Accommodation stimulus and response determinations with autorefractors

Wavefront sensing: A breakthrough for objective evaluation of dynamic accommodation in accommodative dysfunctions

The purpose of this study was to use wavefront sensing as an objective method to detect and assess dynamic accommodation in subjects with accommodative dysfunctions and symptoms related to near-vision tasks. Sixty-three subjects were divided into control (N = 18), symptomatic without any accommodative dysfunction (SWD) (N = 18), infacility of accommodation (INFA) (N = 6), excess of accommodation (EA) (N = 9), and insufficiency of accommodation (INSA) (N = 12) groups. Accommodation was stimulated in different cycles of accommodation and disaccommodation while ocular aberrations were measured. Dynamic accommodation was computed from ocular wavefront aberrations and then analysed, including response time, peak velocity, and microfluctuations. Subjects with accommodative dysfunctions showed alterations in accommodative responses compared to the control group, characterized by slower and excessive/reduced responses, as well as an increase in accommodative microfluctuations and difficulty in relaxing accommodation to different accommodative demands. The SWD group showed significant changes compared to the control group, suggesting accommodative problems not previously detected in clinical examinations and explaining the symptoms reported by these subjects. The specific patterns of the characteristics of dynamic accommodation are presented for the different accommodative dysfunctions. The objective assessment of dynamic accommodation using wavefront sensing, analysed for different accommodative demands, provides a comprehensive approach to the detection and characterisation of accommodative dysfunctions. This method enables the improvement of the precision of the diagnosis of accommodative dysfunctions and allows its detection in cases that may not be detected by current clinical examinations. In addition, this method may contribute to personalized treatment planning, potentially improving patient outcomes in clinical practice.

Accommodating version of a schematic eye for emmetropia and myopia

AIM

To develop an accommodating, wide-angle, schematic eye for emmetropia and myopia in which spectacle refraction and accommodation level are input parameters.

METHOD

The schematic eye is based on an earlier unaccommodated refraction-dependent eye for myopia developed by Atchison in 2006. This has a parabolic gradient index lens and parameters derived from biometric and optical measurements on young adults. Several parameters are linearly dependent upon spectacle refraction (anterior radius of curvature of the cornea, axial length and vertex radii of curvature and conic asphericities of a biconic retina). The new accommodated schematic eye incorporates accommodation-dependent changes in several lens-related parameters. These changes are based on literature values for anterior chamber depth, lens thickness, vitreous chamber depth, lens surface radii of curvature and lens front surface asphericity. A parabolic variation of refractive index with relative distance from the lens centre is retained, with the same edge and centre refractive indices as the earlier model, but the distribution has been manipulated to maintain focus near the retina for the emmetropic case at 0 and 4 D accommodation. The asphericity of the lens back surface is changed so that spherical aberration and peripheral refraction approximately match typical literature trends. The model is used to compare spherical aberration and peripheral refraction in eyes with up to 4 D of myopia and 4 D of accommodation.

RESULTS

The levels of spherical aberration in the unaccommodated schematic eyes are similar to literature values for young adults, but the changes in spherical aberration with accommodation are approximately two-thirds of that found in an experimental study. As intended, peripheral refractions in the accommodated schematic eyes are similar to those of their unaccommodated counterparts.

CONCLUSION

The wide-angle model extends the range of schematic eyes to include both refraction and accommodation as variable input parameters. It may be useful in predicting aspects of retinal image quality.

Accommodative response and visual fatigue following a non-congruent visual task in non-asthenopic and asthenopic individuals

PURPOSE

Asthenopia is related to near vision activities or visual tasks that dissociate accommodation from vergence. Since the results of previous studies using objective measures to diagnose asthenopia are inconsistent, this study compared optometric tests and objective metrics of accommodation in non-asthenopic and asthenopic young adults before and after a visual fatigue task.

METHODS

The accommodative response was recorded objectively for 6 min at a 3.33 D accommodative demand using an autorefractor, before and after a 5-min non-congruent visual task. Accommodation was disassociated from vergence with a ±2.00 D accommodative flipper while reading at the same distance. Optometric tests and subjective evaluations of asthenopia were performed before and after the task. Twenty-six non-presbyopic adults (23.15 ± 2.56 years) were included and identified as asthenopic (n = 14) or non-asthenopic (n = 12) based on their score on the Computer Vision Syndrome Questionnaire.

RESULTS

A mixed ANOVA found no significant difference between the groups for objective (accommodative response) or subjective metrics (feeling of fatigue, optometric tests), although all participants reported greater visual fatigue after the task. A significant effect of time (before and after the non-congruent task) was identified for the overall sample for mean accommodative lag (+0.10 D, p = 0.01), subjective visual fatigue (+1.18, p < 0.01), negative relative accommodation (-0.20 D, p = 0.02) and near negative fusional reserve (blur: +2.46Δ, p < 0.01; break: +1.89Δ, p < 0.01; recovery: +3.34Δ, p = 0.02).

CONCLUSIONS

The task-induced asthenopia, measured both objectively and subjectively, was accompanied by a change in accommodative lag, greater visual fatigue and a decrease in negative relative accommodation. Conversely, near negative fusional reserves seem to adapt to the task. No significant differences were found between the two groups with respect to accommodative metrics (objective) or subjective and optometric tests.

Addition of Auricular Acupoint Stimulation to 0.01% Atropine for Myopia: 12-Month Results from a Randomized Trial

Introduction: A previous 6-month report showed that adjunctive auricular acupoint stimulation (AAS) slowed myopia progression compared with 0.01% atropine (0.01% A) alone. This 12-month report was to determine whether the antimyopic effect of AAS, when added to 0.01% A, continued beyond treatment cessation, and explore the mode of action of AAS from the accommodative response. Design and Interventions: One hundred four children were randomly assigned to either a 0.01% A group or a 0.01% A + AAS group. Participants in the 0.01% A + AAS group received AAS in addition to 0.01% A for 6 months, and then kept using 0.01% A for the following 6 months. Participants in the 0.01% A group only used 0.01% A. The primary outcome was the difference in the mean cycloplegic spherical equivalent refraction (SER) from the baseline to the 12-month visit. Secondary outcomes included axial length (AL) and accommodative lag assessments. Results: The adjusted mean change from baseline to month 12 in the SER was -0.62 D for 0.01% A and -0.46 D for 0.01% A + AAS (difference, 0.16 D; p = 0.01), with a respective mean increase of 0.37 and 0.31 mm in AL (difference, -0.05 mm; p = 0.05). For the 5D near target, there was a reduction in the accommodative lag in children receiving add-on AAS relative to 0.01% A alone at 1 and 6 months (both p = 0.002). Conclusions: AAS treatment produced additional benefits >0.01% A in slowing myopia progression over the 12-month period, where the efficacy was sustained after the cessation of AAS. An effect of add-on AAS on reducing accommodative lag in response to 5D stimulus was found, but its role in mediating therapeutic response remained unclear. Chinese Clinical Trial Registry number: ChiCTR1900021316.

Higher order aberrations and retinal image quality during short-term accommodation in myopic and non-myopic children

INTRODUCTION

Despite the known associations between near work and myopia, and retinal image quality and eye growth, accommodation-induced changes in higher order aberrations (HOA's) and retinal image quality in children with different refractive errors are poorly understood.

METHODS

Ocular HOA's were measured using a Hartmann-Shack wavefront sensor (COAS-HD, Wavefront Sciences) in 18 myopic and 18 age- and sex-matched non-myopic children during short-term accommodation tasks (four demands of 0, 3, 6 and 9 D) presented using a Badal optometer. Eighth order Zernike polynomials were fitted across a 2.3 mm pupil diameter to determine refractive power vectors (M, J₁₈₀ and J₄₅ ) and the accommodation error, and a 4 mm pupil was used for HOA analyses. Retinal image quality was examined using the visual Strehl ratio based on the optical transfer function (VSOTF) for third to eighth radial orders only.

RESULTS

Most refractive error group differences were observed for the 6 and 9 D demands. Myopic children underwent greater changes in with-the-rule astigmatism (J₁₈₀ ), higher order and third order RMS values, primary vertical ( C 3 - 1 $$ {C}_3^{-1} $$ ) and horizontal coma ( C 3 1 $$ {C}_3^1 $$ ), and several other individual Zernike coefficients compared with non-myopic children (all refractive error group by demand interaction p-values of ≤0.02). Non-myopic children exhibited a greater negative shift in primary ( C 4 0 $$ {C}_4^0 $$ ) and positive shift in secondary spherical aberration ( C 6 0 $$ {C}_6^0 $$ ) (both refractive error group by demand interaction p-values of ≤0.002). The VSOTF degraded for the 6 and 9 D demands in both groups, but the myopic children underwent a greater mean (SE) reduction from 0 D of -0.274 (0.048) for the 9 D demand, compared with -0.131 (0.052) for the non-myopic children (p = 0.001).

CONCLUSION

These results may have implications for the association between near work, accommodation and myopia development, particularly related to the use of short working distances during near tasks.

Visual Performance and Binocular/Accommodative Function of S.T.O.P. Contact Lenses Compared With MiSight

OBJECTIVES

The objective of this study was to compare the visual performance and binocular/accommodative function of two novel S.T.O.P. design (F2 and DT) contact lenses against MiSight when worn by myopic, young adults.

METHOD

This was a prospective, randomized, cross-over, single-masked study. Each lens was worn daily wear with overnight peroxide disinfection for approximately 7 days. Visual performance was assessed with subjective ratings (0-100): clarity of vision and lack of ghosting (far away, intermediate, and near), vision when driving, overall vision satisfaction, and with monocular high-contrast and low-contrast visual acuity (HCVA/LCVA) at 6 m, binocular HCVA (6 m, 70 cm, 50 cm, and 40 cm), binocular LCVA (6 m and 70 cm). Binocular function was assessed with heterophorias (3 m and 40 cm). Accommodative function was assessed with monocular accommodative facility (AF: 40 cm) and dynamic monocular accommodative response (AR: 6 m, 70 cm, and 40 cm).

RESULTS

F2 was rated higher than MiSight for clarity of vision (near and intermediate) and lack-of-ghosting ( P <0.001), while MiSight was rated higher than DT for clarity of vision (near, P <0.001). MiSight was better than F2 and DT for monocular HCVA (6 m) and binocular HCVA (6 m and 40 cm, P ≤0.02), but the maximum difference was ≤2 letters. There were no differences between designs for heterophoria ( P =0.61) nor were there any differences between DT and MiSight for any accommodative measure ( P >0.1). F2 was higher for monocular-AF ( P =0.007) and lower for AR (70 cm and 40 cm; P ≤0.007) compared with MiSight.

CONCLUSIONS

The visual performance and binocular/accommodative function of S.T.O.P. designs F2 and DT were comparable with MiSight. F2 outperformed MiSight in some aspects of subjective visual performance and monocular accommodative function.

Accommodation lags are higher in myopia than in emmetropia: Measurement methods and metrics matter

Purpose

To determine whether accommodative errors in emmetropes and myopes are systematically different, and the effect of using different instruments and metrics.

Methods

Seventy‐six adults aged 18–27 years comprising 24 emmetropes (spherical equivalent refraction of the dominant eye +0.04 ± 0.03 D) and 52 myopes (−2.73 ± 0.22 D) were included. Accommodation responses were measured with a Grand Seiko WAM‐5500 and a Hartmann–Shack Complete Ophthalmic Analysis System aberrometer, using pupil plane (Zernike and Seidel refraction) and retinal image plane (neural sharpness—NS; and visual Strehl ratio for modulation transfer function—VSMTF) metrics at 40, 33 and 25 cm. Accommodation stimuli were presented to the corrected dominant eye, and responses, referenced to the corneal plane, were determined in the fellow eye. Linear mixed‐effects models were used to determine influence of the refractive group, the measurement method, accommodation stimulus, age, race, parental myopia, gender and binocular measures of heterophoria, accommodative convergence/accommodation and convergence accommodation/convergence ratios.

Results

Lags of accommodation were affected significantly by the measurement method (p < 0.001), the refractive group (p = 0.003), near heterophoria (p = 0.002) and accommodative stimulus (p < 0.05), with significant interactions between some of these variables. Overall, emmetropes had smaller lags of accommodation than myopes with respective means ± standard errors of 0.31 ± 0.08 D and 0.61 ± 0.06 D (p = 0.003). Lags were largest for the Grand Seiko and Zernike defocus, intermediate for NS and VSMTF, and least for Seidel defocus.

Conclusions

The mean lag of accommodation in emmetropes is approximately equal to the previously reported depth of focus. Myopes had larger (double) lags than emmetropes. Differences between methods and instruments could be as great as 0.50 D, and this must be considered when comparing studies and outcomes. Accommodative lag increased with the accommodation stimulus, but only for methods using a fixed small pupil diameter.

Comparison of the Amplitude of Accommodation Measured Using a New-Generation Closed-Field Autorefractor with Conventional Subjective Methods

Purpose: This study aims to compare and assess the agreement of the objective amplitude of accommodation (AA) measured using a new-generation closed-field autorefractor with conventional subjective methods. Methods: In total, 84 healthy individuals with an age range of 19 to 50 years participated in this cross-sectional study. AA was measured objectively with a Nidek autorefractor (AR-1a; Nidek Co., Ltd., Tokyo, Japan) and subjectively using push-up (PU) and minus-lens (ML) methods in a random order. Comparison between different methods was performed using repeated-measures analysis of variance and the Bonferroni test for pairwise comparisons. In addition to the Pearson correlation, the Bland and Altman method and the intraclass correlation coefficient were used to determine the agreement between the three techniques. Only the right-eye results were used for analysis. Results: AA measured using the Nidek autorefractor (3.43 ± 1.94 D) was significantly lower than that measured with PU (7.67 ± 2.38 D; p < 0.001) and ML (7.60 ± 2.81 D; p < 0.001) methods. The difference between the subjective methods was not significant statistically (p = 1.0). The correlation for Nidek measurements and PU and ML methods was moderate (r = 0.5502 and r = 0.6832, respectively), while it was strong when comparing subjective methods (r = 0.7821). The limits of agreement for Nidek vs. PU, Nidek vs. ML, and PU vs. ML methods were −8.28 to −0.23 D, −8.19 to −0.15 D, and −3.38 to 3.51 D, respectively. Conclusions: There was a moderate agreement between AA obtained with subjective methods and objective Nidek measurements. The objective AA measurements obtained with a new Nidek autorefractor were significantly lower than subjective measurements.

Associations between Binocular Vision Disorders and Contact Lens Dissatisfaction

SIGNIFICANCE

These data demonstrate that binocular vision disorders (BVDs) contribute to contact lens (CL) dissatisfaction independently of CL discomfort (CLD) in myopic, pre-presbyopic, adult, single-vision CL wearers.

PURPOSE

This study aimed to determine whether BVDs contribute to CL dissatisfaction and whether this contribution is independent of CLD.

METHODS

Participants attended one clinical visit while wearing their habitual CLs. Symptoms from CLD and BVDs were measured with the Contact Lens Dry Eye Questionnaire-8 (CLDEQ-8) and Convergence Insufficiency Syndrome Survey (CISS), respectively. A comprehensive binocular vision (BV) assessment was performed. The Ocular Surface Disease Index (OSDI) was used to measure CL dissatisfaction from CLD and BVDs based on reported correlations between the CLDEQ-8 and the CISS with the OSDI. Participants were categorized according to their CL comfort status (CLD [≥12 on CLDEQ-8] or non-CLD [<12 on CLDEQ-8]) and BV status (BVD or non-BVD).

RESULTS

Seventy-six participants completed the trial, and 19 (25%) were diagnosed with BVD. Those diagnosed with BVD scored higher than did those diagnosed with non-BVD for the OSDI (25.1 ± 12.7 vs. 10.7 ± 7.3, P < .001) and CISS (18.7 ± 7.7 vs. 11.9 ± 5.9, P = .001), but not the CLDEQ-8 (P = .25). Those categorized as having CLD scored higher than did those categorized as having non-CLD for the OSDI (19.0 ± 12.3 vs. 9.3 ± 5.9, P = .003) and CISS (16.1 ± 6.8 vs. 11.0 ± 6.2, P = .001). There were no significant interactions between BV status and CL comfort status for any questionnaire (P > .08).

CONCLUSIONS

Higher scores for OSDI in those with CLD or BVD indicate that both conditions contribute to CL dissatisfaction. Higher scores for the CISS in those with CLD suggest a degree of overlap for some BVD symptoms. Nonsignificant differences between BVD and non-BVD for the CLDEQ-8 suggest that BVDs contribute to CL dissatisfaction independently of CLD.

Higher order aberrations and retinal image quality during short-term accommodation in children

Changes in higher order aberrations (HOA's) and retinal image quality during accommodation have not previously been examined in children. This study measured ocular HOA's in ninety non-myopic, school-aged children during short-term accommodation tasks at 0, 3, 6, and 9 D demands presented via a Badal optometer mounted to a Hartmann-Shack wavefront aberrometer (COAS-HD, Wavefront Sciences). Eighty-four participants who exhibited active accommodation were included in the analyses. An eighth order Zernike polynomial was fit across a 2.3 mm, 4 mm, and natural pupil diameter to evaluate changes in refractive power vectors (M, J₁₈₀, and J₄₅), accommodation errors (lags and leads), HOA root mean square (RMS) variables, individual Zernike coefficients, and the visual Strehl ratio based on the optical transfer function (VSOTF). All HOA RMS variables changed significantly with accommodation, with the greatest change observed for the 9 D demand. Of the individual Zernike coefficients, primary (C₄⁰) and secondary spherical aberration (C₆⁰) exhibited the greatest magnitude of change, becoming negative and positive with increasing accommodation, respectively. The VSOTF changed significantly with greater accommodation for both the 4 mm and natural pupil size, becoming significantly worse for the 9 D demand. HOA's increase and retinal image quality decreases significantly during higher levels of accommodation in children, similar to adults. These findings provide a greater understanding of the optical properties of children's eyes and insights into possible mechanisms for the association between accommodation, near work, and refractive error development.

Ocular Anatomical and Functional Characteristics in Anisometropic Chinese Children

SIGNIFICANCE

This research found that anterior and posterior biometrics differ in many aspects between fellow eyes of anisometropic children. This might shed light on the mechanisms underlying the onset and progression of anisometropia and myopia.

PURPOSE

This study aimed to investigate the ocular biometric parameters, peripheral refraction, and accommodative lag of fellow eyes in anisometropic children.

METHODS

Anisometropic children were recruited. Axial length (AL), vitreous chamber depth (VCD), central corneal thickness, anterior chamber depth (ACD), lens thickness (LT), simulated K readings, central and peripheral refractive errors, and accommodative lag were measured in both eyes. The subfoveal choroidal thickness, average choroidal thickness, and choroid vessel density of the 6 × 6-mm macular area were measured by optical coherence tomography.

RESULTS

Thirty-two children aged 11.1 ± 1.7 years were enrolled. The average degree of anisometropia was 2.49 ± 0.88 D. The AL, VCD, ACD, and simulated K reading values were significantly larger in the more myopic eyes, whereas the LT value was significantly smaller. Subfoveal choroidal thickness (P = .001) and average choroidal thickness (P = .02) were smaller in the more myopic eyes than in the contralateral eyes, whereas choroid vessel density (P = .03) was larger. The amount of anisometropia had a significant positive correlation with the difference in AL (r = 0.869, P < .001), VCD (r = 0.853, P < .001), and ACD (r = 0.591, P < .001) and a negative correlation with the difference in LT (r = -0.457, P = .009).

CONCLUSIONS

Ocular biometrics differ in many aspects between the fellow eyes of anisometropic Chinese children, and the difference is correlated with the degree of anisometropia.

Accommodative Response in Patients with Central Field Loss: A Matched Case-Control Study

Purpose: This study was conducted to evaluate the accommodative response in young participants with visual impairment in comparison with visually normal participants. Methods: Fifteen participants with confirmed visual impairment and 30 visually normal participants aged 12–15 years were recruited. Accommodative response was measured using autorefractor (Grand Seiko WV500) at distances of accommodative demand of 33, 25, and 20 cm. The targets were one-line-above participant threshold acuity. The participants’ accommodative responses were compared between both groups after calibration for refractive errors and the vertex distance of the glasses. Visual acuity and refractive status were also assessed. Results: The age was not significantly different between both participant groups. The visual acuity of visually impaired patients was 6/30 to 6/240, and that of visually normal participants was 6/7.5 or better. Ten of the visually impaired patients and 29 of visually normal participants were myopic. In total, 61–73% of visually impaired patients showed an accommodative lead. Five subtypes of accommodative response were observed. In general, the accommodative inaccuracy increased with increasing accommodative demand. However, the visually normal participants largely exhibited an accommodative lag. A mild-to-moderate relationship was observed between visual acuity and accommodative response (r = 0.3–0.5, p < 0.05). Conclusion: Accommodative response in young visually impaired patients can be variable and on an individual basis. Low vision specialists should anticipate accommodative response outside the normal range. Therefore, we shall consider evaluating each patient’s accommodative response before prescribing any near addition lenses. Accommodation inaccuracy is often more complex than predicted due to increased depth of focus caused by reduced visual acuity.

Capturing attention improves accommodation: An experimental study in children with ADHD using multiple object tracking

The present study was aimed at assessing the impact of manipulating the attentional load using a multiple object tracking (MOT) task on the dynamics of the accommodative response in children with attention deficit hyperactivity disorder (ADHD). The pupil size was recorded to assess the effectiveness of the experimental manipulation, and the role of ADHD medication was also explored. The accommodative and pupil dynamics (magnitude and variability) were monitored with an open-field autorefractometer (WAM-5500) in 41 children with ADHD (24 non-medicated and 17 medicated) and 21 non-ADHD controls, while they performed the MOT task with four different levels of complexity (i.e., tracking zero, one, two, or three targets). We found that increasing the attentional load caused a heightened accommodative response, showing a negative association between MOT complexity and accommodative lag in children with ADHD and non-ADHD controls. Complementarily, the pupil size increased as a function of task complexity, confirming a successful experimental manipulation. The stability of accommodation was insensitive to the attentional manipulation, but it differed between groups. Specifically, non-medicated children with ADHD exhibited a greater variability of accommodation in comparison to controls. Increasing the attentional load is associated with a reduction in the accommodative lag in children with ADHD and controls. Our findings show that the allocation of attention plays an important role in the dynamics of the accommodative response, which may be of relevance in the diagnosis and treatment of accommodative deficits in children with and without ADHD.

The influence of age, refractive error, visual demand and lighting conditions on accommodative ability in Malay children and adults

PURPOSE

Near work, accommodative inaccuracy and ambient lighting conditions have all been implicated in the development of myopia. However, differences in accommodative responses with age and refractive error under different visual conditions remain unclear. This study explores differences in accommodative ability and refractive error with exposure to differing ambient illumination and visual demands in Malay schoolchildren and adults.

METHODS

Sixty young adults (21-25 years) and 60 schoolchildren (8-12 years) were recruited. Accommodative lag and accommodative fluctuations at far (6 m) and near (25 cm) were measured using the Grand Seiko WAM-5500 open-field autorefractor. The effects of mesopic room illumination on accommodation were also investigated.

RESULTS

Repeated-measures ANOVA indicated that accommodative lag at far and near differed significantly between schoolchildren and young adults [F(1.219, 35.354) = 11.857, p < 0.05]. Post hoc tests using the Bonferroni correction showed that at near, there was a greater lag in schoolchildren (0.486 ± 0.181 D) than young adults (0.259 ± 0.209 D, p < 0.05). Repeated-measures ANOVA also revealed that accommodative lag at near demands differed statistically between the non-myopic and myopic groups in young adults and schoolchildren [F(3.107, 31.431) = 12.187, p < 0.05]. Post hoc tests with Bonferroni correction showed that accommodative lag at near was significantly greater in myopic schoolchildren (0.655 ± 0.198 D) than in non-myopic schoolchildren (0.202 ± 0.141 D, p < 0.05) and myopic young adults (0.316 ± 0.172 D, p < 0.05), but no significant difference was found between myopic young adults (0.316 ± 0.172 D) and non-myopic young adults (0.242 ± 0.126 D, p > 0.05). Accommodative lag and fluctuations were greater under mesopic room conditions for all ages [all p < 0.05].

CONCLUSION

Greater accommodative lag was found in myopes than in emmetropes, in schoolchildren than in adults, and under mesopic conditions than under photopic conditions. Accommodative fluctuations were greatest in myopes and in mesopic conditions. These results suggest that differences exist in the amount of blur experienced by myopes and non-myopes at different ages and under different lighting conditions.

Experimental Study of Refraction Effects of Nominally Plano Ophthalmic Prisms and Magnifying Lenses

SIGNIFICANCE

Nominally plano ophthalmic prisms give autorefraction results similar to those predicted on the basis of how effective powers change with pantoscopic tilt, and magnifying lenses give autorefraction results similar to those predicted on the basis of vergence changes. Without appreciation of the optics involved, these effects might wrongly be considered artifacts.

PURPOSE

The purpose of this study was to investigate the interactions of autorefractors with lenses and prisms.

METHODS

There were 15 adult participants across three experiments, with a range of ages and refractions. In experiments 1 and 2, participants wore frames containing base-up and base-down nominally plano prisms. In experiment 3, participants wore a lens that produced either 6.3% magnification or 5.9% minification, depending on which surface faced the eye. Autorefracting instruments with different operating principles were used: Shin-Nippon SRW5000 autorefractor, Grand Seiko 5100K autorefractor, Hoya AR-530 autorefractor, a Complete Ophthalmic Analysis System-High Definition wavefront sensor, and Tomey FC-800 autorefractor. A theory on the likely effects of magnifying lenses was presented.

RESULTS

For ophthalmic prisms, refractions showed results similar to those predicted on the basis of how effective prism powers change with pantoscopic tilt. As tilt increased, base-up prism gave more positive mean refractions and more negative horizontal/vertical astigmatism and vice versa for base-down prisms. In the presence of 10° tilt, 8Δ base-up prisms and 8Δ base-down prisms had different effects by a mean of 0.36 diopters. Magnifying lenses affected refractions similar to those predicted on the basis of vergence changes, with 6% magnification and minification producing mean changes of -11 and +8%, respectively, in absolute mean refraction. There was no strong evidence that different instruments had different effects.

CONCLUSIONS

The results have implications for studies in which prisms and lenses are placed in the front eyes, such as accommodation studies using thick lenses close to the eyes to stimulate accommodation rather than by changing object distance.

Real-Time Measurement of Ocular Wavefront Aberrations in Symptomatic Subjects

The purpose of this work was to study the real-time changes of the optical properties of the eye with accommodation in subjects with symptoms of accommodative disorders. From ocular aberrations, it is possible to compute several parameters like the response and lag of accommodation. The ocular aberrations were measured in 4 subjects, with different accommodative disorders, during several cycles of accommodation/disaccommodation and for different accommodative stimuli. The measurement was done continuously and in real time during different accommodative stimuli. It was possible to see the changes in accommodative response during the several stimuli of accommodation. Subjects with accommodative disorders showed different accommodative responses. The use of wavefront ocular aberrations can be a tool to diagnose accommodative disorders. In some subjects with complaints, this method showed irregularities even when the results of the usual clinical exams were normal.