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Background: Given the lack of standardization in stimulus types for assessing accommodation, we aimed to evaluate accommodative response (AR) and Zernike coefficients using four different stimuli. Methods: Sixteen healthy subjects aged 22–32 years participated. Four black transilluminated stimuli (Snellen 6/12 "E", 6/6 "e", Maltese Cross 6/12 "X", 6/6 "x") were used to stimulate accommodation from 0 D to 5 D, in 1 D increments, using the irx3 aberrometer. From the results, AR was calculated with Seidel defocus and the change in Zernike coefficient value between the non-accommodative state and the fully accommodative state (5 D) was determined. Results: Larger pupils were observed with stimulus "E" (p-value < 0.05). The mean AR at the maximum accommodative level (5 D) for the different stimuli was −1.88 ± 1.00 for "E", −2.60 ± 1.44 for "X", −2.00 ± 1.32 for "e", and −2.40 ± 1.27 for "x". No statistically significant differences were found between AR and Zernike coefficients with the four different accommodative stimuli (p-value > 0.05, one-way ANOVA). Conclusions: The study evaluated accommodative stimulus design and size on AR and Zernike coefficients and found no significant differences. However, stimuli with higher spatial frequencies ("e" and "E") provided larger ARs compared to the other stimuli. [ABSTRACT FROM AUTHOR]

Background: Given the lack of standardization in stimulus types for assessing accommodation, we aimed to evaluate accommodative response (AR) and Zernike coefficients using four different stimuli. Methods: Sixteen healthy subjects aged 22–32 years participated. Four black transilluminated stimuli (Snellen 6/12 “E”, 6/6 “e”, Maltese Cross 6/12 “X”, 6/6 “x”) were used to stimulate accommodation from 0 D to 5 D, in 1 D increments, using the irx3 aberrometer. From the results, AR was calculated with Seidel defocus and the change in Zernike coefficient value between the non-accommodative state and the fully accommodative state (5 D) was determined. Results: Larger pupils were observed with stimulus “E” (p-value < 0.05). The mean AR at the maximum accommodative level (5 D) for the different stimuli was −1.88 ± 1.00 for “E”, −2.60 ± 1.44 for “X”, −2.00 ± 1.32 for “e”, and −2.40 ± 1.27 for “x”. No statistically significant differences were found between AR and Zernike coefficients with the four different accommodative stimuli (p-value > 0.05, one-way ANOVA). Conclusions: The study evaluated accommodative stimulus design and size on AR and Zernike coefficients and found no significant differences. However, stimuli with higher spatial frequencies (“e” and “E”) provided larger ARs compared to the other stimuli.

PURPOSE: To measure the pupillary dynamics and accommodative response in individuals with mild traumatic brain injury (mTBI) as compared to age‑matched controls. MATERIALS AND METHODS: This prospective comparative study was carried out at the neuro‑optometry clinic of a tertiary eye care hospital. Sixty‑three subjects with a history of mTBI and ninety age‑matched controls were enrolled in this study. Subjects in the age range of 18–35 years were included in the study. A comprehensive neuro‑optometric assessment was performed followed by pupillary dynamics and accommodation response measurements using NeurOptics® pupillary light reflex™‑3000 and Grand-Seiko WAM-5500 binocular accommodation auto ref/keratometer | shigiya machinery works LTD. RESULTS: A statistically significant difference was noticed for constriction percentage (%): 32.73 ± 9.20 versus 39.93 ± 7.36 (P < 0.001), average constriction velocity (mm/s): 2.24 ± 0.85 versus 2.62 ± 0.68 (P = 0.002), maximum constriction velocity (mm/s): 3.82 ± 1.33 versus 4.42 ± 0.93 (P = 0.004) and T75 (recovery period to 75% of the baseline pupillary diameter in sec): 1.38 ± 0.36 versus 2.0 ± 0.82 (P < 0.001) in mTBI compared to age‑matched controls. A statistically significant difference was noted for accommodative response (in D) as well as in the sample as compared to age‑matched controls: −1.12 ± 0.64 versus − 1.39 ± 0.47 (P < 0.001). CONCLUSION: Pupillary constriction velocities and accommodative response are significantly affected in mTBI. These findings have important clinical implications in being able to understand the visual symptoms following an mTBI. [ABSTRACT FROM AUTHOR]

PURPOSE: To measure the pupillary dynamics and accommodative response in individuals with mild traumatic brain injury (mTBI) as compared to age-matched controls. MATERIALS AND METHODS: This prospective comparative study was carried out at the neuro-optometry clinic of a tertiary eye care hospital. Sixty-three subjects with a history of mTBI and ninety age-matched controls were enrolled in this study. Subjects in the age range of 18–35 years were included in the study. A comprehensive neuro-optometric assessment was performed followed by pupillary dynamics and accommodation response measurements using NeurOptics® pupillary light reflex™-3000 and Grand-Seiko WAM-5500 binocular accommodation auto ref/keratometer | shigiya machinery works LTD. RESULTS: A statistically significant difference was noticed for constriction percentage (%): 32.73 ± 9.20 versus 39.93 ± 7.36 (P < 0.001), average constriction velocity (mm/s): 2.24 ± 0.85 versus 2.62 ± 0.68 (P = 0.002), maximum constriction velocity (mm/s): 3.82 ± 1.33 versus 4.42 ± 0.93 (P = 0.004) and T75 (recovery period to 75% of the baseline pupillary diameter in sec): 1.38 ± 0.36 versus 2.0 ± 0.82 (P < 0.001) in mTBI compared to age-matched controls. A statistically significant difference was noted for accommodative response (in D) as well as in the sample as compared to age-matched controls: −1.12 ± 0.64 versus − 1.39 ± 0.47 (P < 0.001). CONCLUSION: Pupillary constriction velocities and accommodative response are significantly affected in mTBI. These findings have important clinical implications in being able to understand the visual symptoms following an mTBI.

Purpose: To assess and compare the changes produced by the two most commonly used substances, alcohol and cannabis, on accommodation dynamics. Methods: A total of 38 young participants (19 females) were enrolled in the study. They were assigned to two groups: a cannabis group (N = 19) and an alcohol group. Participants in the cannabis group underwent two randomized sessions: a baseline session and a session after smoking a cigarette. Participants in the alcohol group underwent three randomized sessions: a baseline session, a session after the intake of 300 ml of red wine (Alcohol 1), and other after the ingestion of 450 ml of wine (Alcohol 2). For the accommodation assessment, the open-field autorefractor WAM-5500 was used. Results: The decrease of the mean velocity of the accommodative response produced by Alcohol 2 condition was significantly greater than that observed for Alcohol 1 and Cannabis (p = 0.046). The direction of the accommodation (near-distance and distance-near) had no effect on the deterioration of the accommodation dynamics following substance use. The target distance had a significant effect on the decrease of the mean velocity following substance use (p = 0.002). The decrease of the amplitude of the accommodative response was associated with a decrease of the peak velocity (p = 0.004) and the increase of the accommodative lag (p < 0.001). Conclusions: A moderate-high dose of alcohol impairs accommodation dynamics to a greater extent that lower dose of alcohol or smoked cannabis. The deterioration of the accommodation mean speed was higher for a shorter target distance. [ABSTRACT FROM AUTHOR]

Purpose: to evaluate near visual work performance of those wearing spectacles with Stellest™ lenses and the impact of their continuous wear on refraction changes, accommodation and binocular interaction after 6 months from the start of use. Material and methods. 35 children aged 8-13 with myopia of 3.15 ± 0.19 D were prescribed eyeglasses with Stellest™ lenses. 32 children with myopia of 2.68 ± 0.18 D who used monofocal glasses served as control. Visual performance, refraction, axial length (AL), accommodation and binocular interaction were assessed. Results. According to the Burdon test, the number of errors in counting letters in Stellest™ glasses was 4.5 ± 0.64, whilst in monofocal glasses it was- significantly less, 2.96 ± 0.42 (p < 0.05); the rate of test progress was the same in the two groups. After 6 months from the start of wearing Stellest™ glasses, the objective cycloplegic refraction increased by 0.11 ± 0.04 D, the average year progression rate (YPR) was 0.22 ± 0.08 D. In contrast, the children wearing monofocal glasses showed an average refraction increase of 0.35 ± 0.05 D, and the average YPR value of 0.7 ± 0.09 D. In the Stellest™group, YPG drop was observed in 87 % of cases and averaged 0.95 ± 0.11 D. In the control group, YPR was found to drop in 65 % of cases and averaged 0.49 ± 0.1 D. In the Stellest™ group, AL increased by 0.04 ± 0.02 mm; in the control group, the increase in AL was 2.8 times greater — by 0.11 ± 0.02 mm (p < 0.01). In the Stellest™ group, relative accommodation reserves (RAR) increased by 0.88 ± 0.14 D, which is significantly higher than in the group wearing monofocal glasses, where the increase was 0.39 ± 0.12 D (p < 0.01). No differences were revealed between the groups in objective indicators of accommodation and binocular interaction. Conclusion. Wearing spectacles with Stellest™ lenses for 6 months contributes to slowing down the progression of myopia in children. Over the observation period, the refraction increase in the main group was 3.2 times lower than in the control group, whilst AL growth was 2.8 times lower than that in the control group. The children using spectacles with Stellest™ lenses showed a higher increase in RAR as compared to children wearing monofocal spectacles. The accommodation tone and objective accommodation parameters were essentially the same in both groups. Wearing Stellest™ glasses had no pronounced effect on binocular interaction.

Dual-focus soft contact lenses are effective in slowing myopia progression; however, their influence on near work-induced transient myopia (NITM) remains unknown. When performing a 5-min near task at 20 cm, we observed that dual-focus soft contact lens wear induced greater lags of accommodation and a lower initial NITM than single-vision soft contact lenses, which provides relevant information for better understanding the impact of using this optical design on the accommodative function. NITM has been proposed as a myogenic factor, although it is a matter of debate by the scientific community. The main objective of this study was to assess the short-term effect of wearing dual-focus soft contact lenses for myopia control on the steady-state accommodative response and NITM. Twenty-four young myope adults wore, on two different days, dual-focus and single-vision soft contact lenses, while the accommodative response was dynamically measured with an open-field autorefractor during the execution of the NITM task. The shift and the time required to recover baseline levels in the refractive state after performing the 5-min near task (20 cm) were the main dependent variables. We found a lower magnitude of accommodation during the execution of the near task with the dual-focus in comparison to the single-vision soft contact lenses (p < 0.001). There was a lower initial NITM with the dual-focus when compared to the single-vision lenses (corrected p-value = 0.003, Cohen's d = 0.68), but no statistically significant differences were observed for decay duration (p = 0.984). Dual-focus soft contact lens wear causes a reduced accommodative response during a near task, and an initial small myopic shift at distance after a 5-min period of near viewing. The current findings may help to understand the mechanisms involved in myopia control with this optical strategy. [ABSTRACT FROM AUTHOR]

Introduction: There is scientific evidence that an individual's beliefs and/or expectations play a role in the behavioural and physiological response to a given treatment. This study aimed to assess whether the dynamics of the accommodative response and stereoacuity are sensitive to experimentally induced placebo and nocebo effects. Methods: Nineteen healthy university students performed three experimental sessions (placebo, nocebo and control) in randomised order, with the dynamics of the accommodative response (magnitude and variability), stereoacuity and subjective measures being assessed in all sessions. For the experimental manipulation, participants ingested an inert capsule that was alleged to have positive (white capsule, placebo condition) or negative (yellow capsule, nocebo conditions) effects on the human physiology. In the control condition, participants did not ingest a capsule. Results: The data revealed that the variability of accommodation was sensitive to experimentally induced placebo and nocebo effects, showing a more stable accommodative response for the placebo compared with the nocebo condition (corrected p‐value = 0.04, Cohen's d = 0.60). In addition, better stereoacuity was found with the placebo, compared with the nocebo (corrected p‐value = 0.01, Cohen's d = 0.69) and control (corrected p‐value = 0.03, Cohen's d = 0.59) conditions. Successful experimental manipulation was confirmed by the analysis of subjective perceptions. Conclusions: These findings provide evidence that manipulating expectations about the efficacy of an inert treatment affect the dynamics of the accommodative response (variability of accommodation) and stereoacuity. The results have important applications in both clinical and research outcomes, where individuals´ beliefs/expectations could modulate the visual function. [ABSTRACT FROM AUTHOR]

The virtual lens model has important value in ophthalmic research, clinical diagnosis, and treatment. However, the establishment of personalized lens models and the verification of accommodation accuracy have not been paid much attention. We proposed a personalized lens model establishment and the accommodation accuracy evaluation method based on sweep-source optical coherence tomography (SS-OCT). Firstly, SS-OCT is used to obtain a single lens image in the maximum accommodation state. After refraction correction, boundary detection, and curve fitting, the central curvature radius, thickness, and lens nucleus contour of the anterior and posterior surfaces of the lens were obtained. Secondly, a personalized finite element model improved from Burd's model was established using these individual parameters, and the adaptation process of the lens model was simulated by pulling the suspensory ligament. Finally, the shape and refractive power changes of the real human lens under different accommodation stimuli were collected and compared with the accommodation process of the finite element model. The results show that the accommodation process of the finite element model is highly consistent with that of the real lens. From the un-accommodation state to the maximum-accommodation state, the difference rate of all geometric and refractive parameters between the two is less than 5%. Thus, the personalized lens finite element model obtained by the calibration and correction of the existing model can accurately simulate the regulation process of a specific human lens. This work helps to provide a valuable theoretical basis and research ideas for the study of clinical diagnosis and treatment of related diseases. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to test the accommodative lag and mechanical tension theories for myopia by assessing the influence of the lag of accommodation on axial elongation by using three different near targets that are known to influence the accommodative response differently. Methods: Forty‐two young adults were recruited for the study. Axial length was measured using a non‐contact biometer, before and immediately after a 15 minute visual task, with one of the three near targets placed 20 cm from the eye: reading text from a paper, reading text from a smartphone and watching a video on a smartphone. The accommodative response was determined using an open‐field autorefractor while the participants viewed the near target monocularly. Results: Lag of accommodation was significantly different for the three tasks: watching a video (mean ± standard error of the mean [SEM] 0.92 ± 0.10 D); reading text on the smartphone (0.59 ± 0.08 D); and reading text on paper (0.24 ± 0.09 D). There was a significant (p < 0.05) increase in axial length after reading text from a paper (10.5 ± 1.9 µm after 15‐min) and reading text from a smartphone (5.2 ± 2.7 µm), but not after watching a video on a smartphone (−0.5 ± 1.7 µm, p = 0.47). Vitreous chamber depth increased significantly more with the reading tasks compared with watching a video (reading text from a paper and smartphone: 33.9 ± 4 µm and 31.7 ± 4 µm vs. watching a video on a smartphone: 14.6 ± 5 µm, p = 0.001). Conclusion: Greater changes in axial length associated with the low lag of accommodation failed to support the theory that lag of accommodation during visual tasks could be the trigger for axial elongation. Reading on paper and smartphone at the closest reading distance may stimulate high accommodative demand and axial elongation as a consequence, possibly due to increased "ciliary muscle tension" during accommodation. [ABSTRACT FROM AUTHOR]

Purpose: Cannabis is the most widely consumed illicit drug worldwide. It has been suggested that cannabis could generate blurred vision during reading tasks. The goal of this study was to objectively assess the acute effects of smoking cannabis on the dynamics of ocular accommodation. The influence of other factors, including target distance and the direction of accommodation, as well as personal characteristics, were also analysed. Methods: Nineteen young people who were occasional cannabis users participated in the study (mean age 22.53 [3.12] years). Their usage profiles were evaluated by means of the Cannabis Use Disorders Identification Test‐revised (CUDIT‐r). The dynamics of the accommodative response were evaluated using an open‐field auto refractor (Grand Seiko WAM‐5500). The participants completed two different experimental sessions, one week apart, and in random order (baseline session and after smoking cannabis). During these sessions, the amplitude of the response (D), mean velocity (D/s), peak velocity (D/s), response time (s), accommodative lag (D) and accommodation variability (D) were measured. Results: The results indicated that cannabis use had a significant main effect on the mean accommodation/disaccommodation velocity (F1,13 = 7.21; p = 0.02; ηp2 = 0.396). Cannabis consumption also interacted significantly with other factors. Response time showed a significant two‐way interaction between condition × target distance (F1,13 = 11.71; p = 0.005; ηp2 = 0.474) and condition × accommodation direction (F1,13 = 8.71; p = 0.01; ηp2 = 0.401). For mean velocity, two‐way interactions were found between condition × age (F1,13 = 6.03; p = 0.03; ηp2 = 0.354), condition × CUDIT‐r score (F1,13 = 6.03; p = 0.03; ηp2 = 0.356) and condition × target distance (F1,13 = 7.20; p = 0.02; ηp2 = 0.396). Conclusions: These findings suggest that cannabis use can alter the accommodation process, although further studies should be carried out to explore the role of attention deficits. According to these results, certain daily activities that depend on an accurate accommodative function may be affected by cannabis use. [ABSTRACT FROM AUTHOR]

Purpose: This paper discusses the accommodative relaxation of myopic adults using a simple double-mirror design. This optical design can extend the viewing distance to 2.285 m and can magnify the image up to 3.386 times, and it results in the accommodative relaxation of a single human eye. By using this optical design, accommodative relaxation may improve eye fatigue and, furthermore, it may delay the progression of myopia. Method: This study recruited 32 subjects with an average age of 20.8 ± 0.95 years old. After an examination of their refractive status, disposable contact lenses with a corresponding refractive error were fitted, and the dynamic accommodative response and change in pupil size were measured by using an open-field autorefractor. The subjects gazed at two different viewing distances. First, they gazed at a real object, which was placed 0.4 m in front of them. Second, the subjects gazed at a virtual image through a double-mirror system at a distance of 2.285 m. The dynamic accommodative responses and pupil size data were collected under these two viewing distance conditions. Results: When the subjects gazed at a real object that was 0.4 m away, or a virtual image that was 2.285 m away, the mean value of the accommodative response was 1.69 ± 0.31 D or 0.11 ± 0.05 D, and the pupil size was 3.79 ± 0.49 mm or 4.09 ± 0.72 mm, respectively. The accommodative response decreased, and the pupil size increased when using the double-mirror system, and therefore, accommodative relaxation can be achieved by using this new optical design. Conclusions: In the present study, we first successfully proposed a simple optical design to relax the accommodation, and the fluctuations of the accommodation response were stable, with an extended viewing distance of 2.285 m. This design may be applied for the improvement of visual function in applications such as the reduction of asthenopia and the control of myopia. [ABSTRACT FROM AUTHOR]

The virtual lens model has important value in ophthalmic research, clinical diagnosis, and treatment. However, the establishment of personalized lens models and the verification of accommodation accuracy have not been paid much attention. We proposed a personalized lens model establishment and the accommodation accuracy evaluation method based on sweep-source optical coherence tomography (SS-OCT). Firstly, SS-OCT is used to obtain a single lens image in the maximum accommodation state. After refraction correction, boundary detection, and curve fitting, the central curvature radius, thickness, and lens nucleus contour of the anterior and posterior surfaces of the lens were obtained. Secondly, a personalized finite element model improved from Burd’s model was established using these individual parameters, and the adaptation process of the lens model was simulated by pulling the suspensory ligament. Finally, the shape and refractive power changes of the real human lens under different accommodation stimuli were collected and compared with the accommodation process of the finite element model. The results show that the accommodation process of the finite element model is highly consistent with that of the real lens. From the un-accommodation state to the maximum-accommodation state, the difference rate of all geometric and refractive parameters between the two is less than 5%. Thus, the personalized lens finite element model obtained by the calibration and correction of the existing model can accurately simulate the regulation process of a specific human lens. This work helps to provide a valuable theoretical basis and research ideas for the study of clinical diagnosis and treatment of related diseases.

Purpose. This paper presents the results of objective accommodation measurements taken from patients with concomitant strabismus. Materials and methods. The experiment was performed on 32 patients (64 eyes) ranging from 5-26 years of age (in average 13.5 ± 1.43 years old): 26 patients with esotropia (52 eyes), 2 patients with exotropia (4 eyes), and 4 patients with secondary strabismus (8 eyes). 8 of the patients (10 eyes) identified amblyopia of various degrees. 51 of the eyes exhibited hyperopia from 0.5 to 9.5 D according to spherical equivalent refraction, and 16 eyes exhibited myopia from 0.25 to 10 D. The control group consisted of 30 children with hyperopia (16 eyes), emmetropia (10 eyes), and myopia of various degrees (34 eyes) without strabismus. To determine specific indicators of objective accommodation - Binocular (BAR) and Monocular Accommodative Response (MAR), the options of consensual accommodation, as well as the resting state of accommodation (RSA) in concomitant strabismus - the open field autorefkeratometer Grand Seiko WR - 5100K was used. The degree of deviation was determined using the Hirschberg test and a handheld ophthalmoscope. Results. The MAR ranged between normal and drastically lower values averaging at -1.85 ± 0.1 D. The BAR averaged at 2.23 ± 0.1 D and was greater than the MAR in half of the measured cases (61.3 %). The interocular difference in the BAR reached 2.95 D, averaging at 0.87±0.14 D. The interocular difference in MAR reached 0.85 D, averaging at 0.34 ± 0.07 D. In the control group, BAR values were lower than MAR; the interocular differences consisted of 0.13 ± 0.01 and 0.08 ± 0.01 D, respectively. Highly amblyopic eyes had equal and drastically decreased BAR and MAR (average of -0.16 ± 0.07 D); in the fellow eyes, BAR and MAR were higher -1.08 ± 0.14 and -1.0 ± 0.14 D, respectively. In esotropic eyes, RSA was higher in the misaligned eye, and in exotropic eyes, RSA was lower in the misaligned eye. The straight and concomitant responses were decreased: until -1.43 ± 0.1 and -1.32 ± 0.15 D respectively. In the control group, the straight and concomitant accommodative response was similar (average of -1.77 ± 0.17 D in both cases). Conclusion. The results showed the characteristic changes in accommodative parameters as a result of heterotropia, not typical for orthotropic patients with various types of refraction // Russian Ophthalmological Journal, 2017; 1: 49-54. doi: 10.21516/2072-0076-2017-10-1-49-54.

Purpose: This paper discusses the accommodative relaxation of myopic adults using a simple double-mirror design. This optical design can extend the viewing distance to 2.285 m and can magnify the image up to 3.386 times, and it results in the accommodative relaxation of a single human eye. By using this optical design, accommodative relaxation may improve eye fatigue and, furthermore, it may delay the progression of myopia. Method: This study recruited 32 subjects with an average age of 20.8 ± 0.95 years old. After an examination of their refractive status, disposable contact lenses with a corresponding refractive error were fitted, and the dynamic accommodative response and change in pupil size were measured by using an open-field autorefractor. The subjects gazed at two different viewing distances. First, they gazed at a real object, which was placed 0.4 m in front of them. Second, the subjects gazed at a virtual image through a double-mirror system at a distance of 2.285 m. The dynamic accommodative responses and pupil size data were collected under these two viewing distance conditions. Results: When the subjects gazed at a real object that was 0.4 m away, or a virtual image that was 2.285 m away, the mean value of the accommodative response was 1.69 ± 0.31 D or 0.11 ± 0.05 D, and the pupil size was 3.79 ± 0.49 mm or 4.09 ± 0.72 mm, respectively. The accommodative response decreased, and the pupil size increased when using the double-mirror system, and therefore, accommodative relaxation can be achieved by using this new optical design. Conclusions: In the present study, we first successfully proposed a simple optical design to relax the accommodation, and the fluctuations of the accommodation response were stable, with an extended viewing distance of 2.285 m. This design may be applied for the improvement of visual function in applications such as the reduction of asthenopia and the control of myopia.

Introduction: This paper presents a comparative study of accommodation, pseudoaccommodation (PA) and higher order optical aberrations (HOAs) in children and young people with myopia and hyperopia. Materials and methods: 123 myopic eyes (mean -5.27 ±1.6 D) and 53 hyperopic eyes (mean +3.1 ±1.15 D) of 88 patients aged 5--24 (mean age 12.5 ±0.7) were examined. The parameters measured included objective accommodative response, and relative accom- modation reserves. Pseudoaccomodation amplitude (PA) was determined as the difference between the calculated additional plus lens 3.0 D and the power of the minimum plus lens which allowed reading in cycloplegic conditions (1% cyclopentolate hydrochloride x 2) at a distance of 33 cm. Higher order aberra- tions (root mean square -- RMS), vertical and horizontal trefoil, vertical and horizontal coma (coma7, coma8), and spherical aberration (SA) were also measured. Results: Objective and subjective accommodation parameters were significantly lower in myopia as compared to hyperopia, while wavefront aberrations (RMS HOA, vertical trefoil, coma7) and PA were significantly higher. Aberration and accommodation parameters were found to be differently related in myopia and hyperopia. In myopia, RMS and vertical coma were directly correlated with accommodation, while vertical trefoil and SA were directly correlated with PA. In hyperopia, vertical trefoil was directly correlated to accommodation and PA, while ver- tical coma was negatively correlated with PA, and horizontal trefoil and SA were negatively correlated with accommodation. Spherical aberration measured under cycloplegia correlated dif- ferently with accommodation in myopic and hyperopic patients. In myopia, no correlation with the objective accommodation response was found, while direct correlation with the PA value could be detected. Conversely, in hyperopia, a negative correlation with objective accommodation response and no correlation with PA was detected. A significantly higher value of SA in myopic patients with a broader amplitude of PA was observed. In hyperopic eyes, in contrast to myopic ones, SA was significantly decreasing, moving to negative values in high amplitude PA. Conclusions: Parameters of accommodation were decreased and HOAs, PA were increased in myopia. Accommodation and wave- front parameters exhibit different relationships with each other in myopic and hyperopic eyes. The detected features should be taken into consideration when developing correction methods which are targeted toward refractogenesis. [ABSTRACT FROM AUTHOR]

The aim of the present study was to test if the exposure to transcranial direct current stimulation (tDCS) would change the excitability of the visual cortex and influence an accommodative response of the ocular lens. Twenty four subjects were divided into two groups: real-stimulation of the occipital cortex in which participants were exposed to real stimulation (1 mA for 12 min), and sham in which subjects were tested with placebo stimulation. The results showed that tDCS might indeed influence accommodative response. The strongest and most evident effect was observed when a 3.0 D accommodative stimulus was used: anodal tDCS increased but cathodal tDCS - decreased the accommodative response. The second finding was that the effect of stimulation was dependent on the examined eye. The right eye with slightly lower visual acuity and weaker accommodative response in pre-test, responded more strongly than the left eye. The short-time tDCS might modulate excitability of the neurons in visual cortex and eye sensitivity, reflected in the change of accommodative response. The tDCS method may be considered a technique that could reinforce conventional active visual training to improve accommodative functions. [ABSTRACT FROM AUTHOR]