Subjective Accommodation Research Articles

Spherical Aberration and Accommodative Insufficiency: Is There a Link?

Given the relationship between spherical aberrations and accommodation, the study of these aberrations can be helpful to understand accommodative response in subjects with accommodative dysfunctions. The purpose of this study was to evaluate on-axis and off-axis changes of primary and secondary spherical aberrations, Z(4,0) and Z(6,0), with accommodation in subjects with accommodative insufficiency (AI). Ten subjects with AI and eleven without any accommodative dysfunction (control) participated in this study. On-axis defocus Z(2,0), Z(4,0), and Z(6,0) were obtained in both groups with a Hartmann–Shack aberrometer for the unaccommodated state and with 1.00 D, 2.44 D, 3.83 D, and 4.73 D of accommodative stimuli. Z(4,0) and Z(6,0) were also measured on 11.5° and 23° temporal, nasal, superior, and inferior retinal areas for unaccommodated state and for 2.44 D of accommodative stimulus. In the control group, Z(4,0) became more negative with accommodation and Z(6,0) became more positive, as was expected according to previous studies. This tendency was not observed in the group of subjects with AI group for Z(4,0) or for Z(6,0). No differences on off-axis Z(4,0) and Z(6,0) were observed between the groups. The changes of spherical aberrations with accommodation seem different in subjects with AI compared to those without any accommodative dysfunction. Those with AI do not present a decrease in Z(4,0) and an increase in Z(6,0) with accommodation as occurs in eyes without this type of dysfunction. Understanding how the optics of the eye changes with accommodation can be helpful to understand the origin of accommodative dysfunctions.

Real-time wavefront aberrometry in subjects with accommodative excess

The purpose of this study was to use real-time wavefront aberrometry to detect accommodative excess (AE) and to analyse the optical quality of the eye in subjects with this dysfunction. AE was detected from the accommodative response obtained by real-time wavefront aberrometry. These subjects had a significant accommodative lead to all stimuli and had difficulty relaxing accommodation. The root mean square (RMS) of high order aberrations (HOA) was higher in subjects with AE for lower stimulus and for disaccommodation than in the control group. However, the subjects with AE showed a decrease in the RMS of HOA with an increase in accommodative response. Primary spherical aberration tended to become more negative with accommodation in both subjects and there was no difference between the groups. Real-time wavefront aberrometry can be used as an objective method to detect accommodative excess.

The effect of phenylephrine hydrochloride 2.5 % and sodium hyaluronate solution on visual functions and accommodation in children with myopia and its local tolerability

Purpose: to evaluate visual functions, accommodation, and local tolerance in children instilled with Phenylephrine hydrochloride 2.5 % and sodium hyaluronate solution (Stelphrin Supra). Material and methods. 30 children (60 eyes) aged 8 to 12 (ave. 10.04 ± 0.24) with low (28 eyes) and moderate (32 eyes) myopia (ave. -2.96 ± 0.17 D) were tested. Refractometry, subjective and objective accommodation, optical biometry, anterior corneal surface examination, Norn test, and polling were performed prior to one-time instillation, 30 minutes after it, and after 1 month of daily bedtime instillations of Stelphrin Supra. Results. We noted a significant decrease in the tone of accommodation in the open field by 90 % from the initial value, an approximation of the nearest point of clear vision by 27 %, an increase in the volume of absolute accommodation by 57 % and the objective amplitude of accommodation by 20 %, which indicates an increase in the accommodation ability. The pupil width increased 30 minutes after a single instillation of Stelphrin Supra, which coincided with an increase in the relative accommodation reserve by 25 % from the initial one. After a month, the pupil width significantly decreased, and the positive relative accommodation reserve decreased to a level only 12 % higher than the original one. Tear film break time significantly increased by 0.89 sec, singular spot stainings disappeared in 2 out of 6 patients, lacrimation — in 6 out of 10, pain — in 1 out of 2, blurring in 4 out of 6, feeling of “sand” — in 7 out of 9 patients who had these symptoms before instillations. Conclusion. Regular instillations of Stelphrin Supra reduce the habitual tone of accommodation, increase the accommodation ability, and improve the condition of the eye surface.

Correcting Presbyopia With Autofocusing Liquid-Lens Eyeglasses.

Presbyopia, an age-related ocular disorder, is characterized by the loss in the accommodative abilities of the human eye. Conventional methods of correcting presbyopia divide the field of view, thereby resulting in significant vision impairment. We demonstrate the design, assembly and evaluation of autofocusing eyeglasses for restoration of accommodation without dividing the field of view. The adaptive optics eyeglasses comprise of two variable-focus liquid lenses, a time-of-flight range sensor and low-power, dual microprocessor control electronics, housed within an ergonomic frame. Subject-specific accommodation deficiency models were utilized to demonstrate high-fidelity accommodative correction. The abilities of this system to reduce accommodation deficiency, its power consumption, response time, optical performance and MTF were evaluated. Average corrected accommodation deficiencies for 5 subjects ranged from -0.021 D to 0.016 D. Each accommodation correction calculation was performed in ∼67 ms which consumed 4.86 mJ of energy. The optical resolution of the system was 10.5 cycles/degree, and featured a restorative accommodative range of 4.3 D. This system was capable of running for up to 19 hours between charge cycles and weighed ∼132 g. The design, assembly and performance of an autofocusing eyeglasses system to restore accommodation in presbyopes has been demonstrated. The new autofocusing eyeglasses system presented in this article has the potential to restore pre-presbyopic levels of accommodation in subjects diagnosed with presbyopia.

Compact Models of Presbyopia Accommodative Errors for Wearable Adaptive-Optics Vision Correction Devices

Subjective accommodation refractive error models are essential for implementing adaptive vision correction devices that utilize varifocal optics. This article describes compact empirical models of subjective accommodative refractive errors in subjects with advanced presbyopia. The models are based on measurements of subjective refractive errors from fifteen presbyopes over the age of 45 using commercially available focus-tunable eyeglasses under three different illumination conditions over a 3.08D accommodation stimulus range. The resulting average residual root-mean-squared (RMS) error values for the best fitting 8-parameter model was 0.25D compared to an average RMS error of 0.4D for the conventional DDF and HHG models. The RMS error for the best-fitting model is below the average refractive error of the human eye.

Barriers in Teaching Science to Students with Special Needs: Exploration From Teachers' Perspectives

Previous research has identified the benefits of science learning to support post-school independence of children with special needs [9]. However, the portion and quality of teaching science to these students is still very limited. This study aimed to explore the barriers faced by teachers in teaching science to children with special needs in both special schools and inclusive school settings. A mixed methods approach was employed to understand the implementation of science learning for children with special needs, especially the support and obstacles faced by teachers and students with special needs. Data were collected through structured interviews and observations of science learning. Interviews and observations were conducted in 11 special classes and 9 inclusive classes when teaching science to reveal the didactic method used by the teacher and the student responses. Guided interviews were conducted with teachers (n = 20, 15 female and 5 male) to understand the teaching process and obstacles experienced. The results of the interviews and observations were validated through a focus group discussion, which was attended by 7 participants. The quality of textbooks with adjustments for students with special needs was found to be the major challenge for teachers as they explained that they have limited time to adjust the content themselves. It was also identified that there is a need for teachers to shift their mindset, as they focus on students’ learning problems as teaching barriers. This study calls for professional development for teachers, with a focus on mindset, teaching strategies and accommodation in science subjects, which would enable teachers to support students with special needs in special and inclusive classrooms.
 Keywords: science teaching, students with special needs, barriers in teaching

Diurnal Changes in Accommodation Amplitude and Anterior Segment Parameters During Ramadan Fasting

Background: The purpose of this research was to investigate the diurnal effect of Ramadan fasting on the amplitude of accommodation and anterior segment parameters in visually healthy participants.Materials and Methods: The study included 68 healthy individuals, aged 26–42 years. The subjective accommodation amplitude was measured using the "minus lens" technique. Corneal refraction (K1, K2, and Kmax), central corneal thickness, corneal volume, anterior chamber volume, and anterior chamber depth parameters were evaluated using the Scheimpflug camera system. Participants were evaluated twice, at 08:00 and 16:00, while fasting during Ramadan. Data were analyzed by paired sample t-test.Results: The mean age of the participants, of which 28 were women and 40 were men, was 34.38±4.93 (range: 26–42). Comparison of measurements taken at 08:00 and 16:00 during fasting showed that at 16:00, the K1 values (08:00: 42.81±1.51 diopter and 16:00: 42.85±1.50 diopter, P = 0.016) and Kmax values (08:00: 44.29 ± 1.73 diopter and 16:00: 44.38±1.78 diopter, P = 0.020) were significantly steeper. When data collected at 08.00 and 16.00 were compared, there were no significant differences in diurnal changes: amplitude of accommodation (08:00: 7.39±1.40 diopter and 16:00: 7.37±1.40 diopter, P = 0.783), central corneal thickness (08:00: 535.60 ± 30.43 µm and 16:00: 535.25±30.66 µm, P = 0.694), corneal volume (08:00: 59.72±3.85 mm3 and 16:00: 59.60±3.98 mm3, P= 0.344), anterior chamber volume (08.00: 170.91±30.77 mm3 and 16.00: 171.22±32.61 mm3, P = 0.808) and anterior chamber depth (08:00: 2.91 ± 0.28 mm and 16:00: 2.92 ± 0.29 mm, P = 0.053).Conclusions: The results showed that dehydration due to fasting affects some anterior segment parameters, such as corneal refraction; however, it does not affect the diurnal changes of amplitude of accommodation, corneal pachymetry, or anterior chamber anatomy.

Simultaneous Measurement of Objective and Subjective Accommodation in Response to Step Stimulation.

PurposeThis study aimed to evaluate differences in objective and subjective accommodation dynamically and simultaneously.MethodsThirty-four pre-presbyopic healthy volunteers (mean age ± SD, 41.0 ± 3.2 years) participated in this study. Initially, the reaction time for detecting a change in the target was measured at near. Dynamic accommodation was then monocularly recorded using an open-view Shack–Hartmann aberrometer and compared with the amplitude and velocity of subjective accommodation.ResultsThe objective amplitude of accommodation (0.97 ± 0.32 diopter [D]) was significantly greater than the subjective amplitude of accommodation (0.62 ± 0.43 D; P < 0.001). The accommodative velocity was significantly faster for the “before the accommodation” response time (0.47 ± 0.38 D/s) than the “after the accommodation” response time (0.21 ± 0.22 D/s; P = 0.007).ConclusionsThe human eye under the monocular condition quickly adjusts to the focal plane to clearly archive the nearby object, and the focal plane thereafter is slowly and accurately adjusted to the visual target after visual recognition.

Ocular Biometry and its Relation to Amplitude of Accommodation in Normal Subjects

Ocular Biometry and its Relation to Amplitude of Accommodation in Normal Subjects

Changes in functional, anatomical and optical parameters of the eye in children with habitually excessive accommodation stress and pseudomyopia after regular badminton playing

Purpose. To study the state of refraction, accommodation, and blood flow in eye vessels of children with habitually excessive accommodation stress (HEAS) and pseudomyopia practicing badminton.Material and methods. The study involved 11 patients (20 eyes) aged 7 to 11 years (average M±SD: 9.24 ± 1.06 years) with pseudomyopia and HEAS: 4 patients with myopia (7 eyes), 3 children with hyperopia (6 eyes), 4 children with emmetropia (7 eyes) before they started practicing badminton and after playing it for a certain time. All patients were tested for visual acuity, subjective and objective accommodation, optical biometry, aberrometry, velocity of blood flow in eye vessels, and choroidal thickness.Results. After 1 year of regular badminton workout, the subjects revealed a 0.92 ± 0.82 D weakening of manifest refraction, a decrease in accommodation tone by 0.85 ± 0.77 D, an increase in blood flow rate in ophthalmic artery and the central retinal artery, an increase in positive spherical aberration, a decrease in aberrations associated with mismatch and irregularity ofoptical system elements (tilt, trefoil, coma), which indirectly indicates a strengthening of the ligamentous apparatus of the lens.Conclusion. Practicing sports (badminton) contributes to the elimination of pseudomyopia, improvement of uncorrected visual acuity, accommodative ability, and ophthalmic hemodynamics indicators.

The Working Life of People with Degenerative Cerebellar Ataxia.

The aim of the present study was to characterize and analyze the most important individual and organizational variables associated with job accommodation in subjects with degenerative cerebellar ataxia by administering a series of international and validated work activity-related scales. Twenty-four workers (W) and 58 non-workers (NW) were recruited: 34 with autosomal dominant ataxia and 48 with autosomal recessive ataxia (27 with Friedreich ataxia and 21 with sporadic adult-onset ataxia of unknown etiology). The severity of ataxia was rated using the Scale for the Assessment and Rating of Ataxia. Our results showed that the ataxic W were predominantly middle-aged (41-50years), high school graduate, and married men with a permanent work contract, who had been working for more than 7years. The W with ataxia exhibited a good level of residual working capacity, irrespective of gender, age range, and duration of the disease, and they were observed to have a low or average-to-low job stress-related risk. Supporting patients with ataxia to find an appropriate job is an important priority because about 78% of NW search for a job and W and NW have the same potential work abilities (no relevant differences were found in terms of disease characteristics, gender, and work resilience). In this view, introducing NW to work-life may have a potential rehabilitative aspect. Findings of this study highlight that equal job opportunities for subjects affected by cerebellar ataxia are recommended.

Corneal Curvature: the Influence of Corneal Accommodation and Biomechanics on Corneal Shape.

PurposeVariation in the presence and magnitude of corneal conformational changes during accommodation may predict postoperative ectasia following refractive surgery and assist in the early diagnosis of corneal ectatic disorders. The current study aimed to establish a baseline for corneal refractive changes during ocular accommodation and to clarify the role of biomechanical factors in predicting these changes in a population without corneal pathology.MethodsGALILEI G2 corneal tomography was assessed in 63 participants in both the accommodated and unaccommodated states. Four diopters (D) of physiological accommodation were induced using near-acuity calibrated words viewed through an externally mounted beam splitter mounted on a three-dimensional-printed frame. Corneal biomechanical characteristics were assessed with the CorVis-ST instrument, and statistical analysis was completed in R software.ResultsAnterior chamber depth was reduced by 0.10 ± 0.07 mm with accommodation (P < 0.01). Areas of statistically significant change in corneal curvatures were seen in all participants with accommodation. Mean anterior instantaneous corneal power increased in the superior-nasal periphery (0.1 D, 95% confidence interval [CI] = 0.05–0.2 D) and decreased in the inferior-temporal periphery (0.1 D, 95% CI = −0.05 to −0.15 D). Corneal stiffness and the corneal deformation amplitude ratio predicted peripheral corneal curvature changes with accommodation (P < 0.05).ConclusionCorneal conformational changes occur during accommodation in normal subjects. Further studies are required to assess the magnitude of corneal changes during accommodation in patients with corneal ectasia.Translational RelevanceAn externally mounted beam splitter can be used to modify the visual target presented by clinical ocular imaging instruments. Corneal conformational changes during accommodation may be useful in the diagnosis of corneal ectasia.

Agreement between distance and near minus-lens-to-blur amplitude of accommodation in pre-presbyopic subjects

Background: Guidelines for predicting the amplitude of accommodation (AA) sometimes are based on measurements for the subjective push-up-to-blur method. However, the push-up-to-blur method often overestimates the accommodative response. Another method that is commonly used to measure AA is the minus-lens-to-blur technique. This method is routinely conducted at a viewing distance of 40 cm, with the addition of 2.50 D to correspond with the initial accommodative stimulus. Aim: Although the AA measured using the minus-lens-to-blur method can be performed with the target at 40 cm, this study investigated changing the viewing distance and then comparing the means for participants at 600 cm (6 m), 40 cm (0.4 m) and 33 cm (0.33 m). In this manner, the possibility of using the AA measured at 6 m to estimate AA at 40 cm or 33 cm could be explored. Setting: The study was conducted in the Optometry Department, University of Limpopo. Methods: The AA was measured using the minus-lens-to-blur method over the distance correction when the target was held at viewing distances of 6 m, 40 cm and 33 cm. The minus lens power used to stimulate accommodation was gradually increased in 0.25 D steps. All measurements were performed using a phoropter. Results: The mean AA was 8.46 ± 2.07 D for 6 m, 10.62 ± 2.05 D for 40 cm and 11.31 ± 2.07 D for 33 cm. The measured AA at 6 m was significantly lower than that with the target at 40 cm and 33 cm measurement, p < 0.01. The Bland–Altman plots showed that there was a weaker agreement between the measured AA with the target at 6 m and near; however, there was a better agreement when the target was at 40 cm or 33 cm. Conclusion: The findings of this study suggest that the results for AA measured using the minus-lens-to-blur method at 6 m are not comparable to the results with the target at 40 cm or 33 cm. Even though there was a positive correlation between 6 m and the near distances, the results were not interchangeable or useful to calculate AA at 40 cm and 33 cm. The difference between the AA measured with the target at 40 cm and 33 cm can vary on average by about 0.70 D.

Available methods of the examination of accommodation of the eye in the ophthalmological outpatient department (materials from the Conference on Accomodation, Yaroslavl, 2019)

Time limits in the outpatient department practice do not allow to perform an extensive examination of young patients with refraction and accommodation disorders and to assess the severity and significance of their condition. Constantly redundant tension of accommodation (CRTA), weakness of accommodation, as well as the in¬flexibility of accommodation – all have the similar clinical picture, require a careful approach to differential diagnosis and, thereby, different methods of treatment. Therefore, the examination of accommodation of younger patients must be as comfortable as possible, not tedious, impersonal and informative. Accommodation disorders not only accompany, but also act as triggers as far as a number of diseases are concerned, the role of accommodation response delay has been already proven to be a reason of myopia progression. Underestimation of their role in the development of some pathological conditions can leave a patient with¬out the required assistance and limit his or her visual performance during the most productive age. The authors offer an examination algorithm that does not contradict with global requirements on this issue, but significantly reduces the amount of time that doctors need for detecting an accommodation disorder. The relevance of the suggested algorithm of subjective and objective accommodation examination methods is that they do not require expensive equipment, are not time-consuming and are quite accurate despite their apparent simplicity.

Objective Accommodation Amplitude Measurements Using a New Autorefractometer Device.

Objectives:To measure the value of objective accommodation amplitude (AA) in patients using the new autorefractometer device and to evaluate the effects of age, refraction errors, pupil diameter on objective AA measurements.Methods:Three hundred subjects who were divided into five groups according to age were enrolled in this study. AA and pupil diameter were measured three times from both eyes using Tonoref III (NIDEK Co., Ltd.).Results:The mean AA was 1.6325±0.061 Diopter (D) (0.13-9.11 D). The mean AA values were statistically significantly different between the groups (p=0.000). It was not observed gender effect on AA (p=0.115). Although there was no significant difference between emmetropic and myopic groups, there were significant differences between emmetropic and hyperopic groups and also between myopic and hyperopic groups concerning AA (p=0.000, for both). A statistically significant difference was found for the mean AA between the groups with and without refractive surgery (p=0.028). Correlation analysis revealed that AA is increased as the mean pupil diameter increases (p=0.000, r=0.202) and the mean pupil diameter decreases with increasing age (p=0.000, r=-0.308). When the AA obtained from the patients in group 1 were compared with the AA values obtained by subjective accommodation tests, the AA values obtained by autorefractometer device were found to be correlated with push up, push down and minus lens tests (r=0.577, r=0.682, r=0.427) AA values obtained by autorefractometer device were found to be statistically significantly lower than other subjective tests (p<0.001).Conclusion:The Tonoref III device seems to provide objective AA measurements in presbyopic or non-presbyopic individuals. Age, refractive error, pupil diameter and history of refractive surgery were effective on AA values, while the gender was not effective.

Subjective and objective accommodation of the Crystalens Advanced Optics (AO) in patients 6 months after bilateral implantation

Background: The aim of this study was to analyze and compare objective and subjective accommodation in patients after bilateral implantation of the FDA-approved accommodating Crystalens Advanced Optics (AO). Material and methods: This study was performed on 8 eyes of 4 patients. The subjective accommodation was measured by monocular and binocular defocus curves under photopic and mesopic conditions. The objective accommodation was analyzed using partial coherence interferometry (PCI) and wavefront aberration. Pupil diameter at different set-ups and refraction were derived from wavefront data. Results: Uncorrected and corrected distance and uncorrected near visual acuity improved significantly following implantation of the Crystalens AO in all eyes. Only one patient needed spectacles to correct distance visual acuity. Mean distance uncorrected visual acuity was 0.05 ± 0.06 logMAR. All patients were able to read newspapers without spectacles. Mean near uncorrected visual acuity was 0.17 ± 0.12 logMAR. Subjective accommodative amplitude under photopic conditions was significantly better binocularly than monocularly (p = 0.03) and was significant worse monocularly under mesopic conditions than photopic conditions (p = 0.016). No significant changes in anterior chamber depth were observed by PCI, with a fixation on optical stimuli at different distances. There were also no significant changes in the wavefront aberrations between the different set-ups. Pupil diameter increased significantly in the near set-up under mesopic conditions. Conclusions: No objective change in lens configuration was observed under different set-ups. Due to a variety of factors involved in pseudoaccommodation (e.g. pupil diameter, astigmatism, and multifocality), the subjective accommodative amplitude tends to be overestimated relative to objective measurements. No real accommodative action was observed.

Impact of hypoxic and mesopic environments on visual acuity, contrast sensitivity and accommodation in subjects with LASIK surgery and aircrew candidate

BackgroundThe safety of Laser-assisted in situ keratomileusis (LASIK) in aircrew was unclear, in addition, LASIK was not yet approved for aircrew of Taiwan Air Force. This study was aimed to evaluate visual performance in LASIK eyes in hypoxic and twilight environment. Methods48 myopic eyes of 24 subjects enrolled in this study were divided into LASIK group and control group. Subjects were exposed in hypoxic (15% O2) and mesopic (3 cd/m2) environment. Visual performance was evaluated using the Early Treatment of Diabetic Retinopathy Study (ETDRS) visual chart, and Functional Acuity Contrast Test (FACT) before and after the expirement. Physiological parameters of all subjects were measured and recorded throughout the experiment. ResultsThere was no significant difference of the two groups regarding their age, height, weight, and BMI. There is significant difference of preoperative spherical refractive error between the two groups. The results of physiological parameters were similar between two groups. Under normoxic conditions, there were no significant difference regarding distant vision in photopic and mesopic environments, so as for near vision. As a whole, the contrast sensitivity of the LASIK group were lowered than that of the control group about 35%, under whether normoxic or hypoxic conditions; photopic or mesopic circumstances. Under normoxic conditions, the measured accommodation of the LASIK group were 21% lowered than that of the control group and 31% lowered under hypoxic circumstances. ConclusionThere was no significant difference of visual acuity between the two groups regarding hypoxic and mesopic environment, but reduced contrast sensitivity was significant in LASIK group as compared to those of the control group. Accommodation was significantly lowered in LASIK group, compared with control group, in hypoxic environment. Whether postoperative visual performance after LASIK in aircrew during flying duty is safe might need further investigation.

Short-term effects of low-concentration atropine eye drops on pupil size and accommodation in young adult subjects

PurposeA single eye drop containing 0.01% atropine every evening has previously been found to inhibit myopia progression in young adults. We have tested the short-term effects of very low-dose atropine eye drops on pupil sizes and accommodation in young adult subjects.MethodsFourteen eyes of young adult subjects participated in the clinical observation. A single eye drop was applied with concentrations of either 0.01%, 0.005%, or 0.001% in the evening. Baseline parameters were measured before atropine application. Changes of pupil sizes, under photopic and mesopic conditions, as well as accommodation amplitudes were observed over the next day and analyzed by paired the Wilcoxon signed-rank test.ResultsThe pupil was significantly dilated 12 h after instillation of 0.01% atropine eye drops, both under photopic (3.3 ± 0.5 mm vs. 4.9 ± 0.9 mm) and mesopic (4.8 ± 0.7 mm vs. 6.1 ± 0.7 mm) conditions. Pupil sizes recovered over the day but were still significantly larger in the evening, compared to the baseline parameters measured on the day before (3.9 ± 0.5 mm vs. 5.3 ± 0.6 mm). The subjective near point of accommodation was reduced from 8.0 ± 2.4 to 6.6 ± 2.8 dpt in the morning and to 7.0 ± 2.9 dpt in the evening. At 0.005%, the pattern of results remained still similar, although the magnitude of the effects was generally smaller. At 0.001%, pupil sizes were still weakly significantly larger in the morning.ConclusionsAt a dose of 0.01%, clinically significant short-term effects were detected on pupil size and accommodation for at least 24 h. At the lowest dose of 0.001%, only tiny effects on pupil size were detectable.

Anterior scleral thickness changes with accommodation in myopes and emmetropes

Although a range of changes in anterior segment structures have been documented to occur during accommodation, the quantification of changes in the structure of the anterior sclera during the accommodation process in human subjects has yet to be examined. This study therefore aimed to investigate the presence of short-term changes in anterior scleral thickness associated with accommodation in young adult myopic and emmetropic subjects. Anterior scleral thickness was measured in 20 myopes and 20 emmetropes (mean age 21 ± 2 years) during various accommodation demands (0, 3 and 6 D) with anterior segment optical coherence tomography (AS-OCT). A Badal optometer was mounted in front of the objective lens of the AS-OCT to allow measurements of the anterior temporal sclera (1, 2 and 3 mm posterior to the scleral spur) to be obtained while fixating on an external accommodation stimulus. Anterior scleral thickness was not statistically different between refractive groups at baseline, but thinned significantly with the 6 D accommodation demand (−8 ± 21 μm, p < 0.05), and approached a statistically significant change with the 3 D demand (−6 ± 20 μm, p = 0.066). While both refractive groups thinned by a statistically significant amount at the 1 mm location with the 3 D demand; significant (p < 0.001) refractive group differences occurred at 3 mm, where the thinning found in the myopic group reached statistical significance with both the 3 D (−12 ± 21 μm) and 6 D (−19 ± 17 μm) demands, and the emmetropes showed no significant changes. This demonstrates the first evidence of a small but statistically significant thinning of the anterior sclera during accommodation. These changes were more prominent in myopes, particularly 3 mm posterior to the scleral spur. These regional differences may be associated with previously reported regional variations in ciliary body thickness between refractive groups, regional differences in the contraction of the ciliary muscle with accommodation, or differences in the response of the sclera to these biomechanical forces.

Effects of different contact lens design on accommodative function and binocular vision of young adult subjects

Purpose: To assess the effects of two daily soft contact lenses, one for single vision and another used for presbyopia compensation, on accommodation and near binocular vision functions of young adult subjects.