Examining the Validity of a New Method for the Objective Assessment of Binocular Accommodative Facility (2Q-AF Test): A Comparison with ± 2.00 DS Lens Flippers.

PURPOSE: Recent technological advances have permitted to objectively record the accommodative response while shifting between two different levels of accommodation. This study is aimed at examining the concurrent validity of a new objective method for the qualitative and quantitative assessment of binocular accommodative facility, which is named 2Q-AF test, in comparison to the ±2.00 DS lens flippers. METHODS: Fifty-six individuals took part in this study (36 healthy young adults [24.4 ± 3.2 years] and 20 children [12.2 ± 0.4 years]). Participants randomly performed the 2Q-AF and the ±2.00 DS lens flipper tests. For the 2Q-AF test, a binocular open-field autorefractor was used to record the magnitude of accommodative response during a 60-sec period, while participants repeatedly changed fixation from a 5 m to a 40 cm chart when clarity of vision was achieved at each level. Due to the advantages of the proposed method, we have determined the number of cycles and the 2Q-AF score, with the latter also considering the accuracy of changes in accommodation. A standard procedure was followed for the ±2.00 DS flipper test. RESULTS: Our data exhibited a moderate association between the number of cycles with the ±2.00 DS lens flippers and the number of cycles in the 2Q-AF test in the group of young adults (p = .005, r = 0.46 [0.15-0.68]) and children (p = .007, r = 0.58 [0.19-0.81]), whereas a stronger relationship was observed when considering the number of cycles with the ±2.00 DS lens flippers and the 2Q-AF score (young adults: p < .001, r = 0.83 [0.69-0.91]; and children: p < .001, r = 0.78 [0.52-0.91]). CONCLUSIONS: The current findings show that the 2Q-AF test is a valid method for accommodative facility assessment, as suggested by its good levels of reliability and validity. This method allows to examine the accommodative facility in qualitative terms and solve most of the limitations associated with the ±2.00 DS lens flipper test.

Home- and Office-Based Vergence and Accommodative Therapies for Treatment of Convergence Insufficiency in Children and Young Adults: A Report by the American Academy of Ophthalmology.

PURPOSE: To review home- and office-based vergence and accommodative therapies for treatment of convergence insufficiency (CI) in children and young adults up to 35 years of age. METHODS: Literature searches were conducted through October 2020 in the PubMed database for English-language studies. The combined searches yielded 359 abstracts, of which 37 were reviewed in full text. Twelve of these were considered appropriate for inclusion in this assessment and assigned a level of evidence rating by the panel methodologist. RESULTS: Of the 12 studies included in this assessment, 8 were graded as level I evidence, 2 were graded as level II evidence, and 2 were graded as level III evidence. Two of the level I studies included older teenagers and young adults; the remainder of the studies exclusively evaluated children. Two randomized controlled trials found that office-based vergence and accommodative therapies were effective in improving motor outcomes in children with symptomatic CI. However, the studies reported conflicting results on the efficacy of office-based therapy for treating symptoms of CI. Data were inconclusive regarding the effectiveness of home-based therapies (including pencil push-ups and home computer therapy) compared with home placebo. In young adults, office-based vergence and accommodative therapies were not superior to placebo in relieving symptoms of CI. CONCLUSIONS: Level I evidence suggests that office-based vergence and accommodative therapies improve motor outcomes in children with symptomatic CI, although data are inconsistent regarding symptomatic relief. Evidence is insufficient to determine whether home-based therapies are effective.

Assessment of Refractive Error Changes and Factors for Decompensation in Patients With Fully Accommodative Esotropia.

PURPOSE: To determine the factors affecting the risk of deterioration and evaluate the refractive error change in patients with fully accommodative esotropia. METHODS: Patients diagnosed as having fully accommodative esotropia (esotropic deviation that started before 7 years of age and less than 8 to 10 prism diopters [PD] of esotropia with full hyperopic correction and/or bifocals) were included in this retrospective population-based cohort study. Refractive error changes were recorded. For comparisons, patients were divided into two groups: nondecompensated fully accommodative esotropia group and decompen-sated fully accommodative esotropia group. RESULTS: Two hundred and twenty-three patients met the inclusion criteria. The mean follow-up time was 5.94 ± 0.31 years (range: 5 to 8 years). The changes in spherical equivalent in the younger than 7 years, 7 to 12 years, and 12 to 17 years groups were statistically significant (P < .001). The decrease of hypermetropia was 0.13 diopters/year between 7 and 12 years and 0.06 diopters/year between 12 and 17 years. Forty-one of 223 patients (18.4%) discontinued spectacle therapy during the follow-up period. Hyperopic error and presence of amblyopia were lower, whereas visual acuity level and presence of near-distance disparity were higher in the spectacle discontinuation group (P < .001, .007, .01, and 0.01, respectively). Deterioration of fully accommodative esotropia occurred in 30 of 223 patients (13.5%). Boys were more likely to require strabismus surgery (P = .32). The mean age at presentation, esotropia angle with and without refractive correction at both near and distance fixation, near distance disparity, and inferior oblique overaction were significantly higher in patients with decompensated fully accommodative esotropia. CONCLUSIONS: Hyperopic error increased from the initial level until 7 years of age, followed by a myopic shift thereafter. Few children had resolution of fully accommodative esotropia and could discontinue spectacle therapy. Children with male gender, higher esotropia angle, older age at presentation, near-distance disparity, and inferior oblique overaction experienced a greater deterioration of the fully accommodative esotropia. [J Pediatr Ophthalmol Strabismus. 2020;57(4):217-223.].

Spasm of Near Reflex: Objective Assessment of the Near-Triad.

Purpose: To characterize binocular steady-state accommodation, pupil and convergence responses (near triad) in spasm of near reflex (SNR) before and after optical and pharmacological intervention. To identify the putative source of SNR in the neural control schema of accommodation-vergence interaction using controls-engineering modeling. Methods: Near-triad of 15 patients with SNR (9 to 23 years) was recorded using an infrared photorefractor at 2m viewing distance for 120s during clinical presentation, after optical fogging intended to relieve spasm, with cycloplegia, post-cycloplegia and long-term follow-up visits. Data were also collected without cycloplegia in 15 age-matched controls. Schor (1999) model was used to computationally simulate accommodation and vergence responses of controls and SNR. Results: Both eyes of SNR exhibited significant myopia and refraction fluctuations (<1.0Hz) during clinical presentation [median (25th to 75th IQR) refraction: -1.7D (-3.2 to -0.8D); root mean squared (RMS) deviation: 1.1D (0.5 to 1.5D)], relative to controls [0.8D (-0.03 to 1.4D); 0.2D (0.1 to 0.3D)] (p < 0.001). These decreased after optical fogging, largely eliminated with cycloplegia and partially re-appeared in the post-cycloplegia and follow-up visits. SNR responses could be modeled by increasing the gain and decay time of tonic accommodation, vis-à-vis, controls. Pupil and convergence responses in SNR were similar to controls at all visits (p > 0.1). Conclusions: Exaggerated fluctuations of steady-state accommodation may be a signature feature of SNR, even while their pupil and convergence responses may remain unaffected. These fluctuations may arise from the tonic accommodation controller, the properties of which could be potentially altered after optical fogging to relieve the disorder.

A Normative Study of Objective Measures of Disparity Vergence and Saccades in Children 9 to 17 Years Old.

SIGNIFICANCE: This study establishes normative data for objective outcome measures of vergence and saccade eye movements for the pediatric population. These data should facilitate future clinical trial design. PURPOSE: This study was designed to establish normative data for objective measures of disparity vergence and saccades in children between the ages 9 and 17 years using an objective binocular eye movement tracking system. METHODS: Participants (aged 9 to 17 years) had a vision examination including refraction, accommodative, and binocular vision testing. Eligibility criteria included 20/25 visual acuity with best correction, normal accommodation, and binocular vision. The ISCAN RK-826PCI binocular tracking system (ISCAN, Woburn, MA) was used to objectively record horizontal, symmetrical disparity vergence, and saccadic eye movements. Parameters assessed included peak velocity, time to peak velocity, latency, and response amplitude for both disparity vergence and saccades. RESULTS: One hundred eighteen participants were recruited (54.94% female; mean age, 13.5 years), and 77.1% (91/118) of the participants completed the assessment with usable data. A sample of the normative data included peak velocity (°/s), which had a mean ± standard deviation of 25.4 ± 2.9, 22.0 ± 3.0, 225 ± 16.7, and 332.5 ± 20.5 for 4° convergence, 4° divergence, 5° saccades, and 10° saccades, respectively. The mean ± standard deviation for the latency (seconds) measures were 0.28 ± 0.1, 0.28 ± 0.16, 0.23 ± 0.05, and 0.23 ± 0.05 for 4° convergence, 4° divergence, 5° saccades, and 10° saccades, respectively. CONCLUSIONS: Normative data enable researchers to have benchmark results for comparison with patient populations with binocular dysfunction. These objective disparity vergence measures can serve as outcome measures in future clinical trials to assess the effectiveness of therapeutic interventions by determining whether post-treatment results are similar to normal data.

Validation of an Objective Method for the Qualitative and Quantitative Assessment of Binocular Accommodative Facility.

Purpose: Assessing binocular accommodative facility (BAF) enables the evaluation of the interaction between the accommodative and vergence systems, which is relevant for the diagnosis of accommodative and binocular disorders. However, the tests used to assess BAF present methodological caveats (e.g., lack of objective control, vergence demands, and image size alterations), limiting its external validity. This study aimed to (i) develop a new objective method to quantitatively and qualitatively evaluate the BAF in free-viewing conditions, and explore its validity by the comparison with the Hart Chart test, and (ii) assess the inter-session reliability of the proposed method.Methods: 33 healthy young adults took part in this study. We used a binocular open-field autorefractor to continuously assess the magnitude of accommodative response during a 60-sec period, while participants repeatedly changed fixation from a far to a near chart when clarity of vision was achieved at each level. Accommodative response data were used to characterize the BAF measurement in quantitative (number of cycles) and qualitative terms (percentage of times that correctly accommodating or dis-accommodating in each level of accommodation as well as the magnitude of the accommodative change).Results: Our data revealed that the new proposed method accurately counted the number of cycles per minute when compared with the Hart Chart test (p = .23, ES = 0.02; mean difference = 0.18 ± 0.85). The inter-session reliability of the proposed method was demonstrated to be excellent (Pearson r and intraclass correlation coefficient: 0.95 to 0.98) for the parameters obtained with the BAF test.Conclusions: The present outcomes evidence that the proposed objective method allows to accurately assess the frequency and precision of BAF by the combination of the classical Hart Chart test and a binocular open-field autorefractometer. Our findings may be of relevance for the diagnosis and treatment of accommodative and binocular disorders.

Estimation Dynamic Distance Direct Ophthalmoscopy (eDDDO): A novel, objective method for the quantitative assessment of accommodation in young children.

Purpose: To describe estimation dynamic distance direct ophthalmoscopy (eDDDO) and compare it with the monocular estimation method of dynamic retinoscopy (eDR) for the assessment of accommodation in children. Methods: In this prospective observational cohort study, an ophthalmologist performed eDDDO followed by eDR in children with normal eyes, and then under the partial effects of cyclopentolate and tropicamide to assess performance of eDDDO with eDR under the condition of pharmacologically induced accommodation failure. Only one eye of each child was recruited in the study. To study the inter-observer variation, two masked pediatric ophthalmology fellows performed eDDDO in the similar manner. Results: For the comparison of eDDDO with eDR, 60 eyes of 60 patients were recruited. The mean age of the patients was 10.4 years. The mean accommodation on eDDDO was 3.0D, 5.1D, 9.8D, and 11.3D at 40 cm, 25 cm, 10 cm, and 8 cm, respectively and 3.0D, 5.0D, 9.5D, and 11.0D on eDR. The eDDDO overestimated accommodation by a mean 0.17D (95% CL 0-0.48D, P = 0.5). The correlation of eDDDO with eDR was excellent (Pearson r 0.98, T value 76.0). The inter-observer difference with eDDDO was not significant (mean 1D, 95% CL 0-2.6D, P = 0.9) and the correlation between two observers was excellent (Pearson r 0.9, T value 12.7). The eDDDO and eDR were also performed on 12 eyes of 6 children with a mean age of 8.5 years (range 8-12 years) under the partial effect of cyclopentolate and tropicamide, where eDDDO overestimated the accommodation by a mean 0.3D (95% CL 0- 1.2D, P = 0.7) and the correlation was excellent (Pearson r 1.0, T value 45). Conclusion: eDDDO is a simple, reliable, quantitative, and objective technique of accommodation assessment for children. Further studies with larger sample are required to assess its performance in disorders of accommodation affecting younger children and in children with ocular comorbidities.

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

PURPOSE: 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. METHODS: 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. RESULTS: 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 20 cm did not show any significant change, but AA, AR at 33 cm and AR at 25 cm were greater at 24-month visit compared with baseline (p < 0.05). CONCLUSIONS: DF lenses do not change the binocular and accommodative function in children wearing dual focus CLs. TRIAL REGISTRATION: NCT01917110.

Objective Assessment of Disparity Vergence after Treatment of Symptomatic Convergence Insufficiency in Children.

SIGNIFICANCE: This first report of the use of objective measures of disparity vergence as outcome measures for symptomatic convergence insufficiency in children provides additional information that is not accessible with clinical tests. The study results also demonstrate that objective measures of vergence could be used in future randomized clinical trials of binocular vision disorders with children. PURPOSE: This study was designed to evaluate changes in objective measures of disparity vergence after office-based vergence/accommodative therapy (OBVAT) for convergence insufficiency in children 12 to 17 years old. METHODS: In this prospective trial, we recruited 10 participants with normal binocular vision and 12 with convergence insufficiency. All participants with convergence insufficiency were treated with 12 weeks of OBVAT. The primary outcome measure was average peak velocity for 4° symmetrical convergence steps. Other objective outcome measures of disparity vergence included time to peak velocity, latency, and accuracy. Changes in clinical measures (near point of convergence, positive fusional vergence at near) and symptoms were evaluated. RESULTS: There was a statistically significant increase in peak velocity and more accurate response amplitude to 4° symmetrical convergence step stimuli after OBVAT compared with baseline measurements. Near point of convergence, positive fusional vergence, and symptoms also statistically significantly improved after OBVAT. Ten of the 12 participants met clinical success criteria. CONCLUSIONS: In this prospective study on the treatment of symptomatic convergence insufficiency in children in which both clinical and objective eye movement measurements were used to evaluate the results of treatment, significant changes were found in symptoms and both clinical and objective measures of disparity vergence after completion of OBVAT in children with symptomatic convergence insufficiency.

Repeatability assessment of anterior segment biometric measurements under accommodative and nonaccommodative conditions using an anterior segment OCT.

PURPOSE: As accommodation is a dynamic process changing anterior ocular structures, we aim to compare the repeatability between the biometric measurements taken with and without accommodation. METHODS: Thirty healthy right eyes were measured in a baseline and an accommodative state using Visante-OCT. Three repeated measurements were taken to obtain central corneal thickness (CCT), anterior chamber depth (ACD), angle-to-angle distance (ATA), iridocorneal angles (IA), and crystalline lens thickness (LT). Repeatability was evaluated by the calculation of coefficient of repeatability (CoR), coefficient of variation (CoV), and intraclass correlation coefficient (ICC). In addition, the Passing-Bablok regression method was applied. RESULTS: For the nonaccommodative state, the CoR for CCT, ACD, ATA, and LT was 20.02 µm, 0.09 mm, 0.25 mm, and 0.12 mm respectively. The CoR for CCT, ACD, ATA, and LT in the 6D-accommodative state was 20.85 µm, 0.08 mm, 0.26 mm, and 0.14 mm respectively. IA had similar results for both states; the CoR ranged between 3 and 4°, CoV was less than 4%, and the ICC was between 0.984-0.988. There were no significant differences between the three repeated measurements for any measurement. CONCLUSIONS: Visante-OCT provides good repeatability for anterior segment measurements for both accommodative and nonaccommodative states.

In vivo OCT assessment of anterior segment central axial lengths with accommodation.

PURPOSE: To assess changes in anatomic structures in the anterior eye segment in terms of axial lengths with accommodation via optical coherence tomography. METHODS: In this observational study, 25 eyes of 25 healthy adults were examined using the Visante® omni optical coherence tomography system. Central corneal thickness, anterior chamber depth, central lens thickness, and anterior segment length were assessed. The evaluated parameters were obtained with accommodation using different stimulus vergences, namely 0.0, -1.0, -2.0, and -3.0 D. Variation of these parameters was compared among different levels of accommodation. RESULTS: Central corneal thickness was not altered at any stimulus vergence during accommodation (p>0.05). Conversely, anterior chamber depth was significantly reduced (p<0.05), whereas central lens thickness was significantly increased (p<0.05). Anterior segment length also increased with accommodation (p<0.05), indicating backward movement of the posterior pole. CONCLUSIONS: There are significant variations in anterior segment lengths that occur with accommodation. Studying these changes will provide useful information regarding the accommodation mechanism that can improve our understanding of this process and facilitate clinical decision-making by practitioners.

In vivo OCT assessment of anterior segment central axial lengths with accommodation / Avaliação por OCT in vivo do comprimentos axiais centrais do segmento anterior

ABSTRACT Purpose: To assess changes in anatomic structures in the anterior eye segment in terms of axial lengths with accommodation via optical coherence tomography. Methods: In this observational study, 25 eyes of 25 healthy adults were examined using the Visante® omni optical coherence tomography system. Central corneal thickness, anterior chamber depth, central lens thickness, and anterior segment length were assessed. The evaluated parameters were obtained with accommodation using different stimulus vergences, namely 0.0, -1.0, -2.0, and -3.0 D. Variation of these parameters was compared among different levels of accommodation. Results: Central corneal thickness was not altered at any stimulus vergence during accommodation (p>0.05). Conversely, anterior chamber depth was significantly reduced (p<0.05), whereas central lens thickness was significantly increased (p<0.05). Anterior segment length also increased with accommodation (p<0.05), indicating backward movement of the posterior pole. Conclusions: There are significant variations in anterior segment lengths that occur with accommodation. Studying these changes will provide useful information regarding the accommodation mechanism that can improve our understanding of this process and facilitate clinical decision-making by practitioners.

RESUMO Objetivo: Avaliar as mudanças das estruturas anatômicas no segmento anterior do olho em termos de comprimentos axiais com acomodação por meio da tomografia de coerência óptica. Métodos: Neste estudo observacional, foram incluídos 25 olhos de vinte e cinco adultos saudáveis e medidos com o sistema Visante® omni tomografia de coerência óptica. A espessura corneana central, a profundidade da câmara anterior, a espessura central da lente e o comprimento do segmento anterior foram avaliados. Os parâmetros avaliados foram obtidos com acomodação usando diferentes vergências de estímulo: 0,0, -1,0, -2,0 e -3,0 D. A variação desses parâmetros foi comparada para os diferentes níveis de acomodação. Resultados: A espessura corneana central não foi alterada em nenhum estímulo durante a acomodação (p>0,05). A ACD mostrou uma redução significativa (p<0,05), enquanto a espessura central da lente foi significativamente aumentada (p<0,05). O comprimento do segmento anterior também aumentou com acomodação (p<0,05) indicando um movimento do polo posterior para trás. Conclusões: Há variações significativas nos comprimentos do segmento anterior que ocorrem com acomodação. Estudar essas mudanças fornece informações úteis sobre o mecanismo de acomodação para os profissionais, a fim de obter uma melhor compreensão desse processo e ajudá-los a tomar suas decisões clínicas.

Short-term adaptation of accommodation, accommodative vergence and disparity vergence facility.

Previous studies have found that subjects can increase the velocity of accommodation using visual exercises such as pencil push ups, flippers, Brock strings and the like and myriad papers have shown improvement in accommodation facility (speed) and sufficiency (amplitude) using subjective tests following vision training but few have objectively measured accommodation before and after training in either normal subjects or in patients diagnosed with accommodative infacility (abnormally slow dynamics). Accommodation is driven either directly by blur or indirectly by way of neural crosslinks from the vergence system. Until now, no study has objectively measured both accommodation and accommodative-vergence before and after vision training and the role vergence might play in modifying the speed of accommodation. In the present study, accommodation and accommodative-vergence were measured with a Purkinje Eye Tracker/optometer before and after normal subjects trained in a flipper-like task in which the stimulus stepped between 0 and 2.5 diopters and back for over 200 cycles. Most subjects increased their speed of accommodation as well as their speed of accommodative vergence. Accommodative vergence led the accommodation response by approximately 77 ms before training and 100 ms after training and the vergence lead was most prominent in subjects with high accommodation and vergence velocities and the vergence leads tended to increase in conjunction with increases in accommodation velocity. We surmise that volitional vergence may help increase accommodation velocity by way of vergence-accommodation cross links.

The first and second order dynamics of accommodative convergence and disparity convergence.

Main sequences, the function describing the relationship between eye movement amplitude and velocity, have been used extensively in oculomotor research as an indicator of first-order dynamics yet it is difficult to find main sequence analyses for accommodative vergence or for disparity vergence in isolation when all mitigating factors have been well controlled and there are no studies in which accommodative vergence and disparity vergence main sequences have been generated for the same group of subjects. The present study measured main sequences in: (1) accommodative vergence with disparity vergence open loop, (2) disparity vergence with accommodation open loop, and (3) combinations of accommodative and disparity vergence. A dynamic AC/A ratio was defined and was found to be similar to the traditional static AC/A ratio. Vergence acceleration was measured for all conditions. A pulse-step model of accommodation and convergence was constructed to interpret the dynamics of the crosslinked interactions between the two systems. The model supports cross-coupling of both the pulse and step components and simulates the primary empirical findings that: (1) disparity vergence has a higher main sequence slope than accommodative vergence, (2) both accommodative and disparity vergence acceleration increase with response amplitude whereas accommodation acceleration does not.

Functional assessment of accommodating intraocular lenses versus monofocal intraocular lenses in cataract surgery: metaanalysis.

PURPOSE: To compare accommodating intraocular lens (IOLs) and monofocal IOLs in restoring accommodation in cataract surgery. SETTING: Dartmouth Medical School and Department of Ophthalmology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA. METHODS: In this metaanalysis, 2 researchers independently extracted data, assessed trial quality, and contacted authors for missing information. Because of measurement-scale variations, outcomes were pooled for distance-corrected near visual acuity (DCNVA) as standardized mean differences with 95% confidence intervals [CIs] and anterior displacement of the lens as weighted mean differences (95% CI). RESULTS: The metaanalysis comprised 12 randomized controlled studies of 727 eyes. Based on 10 studies that compared DCNVA, accommodating IOLs were favored but failed the test of heterogeneity (I(2) = 94%). Pooling the 6 homogeneous trials (I(2) = 43%) showed no difference (standardized mean difference, -0.16; 95% CI, -0.56 to 0.25). Heterogeneity could not be explained by any characteristic of the study population or methodology. Based on 4 studies that evaluated pilocarpine-induced IOL shift, there was a significant anterior compared with the control (weighted mean difference, 95% CI, -0.36 - 0.47 to -0.24]), although the studies were heterogeneous (I(2) = 58%). Three of 5 studies mentioning posterior capsule opacification (PCO) reported increased rates in the accommodating IOL group postoperatively. CONCLUSIONS: There was no clear evidence of near acuity improvement despite statistically significant pilocarpine-induced anterior lens displacement. Further randomized controlled studies with standardized methods evaluating adverse effects (eg, PCO) are needed to clarify the tradeoffs.

New methods for the assessment of accommodative convergence.

PURPOSE: The authors introduced a new objective method for measuring horizontal eye movements based on the first Purkinje image with the use of infrared charge-coupled device (CCD) cameras and compared stimulus accommodative convergence to accommodation (AC/A) ratios as determined by a standard gradient method. METHODS: The study included 20 patients, 5 to 9 years old, who had intermittent exotropia (10 eyes) and accommodative esotropia (10 eyes). Measurement of horizontal eye movements in millimeters (mm), based on the first Purkinje image, was obtained with a TriIRIS C9000 instrument (Hamamatsu Photonics K.K., Hamamatsu, Japan). The stimulus AC/A ratio was determined with the far gradient method. The average values of horizontal eye movements (mm) and eye deviation (Delta) (a) before and (b) after an accommodative stimulus of 3.00 diopters (D) were calculated with the following formula: horizontal eye movements (mm/D) and stimulus AC/A ratio (Delta/D) = (b - a)/3. RESULTS: The average values of the horizontal eye movements and the stimulus AC/A ratio were 0.5 mm/D and 3.8 Delta/D, respectively. Correlation analysis showed a strong positive correlation between these two parameters (r = 0.92). Moreover, horizontal eye movements are directly proportional to the AC/A ratio measured with the gradient method. CONCLUSIONS: The methods used in this study allow objective recordings of accommodative convergence to be obtained in many clinical situations.

Accommodative and vergence responses to conflicting blur and disparity stimuli during development.

Accommodative and vergence responses of the typically developing visual system are generated using a combination of cues, including retinal blur and disparity. The developmental importance of blur and disparity cues in generating these motor responses was assessed by placing the two cues in conflict with each other. Cue-conflicts were induced by placing either -2 D lenses or 2 MA base-out prisms before both eyes of 140 subjects (2.0 months to 40.8 years) while they watched a cartoon movie binocularly at 80 cm. The frequency and amplitude of accommodation to lenses and vergence to prisms increased with age (both p < 0.001), with the vergence response (mean +/- 1 SEM = 1.38 +/- 0.05 MA) being slightly larger than the accommodative response (1.18 +/- 0.04 D) at all ages (p = 0.007). The amplitude of these responses decreased with an increase in conflict stimuli (1 to 3 D or MA) (both p < 0.01). The coupled vergence response to -2 D lenses (0.31 +/- 0.06 MA) and coupled accommodative response to 2 MA base-out prisms (0.21 +/- 0.02 D) were significantly smaller than (both p < 0.001) and poorly correlated with the open-loop vergence (r = 0.12; p = 0.44) and open-loop accommodation (r = -0.08; p = 0.69), respectively. The typically developing visual system compensates for transiently induced conflicts between blur and disparity stimuli, without exhibiting a strong preference for either cue. The accuracy of this compensation decreases with an increase in amplitude of cue-conflict.

Functional assessment of two different accommodative intraocular lenses compared with a monofocal intraocular lens.

PURPOSE: To evaluate selected functional and physical properties of 2 models of accommodative intraocular lenses (IOLs) compared with those of a standard monofocal IOL. DESIGN: Prospective randomized comparative trial. PARTICIPANTS: Subjects were divided into 3 groups. In group 1, 30 eyes (19 subjects) received 1CU IOL implantation; in group 2, 29 eyes (19 subjects) received AT-45 IOL implantation; and in group 3, 21 eyes (21 subjects) were implanted with a monofocal IOL as a control. INTERVENTION: Cataract surgery with implantation of the 1CU and AT-45 accommodative IOL models in the study groups, and the ACR6D monofocal IOL in the control group. MAIN OUTCOME MEASURES: Far and near distance visual parameters were assessed at 1, 6, and 12 months after surgery in the accommodative IOL groups, and at 1 and 12 months in the control group. Anterior segment anatomy was investigated by ultrasound biomicroscopy, with and without visual accommodative stimulation. RESULTS: The accommodative IOL groups significantly differed from the controls in terms of lower near-distance refractive addition (NDRA) and better distance-corrected near visual acuity (DCNVA), with P<0.001 at 1 year. The anterior IOL displacement during accommodation (DeltaACD) was significantly larger in the study groups, and this correlated with DCNVA. Until 6 months, the DeltaACD correlated with the solicited sclerociliary process rotation only in the study groups. CONCLUSION: This 12-month study demonstrated that the accommodating IOLs achieved better clinical results than the monofocal IOL in terms of DCNVA and NDRA. These results support the hypothesis that accommodative IOLs proportionally react to ciliary body rotation, although this relationship became less evident at 12 months.