneal higher-order aberrations (HOAs); accommodative and binocular function measurements; defocus curve; contrast sensitivity and a subjective questionnaire assessing near visual ability and visual discomforts were evaluated before and after surgery. ResultsClinical data of 48 cases were analyzed. The mean age was 42.73 ± 2.67 years (40 to 50 years). At the 3-month follow-up, there were 100% (48/48), 92% (44/48), and 56% (27/48) patients who achieved a binocular uncorrected distance, intermediate and near visual acuity (UDVA, UIVA, UNVA) not less than 20/20 separately. Defocus curves revealed better results postoperatively at – 1.00 D and – 1.50 D. The Q value in the dominant eyes was more positive postoperatively (P<0.001), and in the non-dominant eyes, the Q value and corneal spherical aberration (SA) became more negative (P<0.05). The accommodative amplitude (AA) and relative accommodation improved binocularly (P<0.001). The questionnaire demonstrated high patient satisfaction with near vision, and patients’ perceptions of visual discomforts had no significantly difference compare with preoperative. ConclusionFor myopic patients with age-related accommodation deficiency, the Custom-Q ablation could improve near vision without compromising distance vision. It also led to minimal changes in objective optical quality, coordination of accommodative and binocular functions, contrast sensitivity, and subjective visual discomforts perceptions.

Baseline Accommodation and Binocular Vision Measures in Malay Schoolchildren Enrolled in the Myopia Control Study Using Spectacle Lenses in Kuala Lumpur.

Myopia control lenses have been shown to modify visual function; however, it is arguable if these changes are short-term or long-term. We investigated the changes in accommodative behaviour and binocular vision functions of Malay myopic children who participated in a myopia control trial utilising spectacle lenses (n = 40). This article presents baseline accommodation and binocular vision measurements. The mean (± SD) age, spherical equivalent measured by cycloplegic autorefraction, and axial length (AL) for the right eyes were 10.00 ± 1.47 years, -3.02 ± 1.20 D, and 24.42 ± 0.93 mm, respectively. All participants had good distance and near visual acuities with high-contrast charts (100%), which were significantly better than low-contrast charts (10%) (p < 0.001). The mean (± SD) accommodative lag at baseline was 1.14 ± 0.35 D, while monocular and binocular accommodative amplitudes were 15.35 ± 2.07 D and 16.82 ± 2.27 D, respectively. Malay schoolchildren in this study were more esophoric at near compared to distance, with an accommodative-convergence over accommodation (AC/A) ratio of 5.64 ± 0.66 ∆/D. A higher degree of myopia was found to be associated with a longer AL (r = -0.49, p < 0.05) and higher esophoria at near (r = -0.46, p < 0.05). These baseline measures are consistent with data from other studies showing that myopic children have a high accommodative lag, an elevated AC/A ratio, a longer AL, and are more esophoric at near. The measures reported herein will serve as a basis for examining changes that occur within 12 months of wearing myopia control spectacle lenses.

Design of a teleoperated and mixed reality-based electric power live line working robot

This paper presents a novel teleoperation force feedback approach combining graphic and haptic feedback for enhanced telepresence. Visual force feedback is modeled through a fitting process, with the force direction established through coordinate transformations. To construct operational environments, a new scene recognition and reconstruction technique is proposed, based on the principles of binocular stereovision. This method is primarily designed for live-line work scenarios, focusing on power line wires. It involves image preprocessing, target image recognition and extraction, binocular stereo measurements, generating depth point clouds, and ultimately reconstructing three-dimensional models of the target objects. Ultimately, a novel electric power live line working robot system with a strong sense of telepresence is achieved, based on teleoperation and mixed reality.

Binocular vision measurements with a new online digital platform: comparison with conventional clinical measures

ABSTRACT Clinical relevance New digital systems are being developed for evaluating different aspects of the visual function, such as binocularity, and it is important to know their real performance in clinical practice in order to use them appropriately. Background The aim was to compare binocular vision measures obtained with an online digital platform with conventional measures using prisms and printed tests. Methods Prospective study enrolling 49 healthy patients (mean age: 35.5 ± 13.6 years). A complete visual examination was performed including measurement of near phoria (cover test), negative fusional vergence (NFV) and positive fusional vergence (PFV) ranges (prism bar), and stereopsis (24 patients Randot Stereo Test and 25 patients TNO Random Dot Test 19th edition). These same parameters were also measured with the Bynocs system (Kanohi Eye Pvt Ltd). Bland – Altman plots were used to analyse the agreement between methods. Results Digital measurement of near phoria was significantly lower than that obtained with the cover test, with a median difference (MD) of 4.71 (−0.07–20.07) prism dioptres (pd) (p < 0.001). No significant differences were found between Bynocs and prism bar methods in NFV break (MD 2.00, range −21–26 pd, p = 0.584) and recovery points (MD 0.00, range −16–24 pd, p = .571). Near PFV were significantly lower with Bynocs (break: MD −9.00, range −38–12 pd; recovery: MD −14.00, range −43–20 pd; p < 0.001). Bynocs stereoacuity threshold was significantly lower than that obtained with TNO (p = 0.004), but significantly higher compared to Randot (p < 0.001). Large and clinically relevant confidence intervals for the comparison between digital and conventional measures were detected in Passing-Bablok analysis. Conclusions Digital measures of near phoria, NFV, PFV, and stereopsis with the Bynocs platform cannot be used interchangeably with conventional measures. The normal ranges of normality for this new tool are defined.

The effects of breaks on digital eye strain, dry eye and binocular vision: Testing the 20-20-20 rule.

To evaluate the benefits on the eyes of taking breaks based on the 20-20-20 rule. Bespoke computer software using the laptop webcam to assess user breaks, eye gaze and blinking, and emitting personalized reminders of breaks based on the 20-20-20 rule, was downloaded onto the laptops of 29 symptomatic computer users. Digital eye strain (DES), binocular vision and dry eye were assessed before and after two weeks of using the reminders and one week after the discontinuation of the strategy. Binocular measurements included visual acuity, accommodative posture, stereopsis, fixation disparity, ocular alignment, accommodative facility, positive/negative vergences and near point of convergence. Symptoms were evaluated using the computer vision syndrome questionnaire, ocular surface disease index (OSDI), and symptom assessment in dry eye questionnaire (SANDE) versions one and two. Dry eye signs were assessed by measuring tear meniscus height, conjunctival redness, blink rate and incomplete blinking, lipid layer thickness, non-invasive keratograph break-up time, corneal and conjunctival staining and lid wiper epitheliopathy. A decrease in the duration of computer work and the duration of breaks, along with an increase in the number of breaks taken per day was observed as a result of the 20-20-20 rule reminders (p≤0.015). No changes on any binocular parameter were observed after the management period (p≥0.051), except for an increase in accommodative facility (p=0.010). Dry eye symptoms and DES decreased with the rule reminders (p≤0.045), although this improvement was not maintained one week after discontinuation (p>0.05). No changes on any ocular surface and tear film parameter were observed with the rule reminders (p≥0.089). The 20-20-20 rule is an effective strategy for reducing DES and dry eye symptoms, although 2weeks was not enough to considerably improve binocular vision or dry eye signs.

Algorithm for Binocular Vision Measurements Based on Local Information Entropy and Gradient Drift

Algorithm for Binocular Vision Measurements Based on Local Information Entropy and Gradient Drift

Analysis for Clinical Refraction by Optometrists

A total 136 cases of refraction examinations performed between the year 2015 and 2018 by korean optometrists were analyzed based on 16 items to assess the errors observed during these examinations. The results of the analysis showed that history were not administered in 50.7% of the cases. Further, dominant eye testing was not performed in 72.8% of cases; uncorrected visual acuity testing in 86.8%; refractive power measurements of the current prescription in 54.4%; corrected visual acuity testing with the current prescription in 91.9%; subjective refraction test using a phoropter in 45.6%; fogging before refraction testing in 72.1%; maximal visual acuity testing in 80.9%; fogging before astigmatism testing in 72.8%; astigmatic fan chart testing in 49.3%; astigmatic refining testing in 39.0%; maintenance of meridian balance during astigmatic refining testing in 66.2%; binocular balance testing in 29.4%; and spherical end-point testing in 12.5%. The most preferred test for measuring binocular balance was the alternating cover test, which was performed in 27.4% of the cases, and the most preferred method to the measure end-point of refraction was the maximum plus to maximum visual acuity (MPMVA) procedure, performed in 43.4% of the cases. In 45.0% of the cases, optometrists performed the binocular balance test without the dominant eye test, and in 26.5% of cases, they conducted the astigmatic fan chart test without fogging. In 27.2% of the cases, astigmatic refining tests were conducted without the maintenance of the meridian balance; 23.5% of the binocular end-point refraction measurements were conducted without the binocular balance test, and 35.3% of astigmatic tests were conducted with unchanged autorefractometer (AR) values. Such inaccuracies during the examination process could lead to inability in obtaining a complete correction of the refractive errors in the participants and cause various deviations in the refraction test-based binocular visual function findings.

Detection of visual field defects using Eye Movement Pediatric Perimetry in children with intracranial lesions: feasibility and applicability

The study aimed at evaluating the feasibility of Eye Movement Pediatric Perimetry (EMPP) among children in detecting Visual Field Defects (VFDs) associated with Intracranial Lesions (IL). Healthy controls (n = 35) and patients diagnosed with IL (n = 19) underwent a comprehensive clinical evaluation followed by a Goldmann Visual Field (GVF) and a customised EMPP protocol. During EMPP, all the participants were encouraged to fixate on a central target and initiate Saccadic Eye Movement (SEM) responses towards randomly appearing peripheral stimuli. The SEM responses were recorded using an eye-tracking device and further inspected to calculate Performance Scores (PS), Saccadic Reaction Times (SRTs), and an EMPP Index (EMPI). The mean age (years) of the controls and cases were 7.3 (SD: 1.5) and 9.4 (SD: 2.4) respectively. Among the controls, the older children (≥7 years) showed statistically significantly faster SRTs (p = 0.008) compared to the younger group. The binocular EMPP measurements compared between the controls and the cases revealed no statistically significant differences in PS (p = 0.34) and SRT (p = 0.51). EMPP failed in 4 children because of data loss or unacceptably poor PS whereas GVF failed in 7 children due to unreliable subjective responses. Of the 16 reports, with regard to the central 30-degree VF, 63% of the outputs obtained from both methods were comparable. EMPP is a reliable method to estimate and characterise the central 30-degree VF in greater detail in children with IL. EMPP can supplement the conventional methods, especially in those children who fail to complete a long duration GVF test.

Visual performance, safety and patient satisfaction after bilateral implantation of a trifocal intraocular lens in presbyopic patients without cataract

BackgroundThe aim was to evaluate the safety and efficacy of a trifocal intraocular lens (IOL) for the correction of presbyopia and to assess patient satisfaction.MethodsRecords from three centres were reviewed to select presbyopic patients having undergone bilateral refractive lens exchange and implantation of the AT LISA tri 839MP multifocal IOL. Postoperatively, monocular and binocular distance, intermediate and near visual acuities, corrected and uncorrected, and subjective refraction were measured. Patients also completed a quality of life questionnaire. Safety evaluation included IOL stability and postoperative complications.Results72 eyes (36 patients) were analysed. No clinically significant difference between pre- and postoperative corrected distance visual acuity (CDVA) was found for monocular or binocular measurements. Mean postoperative monocular CDVA was 0.02 ± 0.04 logMAR. Mean refractive values all improved statistically significantly compared with preoperative baseline (p ≤ 0.0064). Overall, 82.4% of eyes had spherical equivalent within ± 0.5 D and 97.1% within ± 1.0 D of emmetropia with a mean accuracy of -0.10 ± 0.41 D. Spectacle independence for distance, intermediate and near visual acuity was 87.5%, 84.4% and 78.1% respectively, and 78.1% of patients were satisfied with their postoperative, spectacle-free vision. Eight eyes received Nd:YAG laser treatment. No other IOL-related safety issues were reported.ConclusionAT LISA tri 839MP multifocal IOL bilaterally implanted in presbyopic patients provided excellent distance, intermediate and near visual outcomes with very accurate correction of refraction. These results were associated with a high level of spectacle independence and patient satisfaction.Trial registrationTrial registered on https://clinicaltrials.gov/ under the identification NCT03790592 (31/12/2018).

Changes in Accommodative and Binocular Function following Phakic Intraocular Lens for High and Low-to-Moderate Myopia.

The aim was to evaluate accommodative and binocular function of phakic intraocular lens implantable collamer lens (ICL) in high and low-to-moderate myopia. Prospective comparative cohort study with 38 myopic patients who underwent ICL implantation were divided into two groups of 19 patients, each one based on the spherical equivalent (SE): high-power (SE ≤ −6 D) and low-to-moderate (SE > −6 D). The push-up amplitude of accommodation (AA), monocular accommodative facility (MAF), distance and near ocular deviation, near convergence amplitude, near point convergence (NPC), stereopsis, and accommodative convergence/accommodation (AC/A) ratio were assessed before surgery and 1 week and 1 month postoperatively. The mean residual refractive error at 1 month after surgery improved in both groups, 0.18 ± 0.34 D and 0.09 ± 0.26 D, respectively (p < 0.001). There was a significant decrease in AA in both groups between preoperatively and at 1-week (p = 0.001; p = 0.008, respectively) and 1-month follow-up (p = 0.001; p = 0.008). For the rest of the binocular measurements, no statistically significant postoperative changes were found in any group. This finding suggests follow-up studies on amplitude of accommodation in phakic intraocular lens ICL implantation.

Topical Review: Assessment of Binocular Sensory Processes in Low Vision.

This article summarizes the evidence for a higher prevalence of binocular vision dysfunctions in individuals with vision impairment. Assessment for and identification of binocular vision dysfunctions can detect individuals experiencing difficulties in activities including reading, object placement tasks, and mobility.Comprehensive vision assessment in low vision populations is necessary to identify the extent of remaining vision and to enable directed rehabilitation efforts. In patients with vision impairment, little attention is typically paid to assessments of binocular vision, including ocular vergence, stereopsis, and binocular summation characteristics. In addition, binocular measurements of threshold automated visual fields are not routinely performed in clinical practice, leading to an incomplete understanding of individuals' binocular visual field and may affect rehabilitation outcomes.First, this review summarizes the prevalence of dysfunctions in ocular vergence, stereopsis, and binocular summation characteristics across a variety of ocular pathologies causing vision impairment. Second, this review examines the links between clinical measurements of binocular visual functions and outcome measures including quality of life and performance in functional tasks. There is an increased prevalence of dysfunctions in ocular alignment, stereopsis, and binocular summation across low vision cohorts compared with those with normal vision. The identification of binocular vision dysfunctions during routine low vision assessments is especially important in patients experiencing difficulties in activities of daily living, including but not limited to reading, object placement tasks, and mobility. However, further research is required to determine whether addressing the identified deficits in binocular vision in low vision rehabilitative efforts directly impacts patient outcomes.

Eyes of Aniso-Axial Length Individuals Share Generally Similar Corneal Biometrics with Normal Eyes in Cataract Population.

Aims To determine the characteristics of corneal biometrics in eyes from aniso-axial length cataract patients compared with eyes from non-aniso-axial length individuals. Methods This is a retrospective case series. Cataract patients with preoperative binocular measurements were recruited. A binocular axial difference of ≥1 mm was considered to indicate aniso-axial length. The anterior segmental biometrics were measured using Pentacam HR (Oculus, Wetzlar, Germany) and IOLMaster 500 (Carl Zeiss Meditec, Jena, Germany). Comparisons of biometrics were made among 4 eye conditions: the longer eyes from aniso-axial length patients, the shorter eyes from aniso-axial length patients, the longer eyes from non-aniso-axial length patients, and the shorter eyes from non-aniso-axial length patients. The aniso-axial length eyes were also stratified into 8 subgroups with axial length (AL) increments of 1 mm, and the biometrics of the subgroups were compared. Results There was smaller anterior corneal astigmatism in the shorter aniso-axial length group than those in the longer aniso-axial length group (1.01 ± 0.70 D vs 1.12 ± 0.76 D, P=0.031). The longer aniso-axial length eyes had greater anterior corneal steep curvature (44.13 ± 1.69 D vs 43.87 ± 1.69 D, P=0.009) and anterior corneal astigmatism (1.12 ± 0.76 D vs 1.02 ± 0.69 D, P=0.023) compared with longer non-aniso-axial length subjects. Other corneal biometrics were similar between the aniso-axial length eyes and the non-aniso-axial length eyes. In the longer aniso-axial length group, the posterior corneal aberrations of eyes in the ≥5 mm subgroups were greater than those in the <5 mm subgroups (0.879 ± 0.183 μm vs 0.768 ± 0.178 μm for total aberrations, P < 0.001; 0.228 ± 0.086 μm vs 0.196 ± 0.043 μm for high-order aberrations, P=0.036; 0.847 ± 0.173 μm vs 0.741 ± 0.179 μm for low-order aberrations, P=0.001). Conclusion Eyes of aniso-axial length individuals share generally similar corneal biometrics with normal eyes in cataract population. Anterior corneal astigmatism of the longer eyes from the aniso-axial length cataract patients was higher than that of the longer eyes from the non-aniso-axial length individuals. Total posterior corneal aberrations of the longer aniso-axial length eyes increased when the binocular axial difference was over 5 mm.

Cholinergic Modulation of Binocular Vision.

The endogenous neurotransmitter acetylcholine (ACh) is known to affect the excitatory/inhibitory (E/I) balance of primate visual cortex, enhancing feedforward thalamocortical gain while suppressing corticocortical synapses. Recent advances in the study of the human visual system suggest that ACh is a likely component underlying interocular interactions. However, our understanding of its precise role in binocular processes is currently lacking. Here we use binocular rivalry as a probe of interocular dynamics to determine ACh's effects, via the acetylcholinesterase inhibitor (AChEI) donepezil, on the binocular visual system. A total of 23 subjects (13 male) completed two crossover experimental sessions where binocular rivalry measurements were obtained before and after taking either donepezil (5 mg) or a placebo (lactose) pill. We report that enhanced cholinergic potentiation attenuates perceptual suppression during binocular rivalry, reducing the overall rate of interocular competition while enhancing the visibility of superimposition mixed percepts. Considering recent evidence that perceptual suppression during binocular rivalry is causally modulated by the inhibitory neurotransmitter GABA, our results suggest that cholinergic activity counteracts the effect of GABA with regards to interocular dynamics and may modulate the inhibitory drive within the visual cortex.SIGNIFICANCE STATEMENT Our research demonstrates that the cholinergic system is implicated in modulating binocular interactions in the human visual cortex. Potentiating the transmission of acetylcholine (ACh) via the cholinergic drug donepezil reduces the extent to which the eyes compete for perceptual dominance when presented two separate, incongruent images.

Clinical outcomes after mix-and-match implantation of diffractive multifocal intraocular lenses with +\u20092.75 and\u2009+\u20094.00 diopter add powers

BackgroundTo evaluate the clinical outcomes of bilateral mix-and-match implantation of diffractive multifocal intraocular lenses (IOLs) with different add powers.MethodsWe retrospectively reviewed the medical records of 18 patients who underwent bilateral mix-and-match implantation of diffractive multifocal IOLs with different add powers. Multifocal IOLs with add powers of + 2.75 diopters (D) and + 4.00 D were implanted into the patients’ dominant and nondominant eyes, respectively. At 1 and 3-month postoperatively, monocular and binocular visual acuity was measured using logMAR charts and manifest refraction was performed. Specifically, logMAR charts were used to measure uncorrected distance visual acuity (UDVA), uncorrected intermediate visual acuity (UIVA), uncorrected near visual acuity (UNVA), and corrected distance visual acuity (CDVA). Defocus curves, contrast sensitivity, and patient satisfaction were assessed at 3-month postoperatively.ResultsBinocular logMAR measurements (mean ± standard deviation) at 3-month postoperatively were 0.01 ± 0.04 (UDVA), 0.16 ± 0.05 (UIVA), and 0.11 ± 0.07 (UNVA). Postoperative spherical equivalent was − 0.43 ± 0.35 D and − 0.39 ± 0.21 D in the dominant and nondominant eyes, respectively. Defocus curves showed significant differences between − 1.50 and − 4.00 D among binocular, dominant, and nondominant eye measurements, except between − 2.50 and − 3.00 D. Eyes implanted with + 2.75 and + 4.00 D IOLs showed good contrast sensitivity under photopic and mesopic conditions. Over 80% of patients reported high satisfaction with their near vision.ConclusionsBilateral mix-and-match implantation of diffractive multifocal IOLs with add powers of + 2.75 D and + 4.00 D showed good near, intermediate, and far vision.

Reply.

We thank Dr. Galvis and team for the attentive reading of our study on defocus curves. In our study, we compared the visual performance of 4 presbyopia-correcting IOLs and found that the 4 IOLs provided patients with equally good corrected distance visual acuity (CDVA). The extended depth-of-focus IOL demonstrated a slightly better intermediate CDVA, however a worse near CDVA than the other IOLs, with only the panfocal IOL presenting a better intermediate VA at 50 cm. We agree that the patients' uncorrected vergence is 0.25 D for an object at 4 m distance. In our study, the manifest refraction was performed with Early Treatment Diabetic Retinopathy Study charts at 4 m distance, and the defocus curves were performed with the values of this manifest refraction. Thus, the vergence of 0.25 D of measuring VA at 4 m was already included in the manifest refraction used for defocus curve measurement, and consequently, the 4 m distance of the defocus curve can be seen as the reciprocal of the diopters used for measurement. The same defocus curve testing was used for all IOLs, allowing a relative comparison of the differences between the IOLs. Other published studies on the visual performance of IOLs, including that of Gundersen and Potvin, used the same methods to test VA and defocus curves.1–3 One of the main purposes of defocus curves is that they allow the comparison of the visual performance of IOLs with different designs, not just the simulation of visual performance in daily life. We agree that binocular measurements reflect more real-world viewing because of the presence of retinal disparity cues in addition to blur. However, the monocular defocus curve approach is suitable to compare the visual performance of various IOL designs. Because the main aim of our study was to compare the visual performance of presbyopia-correcting IOLs, the monocular defocus curve was the method of choice. The testing of positive IOLs in defocus curves is traditionally performed to compare the vision of preoperated patients with that of postoperated patients.4 We included positive defocus testing to allow the comparison of other published studies that had tested with an overcorrection of +1.00 to −4.00 D.2,3 We agree with the authors that positive IOL-simulated defocus testing takes some additional time; however, in our study, only 3 additional lens powers per eye were tested up to +1.50 D vs 8 lens powers for the myopic side up to −4.00 D.5 Thus, the impact on additional test time was rather low. In addition, defocus curves for both positive and negative IOLs have an important advantage in that they allow an understanding of how well residual refractive errors are tolerated by IOL designs and if the VA reduces monotonically as a function of defocus on this side. In our study, there were no differences between IOLs identified, with all IOLs showing a similar drop of VA as a function of induced positive IOLs. In conclusion, we agree that the relationship between lens vergence and distance defocus is essential for interpreting the resultant defocus curves as performed in our study.

Improved separated-parameter calibration method for binocular vision measurements with a large field of view.

Large field-of-view (FOV) calibration is indispensable to ensure the accuracy of vision measurement systems for large aviation components. We propose an improved separated-parameter calibration method for large-FOV binocular vision measurements with a high flexibility and accuracy. Firstly, the camera parameters are separately calibrated according to the sub-area features of image. Subsequently, based on the spatial-calibration accuracy, a stereoscopic calibration object is devised. The mean error of the proposed method is experimentally obtained as 0.13 mm for a FOV of 2.0 m × 1.5 m. Its feasibility and effectiveness for the measurement in the field is validated by workshop calibration.

Use of a computer simulation program to quantify the influence of masking calculation methods on ISO 5006-1 visibility results

IntroductionThe ISO 5006-1 is used to evaluate visibility on earth-moving machinery but has been criticized for a cumbersome field method. Field conditions are difficult to reproduce. Investigators may be required to evaluate a particular machine's line of sight profile to examine how it contributed to an accident. However, the standard relies on values such as operator size and positioning that accident investigators may not possess. Furthermore, practitioners in various settings face limitations related to lighting, time, and space. MethodsA computer simulation version of the standard was completed on a small lift truck machine and a larger haul truck. Variations on obstruction, or masking, calculation methods were completed to highlight the variability within the ISO 5006-1 standard under controlled conditions. Additionally, the impact of operator anthropometrics and seat positioning on masking measurements were quantified. ResultsGenerally, ISO 5006-1 calculated masking widths and those measured using a monocular view point underestimated masking sizes as compared to a gold standard binocular measurement. Binocular and monocular measurements of the percentage visibility on a horizontal plane showed little difference (<1%). Furthermore, variations in operator anthropometrics and seat positioning showed minimal changes in measures of visibility (<2%). ConclusionsDepending on the accuracy required for a given application, variations in visibility measurements may be considered acceptable or unacceptable. The variation of 300 mm observed in one case between a binocular masking width and monocular width exceeds the acceptable masking width (300 mm) defined by the ISO. However, variations in seat positioning and anthropometrics showed much smaller differences.

The influence of vergence facility on binocular eye movements during reading.

Optometrists regularly use binocular measurements in patients with asthenopic complaints when performing close-up work. The focus of this work was therefore on the correlation of optometric parameters and objective fixation disparity (FD) measured by an eye tracker.In our investigation, 20 participants (6 male, 14 female) were subjected to a classical optometric procedure. Subsequently, these subjects read various sentences on a screen and eye movements were registered by using a RED500 eye tracker. The experiment was performed under two reading distance conditions. In order to be comparable with previous work, the present study was conducted under dark illumination conditions [12]. FD values were deduced from objective eye tracking data during reading. Data analysis was done using linear mixed-effects models.FD was found to depend on vergence facility (t=3.3, p=0.004). Subjects with a low vergence facility showed more eso fixation disparity than subjects with a normal vergence facility.If studies of binocular coordination using eye tracking methods are performed under dark illumination conditions, vergence facility is an important parameter and should be accounted for. Neglecting this parameter may mask other important parameters. Vergence facility in context of reading difficulties may be important.

The Convergence Insufficiency Neuro-mechanism in Adult Population Study (CINAPS) Randomized Clinical Trial: Design, Methods, and Clinical Data

ABSTRACTPurpose: To describe the design and methodology of the Convergence Insufficiency Neuro-mechanism in Adult Population Study (CINAPS), the first randomized clinical trial (RCT) studying young adults with symptomatic convergence insufficiency (CI) using a combination of traditional clinical tests, objective eye movement recordings, and functional brain activities as outcome measures.Methods: In this double-masked RCT, binocularly normal controls (BNC) (N = 50) and CI patients (N = 50) are randomized into office-based vergence/accommodative therapy (OBVAT) or office-based placebo therapy (OBPT). Outcome measures included clinical signs and symptoms, phoria adaptation, forced fixation disparity curves, binocular rivalry, vergence and saccadic objective eye movements, and task-induced functional brain activities. This study is registered on ClinicalTrials.gov NCT03593031.Results: No significant baseline differences are observed between the BNC (p > .4) or CI (p > .3) participants assigned to OBVAT or OBPT for age, near point of convergence (NPC), positive fusional vergence (PFV), phoria at distance and near, amplitude of accommodation, or the Convergence Insufficiency Symptom Survey (CISS). Significant differences are observed between the CI and BNC cohorts at baseline measurements for NPC, PFV, difference in phoria from far to near, amplitude of accommodation, and CISS (p < .001). For the CI patients, 26% had a comorbidity of accommodation insufficiency, and 16% self-reported ADHD.Conclusion: Features of the study design include the following: standardized diagnostic and office-based therapeutic intervention, placebo treatment arm, masked clinical outcome examinations, objective eye movement recordings, functional imaging, phoria adaptation, fixation disparity curves and binocular rivalry measurements.

Optic nerve sheath diameter asymmetry in healthy subjects and patients with intracranial hypertension.

Ultrasonography of the optic nerve sheath diameter (ONSD) is used for the non-invasive assessment of increased intracranial pressure (ICP). ONSD values are usually obtained by averaging the measurements of the two eyes, but asymmetric ONSD dilation is possible, leading to potentially inaccurate ICP estimation when using binocular averaging. In addition, few data are available about the asymmetry of the ONSD and the use of the maximum ONSD value between eyes for raised ICP detection. The aim of the study was to evaluate the interocular ONSD asymmetry in healthy subjects and patients with intracranial hypertension (IH) by ultrasonography and to investigate whether the maximum ONSD could be as useful as the binocular assessment. Forty healthy subjects and 40 patients with IH (20 with idiopathic intracranial hypertension and 20 with intracerebral hemorrhage) who underwent transorbital sonography were retrospectively enrolled. The prevalence and degree of ONSD asymmetry were compared among groups; ONSD median binocular and maximum values were compared. Forty-two out of 80 subjects (52.5%) showed significant ONSD asymmetry, without significant differences in prevalence among groups (p = 0.28). The median asymmetry was higher in patients than in healthy subjects (0.45mm vs 0.23mm; p = 0.007), without significant differences between the two pathologies (p = 0.58). Both binocular and maximum ONSD measurements were significantly higher in patients with IH than in controls (p < 0.001). Interocular ONSD asymmetry occurs both in healthy subjects and, more consistently, in patients with IH. Both binocular and maximum ONSD may be useful markers for increased ICP detection.