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Purpose: The goal of this study was to compare the difference in binocular visual function for high and low?moderate myopes before and after femtosecond laser?assisted in situ keratomileusis (FS?LASIK). Methods: Thirty?three subjects (17 males and 16 females) were divided into two groups according to their preoperative refractive errors in spherical equivalent (SE): low?moderate myopia group (SE ??6.00 D) and high myopia group (SE <?6.00 D). The binocular visual function including accommodative amplitude (AA), accommodative facility (AF), positive and negative relative accommodation (PRA and NRA, respectively), horizontal phoria measurement, positive and negative fusion vergence, accommodative–convergence over accommodation (AC/A) ratio, and stereopsis were assessed with the best?corrected vision before patients received FS?LASIK and 7 and 30 days after the surgery. Repeated measures analysis of variance (ANOVA) was applied to study the change in binocular visual function. Results: The AF values in both groups were significantly reduced after 7 days of FS?LASIK (baseline vs. day 7 (mean): high myopia group: 7.85 vs. 5.62 cpm, repeated ANOVA, P = 0.01; low?moderate myopia group: 5.95 vs. 4.40 cpm, repeated ANOVA, P = 0.04). This change returned to the baseline level 30 days after the operation. In addition, the horizontal phoria values in both groups were significantly reduced for both distant (P = 0.019 and P = 0.001, respectively) and near (P = 0.003 and P = 0.049, respectively) 7 days after the operation, but they rebound to preoperative state after 30 days. Conclusion: A transient change in binocular visual function was noticed after 7 days of FS?LASIK operation, which could cause symptoms of asthenopia. Our data showed all the binocular visual functions returned to baseline level after 30 days of operation.
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@#Introduction: The frequency and the trend of smartphone use increase rapidly, and 85% of Malaysians owns a smartphone and spend an average of 187 minutes per day to use the smartphone. Aims: To evaluate the potential effects of smartphone use on Accommodation and Vergence of the users. Methods: A total of 18 articles were selected in this review following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, and the research question was formulated based on the population, intervention, control, and outcomes (PICO) method. This review was registered with PROSPERO (reference number: CRD42022293325). Data Sources: Databases namely PubMed, Web of Science, and Science-Direct were used in the article search using appropriate keywords, phrases, and Medical Subject Heading (MeSH) terms. The inclusion criteria of this review were journal articles published from January 2010 until December 2021 with full articles or abstract in English available. Results: Accommodative function has been reported to changed significantly with 20 minutes of smartphone use, with reduced amplitude, facility, relative and increased lag. In addition, vergence function has been reported to be altered significantly with receded near point of convergence. Conclusion: Smartphone use has an effect on the accommodation and vergence parameters among adults. Assessments of accommodation and vergence parameters need to be conducted in patients with the symptoms of Computer Vision Syndrome to prevent vision problems. Future reviews are required in younger cohorts with various smartphone features.
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@#AIM: To analyze the clinical application of calculated and gradient accommodative convergence/accommodation ratio(AC/A)in different eye positions.<p>METHODS: A total of 127 myopes in ophthalmology were included. The calculated AC/A was obtained by near/distance phoria and the gradient AC/A was obtained by near addition +1.00D. The differences of eye positions of the calculated and gradient AC/A were compared. <p>RESULTS:The calculated AC/A value was higher than the near +1.00D gradient AC/C(<i>P</i><0.01); Comparing the same method in different eye positions revealed that the calculated AC/A and gradient AC/A were significantly different, which has the highest AC/A in the esophoria group and the lowest AC/A in the exophoria group; Comparing the two methods in the same group revealed that the calculated AC/A in the esophoria group and the normal group was higher than the gradient AC/A(<i>P</i><0.01), and there was no significant difference in the AC/A measured by the two methods in the exophoria group(<i>P</i>>0.05).<p>CONCLUSION: The calculated AC/A is higher than the gradient AC/A, especially in patients with esophoria and emmetropia, it is easy to obtain high AC/A values by using the calculation method, resulting in erroneous diagnosis. The gradient method is more recommended.
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AIM:To analyse visual modifications such as amplitude of accommodation, near point of convergence (NPC) reopsis and near phoria associated with asthenopic symptoms after 3D viewing at varying distances. METHODS: A prospective study. Thirty young adults were randomly selected. Each individual was exposed to 3D viewing thrice in a day for a fixed distance and the distance was varied on three consecutive days. Same video of equal duration and different screen sizes were used for every distance. Cyclic 3D mode of K-multimedia (KM) player was used for projecting the 3D video. Different variables like stereopsis, amplitude of accommodation, near point of accommodation, near phoria and asthenopic symptoms were recorded immediately after 3D video viewing. Stereopsis was measured with "Toegepast Natuurwetenschappelijk Onderzoek冶 or"Netherlands Organisation for Applied Scientific Research 冶 ( TNO test ), amplitude of accommodation and NPC were measured using RAF ruler, near phoria was measured using prism bar and a closed ended sample questionnaire was used to know the occurrence of asthenopic symptoms. Statistical analyses were performed using descriptive statistics, paired t-test etc. Qualitative data was analyzed using Chi-square test. RESULTS: For every distance of 40 cm, 3 m and 6 m, amplitude of accommodation was significantly reduced by 0.66 D,1.12 D and 1.44 D. NPC got significantly receded by 0.63 cm, 0.93 cm and 1.23 cm, and the near phoria was significantly increased by 0. 87, and 2. 2 prism dioptres (PD) base-in respectively. It was found that most of the subjects got pain around the eyes, headache and irritation for each viewing distance. This study also revealed that 3D video viewing in theaters may increase the symptoms of headache, watering and irritation. Symptoms like headache,watering,fatigue,irritation and nausea may increase considerably at home environment and symptoms such as headache and watering may cause significant discomfort by 3D viewing using a laptop. CONCLUSION: There was a significant difference in amplitude of accommodation, NPC, near phoria and asthenopic symptoms before and after viewing a 3D video and also at three viewing distances. There was a predominant occurrence of asthenopic symptoms after 3D video viewing at different distances.
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@#AIM:To comprehensively identify the effects of persistent viewing of 3D TV on visual function and find out the relationship between different visual functional parameters.<p>METHODS: The following four visual functional parameters: accommodation(accommodative response; accommodative microfluctuation; accommodative facility; PRA, positive relative accommodation; NRA, negative relative accommodation; gradient AC/A, the gradient accommodative convergence to accommodation ratio), vergence(DBI, distance base-in; DBO, distance base-out; NBI, near base-in; NBO, near base-out), phoria(distance and near lateral phoria), and stereopsis were measured for nineteen health participants before and after viewed 2D TV for 90min and 3D TV for 90min.<p>RESULTS: Both compared with the baseline data and the data after 2D viewing, increased near accommodative responses, decreased convergence, changed phoria(more exophoric)at distance were detected after 3D TV viewing(all <i>P</i> <0.05).<p>CONCLUSION: Prolonged viewing of 3D TV will influence human visual function, especially the disruption of the natural relationship between binocular convergence and accommodation induced by conflicting stimulus. Manufacturers and the public should consider the parameters of accommodation, vergence, and phoria as main indicators for detecting the safety of 3D TV.