A comparison of the reliability of dynamic retinoscopy and subjective measurements of amplitude of accommodation

Objective and subjective assessment of accommodative insufficiency

SIGNIFICANCE

A variety of subjective and objective procedures are available to measure the amplitude of accommodation. However, it is unclear whether the standard criterion of Hofstetter's minimum minus 2 D can be used to diagnose accommodative insufficiency with each of these techniques.

PURPOSE

The use of objective dynamic retinoscopy and three subjective techniques to diagnosis accommodative insufficiency was examined.

METHODS

A total of 632 subjects between 8 and 19 years of age were enrolled. Accommodative lag, monocular accommodative facility, and subjective (push-up, modified push-down, and minus lens) and objective (dynamic retinoscopy) amplitude of accommodation were quantified. Accommodative insufficiency was diagnosed based on Hofstetter's minimum minus 2 D for each subjective method, as well as adding an additional subjective criterion (either accommodative lag exceeding 0.75 D or monocular accommodative facility falling below the age-expected norms).

RESULTS

The prevalence of accommodative insufficiency was lowest and highest with the push-up (7.9 and 1%) and dynamic retinoscopy (94 and 12%) procedures when measured without and with the additional subjective criteria, respectively. Comparing the validity of dynamic retinoscopy against the traditional criterion, moderate to low sensitivity and high specificity were found. However, adding the additional subjective criteria improved the findings with moderate to high sensitivity and high specificity. Using a cutoff for dynamic retinoscopy of 7.50 D showed moderate diagnostic accuracy based on likelihood ratios.

CONCLUSIONS

It is clear that a revised definition of accommodative insufficiency is required, which must include the method of assessing accommodation. The various objective and subjective methods for quantifying the amplitude of accommodation are not interchangeable, and subjective assessment does not provide a valid measure of the accommodative response.

Accommodative Lag Persistence in Treated Anisometropic, Strabismic, and Mixed Amblyopia

Background

Amblyopic eyes typically exhibit greater lag of accommodation. Whether this improves after amblyopia treatment is inconclusive. The aim of this study is to report post-treatment accommodative response in amblyopia and to investigate if the lag is associated with visual acuity, treatment duration, and amblyopia type.

Methods

Monocular and binocular accommodative responses were measured using Nott's method of dynamic retinoscopy in amblyopia of anisometropic, strabismic, and combined anisometropic-strabismic types and age-matched controls with normal vision. The results were compared using the nonparametric Wilcoxon signed ranks test. Linear regression analysis was used to examine association of the lag to refractive error, duration of therapy, and visual acuity.

Results

Mean ± SD age of 46 amblyopic and 20 control subjects were 6.9 ± 1.8 and 6.9 ± 2.2 years, respectively. At the time of the study, 30 amblyopic subjects were receiving patching therapy and ceased in the remainder. In amblyopic eyes, mean ± SD monocular and binocular lags were 1.2 ± 0.6D and 1.0 ± 0.5D (p < 0.001), respectively, compared to 0.6 ± 0.3D and 0.5 ± 0.2D (p < 0.005), respectively, in nonamblyopic eyes and 0.4 ± 0.2D and 0.3 ± 0.2D (p=0.093), respectively, in the controls. By types, the monocular lag was significantly higher than the binocular lag (p=0.001) in mixed amblyopia (p=0.004); they were similar in anisometropic (p=0.283) and strabismic (p=0.743) amblyopia. Monocular lag was significantly correlated to BCVA (r = 0.46; p=0.001) and refraction (r = 0.42; p=0.001) but not to patching duration (r = 0.1; p=0.280).

Conclusion

Inadequate accommodative response, a higher lag, persists in amblyopic eyes even after the treatment. Impaired accommodative response is partly determined by posttherapy visual acuity. Further studies investigating the effect of accommodative lag on visual recovery and whether optical correction of the deficiency may improve visual outcome of the treatment are recommended.

Quantitative analysis of internal components of the human crystalline lens during accommodation in adults

To quantitatively analyze changes in the inner components of the human crystalline lens during accommodation in adults. Eyes of 23 subjects were sequentially examined using CASIA2 Optical Coherence Tomography under 0D, - 3D and - 6D accommodation states. The anterior chamber depth (ACD), anterior and posterior crystalline lens radius of the curvature (ALRC and PLRC) were obtained using built-in software. The lens thickness (LT), lenticular nucleus thickness (NT), anterior cortex thickness (ACT), posterior cortex thickness (PCT), anterior and posterior lenticular nucleus radius of the curvature (ANRC and PNRC), anterior and posterior lenticular nucleus vertex (ANV and PNV) were quantified manually with the Image-pro plus software. During accommodation, the ACD became significantly shallower and LT significantly increased. For changes in the lens, the ALRC decreased by an average magnitude (related to accommodative stimuli) 0.44 mm/D, and PLRC decreased 0.09 mm/D. There was no difference for the ACT and PCT in different accommodation states. For lenticular nucleus response, NT increased on average by 30 μm/D. Both the ANRC and PNRC decreased on average by 212 μm/D and 115 μm/D respectively. The ANV moved forward on average by 0.07 mm under - 3D accommodative stimuli and 0.16 mm for - 6D. However, there was no statistically significant difference between different accommodation states in the PNV movement. Under accommodation stimulation, lens thickness changed mainly due to the lenticular nucleus, but not the cortex. For the lenticular nucleus, both the ANRC and PNRC decreased and ANRC changed the most. The anterior surface of the nucleus moved forward while the posterior surface of the nucleus moved backward but only slightly.

Traumatic Brain Injury in Children: Do the Eyes Have It? The Orthoptic Evaluation of Traumatic Brain Injury

Because the neuropathological changes caused by mild traumatic brain injury (mTBI) more often manifest as functional impairments than structural abnormalities, the clinical diagnosis of mTBI may rely too heavily on a combination of history and self-reported symptoms. The mechanism of injury in mild traumatic brain injury (mTBI) predicts that supranuclear pathways controlling eye movement systems would be vulnerable to damage, and diagnostic tests of these systems would be high-yield. In fact, tests of oculomotor function have proven to be highly sensitive in detecting neurological soft signs, but may require expensive, specialized equipment. Fortunately, Certified Orthoptists (COs) are skilled at the evaluation of accommodative dysfunction, abnormalities of saccades, smooth pursuit, and vestibular eye movements, and vergence errors using standard ophthalmic equipment. Because COs are accustomed to adapting the sensorimotor exam to infants and pre-verbal children, they are able to modify or design objective methods, the results of which may be difficult for the patient with a functional overlay to decipher and deceive. When the patient with a history of mTBI presents to the ophthalmologist with visual symptoms and a normal routine eye exam, it is important to order a sensorimotor examination by a CO to confirm the diagnosis.

Controlled blood sugar improves the eye's accommodative ability in type-1 diabetes

PURPOSE

To evaluate the impact of blood sugar level on ocular measures, including refractive error (RE), amplitude of accommodation (AoA), and lag of accommodation (LoA), in pre-presbyopes with type-1 diabetes.

METHOD

The fasting blood sugar (FBS) and ocular measures of type-1 diabetes patients (age: 14-39 years; n = 30) on insulin treatment was recorded while they fasted on two separate visits, at baseline and 3 months later. The AoA and LoA was measured with the appropriate spectacle correction worn. The Welch's t-test was used for comparison of the baseline measures between the normal FBS ≤ 7 (n = 10) and higher FBS > 7 (n = 20) patients, and the paired t-test used to investigate for differences between the baseline and follow-up data in patients with changes in FBS.

RESULTS

On average, the spectacle correction for the normal FBS group was marginally more myopic (RE: -0.30 ± 0.67 D vs. +0.18 ± 1.00 D, p = 0.032), and they showed greater AoA (5.38 ± 1.08 D vs. 3.68 ± 1.43 D, p < 0.001) and lower LoA (1.00 ± 0.30 D vs. 1.30 ± 0.38 D, p = 0.004) compared with the higher FBS group at baseline. On the follow-up visit attended by 25 patients, the FBS of 15 patients was reduced by an average of 7.0 mmol/L, 8 patients had an average increase of 5.2 mmol/L, while 2 patients recorded no changes relative to the baseline. The patients whose FBS was reduced showed improvement in the mean AoA from 3.78 ± 1.58 D to 4.88 ± 1.61 D (p < 0.001) and a reduction in the mean LoA from 1.37 ± 0.40D to 0.87 ± 0.19D (p < 0.001), whereas those with deteriorated control of the FBS showed an opposite trend.

CONCLUSIONS

Controlling hyperglycemia improves ocular accommodation in type-1 diabetes.

Sources of error in clinical measurement of the amplitude of accommodation

Measurement of the amplitude of accommodation is established as a procedure in a routine optometric eye examination. However, clinical methods of measurement of this basic optical function have several sources of error. They are numerous and diverse, and include depth of focus, reaction time, instrument design, specification of the measurement end-point, specification of the reference point of measurement, measurement conditions, consideration of refractive error, and psychological factors. Several of these sources of inaccuracy are composed of multiple sub-sources, and many of the sub-sources influence the common methods of measurement of amplitude of accommodation. Consideration of these sources of measurement error casts doubt on the reliability of the results of measurement, on the validity of established normative values that have been produced using these methods, and on the value of reports of the results of surgery designed to restore accommodation. Clinicians can reduce the effects of some of the sources of error by modifying techniques of measurement with existing methods, but a new method may further improve accuracy.

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.

Comparison of Dynamic Retinoscopy and Autorefraction for Measurement of Accommodative Amplitude

SIGNIFICANCE

This study promotes the use of dynamic retinoscopy to obtain objective measures of accommodative amplitude (AA) in the clinical setting in lieu of the subjective push-up technique.

PURPOSE

This study compared the agreement between open-field autorefraction and a modified dynamic retinoscopy for the objective measurement of AA.

METHODS

Accommodative amplitude was measured using two objective techniques for subjects aged 5 to 60 years. Test order was randomized and monocular AA was measured as subjects viewed printed letters 0.9 mm in height with their dominant eye and distance refraction. For retinoscopy, subjects held a near rod and viewed the target at the nearest (most proximal) point of clear vision. The examiner then performed dynamic retinoscopy along the horizontal meridian and identified the physical location of neutrality of the reflex, which was converted to AA in diopters. Autorefraction was performed obtaining repeated measures of refraction beginning from a target demand of 2.5 D and increasing in discrete steps until there was no subsequent increase in accommodative response. Refractions were converted to power in the horizontal meridian and expressed as accommodation in diopters with the maximal value termed the AA. Distance overrefractions were measured for both techniques to adjust AA for any uncorrected refractive error. Difference versus mean analysis was used to compare agreement between tests.

RESULTS

The 95% limits of agreement between techniques were calculated after removal of two young outliers who responded poorly to one of the techniques. The overall mean difference for 95 subjects was 0.02 ± 0.97 D, with limits of agreement spanning -1.87 to 1.92 D. No significant linear relationship between the magnitude of the AA and the differences between techniques was observed.

CONCLUSIONS

Agreement between dynamic retinoscopy and open-field autorefraction was less than 2 D with no systematic bias, suggesting that dynamic retinoscopy may be a suitable clinical technique to measure objective AA.

Should Pearson's correlation coefficient be avoided?

PURPOSE

To survey the use of Pearson's correlation coefficient (r) and related statistical methods in the ophthalmic literature, to consider the limitations of r, and to suggest suitable alternative methods of analysis.

RECENT FINDINGS

Searching Ophthalmic and Physiological Optics (OPO), Optometry and Vision Science (OVS), and Clinical and Experimental Optometry (CXO) online archives using correlation and Pearson's r as search terms resulted in 4057 and 281 hits respectively. Coefficient of determination, r square, or r squared received fewer hits (65, 8, and 22 hits respectively). The assumption that r follows a bivariate normal distribution was rarely encountered (3 hits) although several studies applied Spearman's rank correlation (70 hits). The intra-class correlation coefficient (ICC) was widely used (178 hits), but fewer hits were recorded for partial correlation (43 hits) and multiple correlation (13) hits. There was little evidence that the problem of sample size was addressed in correlation studies.

SUMMARY

Investigators should be alert to whether: (1) the relationship between two variables could be non-linear, (2) the data are bivariate normal, (3) r accounts for a significant proportion of the variance in Y, (4) outliers are present, the data are clustered, or have a restricted range, (5) the sample size is appropriate, and (6) a significant correlation indicates causality. In addition, the number of significant digits used to express r and the problems of multiple testing should be addressed. The problems and limitations of r suggest a more cautious approach regarding its use and the application of alternative methods where appropriate.

Measuring changes in Schlemm's canal and trabecular meshwork in different accommodation states in myopia children: an observational study

PURPOSE

The aim of the study was to evaluate changes in size of Schlemm's canal (SC) and trabecular meshwork(TM) in response to accommodation stimuli and cycloplegia states in myopia children.

METHODS

In total, 34 children were enroled in this study. A -6.0 D accommodation stimulus was achieved by looking at an optotype through a mirror. Cycloplegia state was induced with 1% tropicamide. Two states were confirmed by measuring the central lens thickness (CLT), anterior chamber depth and pupil diameter. The size of SC and TM was measured using swept-source optical coherence tomography. The association between changes in SC size and CLT was analysed.

RESULTS

Compared with that in the relaxation state, SC size increased significantly under -6.0 D accommodation stimuli. SC area (SCA) increased from 6371 ± 2517 μm² to 7824 ± 2727 μm², SC length (SCL) from 249 ± 10 μm to 295 ± 12 μm and SC width (SCW) from 27 ± 9 μm to 31 ± 8 μm. Under the cycloplegia state, SCA decreased to 5009 ± 2028 μm²; SCL to 212 ± 14 μm, and SCW to 22 ± 5 μm. Changes in SCA (r = 0.35, P = 0.0007), SCL (r = 0.251, P = 0.0172) and SCW (r = 0.253, P = 0.016) were significantly correlated with changes in CLT. TM size was not significantly altered compared to that in the relaxation state. TM length (TML) increased from 562 ± 45 μm to 587 ± 47 μm after exposure to -6.0 D accommodation stimulus.

CONCLUSION

SC size enlarged in response to -6.0 D accommodation stimuli and shrunk under cycloplegia. TM length increased under the accommodation stimulus state.

Repeatability of two subjective accommodative amplitude measurements and agreement with an objective method

BACKGROUND

The aim was to compare the repeatability of subjective accommodative amplitude (AA) measurements obtained using the modified push-up and minus-lens methods and determine the agreement with objective AA by an autorefractor.

METHODS

The right eyes of 47 adults aged 22-30 years (mean 25.1 ± 1.9) were measured by subjective AA using the modified push-up and minus-lens methods. Subjective AAs with first sustained blur and unreadable criteria were obtained with an average of three consecutive measurements. Measurements of the objective AA were simulated by the minus lens using an open-field autorefractor. The repeatability of two subjective AA methods and the agreement among the different methods was assessed.

RESULTS

The AA value was dependent on the measuring method (F = 139.68, p < 0.001). The AA of the minus-lens method with first sustained blur criterion (10.10 ± 1.71 D) was closest to the objective AA (9.01 ± 1.49 D). The minus-lens method with unreadable criterion had the best repeatability. The agreement between the minus-lens method and the objective methods was better than that between the modified push-up and the objective methods based on the difference and 95 per cent limits of agreement. The agreement was highest between the minus-lens method with the first sustained blur criterion and the objective method, which had the lowest average difference and a narrow 95 per cent limits of agreement.

CONCLUSIONS

The subjective minus-lens method was more accurate for assessing the subjective AA in adults than the modified push-up method. The minus-lens method with the first sustained blur criterion was the optimal method for subjective AA. The minus-lens method with unreadable criterion can also be applied to clinical measurements, although it was approximately 0.95 D larger than the minus-lens method with the first sustained blur criterion.

Validation of Novel Metrics from the Accommodative Dynamic Profile

Objective and subjective methods of assessing time taken for accommodative change (ToAC) include accommodative dynamics (AD) and accommodative facility (AF). This study investigates the validity of novel metrics derived from the AD-profile and explores their relationship with AF. AD were assessed using a modified open-field autorefractor in 43 healthy adults. Non-linear regression curves were fitted to the data to derive: latency-of-accommodation (nLoA) and -disaccomodation (nLoD), Time-for-accommodation (ToA) and -disaccommodation (ToD), and objective-ToAC (oToAC). Latencies were also calculated through visual inspection of the AD data as in previous studies (pLoA and pLoD). AF was used to assess subjective-ToAC. Statistical analysis explored the relationships between the AD-metrics and AF. Subjects were assessed on three visits to examine intra- and inter-observer repeatability. nLoA and nLoD were greater than pLoA (p = 0.001) and pLoD (p = 0.004) respectively. nLoA and nLoD also demonstrated greater intra- and inter-observer repeatability than pLoA and pLoD. AF demonstrated a moderate, inverse correlation with ToA (p = 0.02), ToD (p = 0.007), and oToAC (p = 0.007). ToD was the single best accommodative predictor of AF (p = 0.011). The novel method for deriving latency was more repeatable, but not interchangeable with the techniques used in previous studies. ToD was the most repeatable metric with the greatest association with AF.

Comparison of the amplitude of accommodation determined subjectively and objectively in South African university students

Background: Historically, two clinical methods have been used for measuring the amplitude of accommodation, which are the push-up and minus lens methods. However, it has been documented that the push-up method overestimates amplitude of accommodation, while the minus lens method underestimates it.Aim: The purpose of this study was to compare subjective and objective procedures for determining the monocular amplitude of accommodation in young optometry students.Setting: The study was conducted in the optometry clinic at the university.Methods: Amplitude of accommodation was measured on 45 optometry students (17 males and 28 females, whose ages ranged from 21 to 27 years) using the push-up, push-down, minus lens, modified dynamic retinoscopy and Pascal dynamic retinoscopy methods. Data were collected by three different examiners in this study. One examiner measured all the subjective tests, while another examiner measured the modified dynamic retinoscopy. The third examiner measured the Pascal heterodynamic retinoscopy.Results: The highest amplitude of accommodation was obtained using the push-up method (10.23 ± 1.67 D), while the minus lens method gave the lowest subjective finding (8.43 ± 1.68 D). However, the subjective methods generally produced comparable results. Both retinoscopic methods showed the lowest mean amplitude of accommodation of approximately 6.50 ± 1.40 D. However, there was a high correlation between the various methods.Conclusion: The push-up and push-down methods overestimate the true amplitude of accommodation because of the relative magnification, while the minus lens method creates an abnormal viewing environment in which the target is stationary but the stimulus becomes increasingly minified. Subjective amplitude of accommodation is an inadequate measure to assess any true accommodation because it fails to differentiate between passive depth of focus and an active accommodative power change in the eye. Therefore, subjective measurement of the amplitude of accommodation may suggest that accommodation is present when it is not. Further research is needed to further validate dynamic retinoscopy as the optimal or best possible routine clinical method to assess the true amplitude of accommodation.

Clinical application of accommodating intraocular lens

The present review describes recent advances in application of accommodating intraocular lenses (AIOLs). Standard monofocal intraocular lenses (MIOLs) only correct distance vision, while AIOLs are designed to allow both good distance vision and near vision, which is achieved through the contraction and relaxation of ciliary muscles by providing transformation of the axial movement or curvature of the lens. Thus, AIOLs may be a better choice for those patients who demand a higher level of visual performance. Since techniques to analyze the performance of AIOLs have not been standardized, and there is a variety of both subjective and objective methods, it is hard to measure the performance of these intraocular lenses. By evaluating advantages and disadvantages of various AIOLs, and introducing techniques for measurement the performance postoperative, this paper can provide some relative information on choosing the type of AIOLs in the clinic.

Accommodative amplitude using the minus lens at different near distances

Purpose:

The purpose of this study was to compare the mean findings and the repeatability of the minus lens (ML) amplitude of accommodation (AA) at 33 cm and 40 cm.

Materials and Methods:

AA was measured from the dominant eye of 120 fully corrected subjects using the ML procedure when viewing the target at both 33 and 40 cm. Each measurement was repeated between 24 and 48 hours after the first trial.

Results:

Mean AA when tested at 33 cm and 40 cm was 10.20 diopter (D) (standard deviation [SD] =1.24) and 8.85 D (SD = 1.23), respectively (P < 0.001). The limits of agreement of the measured amplitude calculated with taking into account of the replicates at 33 and 40 cm were − 0.19 (95% confidence interval [CI]: −0.34 to −0.04) and 2.53 (95% CI: 2.38 to 2.68), respectively. The repeatability of testing at the two distances 33 and 40 cm was ± 1.24 and ± 0.99, respectively. In addition, the retest reliability of measured amplitude using the intraclass correlation coefficient was 0.87 (95% CI: 0.789–0.920) at 33 cm and 0.91 (95% CI: 0.872–0.945) at 40 cm.

Conclusion:

There is no agreement in the obtained amplitude at the two measurement distances. Testing the ML AA at 40 cm may be superior given that a lower repeatability coefficient was observed. However, it is unclear whether the larger amplitude measured at 33 cm reflects a larger increase in accommodation (greater proximity effect) or a decrease in the ability to perceive the first slight sustained blur.

Comparison of three monocular methods for measuring accommodative stimulus-response curves

PURPOSE

The aim was to evaluate the repeatability of dynamic measurement of the accommodative stimulus-response curve (ASRC) at three different dioptric speeds using a modified instrument and its agreement with two other methods.

METHODS

Twenty-nine adults (23.5 ± 2.0 years) were enrolled in the study. ASRC was measured monocularly using three methods: dynamic and static measurement using a motorised Badal system mounted on an open-field auto-refractor (WAM-5500, Grand Seiko Co., Ltd, Japan) and the minus lens technique. Dynamic measurements were conducted at three dioptric stimulus speeds to simulate continuous stimuli for ASRC (0.25, 0.40 and 0.55 D/s), with three repetitions for each speed. All three types of ASRCs were fitted with third-degree polynomial equations. The slope and objective accommodative amplitude of the ASRC were analysed.

RESULTS

The repeatability of objective accommodative amplitude worsened as the speed of the stimuli increased. The repeatability of the slope was best at a speed of 0.40 D/s and worst at 0.55 D/s. The measurement method significantly influenced the objective accommodative amplitude values and slope (both, p < 0.001). The minus lens technique yielded the highest amplitude of accommodation (6.21 ± 0.84 D) and steepest slope (1.11 ± 0.14), followed by the static Badal method (5.60 ± 0.83 D and 0.89 ± 0.09 D). The objective accommodative amplitude decreased with increasing speed during dynamic measurements. There was no difference between the slopes at 0.25 D and 0.40 D/s (p > 0.05) and the slope was lowest at 0.55 D/s.

CONCLUSION

The accommodative stimulus-response curve values are method-dependent and the significant differences between three methods used to determine the ASRC based on slope and accommodative amplitude indicate that these methods are non-interchangeable. Using dynamic measurements, accommodative behaviour varies with the speed of dioptric-change of the stimulus. A speed of 0.40 D/s appears to be the best compromise in terms of time, results and repeatability for dynamic ASRC measurement.

A comparison in university students of the amplitude of accommodation determined subjectively

Background: Historically, the push-up and the minus lens methods have been used for the measurements of the amplitude of accommodation, and the differences between the results of these methods are well known.Aim: The purpose of this study was to compare three methods for determining the monocular amplitude of accommodation and consider whether agreement exists between such methods.Setting: The study was conducted at the Optometry Clinic, University of Limpopo.Method: Thirty-four (N = 34) African optometry students participated in this study. There were 20 female and 14 male students. The age range of the participants was 20–34 years. Amplitude of accommodation was measured via the subjective push-up, push-down and minus lens methods only on the right eyes of the sample.Results: The highest average amplitude of accommodation was obtained with the push-up method (10.20 D ± 0.96 D), while the minus lens method produced the smallest mean amplitude of accommodation (9.66 D ± 0.75 D). A higher correlation was found between the push-up and push-down methods (r = 0.80, p = 0.06). The smallest correlation was observed between the push-up and the minus lens methods (r = 0.60, p = 0.062). There were no statistically significant differences between the amplitude of accommodation in male and female students for all three methods (p > 0.005).Conclusion: It seems easier to recognise the point where one can identify a target in pushdown amplitude than the point of first sustained blur in the push-up method. The push-up method tends to overestimate the actual amplitude of accommodation because of the effects of depth of focus. The less evaluated method in the literature is the push-away method; however, further research is necessary to answer the question of which (if any) method is more accurate.

Comparing measurement techniques of accommodative amplitudes

Aim and Background:

This study was designed to compare four standard procedures, for determining the monocular accommodative amplitudes.

Materials and Methods:

Fifty-two students participated in this analytical-descriptive study. Accommodative amplitudes were measured using four common clinical techniques, namely: Push-up, push-down, minus lens, and modified push-up.

Results:

The highest amplitude was obtained using the push-up method (11.21 ± 1.85 D), while the minus lens technique gave the lowest finding (9.31 ± 1.61 D). A repeated-measures Analysis of Variance (ANOVA) showed a significant difference between these methods (P < 0.05), further analysis showed that this difference was only between the minus lens and other the three methods (the push-up (P < 0.001), the push-down (P < 0.001) and the modified push-up (P < 0.001)). The highest and the lowest mean difference was related to the push-up with the minus lens, and the push-down with the modified push-up, while the highest and the lowest 95% limits of agreement were related to the push-up with the modified push-up and the push-up with the push-down methods. There was almost a perfect agreement between the push-up and the push-down method, whereas, a poor agreement was present between the modified push-up and the minus lens technique, and a fair agreement existed between the other pairs.

Conclusions:

The quick and easy assessment of the amplitude using the push-up and the push-down methods compared to other methods, and the obtained perfect agreement between these two methods can further emphasize their use as a routine procedure in the clinic, especially if a combination of the two techniques is used to offset their slight over- and underestimation.

Study on accommodation by autorefraction and dynamic refraction in children

PURPOSE

Childhood accommodation interferes with accurate diagnosis of the latent refractive errors. Dynamic retinoscopy offers accurate measurements of accommodative response, while an autorefractometer can predict the accommodative system activation in children. A correlation of the accommodative effort with the dynamic refraction has been investigated in emmetropic children, before and after cycloplegia.

METHODS

A prospective clinical study of accommodative effort in 149 emmetropic children, in the age group 3-16 years, has been conducted using TOPCON AR RM-8000B autorefractor. Dynamic refraction was performed by monocular estimation method before and after cycloplegia, using the retinoscope mirror light as target. Retinoscopic reflex produced 'with the motion' was corrected with positive spherical lenses, and that 'against the motion' was corrected with negative spherical lenses, to achieve neutralization.

RESULTS

Mean accommodative effort measured for 149 children included in the study was -0.63±0.69D and dynamic refraction was -0.07±0.44D before cycloplegia, while the mean was+0.52D after cycloplegia, irrespective of the method used. Autorefractor measured -0.17D of accommodative effort per unit change in dynamic refraction before cycloplegia and +0.90D after cycloplegia.

CONCLUSIONS

The performance of TOPCON AR RM-8000B autorefractor was comparable to dynamic retinoscopy. Presence of many children, and in turn, large number of accommodative response data in 11-13 and 14-15 years group is probably linked to prolonged reading/writing. The accuracy and the agreement of the actual accommodative measurements revealed after cycloplegia.

Association between accommodative amplitudes and amblyopia

PURPOSE

To evaluate the relationship between amblyopia and accommodative ability.

METHODS

The open-field Grand Seiko binocular autorefractor has become the gold standard for automated measurement of static accommodation. We measured the accommodation amplitudes in 52 children ages 3 to 14 years employing the Grand Seiko auto refractor. Children wore their glasses for this test, which was prescribed based on a cycloplegic refraction performed by one pediatric ophthalmologist. No readings could be obtained for 9 eyes (5 patients).

RESULTS

Normal accommodation with correction utilizing full accommodative effort at 1/3 meter is 3D assuming no accommodative lag, and would generate a reading of -3.00D from the Grand Seiko auto refractor. Lack of any accommodative should give a reading of 0.00D. Accommodative gradually declined as the acuity worsened.

CONCLUSION

Our results suggest that amblyopic eyes do not accommodate as well as non-amblyopic eyes. Because accommodation amplitude is not subjective it may be a more sensitive indicator of regression of amblyopia than visual acuity. The Grand Seiko autorefractor could prove to be a useful tool to monitor the progress of patients with amblyopia.

Effect of target distance on accommodative amplitude measured using the minus lens technique

BACKGROUND

The aim was to investigate the effect on the measured amplitude of accommodation and repeatability of using the minus lens technique with the target at distance or near.

METHODS

Forty-three students (average age: 21.17 ± 1.50 years, 35 female) had their amplitude of accommodation measured with minus lenses on top of their distance correction in a trial frame with the target at far (6.0 m) or near (0.4 m). The minus lens power was gradually added with steps of 0.25 D. Measurements were taken on two occasions at each distance, which were separated by a time interval of at least 24 hours.

RESULTS

The measured amplitude at six metres was significantly lower than that with the target at 40 cm, by 1.56 ± 1.17 D (p < 0.001) and this varied between individuals (r = 0.716, intraclass correlation coefficient = 0.439). With either target distance, repeated measurement was highly correlated (r > 0.9) but the agreement was better at 6.0 m (±0.74 D) than at 40 cm (± 0.92 D).

CONCLUSION

The measurements of the amplitude of accommodation with the minus lens technique using targets at far or near are not comparable and the difference between the target distances may provide clinically relevant information.