Point Of Accommodation Research Articles

A Study on Visual Fatigue and Binocular Visual Function before and after Watching VR Image

Purpose : This study was designed to determine how VR video viewing using HMD devices had an effect on the visual function, EEG, and the visual fatigue. Methods : This study analyzed the 30 subjects(in their 20s to 30s) who used smart devices the most. They had to have no systemic and eye diseases and their corrected vision were 1.0 or higher. The far and near phoria test were repeated three times each using Howell cards(3 m, 40 cm) and 6 Δ prism. The push-up testing to check near point of accommodation and the NPC test were repeated three times. EEG signals were recorded using a Quick cap with 62 Ag-AgCl electrodes and NeuroScan SynAmps. We analyzed the resting EEG data with eyes open and eyes closed using CURRY7, which was commonly used for EEG pre-processing. Results : There were significant differences in near point of convergence(p<0.001), near phoria(p=0.004), and AC/A ratio(p=0.023) after VR image viewing. Accommodation and far phoria were not significant differences. In the brainwave analysis, the relative power of the alpha 1 band(p<0.001) and the relative power of the alpha 2 band(p=0.003) showed the difference in anterior, middle, and posterior. After watching VR images, the simulator sickness questionnaire showed a significant overall difference(p<0.001). In the correlation analysis, alpha 1 band relative power was significantly correlated with near phoria(p=0.038) and AC/A Ratio(p=0.041). Alpha 2 band relative power showed significant correlation with nausea(p=0.029), oculomotor(p=0.021), and disorientation(p=0.010). Conclusion : After watching VR images, NPC significantly increased and exophoria significantly increased in near. And there was a significant increase in the alpha wave. In addition, cyber motion sickness was felt by all subjects, and the degree of disorientation was the biggest increase.

Near Points of Convergence and Accommodation in a Population of University Students in Iran.

PurposeTo determine the distribution of the near point of convergence (NPC) and near point of accommodation (NPA) in a young student population in Iran.MethodsThe subjects were selected using a cluster sampling method. All students underwent optometry tests, including visual acuity measurement, refraction, and cover test, as well as ophthalmic examinations. The NPC and NPA were measured using an accommodative target (near Snellen chart).ResultsOf 1,595 students, the data of 1,357 were analyzed. The mean NPC and NPA in the total sample were 7.25 cm (95% confidence interval [CI], 7.02 to 7.48) and 9.99 cm (95% CI, 9.69 to 10.29), respectively. Older age was associated with an increase in the NPC, which increased from 6.98 cm in 18–20 years olds to 9.51 cm in those over 30 years. The NPA was significantly associated with age and refractive errors in the multiple linear regression model, increasing from 9.92 cm in 18–20 years olds to 11.44 cm in those over 30 years ( = 0.003). Hyperopic eyes had lower NPA than myopic and emmetropic eyes ( = 0.001). In younger age groups, the mean accommodation amplitude was lower than the mean Hofstetter value. Moreover, with age, especially after 30 years, the mean values surpassed those determined using the Hofstetter formula.ConclusionThe NPC values in this study were lower than those previously reported for identical age groups. The Hofstetter formula is not always an accurate predictor of the accommodation amplitude in the Iranian adult population.

Effects of corneal plastic surgery on stereopsis and dynamic regulation of myopia and the mechanism of controlling myopia progression

Objective To investigate the effect of corneal plastic surgery on stereopsis and dynamic regulation of myopia and the mechanism of myopia. Methods From March 2015-March 2016, 83 cases (166 eyes) myopia children in our hospital were subjected to corneal plastic surgery. The naked eye distant visual acuity, naked eye near visual acuity, naked eye near stereoscopic sharpness, dynamic adjustment function [Near point of accommodation (NP), adjusted sensitivity (AF), negative relative adjustment (NRA), positive relative adjustment (PRA)] and intraocular pressure, anterior chamber depth, central corneal thickness and axial length of children before wearing glasses, wearing glasses 6 months later, wearing glasses 12 months later were compared. Results The distant and near visual acuity, AF and PRA of naked eyes after 12 months wearing glasses were higher than those after 6 months wearing glasses, and all the above indexes were higher than those before wearing glasses , with statistically significant difference (P 0.05). Conclusions Corneal plastic surgery can significantly correct the visual acuity of children, improve their stereovision, control the progression of myopia, improve the ocular adjustment function of children, and its safety is high. Key words: Child; Myopia; Orthokeratologic procedures; Depth perception; Intraocular pressure

Digital Asthenopia: Portuguese Group of Ergophthalmology Survey.

Given the increasing use of electronic devices, and the increasing number of complaints with its use, we intend to evaluate the prevalence of manifestations of dry eye and ocular fatigue in a population of individuals, who use the computer daily to perform all their professional tasks, as well as to correlate these complaints with the number of hours of digital use as well as their possible improvement with behavioural measures and use of tear drops. A total of 77 individuals (154 eyes) were evaluated on two separate days with a 1-month interval. They completed two questionnaires: OSDI and PEG Eye Fatigue. An objective ocular surface assessment was performed: Schirmer test without anesthetic, DR-1a Dry Eye Monitor™, hyperemia evaluation, lacrimal break up, presence of keratitis and lesions in the conjunctiva, as well as near accommodation point and near convergence point. After the first evaluation, the subjects were divided into two groups: group A (< 2 hours of computer working) and group B (> 2 hours of computer working). Some environmental measures to reduce complaints and recommendation of use of artificial tears were explained to the latter. There was a statistically significant difference in the majority of the parameters evaluated in the group B, in relation to the morning period (group A) - tear film (p = 0.032), hyperemia (p < 0.001), BUT (p < 0.001), keratitis (p < 0.001), conjunctival lesion (p = 0.002) and accommodation point (p < 0.001). In the evaluation - one month later - there were no statistically significant differences in any of the parameters analysed in the group A, and in group B there was a decrease in most parameters at the end of that period - Schirmer test (p = 0.005), lacrimal film (p = 0.022), keratitis (p < 0.001), conjunctival lesion (p = 0.005) and fatigue score (p < 0.001). It was thus possible to show the appearance of ocular fatigue and ocular surface changes with prolonged use of computers (> 2 hours) as well as a significant improvement in symptomatology (subjective assessment) as well as of ocular surface changes (objective evaluation) with the implementation of postural measures, regular breaks and use of lubricants. This is the first study, to the best of our knowledge, of digital asthenopia in which, in addition to the subjective evaluation, the presence of ocular surface modifications (objective assessment) were evaluated and the respective improvement with the aforementioned ergophthalmological measures were evaluated. This survey highlights the increased overall level of awareness that we need to have to face the rapid and wide-scale changes driven by the emergence of digital technology and, more particularly, its impact on user's vision and posture. We concluded that the longer we use the electronic devices (more than two hours) the more severe the complaints and rates of ocular surface changes are. Environmental and ocular strategies can attenuate or even eliminate the discomfort caused by this syndrome, and increase professional performance and quality of life.

Binocular Function in Subjects with Orthotropic Duane Retraction Syndrome

ABSTRACTIntroduction and Purpose: The aim of this study is to evaluate binocular vision parameters such as near point of accommodation (NPA), near point of convergence (NPC), fusional vergence ranges in subjects with orthotropic Duane retraction syndrome (DRS) and to compare with normal age-matched controlsPatients and Methods: A total of 24 subjects (14 Type 1, 2 Type 2, 8 Type 3 DRS) who were diagnosed to have DRS and 15 normals were included in the study. The following binocular vision parameters were assessed in all subjects: amount of the deviation (for near and distance in all gazes), NPC, NPA, positive and negative fusional vergence (PFV and NFV) reserve and stereopsis.Results: Accommodative amplitude was normal in subject with DRS (median (95% confidence interval (CI):15D (11.9–18.1)) compared to age-matched controls. However, NPC was significantly receded (median [95% CI]:17 cm [14.4–19.6]). PFV reserve and NFV reserve were reduced in subjects with DRS. Subjects with Type 3 DRS have poor PFV reserve and NFV reserve for distance when compared to Type 1 DRS (p = 0.009 and 0.006 respectively). Stereopsis was poor in the subjects with DRS (p < 0.001).Conclusion: Subjects with DRS have good accommodation, but have poor convergence and fusional vergence. Stereopsis was noted to be poor as well.

Study of the Amplitude of Accommodation and its Relation to Errors of Refraction: A Hospital Based Study

Background: The unique ability of the eye to vary the refractive power of the lens and to focus on things at a range of distances is called accommodation. The reduction of this ability in which the near point recedes further away from comfortable reading distance is called presbyopia. There is continuing research to understand this process and correct this affliction that affects each and every person at the peak of their productive life. With an aging population, the proportion of people above 40 years is on the rise. This will therefore have public health and economic implications.&#x0D; Materials and Methods: This is a hospital based retrospective study which was conducted in 100 presbyopic patients in age group of 35 to 60 years at outpatient department of ophthalmology in Nobel Medical College and Teaching Hospital, Biratnagar, from 1st October 2016 to 30th March 2017. The amplitude of accommodation was calculated by measuring near point of accommodation with the help of RAF rule and the data collected was subjected to statistical analysis.&#x0D; Results: Out of 100 patients in this study who visited our OPD with presbyopic complains, the no. of hypermetropic patients were highest (56%) and they presented with presbyopic symptoms at an early age as compared to myopes, while the no. of myopic patients were less(13%) and they presented late with presbyopic symptoms. The mean amplitude of accommodation was highest in myopes in all age group (3.35 D in 36-40 year age group which reduced to 2.65 D in 56-60 year age group).There was stastistically significant difference in amplitude of accommodation between myopia and hypermetropia in all age groups except in 56-60 year age group.&#x0D; Conlusion: The amplitude of accommodation is generally higher in myopes in all age groups as compared to hypermetropes and emmetropes and they usually develope presbyopic symtoms later in life.

Clinical feasibility of pinhole glasses in presbyopia.

To investigate the ocular physiologic changes and subjective symptoms of wearing multiple-pinhole glasses in subjects with presbyopia. This prospective study included 32 eligible subjects with presbyopia. Objective ocular functions and a survey of ocular discomfort were performed at baseline. All participants underwent the same examinations after reading while wearing the pinhole glasses and not wearing these glasses at a 1-week interval in random order. The pinhole glasses improved uncorrected distance and near visual acuity in presbyopia. These glasses also required 15% less accommodative power over the near stimulus of 25 cm than did eyes without pinholes. Compared to reading without pinhole glasses, reading with pinhole glasses led to the following changes: increase in monocular near point of accommodation from 4.39 ± 0.78 diopter (D) to 5.19 ± 1.12 D, increase in depth of focus from 1.42 ± 0.44 D to 2.00 ± 0.33 D, and increase in amplitude of fusional convergence from 13.38 ± 6.88 prism D to 21.62 ± 10.00 prism D. In contrast, the reading speed decreased, inter-blink interval increased, tear break-up time shortened, and subjective ophthalmic symptoms worsened with pinhole glasses compared to without. In presbyopia, pinhole glasses improve visual acuity and accommodation-related parameters by pseudo-accommodation and the pinhole effect. However, the low legibility, increased inter-blink interval, and shortened break-up time of pinhole glasses cause an uncomfortable feeling and excessive eye fatigue. Pinhole glasses have strengths and limitations that must be considered to provide appropriate guidance in patients with presbyopia. Clinical trial registration was done at www.ClinicalTrials.gov (identifier: NCT02722291).

Test‐retest reproducibility of accommodative facility measures in primary school children

BackgroundTo determine the test‐retest reproducibility of accommodative facility (AF) measures in an unselected sample of UK primary school children.MethodsUsing ±2.00 DS flippers and a viewing distance of 40 cm, AF was measured in 136 children (range 4–12 years, average 8.1 ± 2.1) by five testers on three occasions (average interval between successive tests: eight days, range 1–21 days). On each occasion, AF was measured monocularly and binocularly, for two minutes. Full datasets were obtained in 111 children (81.6 per cent).ResultsIntra‐individual variation in AF was large (standard deviation [SD] = 3.8 cycles per minute [cpm]) and there was variation due to the identity of the tester (SD = 1.6 cpm). On average, AF was greater: (i) in monocular compared to binocular testing (by 1.4 cpm, p < 0.001); (ii) in the second minute of testing compared to the first (by 1.3 cpm, p < 0.001); (iii) in older compared to younger children (for example, AF for 4/5‐year‐olds was 3.3 cpm lower than in children ≥ 10 years old, p = 0.009); and (iv) on subsequent testing occasions (for example, visit‐2 AF was 2.0 cpm higher than visit‐1 AF, p < 0.001). After the first minute of testing at visit‐1, only 36.9 per cent of children exceeded published normative values for AF (≥ 11 cpm monocularly and ≥ 8 cpm binocularly), but this rose to 83.8 per cent after the third test. Using less stringent pass criteria (≥ 6 cpm monocularly and ≥ 3 cpm binocularly), the equivalent figures were 82.9 and 96.4 per cent, respectively. Reduced AF did not co‐exist with abnormal near point of accommodation or reduced visual acuity.ConclusionsThe results reveal considerable intra‐individual variability in raw AF measures in children. When the results are considered as pass/fail, children who initially exhibit normal AF continued to do so on repeat testing. Conversely, the vast majority of children with initially reduced AF exhibit normal performance on repeat testing. Using established pass/fail criteria, the prevalence of persistently reduced AF in this sample is 3.6 per cent.

Short-term effects of low-concentration atropine eye drops on pupil size and accommodation in young adult subjects

PurposeA single eye drop containing 0.01% atropine every evening has previously been found to inhibit myopia progression in young adults. We have tested the short-term effects of very low-dose atropine eye drops on pupil sizes and accommodation in young adult subjects.MethodsFourteen eyes of young adult subjects participated in the clinical observation. A single eye drop was applied with concentrations of either 0.01%, 0.005%, or 0.001% in the evening. Baseline parameters were measured before atropine application. Changes of pupil sizes, under photopic and mesopic conditions, as well as accommodation amplitudes were observed over the next day and analyzed by paired the Wilcoxon signed-rank test.ResultsThe pupil was significantly dilated 12 h after instillation of 0.01% atropine eye drops, both under photopic (3.3 ± 0.5 mm vs. 4.9 ± 0.9 mm) and mesopic (4.8 ± 0.7 mm vs. 6.1 ± 0.7 mm) conditions. Pupil sizes recovered over the day but were still significantly larger in the evening, compared to the baseline parameters measured on the day before (3.9 ± 0.5 mm vs. 5.3 ± 0.6 mm). The subjective near point of accommodation was reduced from 8.0 ± 2.4 to 6.6 ± 2.8 dpt in the morning and to 7.0 ± 2.9 dpt in the evening. At 0.005%, the pattern of results remained still similar, although the magnitude of the effects was generally smaller. At 0.001%, pupil sizes were still weakly significantly larger in the morning.ConclusionsAt a dose of 0.01%, clinically significant short-term effects were detected on pupil size and accommodation for at least 24 h. At the lowest dose of 0.001%, only tiny effects on pupil size were detectable.

The Influence of the 4 weeks Intake of Water-soluble &lt;i&gt;Perilla frutescens&lt;/i&gt; var. acuta Extract on Refractive Error and Visual Function

Purpose : The purpose of this study is to find how it influences on refractive error and visual function by intaking water soluble Perilla frutescens var. acuta (PFA) extract for 4 weeks. Method : After the permission of the institutional review board of medical devices (IRB Permission No.: DSGOH-042), This study was tested on 30 adult men and women. Two hours after PFA or placebo was taken in, smart device based VDT work had been done for 2 hours. And then, the results before and after PFA intake were compared with those in control group. Result : As a result, the PFA intake group tended to improve Spherical Equivalent Refractive Error statistically and significantly(p=0.001, p=0.000). Compared to the placebo intake group, the PFA intake group had statistically significant improvements in the near point of convergence and the near point of accommodation(p=0.007, p=0.001, p=0.001, p=0.000). According to the test on binocular accommodative facility, the PFA group showed a more significant rise after intake than before intake(p=0.021). The placebo group had no significant difference. Also, there was no significant difference between the two groups(p=0.876). After intake of PFA or placebo for 4 weeks, the safety before and after intake was evaluated. As a result, the two intake groups had no abnormal reaction. It was judged that taking in water-soluble PFA extract was safe to the human body. Conclusion : PFA increased activity of ciliary body muscles more than placebo. Therefore, it is considered to suppress a rise in refractive error and to improve convergence, accommodation, and asthenopia.

Near Point of Convergence in Iranian Schoolchildren: Normative Values and Associated Factors

ABSTRACTPurpose: To determine the distribution of near point of convergence (NPC) and its related factors in 6 to 12-year-old children. Methods: In a cross-sectional study in 2015, the urban and rural children of Shahroud, north of Iran, were sampled. All rural schoolchildren were invited to the study, and in the urban area, we conducted random cluster sampling. Examinations included measurement of uncorrected and corrected visual acuity, manifest, subjective, and cycloplegic refraction. NPC and near point of accommodation (NPA) were measured with the best optical correction. Results: Of the 6624 sampled schoolchildren, 5620 participated in the study, and after applying the exclusion criteria, the final analysis was conducted on data from 5444 students; their mean age was 9.24 ± 1.71 years (6–12 years) and 53.6% (n = 2918) of them were male. Mean NPC was 8.08 cm [95% confidence interval (CI): 7.96–8.19]; 8.07 cm (95% CI: 7.92–8.22) in males and 8.08 cm (95% CI: 7.91–8.25) in females (p = 0.954). NPC significantly recessed with age (p < 0.001). Mean NPC in emmetropic, myopic, and hyperopic children were 8.13, 7.04, and 8.23 cm, respectively (p < 0.001). The multiple linear regression model revealed significant associations for NPC with age (coefficient = 0.10, 0.95% CI: 0.05–0.15, p < 0.001), spherical equivalent refraction (coefficient = 0.17, 95% CI: 0.10–0.24, p < 0.001), and NPA (coefficient = 0.83, 0.95% CI: 0.76–0.90, p < 0.001). Conclusion: Mean NPC in 6–12-year-old Iranian children was 8.08 cm, which is worse than values reported in previous studies. Mean NPC showed a slight recession with age. Myopic schoolchildren had the least remote and hyperopes had the most remote NPC values. More remote values of NPA were associated with receded NPC.

Changes in Visual Function According to the Addition of Center-near Designed Multifocals and Utilization as Contact Lenses for Fatigue

Purpose: To compare changes in visual function according to single vision and additions of center-near simultaneous vision multifocal contact lenses and investigate the use as a functional contact lens for fatigue. Methods: Twenty young adult subjects(40 eyes, 26.63±4.36 years) participated in this study. Mean spherical refractive errors were–3.38±2.57 D, mean cylinderical errors were–0.46±0.31 D and mean spherical equivalent errors were -3.61±2.64 D. Subjects visited four times and wore single vision, multifocal LOW, MID, and HIGH addition lenses for each visit. They were asked to watch a video with subtitles on a cell phone (4.7 inches) at 40 cm for 60 minutes in order to induce accommodation. After that, MEM, distance and near contrast visual acuity (100% and 10%), near range of clear vision, near point of accommodation, near point of convergence, accommodative facility and stereoacuity were measured and subjective satisfaction was evaluated. Results: As the addition increased, MEM tended to increase and near point of accommodation decreased(p 0.05). Satisfaction with distance vision showed the highest score in single vision contact lenses. Conclusion: As the addition increases, an increase in MEM and a decrease in near point of accommodation are verified. However, differences in the other tests were mostly not significant. Therefore, in order to use the multifocal contact lenses as functional contact lenses, it may be necessary to trance changes in visual function after wearing for a longer period of time.

Accommodation, Convergence, and Stereopsis in Dyslexic Schoolchildren.

BACKGROUND:Previous studies have shown a correlation between reading problems and binocular function, but few studies have assessed visual skills in dyslexic students, particularly in Iranian Farsi-language students. This study is aimed to determine some of the binocular functions of dyslexic children and compare it with a group of age, sex, and social class-matched control children.MATERIALS AND METHODS:We conducted a case–control study on 27 dyslexic children and 40 age, sex, and social class-matched control children (all between 7 and 13 years old) in grades one to six. This study was performed at three elementary schools in Tehran, Iran. Monocular and binocular near point of accommodation (NPA) were measured using the subjective push-up method, near point of convergence (NPC) was determined using the standard push-up technique, and stereoacuity was tested with the Titmus stereotypes in all of the children.RESULTS:Mean NPA of the right eye was 6.90 cm in dyslexic group and 5.98 cm in the control group (P = 0. 003). Mean NPA of the left eye in dyslexic children was 7.32 cm and in the control group was 6.23 cm (P = 0. 003). Mean binocular NPA was 6.66 cm in dyslexic and 6 cm in the control group (P = 0. 049). However, mean NPC (P = 0.33) and mean stereoacuity (P = 0.785) did not differ significantly between the dyslexic and control groups.CONCLUSION:Our findings showed a reduced monocular and binocular NPA in dyslexic children so that this function should be assessed by an optometric clinician in children with dyslexia.

Influence of spectral distribution on accommodation—vergence and reading performance

Background: To assess the influence of different spectral energy distribution on accommodation, vergence and reading performance. Methods: A Randomized experimental study was conducted after getting the approval of the Ethical Committee of University of Hyderabad. Forty participants with an age group of 18–21 years was integrated, out of which 50% was male and 50% was female. Subjects with emmetropia and no history of ocular pathology were included in the study. Near point of accommodation (NPA) & near point of convergence (NPC) was measured with the help of royal air force (RAF) ruler followed by near visual task of a readability passage. Results: A statistically significant result was obtained when reading rate, reading speed and NPC was compared among different spectral distribution of light (P Conclusions: This study concluded that reading performance (reading rate and reading speed) and NPC has a significance change if we use inappropriate lighting during visual tasks. It will cause visual fatigue and strain after sustained near work. In addition, tungsten spectral energy influences the convergence which can also show an impact on reading and near visual tasks because of its brightness and miosis. Prolonged reading and working under this lighting can cause convergence disorders and visual fatigue.

Amelioration of Visual Display Terminal-induced Ocular Fatigue by Aqueous Extracts of &lt;i&gt;Perilla frutescens &lt;/i&gt;var. acuta

In this study, we investigated the effects of Perilla frutescens var. acuta aqueous extract (PFA) on eyestrain using in vitro, ex vivo, and clinical tests. We confirmed the antioxidant activity of compounds present in the extract by using high-performance liquid chromatography. PFA contains antioxidant compounds such as rosmarinic acid, luteolin-7-O-glucuronide, and apigenin-7-O-glucuronide, and has been shown to inhibit reactive oxygen species generation in C2C12 muscle cells. In an ex vivo study, PFA inhibited the carbachol (100 μM)-induced contraction of ciliary muscle from rabbit eyeball. We then investigated the mechanism by which PFA caused muscle relaxation and found that it effectively increased cyclic GMP production and inhibited PDE5A activity, but did not affect the cyclic AMP pathway, in cultured human aortic smooth muscle cells. In addition, PFA (50, 100, and 200 µg/mL) dose-dependently decreased basal intracellular calcium in smooth muscle cells and attenuated the endothelin-1-stimulated increase in intracellular calcium. Finally, we performed a clinical study to evaluate the effects of PFA on the near point of accommodation (NPA) after visual display terminal (VDT) work. Thirty participants were randomized to either PFA (500 mg/day) or placebo, and intake for one consecutive week. NPA was evaluated before and after 2 h of VDT work, and was found to be improved in the PFA-treated group. Thus, our findings show that PFA may ameliorate visual fatigue.

Visual demands and visual fatigue among ophthalmologists.

Visual demands, especially for near vision, are becoming increasingly more frequent at the workplace, and might cause visual fatigue or asthenopia. The tasks performed by ophthalmologists involve visual effort, raising interest in their study within the context of occupational health. To estimate the prevalence of visual complaints and its relationship to work demands among ophthalmologists at a university hospital in Lisbon. Occurrence of visual fatigue symptoms was assessed by means of a symptom questionnaire - College of Optometrists in Vision Development Quality of Life (COVD-QoL) - and through the identification of near points of accommodation and convergence. Schirmer's test was used to assess tear production. The results were analyzed by means of descriptive statistics, Spearman's coefficient and the Wilcoxon test for p<0.05. Most among the 27 analyzed physicians reported visual fatigue (n=25), dry eyes and frequent blinking (n=27). Schirmer's test evidenced differences at the end of the working day and the near points of accommodation and convergence indicated occurrence of visual fatigue. The results showed significant differences between the beginning and the end of the working day among ophthalmologists, with occurrence of visual fatigue at the end of the working day. These findings point to the need to implement a health surveillance program to prevent occupational visual disorders.

Modeling Visual Symptoms and Visual Skills to Measure Functional Binocular Vision

Obtaining a clear image of the world depends on good eye coordination (“binocular vision”). Yet no standard exists by which to determine a threshold for good vs poor binocular vision, as exists for the eye chart and visual acuity. We asked whether data on the signs and symptoms related to binocular vision are sufficiently consistent with children's self-reported visual symptoms to substantiate a construct model of Functional Binocular Vision (FBV), and then whether that model can be used to aggregate clinical and survey observations into a meaningful diagnostic measure. Data on visual symptoms from 1,100 children attending school in Los Angeles were obtained using the Convergence Insufficiency Symptom Survey (CISS); and for more than 300 students in that sample, 35 additional measures were taken, including acuity, cover test near and far, near point of convergence, near point of accommodation, accommodative facility, vergence ranges, tracking ability, and oral reading fluency. A preliminary analysis of data from the 15-item, 5-category CISS and 15 clinical variables from 103 grade school students who reported convergence problems (CISS scores of 16 or higher) suggests that the clinical and survey observations will be optimally combined in a multidimensional model.

Factors Associated with Visual Fatigue from Curved Monitor Use: A Prospective Study of Healthy Subjects.

PurposeTo investigate the factors associated with visual fatigue using monitors with various radii of curvature.MethodsTwenty normal healthy adults (8 men, 12 women; mean age, 26.2 ± 2.5 years) prospectively watched five types of monitors including flat, 4000R, 3000R, 2000R, and 1000R curved monitors for 30 min. An experienced examiner measured the ophthalmological factors including near point of accommodation (NPA), near point of convergence (NPC), refraction, parameters during pupil response at light and saccadic movement just before and after the visual tasks. The questionnaires about subjective ocular symptoms were also investigated just before and after the visual tasks.ResultsThe NPA increased after the visual tasks with a flat monitor compared with the curved monitors, with the 1000R curved monitor showing the smallest change (p = 0.020). The NPC increased for every monitor after the visual tasks; the largest increase occurred with the flat monitor (p = 0.001). There was no difference in refractive error, pupil response, or saccadic movement in the comparison of before and after the visual tasks. Among the nine factors in the questionnaire, the score of “eye pain” was significantly higher for the flat monitor versus the 1000R curved monitor after the visual tasks (p = 0.034).ConclusionsWe identified NPA, NPC, and eye pain as factors associated with visual fatigue. Also, the curvature of the monitor was related to the visual fatigue.

Effectiveness of a Virtual Reality Head-Mounted Display System-based Developmental Eye Movement Test

By transplanting the Developmental Eye Movement (DEM) test chart to a virtual reality head-mounted display (VR HMD) system, this study sought to evaluate the effectiveness of the DEM test for measuring dynamic visual acuity.Thirty-nine adults aged 20–39 years of both genders were the subjects of the study. After undergoing measurement of their visual function, through medical questionnaire, interpupillary distance, near point of convergence (NPC), near point of accommodation (NPA), and far and near phoria, the correlation between the tests was analyzed performing DEM vertical, horizontal test and VR HMD DEM (VHD) vertical, horizontal test.NPC and NPA decreased significantly after the VHD test, while phoria did not. The horizontal was quicker than the vertical in the DEM test, and vice versa in the VHD test. DEM was quicker than VHD in both the vertical and horizontal directions. There was no notable difference in error frequency between DEM and VHD. In terms of DEM and VHD test, there was no notable difference in the short-range IPD and subjective symptoms of the top 10 and bottom 10 subjects. There was also no notable difference between the exercise and non-exercise groups and the game and non-game groups.The performance time for VHD, in which the chart must be read while moving the body, was longer than that of DEM. Therefore, based on the consistency of the results of both tests and the lack of a difference in error frequency and subjective symptoms, the VHD equipment proposed in this thesis is as effective as dynamic visual acuity measurement equipment. In addition, the lack of a difference between the exercise and non-exercise groups and the game and non-game groups demonstrated that the amount of exercise and game by an ordinary person does not influence their dynamic visual function.

Pattern of Change in Accommodation and its Correlation with Mydriasis in Young Emmetropes After Instillation of Tropicamide Phenylephrine Eye Drops

Cycloplegics relax accommodation by blocking the action of ciliary muscles. The mydriasis obtained with these drugs is expected to be related to the degree of cycloplegia. This study evaluates the change in accommodation in young emmetropes and its correlation with mydriasis post instillation of tropicamide phenylephrine eye drops. A prospective descriptive study. Young adults of age group 18-22 years with uncorrected visual acuity of 6/6, near vision N6 and no asthenopic symptoms were included in the study. Age of the subject, NPA (near point of accommodation), NPC (near point of convergence), AA (accomodation amplitude), objective refraction with Autorefractometer, pupillary size and near vision (NV) were noted. The study group included 25 cases; mean age of 20.54 years (SD 1.046years). The amount of accommodation relaxed by drug ranged from 2.75D to 4.50 D. NPA, NPC, AA were inversely proportional to accommodation relaxed (p=0.00). The rate of change of pupillary dilatation and cycloplegia differed. The cycloplegic effect had a positive correlation with the increase in the visual angle; but was independent of the mydriatic effect.