Accommodative Convergence/accommodation Research Articles

Association of smartphones use, ocular symptoms and binocular dysfunctions in adolescents: a hospital-based cross-sectional study

ABSTRACT Purpose Given the current scenario of increased smartphone use in youth, this study aims to evaluate the proportion of ocular symptoms and binocular dysfunction and their association with smartphone use in adolescents through a hospital-based cross-sectional study. Methods The participants were asked to fill out questionnaires related to smartphone use and symptoms of eyestrain experienced (Balik et al. and Kucer). They were asked about the following seven symptoms: blurring of vision, redness, visual disturbance, secretion, inflammation, lacrimation, and dryness. Each symptom out of the 7, was scored on a scale of 0–1 and was used to calculate an Ocular Symptom Score (OSS) by summing the scores of each symptom.Depending upon the duration of smartphone usage, the participants were classified into four groups: <2 hours/day, 2–4 hours/day, 4–6 hours/day, and >6 hours/day. Binocular functions were assessed using near point of convergence (NPC), near point of accommodation (NPA), Accommodative convergence/Accommodation (AC/A) ratio, dissociated heterophoria, and binocular accommodative facility (BAF). Results A total of 123 smartphone user adolescents, aged 10–19 years were included in this study. The mean age of the study population was 16.58 + 2.8 years, out of which 52.03% were males. Prevalence of ocular symptoms was higher in groups with greater duration of smartphone use (2 to 4, 4 to 6, and >6 hours/day as compared to <2 hours/day: 90.48%, 94.74%, 100% vs. 75% respectively). The mean of NPC was 8.51, it was highest in subjects using smartphones for >6 hours. (p-value = .001). The mean AC/A ratio was 2.83 + 1.03: 1. A low AC/A ratio was associated with a longer duration of smartphone usage (p-value = .0001). The mean of BAF was 7.4 + 3.18 cycles/min, only 30 (24.4%) participants had BAF beyond the normal range (<5 cycles/min). The mean of BAF was lowest in the group with >6 hours/day of smartphone use (p-value < .0001). No significant change was found in NPA and dissociated heterophoria with the duration of smartphone usage. Conclusion Higher duration of smartphone use (>2 hours/day) is associated with various ocular symptoms and binocular dysfunction. However, additional research is necessary to authenticate the results of the study.

Long-term Ocular Alignment and Sensory Outcomes After Medial Rectus Recession for High AC/A Ratio Esotropia.

To report long-term ocular alignment and sensory outcomes after medial rectus recession for high accommodative convergence/accommodation (AC/A) ratio esotropia. The medical records of consecutive patients who had undergone unilateral or bilateral medial rectus recession for high AC/A ratio esotropia and were observed postoperatively for a minimum of 5 years were reviewed retrospectively. A total of 34 patients were included. Twenty-three patients (68%) used bifocals preoperatively. The mean age at surgery was 11.5 ± 4.4 years (range: 2.5 to 19.0 years). The mean postoperative follow-up was 7.5 ± 2.3 years (range: 5.0 to 15.25 years). Overall, 21 patients (62%) had surgical success at their last follow-up visit. Age at surgery, preoperative angle of distance and near deviation, distance-near disparity, and preoperative bifocal wear did not predict motor outcome after surgery. Preoperative presence of peripheral binocular single vision was a significant favorable factor for surgical success. At the last follow-up visit, 21% of patients had a recurrence of high AC/A ratio esotropia and 9% each had consecutive exotropia (intermittent [3%] and constant [6%]) and basic esotropia. Peripheral binocular single vision was achieved in 64% of patients and stereopsis in 28%. Bifocal segment was eliminated postoperatively in 70% of patients. Nearly two-thirds of patients with high AC/A ratio esotropia achieved a successful long-term motor outcome and peripheral binocular single vision, and nearly one-fourth achieved stereopsis. Recurrence of high AC/A ratio esotropia occurred in some patients, and consecutive exotropia and basic esotropia in a few. Bifocal segment was eliminated postoperatively in 70% of patients. [J Pediatr Ophthalmol Strabismus. 20XX;X(X):XX-XX.].

The relationship between accommodative and binocular function with myopia progression in myopic children undergoing orthokeratology

PurposeTo determine the relationship between changes in accommodative and binocular function with myopia progression in myopic children over a two-year follow-up period, and to determine when changes in visual functions stabilized after switching from spectacles to orthokeratology (Ortho-K). MethodsThis prospective, self-controlled study followed thirty-six participants (aged 8–14 years) for two years after they switched from spectacles to Ortho-K. Accommodative and binocular function were assessed prior to and 1, 3, 6, 12, 18 and 24 months after commencing Ortho-K. Measurements included accommodative amplitude, accommodative response, accommodative facility, accommodative convergence/accommodation (AC/A), ocular alignment, positive relative accommodation (PRA), negative relative accommodation (NRA), horizontal vergence range, reading ability and stereoacuity. Myopia progression was quantified by the change in axial length. ResultsOcular alignment, monocular and binocular accommodative facility, and PRA stabilized after 1 month. The distance blur point in the convergence range, the distance break and recovery point in the divergence range, accommodative amplitude, calculated AC/A, stereoacuity and reading ability stabilized within 6 months. After two years of Ortho-K, NRA significantly increased (p = 0.044), while it showed no significant difference after one-year of lens wear (p = 0.49). The distance break point in the convergence range showed no significant difference (p = 0.20), but significantly decreased after one-year (p = 0.005). There were no significant correlations between the change in axial length with changes in accommodative or binocular function (p > 0.05). ConclusionAccommodative and binocular function changed significantly after switching from spectacles to Ortho-K and most of the parameters stabilized within the first 6 months. There was no association between the change in accommodative or binocular function and myopia progression.

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 (&lt;i&gt;p&lt;/i&gt; = 0.001). The high-frequency component of accommodative microfluctuation increased in both eyes (&lt;i&gt;p&lt;/i&gt; &lt; 0.05). Accommodation amplitude was decreased, and temporary myopia was observed in both eyes (all &lt;i&gt;p&lt;/i&gt; &lt; 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 (&lt;i&gt;p&lt;/i&gt; &gt; 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.

The Effect of Cycloplegia on Ocular Alignment and AC/A Ratio.

The present study sets out to investigate the effect of cyclopentolate-induced cycloplegia on distance and near deviation and the accommodative convergence/accommodation (AC/A) ratio. This prospective study was performed on 30 subjects. The inclusion criteria included a lack of any active ocular pathology and systemic diseases, no history of ocular surgery, and nonuse of various medications. Refraction, near and distance deviation were measured for all subjects, and the same examinations were repeated after the administration of two drops of cyclopentolate 1% to both eyes. The obtained data from 30 subjects, including 19 males, with a mean age of 22.53 1.74 years were analyzed. The mean SD of near deviation in dry and cycloplegic conditions were -6.9 8.1 and +6.4 9.1 prism diopters, respectively, which were statistically significant (P 0.001). Distance deviation in cycloplegic conditions demonstrated an average difference of 0.8 prism diopters, compared to dry conditions (P 0.001). AC/A ratios were 4.7 2.5 and 9.7 3.9 (Δ/D) in non-cycloplegic and cycloplegic conditions, respectively, which was a statistically significant difference (P 0.001). The multiple regression indicated that among all under study variables, refraction (B coefficient: -2.4; P 0.001) and near pre-cycloplegic deviation (B coefficient: 0.56; P 0.001) were significantly associated with post-cycloplegic near deviation. The results of this study indicated that cycloplegia causes a considerable esophoric shift in near deviation and a negligible esophoric shift in distance deviation. As a result, the AC/A ratio demonstrated a significant increase due to unequal changes in near and distance deviation.

Preoperative visual function characteristics having an effect on the success of exotropia surgery

Background: There are individual reports on the effect of some preoperative characteristics of visual functions (like convergence, angle of deviation, presence of fusion and type of binocular vision) on the success of exotropia surgery. To date, however, it has not been established what are the major diagnosis-related prognostic factors for the success of surgery for exotropia. Purpose: To identify the preoperative characteristics of visual functions which have an effect on the success of surgery for exotropia. Material and Methods: Of the 59 exotropes (age range, 10 to 21 years) included in this study, 33 had basic constant exotropia (group 1) and 26, intermittent exotropia (group 2). Patients underwent an ophthalmological and ortoptic examination of the motor and sensory systems of the eye. Patients with surgery success (postoperative orthotropes) were compared to those who had a residual exotropia of more than 10 prism diopters (PD) postoperatively in terms of the preoperative accommodative convergence–accommodation (AC/A) ratio, near point of convergence (NPC), distance stereopsis and near stereoacuity threshold. Results: Our analysis of the preoperative NPC, AC/A ratio and stereopsis for the group with postoperative orthotropic alignment and the group with postoperative exotropic alignment found preoperative close to normal values of AC/A ratio (4.0 ± 1.65 PD/D), NPC (8.03 ± 3.02 cm), the presence of distance stereopsis and near stereopsis (passing the 200 second of arc image on the Lang II stereo card) and the absence of medial rectus hypofunction of hyperfunction in 83.05% of patients of the former group. Conclusion: Preoperative close to normal values of AC/A ratio (4.0 ± 1.65 PD/D), NPC (8.03 ± 3.02 cm), the presence of distance stereopsis and near stereopsis (passing the 200 second of arc image on the Lang II stereo card) and the absence of medial rectus hypofunction of hyperfunction can be the factors favoring the success of exotropia surgery.

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

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

Accommodation and vergence function in children using atropine combined with orthokeratology

PurposeThis study aimed to evaluate binocular vision in terms of vergence and accommodative measurements in children treated with 0.01% atropine combined with orthokeratology (OK). MethodsThis was a prospective and randomized controlled clinical trial involving participants aged 8 to 12 years, with a spherical equivalent (SE) ranging from − 1.00 to − 6.00D. Participants were randomly divided into four groups: 1) a combination group using 0.01% atropine solution and OK lens; 2) an OK group using placebo solution and OK lens; 3) an atropine group using 0.01% atropine solution and wearing spectacles; and 4) a control group using placebo solution and wearing spectacles. Binocular vision was determined at baseline and at 3-month visits, with evaluations including horizontal phoria, fusional vergence, the accommodative convergence/accommodation (AC/A) ratio, accommodative lag, and accommodative amplitude (AA). The Wilcoxon signed-rank test was used to compare the changes in binocular vision in each group, and the Kruskal–Wallis test was used for comparisons of four groups. ResultsSixty-two participants completed the study. There was no significant difference in baseline refraction, accommodation or vergence measurements among the groups (all P > 0.05). Three months later, the accommodative lag significantly decreased in the OK group (P = 0.002) but remained unchanged in the other three groups (all P > 0.05). In addition, binocular accommodative facilities and positive relative accommodations increased in the combination and OK groups (both P < 0.05) but remained unchanged in the atropine and control groups (both P > 0.05). Only the participants with esophoria in the OK group had a significant decrease in esophoria (P = 0.008). Moreover, the changes in fusional vergence and AC/A did not significantly differ between the four groups (all P > 0.05). ConclusionAccommodative measurements changed similarly in the groups treated with OK. Changes in vergence measurements after treatment with 0.01% atropine were not significant.

Deterioration of binocular vision after alcohol intake influences driving performance

In this study, we assessed the influence of moderate alcohol intake on binocular vision, vergence system and simulated driving performance by analyzing the interactions between visual deterioration and driving variables. Thirty young healthy subjects were recruited. For the analysis, we measured: visual function (visual acuity and stereoacuity), phorias and fusional reserves. Also, we checked Sheard’s and Percival’s criteria at near and far. The accommodative convergence/accommodation (AC/A) ratio was calculated and vergence facility was also obtained at near. A driving simulator was used to assess driving performance under natural conditions and after alcohol consumption with a breath alcohol content of 0.40 mg/l. Alcohol intake significantly reduced binocular visual performance and vergence function, except for vertical phorias, horizontal phoria at near and Sheard’s and Percival’s criteria at near. Driving performance parameters also presented a statistically significant deterioration after alcohol consumption. A statistically significant correlation was found between the deterioration in overall visual function and overall driving performance, highlighting the influence of the visual deterioration on the driving performance. Moderate alcohol consumption impairs binocular visual and simulated driving performances, implying a greater safety hazard. In addition, deteriorations in binocular visual function and vergence correlated with simulated driving impairment, which indicates that the deterioration of binocular vision due to alcohol consumption affects driving, thus reducing road safety.

Surgical outcomes for esotropia in children with high accommodative convergence/accommodation ratio.

Purpose:To assess if high accommodative convergence/accommodation (AC/A) ratio impacts surgical outcomes in children with esotropia (ET), and evaluate the appropriate target angle in surgical dosing in the presence of high AC/A ratio.Methods:A retrospective chart review identified patients who underwent primary bilateral medial rectus (BMR) recessions for ET. Patients were excluded if follow-up was ≤2 months. Basic demographic information, visual acuity, stereopsis, alignment, and target angle for surgery were collected. High AC/A was defined as ≥10 prism diopter (Δ) deviation at near compared to distance. Outcome parameters were near and distance deviations ≤10Δ within orthophoria, and/or stereopsis postoperatively. Yates’ continuity correction, unpaired t-test, regression analysis, and one-way ANOVA were used.Results:We identified 103 patients, 23 with high AC/A and 80 with normal AC/A, preoperatively. Mean age was 4.0 ± 2.5 years. Surgical success measured by postoperative alignment was 48% and 45% in the high AC/A and normal AC/A groups, respectively (P = 1.0). There was a statistically significant difference in preoperative near deviation between high AC/A and normal AC/A groups (P = 0.0015); however, there was no significant difference in preoperative distance deviation (P = 0.061). In addition, there was not a significant difference in preoperative or postoperative stereopsis between high AC/A and normal AC/A groups (P = 0.88 and P = 0.44, respectively). There was a significant difference in the normal AC/A and high AC/A groups when target angle was directed toward preoperative near deviation as determined by one-way ANOVA (F = 170.88, P < 0.0001 and F = 14.61, P = 0.0010, respectively).Conclusion:In the setting of ET treated with BMR recession, the presence of high AC/A does not affect surgical success as measured by alignment and stereopsis. In addition, when high AC/A is present, surgical dosing with a target angle toward near deviation was found to yield the best surgical outcomes in our patient population.

Functional acute acquired comitant esotropia: clinical characteristics and efficacy of single Botulinum toxin type A injection

BackgroundTo examine the clinical features of acute acquired comitant esotropia (AACE) and to evaluate the clinical effectiveness of a single injection of botulinum toxin type A (BTXA) on binocular visual function (BVF).MethodsThis retrospective, observational case series study enrolled patients with AACE examined from October 2018–May 2019. BTXA was injected into the both medial rectus muscles. The refractive error, best-corrected visual acuity (BCVA), stereoacuity, vergence, accommodation, the horizontal angle of deviation, and the gradient accommodative convergence/accommodation (AC/A) ratio were measured pre- and post-BTXA injection. Data pre- and postinjection were compared by the Wilcoxon signed-rank test. A Spearman correlation coefficient was calculated to explore the relationships between demographic characteristics and BVF.ResultsTwenty-two AACE cases were included. Compared with preinjection deviation, the postinjection deviation in the primary position was smaller for near (p < 0.001) and distance (p < 0.001) fixation at 3 months after injection (BTXA). Furthermore, convergence was better for near (p = 0.003) and distance (p < 0.001) fixation, divergence was better for near (p = 0.021) and distance (p < 0.001) fixation, accommodation was better in the right (p = 0.011) and left (p = 0.004) eyes, and the gradient AC/A ratio was better at the third month after injection (p = 0.001). Stereoacuity was improved in 11 (50%), unchanged in 5 (22.73%) and decreased in 6 (27.27%) patients. The preinjection stereoacuity (p = 0.013, r = 0.522) and preinjection deviation for near (p = 0.015 r, = − 0.512) and distance (p = 0.009, r = − 0.541) were significantly associated with patient age.ConclusionsAACE is characterized by a high AC/A ratio and low accommodation. A single injection of BTXA is effective for AACE. Deviation, stereoacuity, and the therapeutic effect of BTXA may be correlated with patient age.

Accommodative-Convergence Mechanism failure in HIV-Positive Non Presbyopic Patient on Highly Active Anti-Retroviral Therapy: A case report

Purpose: Accommodative-convergence mechanism failure could occur in non presbyopic HIV- sero positive patients on Highly Active Anti-Retroviral Therapy (HAART). This could be due to either direct neuronal infection by HIV, pathologic changes of the lens or the ciliary body or adverse effects of some individual drugs constituting the HAART regimen on the cranial nerves which play vital roles in the mechanism of accommodation and convergence.&#x0D; Case report: This is a case report of an accommodative- convergence mechanism failure in HIV positive non presbyopic 32-year-old male patient that was on HAART for more than five years. He presented with distance visual acuity (VA) of OD: 6/9 +2, OS: 6/9, and near visual acuity (NVA) of N24 both eyes, 3Δ esophoria at distance and 4Δ esophoria at near. Amplitude of accommodation (AA) was 3.50D and accommodative convergence/accommodation (AC/A) ratio was 6/1. Following comprehensive evaluation, his refractive correction was OD: Plano/-0.50DC X 180 6/5 and OS: Plano/-0.50DC X 90 6/5 at distance with near addition (Add) 2.50D N5. This was prescribed for regular wear in form of D-Top bifocal lens.&#x0D; Conclusion: These findings showed that HIV sero-positive adults on HAART could develop accommodativeconvergence mechanism failure, which may be characterized by low amplitude of accommodation, receded near point of convergence and high non presbyopic reading addition. These conditions may be under-recognized and need for reading addition of a non presbyopic age is often overlooked.&#x0D; Key Words: Accommodative-Convergence, HIV, Lateral Phoria, Refractive error.

Botulinum toxin in the treatment of partially accommodative esotropia with high AC/A ratio.

To study the outcome of botulinum toxin (BTX) treatment (group 1) in partially accommodative esotropia with high accommodative convergence/accommodation (AC/A) ratio, in comparison with bilateral medial rectus muscles recessions and posterior fixation (group 2). In a retrospective comparative study, children aged 3-8 years old treated between 2011 and 2016, with partially accommodative esotropia with high AC/A ratio, deviation at distance of 10 prism diopters or more, and at least 1 year of follow-up, were included. Visual acuity, alternate prism and cover test, stereoacuity, biomicroscopy, and cycloplegic retinoscopy were carried out at initial, baseline visit, 6 months and 1 year after BTX injection or surgery. Main outcome variables were deviation at distance and near, improvement in stereoacuity, and percentage of success. We used multiple regression or proportional odds analysis to control for potential confounding variables. Of 95 patients, 84 were eligible, 48 children in group 1 and 36 in group 2. Deviation and stereoacuity were similar in the two groups at 6 months, but significantly better in the BTX group at 1 year (median distance deviation 0 prism diopters vs 5 prism diopters, p<0.01), although differences were not clinically relevant. Percentage of success was also significantly better only at 1 year (93% vs 72%, p = 0.01). Change in distance-near disparity was not significantly different in the two groups in the period of study. Botulinum toxin could be superior to, or as effective as surgery, at middle term, in the treatment of partially accommodative esotropia with high AC/A ratio.

The effect of base‐in prism on vision‐related symptoms and clinical characteristics of young adults with convergence insufficiency; a placebo‐controlled randomised clinical trial

The aim of the present study was to evaluate the effect of base-in prism on symptoms and clinical characteristics of young adults with convergence insufficiency. In this randomised clinical trial, 64 CI patients aged 18-38years who presented to Bina Eye Hospital, Tehran, Iran between November 2018 and April 2019 were selected and randomly assigned to either prism or placebo groups. All participants underwent complete optometric examinations, including the measurement of visual acuity, objective and subjective refraction, and complete accommodative and binocular vision examinations. Clinical examinations were repeated after three months. The overall score of the Convergence Insufficiency Symptom Survey (CISS) was considered as the primary outcome measure. Secondary outcome measures included near exophoria, positive fusional vergence at near, near point of convergence, vergence facility, monocular accommodative facility, accommodative response, negative relative accommodation and accommodative convergence/accommodation (AC/A) ratio. The mean (S.D.) age of the participants was 25.5 (5.5) years and 44% of them were male. The mean CISS score was significantly lower in the prism group compared to the placebo group in the outcome examination (p<0.001). Moreover, the values of monocular accommodative facility, accommodative response, and negative relative accommodation were significantly higher in the prism group versus the placebo group (p<0.001). There was no significant difference in other parameters, including near positive fusional vergence, near point of convergence, vergence facility, and AC/A ratio between the two groups in the outcome examination (p>0.10). The base-in prism reduced symptoms in young adults with convergence insufficiency, while it had no significant effect on the near point of convergence, near positive fusional vergence, vergence facility and AC/A ratio. However, the results of this study only supports the symptomatic effectiveness of prism in the short term and further studies are needed to assess the long-term effect of prism.

Accommodation and its role in myopia progression and control with soft contact lenses.

To examine the impact of contact lens optical design on accommodative behaviour of children and the correlation between myopia progression and the accommodative response of the eye while wearing a contact lens designed for myopia control. A post-hoc analysis was conducted on data from a previously published myopia control trial. A total of 109 subjects (aged 8 to 11years, myopia: -0.75 to -4.00D) wore either a Control (single-vision, n=57) or a Test (with positive spherical aberration, +SA, n=52) soft contact lens, binocularly for 1year. Accommodative response was measured as the subject observed targets at -1.00 to -4.00D vergence using the Grand Seiko WAM-5500 open-field autorefractor (www.grandseiko.com). Slope of accommodative response (SAR) as well as distance and near phoria and stimulus accommodative convergence/accommodation (AC/A) were compared between each group at baseline without study lenses and at 1-week and 1-year visits with study lenses. The SAR was also compared to changes in axial length (AL) and spherical equivalent cycloplegic auto refraction (SECAR). At baseline, there was no significant difference in SAR between the two study groups (ΔSAR=-0.039, p=0.84). At 1week, mean SAR of the Test group was significantly less than for the Control group (ΔSAR=-0.203, p<0.0001), an effect that persisted to 1year (ΔSAR=-0.129, p<0.0001). In the Test group, greater SAR was associated with less change in AL (regression coefficient: -0.59mm, p<0.0001) and SECAR (regression coefficient: 1.12D, p=0.006) at 1year. In the Control group, associations between SAR and change in AL and SECAR were not statistically significant. Compared to the Control group, eyes of the Test group appeared to be more exophoric with study lenses, however, the difference between the two groups was only significant at 1week for distance phoria and 1year for near phoria. The soft contact lens with +SA for controlling myopia progression resulted in an apparent decrease in mean accommodation. Within the Test group, reduced accommodative response correlated with greater myopia progression, suggesting some subjects in the Test group utilised the +SA for near viewing, inducing hyperopic defocus at the retina. Accordingly, the potential impact of a lens optics on accommodative function should be considered during design of myopia control lenses.

The Normal Accommodative Convergence/Accommodation (AC/A) Ratio

ABSTRACTBackground and Purpose: To measure the Accommodative Convergence (PD)/Accommodation ratio (D) (AC/A) in a cohort of visually normal participants using common clinical methods.Patients and Methods: AC/A ratios of 50 visually normal subjects were measured using the distance gradient (DG), near gradient (NG), gradient using synoptophore, (SG) and heterophoria (H) methods in line with current clinical practice.Results: Median AC/A ratios for NG, DG, SG, and H were 2.0 (IQR 2.0), 1.0 (IQR 0.6), 1.0 (IQR 0.6), and 5.0 (IQR 1.7), respectively. There was a statistically significant difference in ratios calculated between all methods in the same subjects (p < 0.05). There were differences in DG vs NG, DG vs H, SG vs H, and NG vs H (p < 0.05); only DG vs SG did not differ significantly (p > 0.05). Lens power toleration was found to affect AC/A ratio in DG (p < 0.05) and latent deviation was significantly associated with (p < 0.05) AC/A ratio in NG.Conclusion: Calculated AC/A ratios in this cohort were lower than historically cited normal (3–5:1) in all gradient methods. There were differences in AC/A values in the same subjects calculated with different gradient methods, indicating that these methods are not interchangeable and a universal normal range should not be applied for all methods.

Binocular and accommodative function in the controlled randomized clinical trial MiSight® Assessment Study Spain (MASS).

To evaluate the binocular and accommodative function in children wearing dual focus (DF) MiSight® contact lenses (CLs) for myopia control compared with children wearing single-vision (SV) spectacles. This was a randomized, controlled clinical trial involving subjects aged 8 to 12, with myopia ranging from - 0.75 to - 4.00D and astigmatism < 1.00D, allocated to MiSight® study CLs group or control group wearing SV. Binocular and accommodative function was determined at baseline, 12-, and 24-month visits, assessed by the following sequence of tests: distance and near horizontal phoria, accommodative convergence/accommodation (AC/A) ratio, stereopsis, accommodative amplitude (AA), and accommodative response (AR) at 33, 25 and 20 cm. Seventy-four children completed the study: 41 in the CL group and 33 in the SV group. CLs group did not show any significant differences in binocular and accommodative measurements throughout the study. In control group, distance and near phoria, stereopsis, AC/A and AR at 20cm did not show any significant change, but AA, AR at 33cm and AR at 25 cm were greater at 24-month visit compared with baseline (p < 0.05). DF lenses do not change the binocular and accommodative function in children wearing dual focus CLs. NCT01917110.

Amblyopia in High Accommodative Convergence/Accommodation Ratio Accommodative Esotropia. Influence of Bifocals on Treatment Outcome

To study the influence of bifocal use on amblyopia treatment outcome in high accommodative convergence/accommodation (AC/A) ratio accommodative esotropia with deviation only at near. Retrospective comparative case series. Setting: Tertiary referral center. Children with high AC/A ratio accommodative esotropia aged 3-8 years old, with deviation only at near with glasses, neutralized with bifocal lenses (follow-up 1 year). Amblyopia was treated with patching. We compared bifocal and single-vision glasses users at 6months and 1 year, with control of potential confounding variables (multiple regression). LogMAR lines of improvement in visual acuity of the amblyopic eye, and improvement in stereoacuity. Of 78 children, 61 were eligible. All patients wore single-vision glasses for 2months (baseline visit), 46 of them changed to bifocals. Of 27 initially amblyopic children, 21 remained amblyopic at 2-month baseline (13of them changed to bifocals). After adjustment for initial deviation, refraction, age, and amblyopia, improvement of visual acuity in the amblyopic eye was larger in the bifocal vs single-vision group at 6months (mean 2.6 [95% confidence interval (CI): 1.9-2.9] logMAR lines vs mean 1.9 [95% CI: 0.5-2.2] logMAR lines, respectively, P= .01), but not at 1 year (mean 2.7 [95% CI: 2.2-3.1] logMAR lines vs mean 2.3 [95% CI: 1.6-3.1] logMAR lines, respectively, P= .3). Improvement of stereoacuity was not significantly different between the 2 groups. Use of bifocals may provide a transient advantage, but improvement in visual acuity and stereopsis is equal with single-vision glasses over time.

Differences in the Stimulus Accommodative Convergence/Accommodation Ratio using Various Techniques and Accommodative Stimuli

ABSTRACTPurpose: To investigate differences in the stimulus accommodative convergence/accommodation (AC/A) ratio using various techniques and accommodative stimuli, and to describe a method for determining the stimulus AC/A ratio.Methods: A total of 81 subjects with a mean age of 21 years (range, 20–23 years) were enrolled. The relationship between ocular deviation and accommodation was assessed using two methods. Ocular deviation was measured by varying the accommodative requirement using spherical plus/minus lenses to create an accommodative stimulus of 10.00 diopters (D) (in 1.00 D steps). Ocular deviation was assessed using the alternate prism cover test in method 1 at distance (5 m) and near (1/3 m), and the major amblyoscope in method 2. The stimulus AC/A ratios obtained using methods 1 and 2 were calculated and defined as the stimulus AC/A ratios with low and high accommodation, respectively, using the following analysis method. The former was calculated as the difference between the convergence response to an accommodative stimulus of 3 D and 0 D, divided by 3. The latter was calculated as the difference between the convergence response to a maximum (max) accommodative stimulus with distinct vision of the subject and an accommodative stimulus of max minus 3.00 D, divided by 3.Results: The median stimulus AC/A ratio with low accommodation (1.0 Δ/D for method 1 at distance, 2.0 Δ/D for method 1 at near, and 2.7 Δ/D for method 2) differed significantly among the measurement methods (P < 0.01). Differences in the median stimulus AC/A ratio with high accommodation (4.0 Δ/D for method 1 at distance, 3.7 Δ/D for method 1 at near, and 4.7 Δ/D for method 2) between method 1 at distance and method 2 were statistically significant (P < 0.05), while method 1 at near was not significantly different compared with other methods.Conclusions: Differences in the stimulus AC/A ratio value were significant according to measurement technique and accommodative stimuli. However, differences caused by measurement technique may be reduced by using a high accommodative stimulus during measurements.

Binocular and Accommodative Characteristics in a Normal Population

ABSTRACTPurpose: To study binocular and accommodative characteristics and their associations with age and gender in an Iranian young adult population.Methods: In this cross-sectional study, multistage cluster sampling was done from the students of Mashhad University of Medical Sciences. All participants had visual acuity, refraction, and cover tests followed by measurements of the near point of convergence (NPC), amplitude of accommodation (AA), monocular and binocular accommodative facility (MAF and BAF) using ±2.00 diopter (D) flipper lenses, and negative and positive relative accommodation (NRA and PRA). Near and distance fusional vergence reserves were measured using prism bar, and near associated phoria was assessed using the Mallett unit.Results: The mean age of the participants was 22.5±4.4 years (range: 18-35 years). The binocular and accommodative characteristics and their means in the studied sample included: mean distance dissociated phoria: 1.15 exophoria±2.04 prism diopters (PD), near dissociated phoria: 5.02 exophoria±4.74 PD, near associated phoria: 0.55 base-in±1.02, gradient accommodative convergence/accommodation (AC/A) ratio: 4.66±1.59, NPC: 5.27±3.60 cm, MAF: 11.33±5.58 cpm, BAF: 8.84±4.47 cpm, NRA: 2.08±0.33 D, PRA:-2.92±0.76 D, and AA: 11.14±2.6 D. In the multiple regression model including age and gender, near exophoria was significantly higher in men and levels of near base-out-break and near base-out-recovery were higher in females. Distance exophoria, distance base-in-break, distance base-in-recovery, and NPC increased with age and near base-out-break, PRA, BAF, MAF, and AA significantly decreased with age.Conclusion: Studied indices in this study significantly differ from available guidelines and these differences must be considered when making diagnostic or therapeutic decisions. Certain indices can be affected by age and gender.