Accommodative Microfluctuations Research Articles

Optical coherence tomography quantifies gradient refractive index and mechanical stiffness gradient across the human lens

BackgroundAs a key element of ocular accommodation, the inherent mechanical stiffness gradient and the gradient refractive index (GRIN) of the crystalline lens determine its deformability and optical functionality. Quantifying the GRIN profile and deformation characteristics in the lens has the potential to improve the diagnosis and follow-up of lenticular disorders and guide refractive interventions in the future.MethodsHere, we present a type of optical coherence elastography able to examine the mechanical characteristics of the human crystalline lens and the GRIN distribution in vivo. The concept is demonstrated in a case series of 12 persons through lens displacement and strain measurements in an age-mixed group of human subjects in response to an external (ambient pressure modulation) and an intrinsic (micro-fluctuations of accommodation) mechanical deformation stimulus.ResultsHere we show an excellent agreement between the high-resolution strain map retrieved during steady-state micro-fluctuations and earlier reports on lens stiffness in the cortex and nucleus suggesting a 2.0 to 2.3 times stiffer cortex than the nucleus in young lenses and a 1.0 to 7.0 times stiffer nucleus than the cortex in the old lenses.ConclusionsOptical coherence tomography is suitable to quantify the internal stiffness and refractive index distribution of the crystalline lens in vivo and thus might contribute to reveal its inner working mechanism. Our methodology provides new routes for ophthalmic pre-surgical examinations and basic research.

Effects of Smart Glasses on the Binocular Vision and Ocular Fatigue

Purpose: The aim of this study was to investigate binocular visual function and ocular fatigue after the use of smart glasses.Methods: A total of 17 healthy volunteers (age range 13-45 years) were examined for ocular fatigue before and after watching videos for 20 minutes with a binocular smart glasses device. Subjective ocular fatigue was evaluated using a Virtual Reality Symptom Questionnaire (VRSQ). Objective fatigue was measured using the high-frequency component of accommodative microfluctuation. Accommodation amplitude was measured using the push-up method. Changes in the spherical equivalent were also measured using an autorefractometer. Strabismus angles were measured at distant (6 m) and near fixation (33 cm) in primary. Contrast sensitivity tests using the Pelli-Robson chart was performed. Accommodative convergence/accommodation (AC/A) ratio was measured by gradient methods.Results: Subjective ocular fatigue, as indicated by the VRSQ scores, significantly increased after using the smart glasses (<i>p</i> = 0.001). The high-frequency component of accommodative microfluctuation increased in both eyes (<i>p</i> < 0.05). Accommodation amplitude was decreased, and temporary myopia was observed in both eyes (all <i>p</i> < 0.05). However, there was no significant increase in general fatigue according to the VRSQ. Parameters including strabismus angle, AC/A ratio, and contrast sensitivity showed no significant differences before and after smart glasses usage (<i>p</i> > 0.05).Conclusions: The increased high-frequency component of accommodative microfluctuation, decreased accommodation amplitude, and elevated ocular fatigue scores measured by the VRSQ indicate a potential association between the use of smart glasses and ocular fatigue. Further investigations are warranted to explore methodologies for mitigating ocular fatigue and elucidating the potential risk of temporary myopic shifts arising from the utilization of smart glasses.

Effect of myopia management contact lens design on accommodative microfluctuations and eye movements during reading

BackgroundSoft contact lenses have been developed and licensed for reducing myopia progression. These lenses have different designs, such as extended depth of focus (EDOF) and dual focus (DF). In this prospective, double-masked, cross-over study, different lens designs were investigated to see whether these had impact on accommodative microfluctuations and eye movements during reading. MethodsParticipants were fitted with three lenses in a randomised order; a single vision (SV) design (Omafilcon A2; Proclear), a DF design (Omafilcon A2; MiSight), and an EDOF lens design (Etafilcon A; NaturalVue),. Accommodative microfluctuations were measured at 25 cm for at least 60s in each lens, using a Shin-Nippon SRW-5000 autorefractor adapted to continuously record accommodation at 22Hz. Eye movement data was collected with the Thomson Clinical Eye Tracker incorporating a Tobii Eye bar. Eye movements include fixations per row, fixations per minute, mean regressions per row, total number of regressions, and total rightward saccades. Accommodation data was analysed using power spectrum analysis. Differences between the lenses were compared using a related sample two-way Friedman test. ResultsTwenty-three participants (18–29 years) were recruited to take part. The average mean spherical error was −2.65D ± 1.42DS, with an average age of 23.4 ± 3.5 years. No significant difference for accommodative microfluctuations was found. Significant differences were found for fixations per row (P = 0.03), fixations per minute (P = 0.008), mean regressions per row (P = 0.002), and total number of regressions (P = 0.002), but not total rightward saccades (P = 0.10). Post-hoc analysis indicated the EDOF lens results were significantly different from the other lenses, with more regressive eye movements observed. ConclusionsRegressive saccades appear to increase when wearing EDOF lens designs, which may impact visual comfort. Further studies in children, over a longer period of adaptation are necessary to assess the potential impact of this finding on daily reading activities in children.

Spasm of Near Reflex in a Patient with Autism Spectrum Disorder: A Case Report

Spasm of near reflex (SNR) involves intermittent spasm of one or more of the three near reflex components. Psychiatric disorders are one cause of SNR. We describe a patient with SNR diagnosed with autism spectrum disorder (ASD). A 36-year-old male with esotropia since childhood was referred due to headache and dizziness. The alternate prism cover test showed 30 prism diopters at both near and distant fixation. Four months after his first visit, he was diagnosed with ASD. Twenty-nine months after his first visit, he underwent strabismus surgery to treat concomitant esotropia. Postoperatively, the angle of strabismus improved but remained variable. Because the angle of strabismus varied, we suspected SNR; the diagnosis was performed after evaluating the patient’s microfluctuations in accommodation with Speedy-K. However, it was difficult to distinguish convergence spasm from concomitant esotropia in this patient because he has had a history of esotropia since childhood. In a patient with concomitant esotropia, if the symptoms are not exclusively due to strabismus, SNR should be suspected. Although the relationship between SNR and the pathology of ASD is unknown, it is possible that patients with ASD are more likely to develop SNR.

Prevalence of Accommodative Microfluctuations in Eyes after Cataract Surgery.

We aimed to evaluate the existence of accommodative microfluctuations in eyes after cataract surgery. This retrospective observational cohort study included 1160 eyes of 713 patients (mean age: 72.5 ± 8.3 years) who underwent phacoemulsification, intraocular lens insertion, and an evaluation of accommodative microfluctuations with an autorefractometer. Patients with posterior segment disorders resulting in visual acuity impairment and those with unavailable medical information were excluded. High-frequency components (HFCs), between 1.0-2.3 Hz, based on fast Fourier transform analysis of the accommodative microfluctuation data were examined at postoperative 2-3 (2 M) and 6 months (6 M). The relationships between the HFCs and patient age, manifest refraction, and axial length were analyzed. Increased HFC values (>65) were observed at a constant rate after cataract surgery, with prevalence rates of 33.4% at 2 M and 34.7% at 6 M. Postoperatively, at 2 M, increased HFC values were significantly more common for eyes with axial length ≥26 mm than for those with axial length <26 mm (p = 0.0056). However, they were not significantly correlated to age or postoperative manifest refraction. At 2 M postoperatively, increased HFC values presented more frequently in eyes with a greater axial length; hence, the precise detection and understanding of postoperative accommodative spasms in high myopia patients is important.

Impact of temporal fluctuations in optical defocus on visual acuity: Empirical results and modeling outcomes.

Optical defocus in human eyes is seldom steady during naturalistic steady-state viewing. It fluctuates by 0.3 to 0.5 diopters (D) from accommodative microfluctuations and by 1.5 to 2.5D in dysfunctions such as spasm of near reflex, both with ≤2Hz low-pass frequency spectra. This study observed losses in monocular visual acuity of cyclopleged adults who encountered varying amplitude (0.25-2.0D) and temporal frequency (0.25-2.0Hz) combinations of sinusoidal defoci induced using an electrically tunable lens. Visual acuity, recorded for 300-ms flashes of Sloan optotype presentation using the method of constant stimuli, deteriorated with defocus amplitude at a rate steeper for lower than higher temporal frequencies. A template matching model of acuity, incorporating optical and neural low-pass filters, neural noise, and a cross-correlated decision operator, showed the best match with empirical data when acuity was governed by the minimum defocus available during optotype display. This criterion minimized acuity loss for higher temporal frequencies due to the increased probability of zero-defocus encounters within the presentation duration. Other decision criteria such as defocus averaging across the entire or parts of the presentation duration yielded less satisfactory results. These results imply that vision loss in humans encountering broadband time-varying defocus is dictated by the dominant low frequencies, with higher frequencies largely compensated using the least defocus decision strategy.

Wavefront sensing for objective assessment of vision therapy efficacy: Preliminary results

The aim of this study was to use wavefront sensing to objectively evaluate the effects of vision therapy in subjects with insufficiency (AI) and infacility of accommodation (AINF). Aberrometry was performed with a Shack-Hartmann wavefront aberrometer for different accommodative stimuli in one subject with AI and one with AINF before and after treatment with vision therapy (VT). A control subject received a placebo treatment. Real-time accommodative response, accommodation and disaccommodation reaction time, accommodative microfluctuations and root mean square of higher order aberrations were compared before and after VT/placebo. VT was effective and wavefront sensing can be used to detect AI and AINF and evaluate these subjects during VT.

Effect of Spectacle Lenses with Highly Aspherical Lenslets on Binocular Vision and Accommodation in Myopic Children with and without Intermittent Exotropia.

Purpose To evaluate the influence of spectacle lenses with highly aspherical lenslets (HAL) on binocular vision and accommodation in myopic children with intermittent exotropia (IXT) and compare the changes after wearing HAL in binocular vision and accommodation in myopic children with or without IXT. Method Forty myopic subjects aged 8–12 years were recruited: 20 with IXT and 20 visually normal children. Stereoacuity, phoria, accommodative facility, fusional vergence, vergence facility, near point of convergence, amplitude of accommodation, and accommodative response (AR) were measured by wearing HAL or single vision spectacle lenses (SVL) in a random order after adapting for 20 minutes. Accommodative microfluctuation (AMF) was defined as the standard deviation of AR. Changes in binocular vision and accommodation after wearing HAL were compared between the two groups. Results No significant differences were found in binocular vision after wearing HAL versus SVL in either group (all P > 0.05). A greater AMF was found after wearing HAL than after wearing SVL in both groups (0.04 D, 95% confidence interval (CI), 0.03 to 0.05 D, P < 0.001 for the IXT group; 0.05 D, 95% CI, 0.03 to 0.07 D, P < 0.001 for the visually normal group); however, the other accommodation parameters did not change significantly (all P > 0.05). There were no differences in the changes after wearing HAL in any parameter between the two groups (all P > 0.05). Conclusion HAL did not significantly change the binocular vision and accommodation for myopic children with or without IXT except for AMF in the short term.

Seeing the future: Predictive control in neural models of ocular accommodation.

Ocular accommodation is the process of adjusting the eye's crystalline lens so as to bring the retinal image into sharp focus. The major stimulus to accommodation is therefore retinal defocus, and in essence, the job of accommodative control is to send a signal to the ciliary muscle which will minimize the magnitude of defocus. In this article, we first provide a tutorial introduction to control theory to aid vision scientists without this background. We then present a unified model of accommodative control that explains properties of the accommodative response for a wide range of accommodative stimuli. Following previous work, we conclude that most aspects of accommodation are well explained by dual integral control, with a “fast” or “phasic” integrator enabling response to rapid changes in demand, which hands over control to a “slow” or “tonic” integrator which maintains the response to steady demand. Control is complicated by the sensorimotor latencies within the system, which delay both information about defocus and the accommodation changes made in response, and by the sluggish response of the motor plant. These can be overcome by incorporating a Smith predictor, whereby the system predicts the delayed sensory consequences of its own motor actions. For the first time, we show that critically-damped dual integral control with a Smith predictor accounts for adaptation effects as well as for the gain and phase for sinusoidal oscillations in demand. In addition, we propose a novel proportional-control signal to account for the power spectrum of accommodative microfluctuations during steady fixation, which may be important in hunting for optimal focus, and for the nonlinear resonance observed for low-amplitude, high-frequency input. Complete Matlab/Simulink code implementing the model is provided at https://doi.org/10.25405/data.ncl.14945550.

Objective characteristics of accommodation in present-day schoolchildren with progressive myopia

Purpose: to study the accommodative function in contemporary schoolchildren using the method of computer accommodography.Material and methods. 74 children aged 10–16 (54 with different degrees of myopia and the control group of 20 emmetropic children) were tested on a Righton Speedy-K ver. MF-1 computer accommodograph to determine the accommodative response to accommodation stimulus (by calculating the coefficient of the accommodative response, CAR) and the contraction of ciliary muscle fibers (by determining the microfluctuation coefficient, CMF).Results. In groups of patients with emmetropia and weak myopia, CAR and CMF were found to exceed the normal values. The low myopia group demonstrated especially pronounced changes. In moderate and high myopia, the CAO is significantly lower than in low myopia or emmetropia, while the CMF also exceeds normal values.Conclusion. The spastic component of accommodation is of great importance in the pathogenesis of progressive myopia of present-day schoolchildren, which is expressed in the strengthening of the accommodation response with regard to the accommodation stimulus and pathological frequency increase of accommodative microfluctuations.

Variability of Accommodative Microfluctuations in Myopic and Emmetropic Juveniles during Sustained near Work.

Near work has been considered to be a potential risk factor for the onset of myopia, but with inadequate evidence. Chinese adolescents use digital devices for near work, such as study and entertainment purposes, especially during the COVID-19 pandemic. In this study, we investigated the influence of prolonged periods of near work on accommodative response, accommodative microfluctuations (AMFs), and pupil diameter between juvenile subjects of myopia and emmetropia. Sixty juveniles (30 myopes and 30 emmetropes) were recruited for the study. Participants were instructed to play a video game on a tablet PC at a distance of 33.3 cm for 40 min. Accommodative response and pupil diameter were measured with an open-field infrared refractometer in High-speed mode. Parameters of the subjects were measured once every 10 min, and analyzed by one-way repeated measure ANOVA for variation tendency. There were no significant differences between emmetropia and myopia groups with respect to age and sex (p > 0.05). The low-frequency component (LFC) of myopia gradually increased with time, reached a peak at 30 min, and then declined (p = 0.043). The high-frequency component (HFC) of myopia also reached a peak at 30 min (p = 0.036). Nevertheless, there was no significant difference in the LFC (p = 0.171) or HFC (p = 0.278) of the emmetropia group at each time point. There was no significant difference in the mean and standard deviation of the accommodative response and pupil diameter both in emmetropic and myopic juveniles. Compared with juvenile emmetropes, myopes exhibit an unstable tendency in their accommodation system for prolonged near work at a certain time point. Accommodative microfluctuations may be a sensitive, objective indicator of fatigue under sustained near work in juvenile myopes.

Analysis of the therapeutic effect of Midrimax® on accommodation overstrain in patients with orthokeratological correction

Purpose: a year-long study of the accommodative function of the eye in patients with orthokeratologic (OK) correction, and the analysis of the therapeutic effect of the drug Midrimax® on accommodation overstrain in patients with OK lenses.Material and methods. The study group included 88 patients (176 eyes) with progressive myopia and OK lenses. The control group included 108 patients (216 eyes) who had optical correction with monofocal glasses and soft contact lenses. During the year, the accommodative function of patients of these two groups was studied using a Speedy-I Accommodograph that involved the calculation of accommodative coefficients: the coefficient of accommodative response and the coefficient of accommodative microfluctuations (CMF). The accommodographic examination in the study group was conducted before wearing OK lenses, after 1 month, 6 months and a year of wearing OK lenses. In the control group, the study of accommodation was carried out after 6 and 12 months. To assess the nature of the effect of Mydrimax® on accommodation overstrain, 70 children (140 eyes) with OK correction and varying degrees of accommodation overstrain were examined. A control group and a study group of 35 people (70 eyes) each were formed. In the study group, Mydrimax® was instilled daily before going to bed, 2 drops in each eye for 30 days. The study of accommodation on the Speedy-i accommodograph was conducted before treatment and after 30 days of treatment.Results. Before wearing OK lenses, 50.5 % had normal accommodative function, 33 % revealed lack of accommodation and only 16.5 % had various degrees of accommodation overstrain. After 6 months of using OK lenses, the accommodation pattern changed: 33.5 % of patients retained normal accommodation function, in 15.5 % of cases accommodation insufficiency decreased, but the number of patients (51.0 %) with accommodation overstrain of varying degrees increased. During the next 6 months of wearing OK lenses, the state of accommodation practically did not change: 39.5 % retained normal accommodative function, 10.5 % had insufficient accommodation and 49.5 % accommodation overstrain. The course of treatment with Mydrimax® for 30 days in patients with OK correction was effective at any degree of accommodation overstrain.Conclusion. The use of OK lenses stimulates accommodation by reducing the number of patients with accommodation insufficiency and increasing the number of patients with accommodation overstrain. The use of Mydrimax® for a course of 30 days is effective in patients with OK correction at any degree of accommodation overstrain.

Effects of Extended Viewing Distance on Accommodative Response and Pupil Size of Myopic Adults by Using a Double-Mirror System.

Purposes: This study discussed the accommodative response and pupil size of myopic adults using a double-mirror system (DMS). The viewing distance could be extended to 2.285 m by using a DMS, which resulted in a reduction and increase in the accommodative response and pupil size, respectively. By using a DMS, the reduction of the accommodative response could improve eye fatigue with near work. Method: Sixty subjects aged between 18 and 22 years old were recruited in this study, and the average age was 20.67 ± 1.09. There were two main steps in the experimental process. In the first step, we examined the subjects’ refraction state and visual function, and then fitted disposable contact lenses with a corresponding refractive error. In the second step, the subjects gazed at an object from a viewing distance of 0.4 m and at a virtual image through a DMS, respectively, and the accommodative response and pupil size were measured using an open field autorefractor. Results: When the subjects gazed at the object from a distance of 0.4 m, or gazed at the virtual image through a DMS, the mean value of the accommodative response was 1.74 ± 0.43 or 0.16 ± 0.47 D, and the pupil size was 3.98 ± 0.06 mm or 4.18 ± 0.58 mm, respectively. With an increase in the viewing distance from 0.4 m to 2.285 m, the accommodative response and pupil size were significantly reduced about 1.58 D and enlarged about 0.2 mm, respectively. For three asterisk targets of different sizes (1 cm × 1 cm, 2 cm × 2 cm, and 3 cm × 3 cm), the mean accommodative response and pupil size through the DMS was 0.19 ± 0.16, 0.27 ± 0.24, 0.26 ± 0.19 D; and 4.20 ± 1.02, 3.94 ± 0.73, 4.21 ± 0.57 mm, respectively. The changes of the accommodative response and pupil size were not significant with the size of the targets (p > 0.05). In the low or high myopia group, the accommodative response of 0.4 m and 2.285 m was 1.68 ± 0.42 D and 0.21 ± 0.48 D; and 1.88 ± 0.25 D and 0.05 ± 0.40 D, respectively. The accommodative response was significantly reduced by 1.47 D and 1.83 D for these two groups. The accommodative microfluctuations (AMFs) were stable when a DMS was used; on the contrary, the AMFs were unstable at a viewing distance of 0.4 m. Conclusions: In this study, the imaging through a DMS extended the viewing distance and enlarged the image, and resulted in a reduction in the accommodative response and an increase in the pupil size. For the low myopia group and the high myopia group, the accommodative response and pupil size were statistically significantly different before and after the use of the DMS. The reduction of the accommodative response could be applied for the improvement of asthenopia.

The effect of image resolution of display types on accommodative microfluctuations.

PurposeTo determine whether accommodative microfluctuations (AMFs) are affected by the image resolution of the display type being observed. The effect of refractive error is also examined.MethodsTwenty participants, (10 myopes and 10 emmetropes) observed a target on four different displays: paper, smartphone, e‐reader and visual display unit screen (VDU), whilst their accommodative responses were measured using a continuous recording infrared autorefractor. The accommodative response and AMF measures comprising low frequency components (LFC), high frequency components (HFC) and the root mean square (RMS) of the AMFs were analysed.ResultsA significant increase in LFC power was observed for the paper stimulus when compared to the VDU and smartphone conditions. Myopes demonstrated a significantly higher LFC and mean accommodative response compared to emmetropes across the four displays. A significant difference in the mean AR between the displays with the lowest and highest resolution was found. A higher mean AR was found with higher resolution of the image. The HFC and RMS accommodation were not affected by display type.ConclusionThe mean accommodative response and the mean LFC power appear to respond differently depending on the type of display in use. Higher resolution devices showed a reduced lag of accommodation to the accommodative demand; however, this may cause a lead of accommodation in myopes for higher resolution display types.

Comparison of accommodation and accommodative micro-fluctuation after implantable collamer lens and LASIK surgery for myopia

BackgroundTo longitudinally analyze and compare the accommodative micro-fluctuation (MFs) and accommodative function between myopic patients after implantable collamer lens (ICL) implantation and laser in situ keratomileusis (LASIK).MethodsPatients with good corrected visual acuity (20/20 or better) and underwent ICL (V4c) and LASIK for myopic-correction (ranging from − 3.50 to − 8.50 D) were recruited. Refraction, amplitude of accommodation (AMP), accommodative lag, higher-order aberration (HOA), and MFs were recorded before surgery and 1 and 3 months after surgery. The ACOMEREF automatic refractor was used to measure the high-frequency component (HFC) of the MFs, which suggested tension of the ciliary muscle.ResultsThe study comprised 120 eyes. At 3 months after surgery, the manifest refractive spherical equivalent of the ICL and LASIK groups were − 0.11 and − 0.09 D, respectively (p = 0.46). HFC values were significantly higher at 1 month (p = 0.03) and 3 months postoperatively (p = 0.03) in the ICL group compared to that in the LASIK group. The ocular HOA of the ICL group was 1.08 ± 0.43 μm, which was lower than the LASIK group 1.45 ± 0.54 μm (p = 0.01). No significant differences in AMP and accommodative lag between groups were noted at 3 months postoperatively. There was a positive correlation between HFC and vault of the ICL lens (r2 = 0.14, p = 0.005). There were no correlations between HFC and ocular HOA and postoperative MRSE in the two groups (all p>0.05).ConclusionsThe HFC increased significantly after an early period of ICL implantation compared to laser in situ keratomileusis for myopic correction, which indicated increased tension of the ciliary muscle, and had a positive correlation on the vault of the ICL lens; However, studies with longer follow-up time and more structural evaluation are needed.

Simultaneous measurements of foveal and peripheral aberrations with accommodation in myopic and emmetropic eyes.

The difference in peripheral retinal image quality between myopic and emmetropic eyes plays a major role in the design of the optical myopia interventions. Knowing this difference under accommodation can help to understand the limitations of the currently available optical solutions for myopia control. A newly developed dual-angle open-field sensor was used to assess the simultaneous foveal and peripheral ( nasal visual field) wavefront aberrations for five target vergences from -0.31 D to -4.0 D in six myopic and five emmetropic participants. With accommodation, the myopic eyes showed myopic shifts, and the emmetropic eyes showed no change in RPR. Furthermore, RPR calculated from simultaneous measurements showed lower intra-subject variability compared to the RPR calculated from peripheral measurements and target vergence. Other aberrations, as well as modulation transfer functions for natural pupils, were similar between the groups and the accommodation levels, foveally and peripherally. Results from viewing the same nearby target with and without spectacles by myopic participants suggest that the accommodative response is not the leading factor controlling the amplitude of accommodation microfluctuations.

Visual fatigue induced by watching virtual reality device and the effect of anisometropia

The effect of small anisometropia on visual fatigue when using virtual reality (VR) devices was investigated. Participants (n = 34) visited three times. In the first visit, VR exposure (10 min) was conducted with the full correction of the refractive error of both eyes. Experimental anisometropia was induced by adding a + 1.0 dioptre spherical lens either on the dominant eyes in the second visit or on the non-dominant eyes in the third visit. At each visit, the participants played a predetermined video game using a head-mounted display VR for 10 min. Visual fatigue was assessed before and after playing VR game using the Virtual Reality Symptom Questionnaire (VRSQ) and high-frequency component of accommodative microfluctuation. Results showed that watching VR induced significant increase of VRSQ score, significant decrease in the maximum accommodation power and objective increase in visual fatigue. Experimental anisometropia induction either on the dominant or non-dominant eyes did not aggravate visual fatigue. Practitioner summary: Mild differences in refractive error (up to 1.0 dioptre) between both eyes do not significantly increase ocular fatigue by viewing virtual reality device (10 min). The impact of small anisometropia may be limited in developing a virtual reality device. Abbreviations: VR: virtual reality; VRSQ: virtual reality symptom questionnaire; HMD: head-mounted display; HFC: high-frequency component

Correction of Low-Moderate Hyperopia Improves Accommodative Function for Some Hyperopic Children During Sustained Near Work.

PurposeThis study investigated whether refractive correction improved accommodative function of hyperopic children while engaged in two sustained near activities.MethodsSustained accommodative function of 63 participants (aged 5–10 years) with varying levels of uncorrected hyperopia (>/= +1.00 D and < + 5.00 D spherical equivalent in the least hyperopic eye) was measured using eccentric infrared photorefraction (PowerRef 3; PlusOptix, Germany). Binocular accommodation measures were recorded while participants engaged in 2 tasks at 25 cm for 15 minutes each: an “active” task (reading small print on an Amazon Kindle), and a “passive” task (watching an animated movie on liquid crystal display [LCD] screen). Participants also underwent a comprehensive visual assessment, including measurement of presenting visual acuity, prism cover test, and stereoacuity. Reading speed was assessed with and without hyperopic correction. Refractive error was determined by cycloplegic retinoscopy.ResultsHyperopic refractive correction significantly improved accuracy of accommodative responses in both task (pairwise comparisons: t = −3.70, P = 0.001, and t = −4.93, P < 0.001 for reading and movie tasks, respectively). Accommodative microfluctuations increased with refractive correction in the reading task (F(1,61) = 25.77, P < 0.001) but decreased in the movie task (F(1,59) = 4.44, P = 0.04). Reading speed also significantly increased with refractive correction (F(1,48) = 66.32, P < 0.001).ConclusionsCorrecting low-moderate levels of hyperopia has a positive impact on accommodative performance during sustained near activity in some schoolchildren. For these children, prescribing hyperopic correction may benefit performance in near vision tasks.

Comparison of Accommodation Microfluctuations before and after 5 Minutes Near Digital Reading in the dark with Night Shift Mode

This study aims to compare the accommodation microfluctuation before and after 5 mins of digital reading in the dark with night shift mode. Nineteen subjects were recruited using convenient sampling and a crossover design was used to compare the accommodation microfluctuations two viewing conditions. There was no significant difference in accommodation microfluctuations before and after 5-minute reading with night shift mode and without night shift mode. The insignificant findings in the accommodation microfluctuation comparison seemed to suggest that Night Shift Mode did not display as an advantage in controlling accommodation. Keywords: Digital eye strain, accommodation microfluctuations, digital reading, night shift mode. eISSN: 2398-4287© 2020. The Authors. Published for AMER ABRA cE-Bsby e-International Publishing House, Ltd., UK. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning &amp; Surveying, Universiti Teknologi MARA, Malaysia. DOI: https://doi.org/10.21834/ebpj.v5iSI3.2568

Changes in accommodation dynamics after alcohol consumption, for two different doses.

The purpose of this work was to evaluate possible changes in accommodation dynamics caused by the intake of different doses of alcohol. A total of 20 emmetropic subjects took part in the study. This involved a baseline session, a session after consuming 300 ml of red wine, and another after consuming 450 ml of the same wine. The accommodation dynamics were characterized for two target vergences (2.5D and 5.0D) using the Grand Seiko WAM-5500 autorefractor, which provided the accommodation and disaccommodation variables. The accommodative facility was measured using flippers of ± 2.00 D. The mean accommodation velocities and velocity peaks were significantly lower after consuming alcohol for the higher intake, particularly for 5.0D (p < 0.05). The response time was significantly higher only for the high-intake condition for 5.0D (p < 0.05). The accommodative microfluctuations were significantly higher for both target vergences for the high-intake condition (p < 0.05). The accommodative facility was significantly impaired in both intake conditions (p < 0.05). The breath alcohol content (BrAC) was correlated with the deterioration of some variables: the accommodative facility (ρ = 0.490), and the velocity peak for 2.5D (ρ = 0.349) and 5.0D (ρ = 0.387). Alcohol intake affects accommodation dynamics, causing deterioration in the mean velocity, velocity peak, response time, accommodative microfluctuations, and accommodative facility, especially for the target vergence of 5.0D and high alcohol dosages.