A Review of Depth of Focus in Measurement of the Amplitude of Accommodation
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paper_title: The depth-of-focus of the human eye for Snellen letters.

paper_content:

Snellen acuity is determined as a function of refractive error for two subjects under cyploplegia, using randomised test charts, constant test chart luminance and a series of artificial pupils. These results allow determination of the depth-of-focus of the eye for Snellen targets, and it is shown that both optical and retinal factors influence the depth-of-focus achieved. Depth-of-focus is found to increase with decreasing pupil diameter and visual acuity. The clinical significance of these results, particularly with respect to the precision with which refractive error may be determined, is discussed.
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paper_title: On the Anomalies of Accommodation and Refraction of the Eye, with a Preliminary Essay on Physiological Dioptrics

paper_content:

Original brown decoratively embossed cloth cover, 225 x 145 mm, with portrait of Donders gold stamped on front and gold stamped with title, author, publisher and date of publication on spine, 635 pages, 175 numbered black and white figures in text, pencil annotations on preliminary pages, old ink stamp for F. W, NIESCHE MD on half title page. Bookplate for Fred T Wright 1882-1832, The Wright Library and the National Library Australian Optometrical Association with photographic portrait of Fred Wright on front fly leaf.
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paper_title: Depth-of-focus of the human eye: theory and clinical implications.

paper_content:

The depth-of-focus, or the perceptual tolerance of the human eye to retinal defocus, is important to and imbedded in many aspects of clinical refraction and physiological optics. Although the depth-of-focus is a common concept in classical optics, there is relatively little detailed discussion of its implications as related to normal vision function and to vision anomalies. With current advances in refractive surgery and ophthalmic lens design, the demand for knowledge in this topic is both timely and important. This review of our current understanding of the depth-of-focus should prove to be useful to clinicians, researchers, and students as an introduction to the subject. Two areas will be considered: 1) basic definitions of and factors affecting the depth-of-focus, and 2) its contemporary clinical implications.
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paper_title: Effect of blur adaptation on blur sensitivity and discrimination in emmetropes and myopes.

paper_content:

PURPOSE ::: To determine whether blur adaptation influences blur sensitivity and blur discrimination thresholds in young adult myopes and emmetropes. In addition, to determine whether there is a differential effect of blur adaptation on blur sensitivity and discrimination between refractive error groups. ::: ::: ::: METHODS ::: Proximal and distal blur sensitivity thresholds and blur discrimination thresholds were measured under cycloplegia with a Badal optometer in 24 young adult subjects (8 emmetropes [EMM], 8 early-onset myopes [EOM], and 8 late-onset myopes [LOM]). Adaptation to 1 D of myopic refractive blur was then undertaken for 30 minutes. Blur sensitivity and discrimination thresholds were then remeasured. ::: ::: ::: RESULTS ::: After blur adaptation, blur sensitivity, and blur discrimination thresholds were found to be elevated. Blur adaptation had a significant effect on distal blur sensitivity threshold, with the largest effect being observed in the EOMs. Mean changes in distal blur sensitivity thresholds were EMMs +0.03 +/- 0.14 D, EOMs +0.30 +/- 0.21 D, and LOMs +0.08 +/- 0.13 D. ::: ::: ::: CONCLUSIONS ::: Adaptation to a degraded stimulus modifies the blur detection mechanisms of the visual system in young adults. Depth of focus is expanded by prolonged exposure to defocus. EOMs are more susceptible to this phenomenon than are LOMs and EMMs.
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paper_title: Subjective Depth-of-Focus of the Eye

paper_content:

Abstract: An experiment is described in which the subjective depth-of-focus (DOF) of the eye, defined as the range of focussing errors for which the image of the target appears to have the same clarity, contrast, and form as the optimal in-focus image, was measured as a function of the size of high contrast (99%) Snellen Es for 5 trained subjects under cycloplegia. Mean DOF increased by approximately 60% as the size of the letter detail increased from -0.2 to 0.87 log min arc (Snellen equivalent: 6/3.8 to 6/45), although there were considerable intersubject variations. DOF declined with increasing pupil diameter, the mean total DOFs being 0.86, 0.59, and 0.55 D for 2-, 4-, and 6-mm pupils, respectively. In a second experiment, use of low (21%) contrast letters with a 4-mm pupil and 4 subjects marginally increased the DOF (by 0.08 ± 0.05 D); refraction also shifted in a myopic direction by a mean of 0.15 ± 0.06 D compared with the high contrast letters. A third experiment with four less-experienced subjects demonstrated the importance of instruction and training in any measurement involving judgement of just-perceptible defocus blur. The clinical implications of the results for measurements of refraction and amplitude of accommodation are discussed.
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paper_title: Clinical Visual Optics

paper_content:

The eye's optical system visual acuity and contrast sensitivity spherical ametropia astigmatism subjective refraction accommodation and near vision ocular motility and binocular vision convergence anomalies of binocular vision - heterophoria and heterotropia stereopsis and the stereoscope the schematic eye subsidiary effects of correcting lenses - magnifying devices anisometropia and aniseikonia ocular aberrations visual examination of the eye and ophthalmoscopy retinoscopy (skiascopy) objective optometers vision screening, new subjective refractors and techniques measurement of ocular dimensions distribution and ocular dioptrics of ametropia entoptic phenomena.
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paper_title: Amplitude of accommodation: population and methodological differences.

paper_content:

A literature survey of amplitudes of accommodation in various countries is presented. Results of push-up and minus-lens determination of 447 patients in Nigeria are compared with previous results. A smaller decrement in amplitude due to temperature than previously accepted is suggested.
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paper_title: Factors affecting light-adapted pupil size in normal human subjects.

paper_content:

PURPOSE ::: To investigate the effect of age, gender, refractive error, and iris color on light-adapted pupil size in humans. ::: ::: ::: METHODS ::: Pupil diameters of 91 subjects (age range, 17 to 83 years) with normal, healthy eyes were measured using an objective infrared-based continuous recording technique. Five photopic ocular illuminance levels were used (2.15 to 1050 lumens m-2), and the accommodative status of each subject was precisely controlled at a constant level. ::: ::: ::: RESULTS ::: Pupil size decreased linearly as a function of age at all illuminance levels. Even at the highest illuminance level, there was still a significant effect of age upon pupil size. The rate of change of pupil diameter with age decreased from 0.043 mm per year at the lowest illuminance level to 0.015 mm per year at the highest. In addition, the variability between pupil sizes of subjects of the same age decreased by a factor of approximately two as luminance was increased over the range investigated. Pupil size was found to be independent of gender, refractive error, or iris color (P > 0.1). ::: ::: ::: CONCLUSIONS ::: Of the factors investigated, only chronologic age had a significant effect on the size of the pupil. The phenomenon of senile miosis is present over a wide range of ocular illuminance levels.
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paper_title: Pupil Size, Information Overload, and Performance Differences

paper_content:

As a test of the hypothesis that pupil dilation during performance is partially due to a task related anxiety component, pupillary patterns were measured while subjects (Ss) processed digit strings of various lengths for immediate recall. Information overload resulted in a leveling of the dilation pattern which suggested a momentary suspension of processing effort. In addition, significant correlations were observed between individual differences in pupil size and recall performance.
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paper_title: Depth-of-focus of the human eye: theory and clinical implications.

paper_content:

The depth-of-focus, or the perceptual tolerance of the human eye to retinal defocus, is important to and imbedded in many aspects of clinical refraction and physiological optics. Although the depth-of-focus is a common concept in classical optics, there is relatively little detailed discussion of its implications as related to normal vision function and to vision anomalies. With current advances in refractive surgery and ophthalmic lens design, the demand for knowledge in this topic is both timely and important. This review of our current understanding of the depth-of-focus should prove to be useful to clinicians, researchers, and students as an introduction to the subject. Two areas will be considered: 1) basic definitions of and factors affecting the depth-of-focus, and 2) its contemporary clinical implications.
---
paper_title: Critical subjective measurement of amplitude of accommodation

paper_content:

ABSTRACT The use of fixed print size to measure amplitude of accommodation by the push-up method will result in a range of angular sizes of the print at the nearpoint for patients with different amplitudes. We investigated the effect of this on measured amplitude of accommodation in 60 subjects aged 25 to 45 years. We designed a near-vision chart, based on the Bailey- Lovie near-vision charts, but for which the letter sizes on adjacent lines are varied so that the difference between the inverse of letter sizes is constant (dioptric scale) rather than the geometric ratio between letters on adjacent lines being constant (logarithmic scale). Using this new chart, we compared the amplitudes obtained using N5 print (N5 Blur method) and with two critical methods for which the print of interest was always close to threshold acuity. This was achieved by having patients' attention drawn to a smaller line of letters every time the chart was moved closer in half-diopter steps. The N5 Blur method gave considerably higher amplitude measures than the two critical methods, but the mean differences decreased markedly as age increased: 1.8 to 2.2 D for a 25- to 29-year-old group to 0.7 to 0.8 D for a 40- to 45-yearold group. We believe that the use of fixed size print for measuring amplitude of accommodation by the push-up method gives overestimations that are more marked the higher the amplitude. This occurs because smaller measuring distances that accompany the higher amplitudes will increase angular size and consequently depth-of-focus (in dioptric terms). A critical method of measuring amplitude of accommodation in clinical practice is described. A comparison of our results with those of previous, large scale studies leads to the conclusion that these studies overestimated amplitude in young subjects relative to those of older subjects.
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paper_title: Pupil diameter tracks changes in control state predicted by the adaptive gain theory of locus coeruleus function

paper_content:

An important dimension of cognitive control is the adaptive regulation of the balance between exploitation (pursuing known sources of reward) and exploration (seeking new ones) in response to changes in task utility. Recent studies have suggested that the locus coeruleus-norepinephrine system may play an important role in this function and that pupil diameter can be used to index locus coeruleus activity. On the basis of this, we reasoned that pupil diameter may correlate closely with control state and associated changes in behavior. Specifically, we predicted that increases in baseline pupil diameter would be associated with decreases in task utility and disengagement from the task (exploration), whereas reduced baseline diameter (but increases in task-evoked dilations) would be associated with task engagement (exploitation). Findings in three experiments were consistent with these predictions, suggesting that pupillometry may be useful as an index of both control state and, indirectly, locus coeruleus function.
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paper_title: Subjective Depth-of-Focus of the Eye

paper_content:

Abstract: An experiment is described in which the subjective depth-of-focus (DOF) of the eye, defined as the range of focussing errors for which the image of the target appears to have the same clarity, contrast, and form as the optimal in-focus image, was measured as a function of the size of high contrast (99%) Snellen Es for 5 trained subjects under cycloplegia. Mean DOF increased by approximately 60% as the size of the letter detail increased from -0.2 to 0.87 log min arc (Snellen equivalent: 6/3.8 to 6/45), although there were considerable intersubject variations. DOF declined with increasing pupil diameter, the mean total DOFs being 0.86, 0.59, and 0.55 D for 2-, 4-, and 6-mm pupils, respectively. In a second experiment, use of low (21%) contrast letters with a 4-mm pupil and 4 subjects marginally increased the DOF (by 0.08 ± 0.05 D); refraction also shifted in a myopic direction by a mean of 0.15 ± 0.06 D compared with the high contrast letters. A third experiment with four less-experienced subjects demonstrated the importance of instruction and training in any measurement involving judgement of just-perceptible defocus blur. The clinical implications of the results for measurements of refraction and amplitude of accommodation are discussed.
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paper_title: Age and the amplitude of accommodation measured using dynamic retinoscopy.

paper_content:

PURPOSE ::: Dynamic retinoscopy (DR) is a procedure for assessing the accommodative response using a standard clinical instrument. The present study compared measurements of the amplitude of accommodation (AA) obtained using this technique with two subjective methods (modified push-down and minus lens). Additionally, the expected ranges for AA when measured by DR were determined. ::: ::: ::: METHOD ::: AA was measured in 1298 subjects between 5 and 60 years of age using the three techniques described above. Subjects were grouped into 5-year bins, and a descriptive univariate analysis of the data performed. Goodness-of fit plots were constructed to examine the overall model fit. Centile curves were calculated from the final model. ::: ::: ::: RESULTS ::: Mean values of AA obtained using DR were significantly lower than for the two subjective techniques. For the DR findings, no significant change was observed between 5 and 19 years of age (mean AA = 8.3 D) and between 45 and 60 years of age (mean AA = 0.6 D). AA values as a function of age were best fit by the polynomial regression equation: logAA = 1.93 + 0.49(age) - 0.19(age)(2) . ::: ::: ::: CONCLUSION ::: Measurements of AA determined using DR are significantly lower than the normative subjective findings published previously. This difference is at least partly due to the depth-of-field of the eye. These norms markedly overestimate accommodative responsivity. DR provides a simple technique for quantifying accommodation in the clinical setting.
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paper_title: The path to presbyopia: straight or crooked?

paper_content:

The non-linear trends in the mean amplitude of accommodation with age that are observed in transverse studies as presbyopia is approached can be explained in terms of the summated effect of many individual linear trends. Increases in the near addition that may be required by patients after their early fifties are probably associated with an age-dependent decrease in acuity, which necessitates a closer working distance to increase angular subtense, rather than with any continuing decline in accommodation.
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paper_title: Studies in Monocular and Binocular Accommodation, with Their Clinical Application.

paper_content:

The results of testing accommodation in 2,000 additional eyes, making in all 4,200, are here recorded, and also those obtained by testing the binocular accommodation in 500 patients. The bearing of these results on the theory of the mechanism of accommodation and their important practical applications are pointed out. Read before the American Ophthalmological Society, May, 1922.
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paper_title: Effects of atropine sulfate, methylatropine nitrate (metropine) and homatropine hydrobromide on adult human eyes.

paper_content:

CERTAIN details of the clinical actions of several mydriatics of the belladonna group are given in tables in the textbooks of pharmacology of Sollmann 1 and Goodman and Gilman, 2 but the relative speeds and durations of the actions of the various drugs are not well defined because ( a ) the solutions used varied in strength from 0.5 to 10 per cent and ( b ) doses are not given. It appeared desirable, therefore, to gather data permitting a more exact comparison of the actions of some of these drugs. Atropine seemed the logical choice as the standard with which homatropine and methylatropine nitrate (Metropine) should be compared. Of the many authors who have described the mydriatic and cycloplegic effects of atropine, homatropine and methylatropine nitrate, only a few have given data pertinent to the present investigations. Consideration of dosage being omitted for the moment, the time for maximal effect and the approximate
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paper_title: Changes in accommodation with age: static and dynamic.

paper_content:

Accommodative amplitude decreases with age, not with aging. The decrease is largely completed by age 40 years; only minor residual accommodation is present in most subjects after the mid-40s. Dynamical measurements show the accommodative response of subjects over 30 years of age to be significantly slowed (time constants of accommodation increases). Accommodation amplitude is less than 3 D by 30 years of age. Thus prepresbyopia is a sign of continual development, not of deterioration of the accommodative mechanism. Accommodation, or the change of clear vision with change in lens power, has been studied by many distinguished scientists including Descartes and Thomas Young. Helmholtz's "Theory of Accommodation" is a dual, indirect, active theory. There are both lenticular, including lens and capsule, and also extralenticular mechanisms, comprised of the zonule of Zinn or suspensory ciliary ligament and the ciliary muscle itself. The ciliary muscle does not act directly on the lens but indirectly through its action on the zonule of Zinn. Active contraction of the ciliary muscle, a unified muscle, produces accommodation; relaxation of the ciliary muscle permits relaxation of accommodation.
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paper_title: Accommodation measurements in a prepresbyopic and presbyopic population

paper_content:

PURPOSE ::: To study the efficacy of several subjective and objective methods of accommodation measurement in normal prepresbyopic and presbyopic populations to identify appropriate methods for measuring the outcome of accommodative restorative procedures. ::: ::: ::: SETTING ::: University of Houston, College of Optometry, Houston, Texas, USA. ::: ::: ::: METHODS ::: Thirty-one normal subjects with a mean age of 43.7 years (range 31 to 53 years) participated. Accommodation was measured monocularly using 3 subjective approaches--the push-up test, minus lenses to blur, and a focometer--and 2 approaches measured with a Hartinger coincidence refractometer, in which accommodation was stimulated with minus lenses to blur and topical pilocarpine 6%. ::: ::: ::: RESULTS ::: The push-up method overestimated accommodative amplitude relative to objective measures in 28 subjects. Two subjective methods, minus lenses to blur and the focometer, produced comparable results, but with lower amplitudes in younger subjects and higher amplitudes in older subjects compared with objective methods. Comparable results were obtained when accommodation was stimulated in 1 of 2 ways and measured with the Hartinger. Pilocarpine elicited stronger accommodative responses than distance blur for subjects with low accommodative amplitudes. Pilocarpine 6% produced stronger responses in subjects with light irides than in those with dark irides. ::: ::: ::: CONCLUSIONS ::: Hartinger-measured accommodation provides more realistic measurement of accommodative amplitude than the subjective methods tested, especially in the presbyopic population. In presbyopic subjects, the subjective tests resulted in accommodative amplitudes up to 4.0 diopters greater than those measured with objective tests. Measurements of accommodative amplitude are best achieved with objective methods to stimulate and measure accommodation.
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paper_title: Clinical Amplitude of Accommodation in Children between 5 and 10 Years of Age

paper_content:

Background: While there have been extensive studies of the amplitude of accommodation (AA) in adults, estimates of AA from studies in children between 5 and 10 years of age vary widely with some of the data being contradictory. Further, since values of AA are used for the diagnosis of several conditions including accommodative insufficiency (AI), it is important to able to compare clinical findings with age-defined norms. Methods: The present study was performed on 60 asymptomatic children between 5 and 10 years of age. Each child was refracted for distance viewing, and both push-up (PU) and push-down (PD) amplitudes were recorded monocularly using a Royal Air Force (RAF) nearpoint rule. Four readings (2 PU and 2 PD) were taken on each subject. The same procedures were also carried out on 38 adult subjects between 20 and 50 years of age. Results: The mean findings (average of PU and PD) declined from 16.2D (SEM=1.7D) at 5 years of age to 12.4D (SEM=1.4D) at 10 years of age. A twophase regression was observed, with a rapid decline between 5 and 7 years of age, but minimal change between 7 and 10 years of age. Conclusions: Both the pediatric and adult data is broadly similar to the classic findings of Donders and Duane. However, a relatively high percentage (36%) of children met the most commonly adopted criterion for AI, suggesting that this standard may need to be reexamined in this particular age group.
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paper_title: Critical subjective measurement of amplitude of accommodation

paper_content:

ABSTRACT The use of fixed print size to measure amplitude of accommodation by the push-up method will result in a range of angular sizes of the print at the nearpoint for patients with different amplitudes. We investigated the effect of this on measured amplitude of accommodation in 60 subjects aged 25 to 45 years. We designed a near-vision chart, based on the Bailey- Lovie near-vision charts, but for which the letter sizes on adjacent lines are varied so that the difference between the inverse of letter sizes is constant (dioptric scale) rather than the geometric ratio between letters on adjacent lines being constant (logarithmic scale). Using this new chart, we compared the amplitudes obtained using N5 print (N5 Blur method) and with two critical methods for which the print of interest was always close to threshold acuity. This was achieved by having patients' attention drawn to a smaller line of letters every time the chart was moved closer in half-diopter steps. The N5 Blur method gave considerably higher amplitude measures than the two critical methods, but the mean differences decreased markedly as age increased: 1.8 to 2.2 D for a 25- to 29-year-old group to 0.7 to 0.8 D for a 40- to 45-yearold group. We believe that the use of fixed size print for measuring amplitude of accommodation by the push-up method gives overestimations that are more marked the higher the amplitude. This occurs because smaller measuring distances that accompany the higher amplitudes will increase angular size and consequently depth-of-focus (in dioptric terms). A critical method of measuring amplitude of accommodation in clinical practice is described. A comparison of our results with those of previous, large scale studies leads to the conclusion that these studies overestimated amplitude in young subjects relative to those of older subjects.
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paper_title: Measurement of amplitude of accommodation in young persons

paper_content:

Background ::: The aim was to evaluate the amplitude of accommodation using test objects designed with constant angular size corresponding to 6/6 visual acuity. ::: ::: Methods ::: In total, 155 young volunteers with good ocular and systemic health aged between eight and 25 years were recruited for the study. A push-up method was conducted, with the near-vision target having a set of Landolt's broken circles. The angular size of the circles corresponded to a 6/6 visual acuity for various distances from 5.0 cm to 40 cm. To ensure precision of the object size, the electron beam lithographic technique was applied. ::: ::: Results ::: A general trend in a reduction in amplitude with the progression of age is coincident with data from previous studies; however, the magnitudes of the volume of accommodation in our study are substantially lower. ::: ::: Conclusion ::: Test objects with constant angular size can increase the accuracy of ‘push-up’ accommodation measures.
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paper_title: A comparison of cycloplegic and manifest refractions on the NR-1000F (an objective Auto Refractometer).

paper_content:

The manifest (dry) and cycloplegic refractions of 50 eyes of 25 patients aged 8 to 28 years were studied on the Nikon Auto Refractometer NR-1000F (AR) and compared with the results of clinical refraction (CR) under homatropine and the final clinical acceptance on postmydriatic testing. Only patients in the younger age groups with low to moderate refractive errors were included in this study; high myopes and hypermetropes and patients with aphakia and mixed astigmatism were excluded. The degree of agreement for spherical equivalents, sphere components, and cylinder components was analysed separately for both cycloplegic and manifest refractions on the AR and CR. The results showed that the fixation target in the NR-1000F induces significant instrument myopia during manifest refraction in the younger patients with lower refractive errors. We recommend that caution should be exercised in interpreting manifest refractions on the AR, especially in younger patients. A cycloplegic automatic refraction would be acceptably accurate.
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paper_title: Clinical Visual Optics

paper_content:

The eye's optical system visual acuity and contrast sensitivity spherical ametropia astigmatism subjective refraction accommodation and near vision ocular motility and binocular vision convergence anomalies of binocular vision - heterophoria and heterotropia stereopsis and the stereoscope the schematic eye subsidiary effects of correcting lenses - magnifying devices anisometropia and aniseikonia ocular aberrations visual examination of the eye and ophthalmoscopy retinoscopy (skiascopy) objective optometers vision screening, new subjective refractors and techniques measurement of ocular dimensions distribution and ocular dioptrics of ametropia entoptic phenomena.
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paper_title: Depth-of-Field of the Accommodating Eye

paper_content:

Our eyes project information from a three-dimensional world to a basically two-dimensional surface, corresponding to the photoreceptor plane in the retina. In theory, only one plane or surface of world can be in focus at one time. However, the eye exhibits a certain tolerance to out-of-focus images, a feature that is known as depth-of-focus (DOF). The corresponding distance range in which the objects are seen “clearly” is known as depth-of-field (DOFi). Although DOF and DOFi refer to an interval of distances or a dioptric range in the image and object space, respectively, both parameters define a similar concept and are usually interchangeable. This article will mainly refer to DOFi because it represents a more practical parameter, which can usually be determined through direct measurement. ::: ::: It is a well-known fact that certain optical and neural factors can change the DOFi. One of the most important ones is pupil size1; the presence of chromatic2,3 and monochromatic aberrations4–6 play a significant role as well. The precise value of DOFi also depends on the specific way DOFi is defined. Whereas some definitions are related to an absolute minimum value of visual acuity (VA),2,7 there are others based on relative VA values, for example, dioptric range over which VA exceeds some percentage of its optimum value.8–10 In practice, DOFi is usually based on a simple letter legibility criterion. In this case, the letter size plays an essential role in the final DOFi value.11,12 As a simple example, most presbyopes recognize the visual loss at near distances when trying to read small text, but not with large font sizes, which are nonetheless out-of-focus by the same amount. ::: ::: Depth-of-field of the presbyopic eye is a critical determinant of the prescribed add power or the design of contact or intraocular lenses13,14 and refractive surgery.15 It has been proposed that DOFi is responsible for some or most of the accommodative errors (lead or lag).5 Although there are some studies that have examined the origins of accommodative errors,10–12 the true origin of the accommodation error remains an unanswered question. Moreover, it has been shown quite recently that the error of accommodation can actually be a “false accommodation error” resulting from criterion differences between the subject (for subjective measurements) and the measuring device (for objective ones) when choosing the best image.16,17 ::: ::: There have been numerous studies devoted to measuring the DOFi on either side of the far point (FP) of paralyzed lens or presbyopic eyes.1,5,10,18 However, there is a lack of data regarding the DOFi as a function of the accommodative state. The reason behind this lack of data is the difficulty to accurately measure the DOFi of the accommodated eye because accommodation cannot be blocked—neither voluntarily nor involuntarily (by means of drugs) to remain at a specific desired accommodation level. The DOFi, although accommodating, can certainly differ from that of the relaxed eye because the pupil size and the aberration pattern change with accommodation.16,19–23 ::: ::: Several authors have used an optical system in which the subject focuses his or her attention on a stimulus located at a given distance, while another stimulus close to it can be moved voluntarily by the subject until its image is no longer clear and sharp, that is, until it falls out of their DOFi.2 However, it is quite difficult to perform this task with accuracy, because VA decreases very rapidly with stimulus eccentricity.24 As far as we are aware, there are only three studies that measured DOFi for objects located between the far and near points.2,25,26 Campbell2 used a stimulus made up of a vertical row of three dark discs. The vergence was set during the experiment to a fixed −2 diopter (D) value and it was used at a fixation point that presumably led to a steady accommodation state. Two plates, one with a single disc on the left of the vertical row and another one having the disc on the right side, were moved by the subject along an optical bench so as to find the distance range in which both discs could be seen clear simultaneously. In 1998, Mordi and Ciuffreda25 used a similar technique to study a large population having a wider age range. For each subject, they measured the subjective DOFi in the middle of the linear part of the stimulus-response curve. Moreover, in 2010, Yao et al.26 performed objective and subjective measures of DOFi for 0, −1.5, and −4 D stimulus vergence under the hypothesis that the accommodative and perceptual systems have different abilities to detect blur. The system used was similar to that from Campbell, but only measured the distal half of the DOFi. Therefore, estimating the total DOFi with this approach assumes that DOFi is symmetric in the object space.5 ::: ::: Although accommodation leads and lags may be influenced by DOFi, there are few studies of DOFi with varying levels of accommodation, and therefore, none of the previous studies answer the key question: why is the actual accommodative response different from the ideal one for most stimulus vergences? In this work, we propose a novel methodology based on wavefront technology to provide an answer for this question.
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paper_title: effect of Relative Distance Magnification on the Monocular Amplitude of Accommodation

paper_content:

Many factors influence the measurement of the amplitude of accommodation. One factor that is frequently stated to have a major effect, the increase in the retinal image size as the target approaches the eye, has not previously been separated statistically from the other influences. In this experiment, the effect of relative distance magnification on the amplitude is assessed by comparing Donder's push-up technique with a Badal optometer technique. The push-up method indicates 0.6 D more amplitude of accommodation than the Badal method for subjects between ages 32 and 40.
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paper_title: Repeatability of clinical measurements of the amplitude of accommodation

paper_content:

In order to determine whether a significant change has occurred in a clinical parameter, it is essential to assess the repeatability of the measurement procedure. Accordingly, the present study has examined the repeatability of three techniques for evaluating the subjective amplitude of accommodation. Clinical amplitudes were determined using the push-up, push-down and minus lens procedures in 13 young individuals (mean age: 24.3 years) on five separate occasions. The standard deviation (SD) of the five examinations was calculated for each individual and the mean values for the population sample determined. The mean SDs for the push-up, push-down and minus lens techniques were equivalent, with 95% confidence limits of approximately 1.4 D being observed for all three procedures. Furthermore, the mean amplitude recorded using the push-up technique was significantly higher than that observed for the other two procedures. It is concluded that a change of at least +/- 1.50 D should be adopted as the minimum significant shift in amplitude of accommodation for this group.
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paper_title: Accommodation measurements in a prepresbyopic and presbyopic population

paper_content:

PURPOSE ::: To study the efficacy of several subjective and objective methods of accommodation measurement in normal prepresbyopic and presbyopic populations to identify appropriate methods for measuring the outcome of accommodative restorative procedures. ::: ::: ::: SETTING ::: University of Houston, College of Optometry, Houston, Texas, USA. ::: ::: ::: METHODS ::: Thirty-one normal subjects with a mean age of 43.7 years (range 31 to 53 years) participated. Accommodation was measured monocularly using 3 subjective approaches--the push-up test, minus lenses to blur, and a focometer--and 2 approaches measured with a Hartinger coincidence refractometer, in which accommodation was stimulated with minus lenses to blur and topical pilocarpine 6%. ::: ::: ::: RESULTS ::: The push-up method overestimated accommodative amplitude relative to objective measures in 28 subjects. Two subjective methods, minus lenses to blur and the focometer, produced comparable results, but with lower amplitudes in younger subjects and higher amplitudes in older subjects compared with objective methods. Comparable results were obtained when accommodation was stimulated in 1 of 2 ways and measured with the Hartinger. Pilocarpine elicited stronger accommodative responses than distance blur for subjects with low accommodative amplitudes. Pilocarpine 6% produced stronger responses in subjects with light irides than in those with dark irides. ::: ::: ::: CONCLUSIONS ::: Hartinger-measured accommodation provides more realistic measurement of accommodative amplitude than the subjective methods tested, especially in the presbyopic population. In presbyopic subjects, the subjective tests resulted in accommodative amplitudes up to 4.0 diopters greater than those measured with objective tests. Measurements of accommodative amplitude are best achieved with objective methods to stimulate and measure accommodation.
---
paper_title: Critical subjective measurement of amplitude of accommodation

paper_content:

ABSTRACT The use of fixed print size to measure amplitude of accommodation by the push-up method will result in a range of angular sizes of the print at the nearpoint for patients with different amplitudes. We investigated the effect of this on measured amplitude of accommodation in 60 subjects aged 25 to 45 years. We designed a near-vision chart, based on the Bailey- Lovie near-vision charts, but for which the letter sizes on adjacent lines are varied so that the difference between the inverse of letter sizes is constant (dioptric scale) rather than the geometric ratio between letters on adjacent lines being constant (logarithmic scale). Using this new chart, we compared the amplitudes obtained using N5 print (N5 Blur method) and with two critical methods for which the print of interest was always close to threshold acuity. This was achieved by having patients' attention drawn to a smaller line of letters every time the chart was moved closer in half-diopter steps. The N5 Blur method gave considerably higher amplitude measures than the two critical methods, but the mean differences decreased markedly as age increased: 1.8 to 2.2 D for a 25- to 29-year-old group to 0.7 to 0.8 D for a 40- to 45-yearold group. We believe that the use of fixed size print for measuring amplitude of accommodation by the push-up method gives overestimations that are more marked the higher the amplitude. This occurs because smaller measuring distances that accompany the higher amplitudes will increase angular size and consequently depth-of-focus (in dioptric terms). A critical method of measuring amplitude of accommodation in clinical practice is described. A comparison of our results with those of previous, large scale studies leads to the conclusion that these studies overestimated amplitude in young subjects relative to those of older subjects.
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paper_title: Test–retest reproducibility of accommodation measurements gathered in an unselected sample of UK primary school children

paper_content:

Purpose To determine the test–retest reproducibility of accommodation measurements gathered in an unselected sample of primary school children. Methods Monocular and binocular amplitudes of accommodation (AA) were collected by five different Testers using the push-up method in an unselected sample of school children (n=137, age: 8.1±2.1 years). Testing was conducted on three occasions (average testing interval: 8 days) in 91.2% of the children. Results The median AA was 19.1D, the variation due to the identity of the Tester was 3.1D (p Conclusions Our results reveal substantial intra-individual variation in AA measurements, raising questions about the usefulness of this test in children aged 4–12 years. We suggest that AA assessment may prove most useful in children in this age range as a pass/fail check for substantially reduced AA, for example, where the AA is
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paper_title: Does the Badal optometer stimulate accommodation accurately

paper_content:

Purpose ::: ::: To study whether the accommodation response to Badal optometer is equivalent to the response for real space targets. ::: ::: Methods ::: ::: Accommodative responses were measured for 28 young eyes with the WAM-5500 autorefractometer in eight configurations for 0.17 D, 2.0 D and 5.0 D accommodation stimuli. Parameters that might contribute to differences in response were systematically isolated: stimulation method (real space vs. Badal targets), field of view, instrument’s cover proximity, the looming effect, and the peripheral interposition of objects in depth. Results ::: ::: Mean accommodative response differences between a natural view configuration and a configuration with a Badal Optometer were 0.50±0.43 D and 0.58±0.53 D for 2.0 D and 5.0 D stimulation, respectively (p < 0.001), with accommodation lags for the latter condition. Of the isolated parameters that might contribute to these differences, varying the interposition of objects in depth affected accommodation response more markedly. ::: ::: Conclusions ::: ::: It is likely that Badal optometers affect accommodation through a combination of some or all of the studied parameters. We conclude that accommodation response to closed-view Badal optometers is not equivalent to real space target response
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paper_title: Subject Instructions and Methods of Target Presentation in Accommodation Research

paper_content:

Purpose. The authors investigated the potential of subject instructions to alter the static accommodative stimulus-response function. They also investigated whether the reduced cue environment of the Badal optical system leads to accommodative responses different from those that occur for targets presented in real space. ::: Methods. Static accommodative responses with three focusing instructions were compared to baselines obtained with minimal instruction to stabilize gaze. Static accommodative responses were recorded for targets presented in real space and in a Badal optical system. ::: Results. Individuals differ widely in their responses to Instruction 1 (". . .make no special effort. . ."), although some adopt a relatively fixed position of focus. Responses with Instruction 2 (". . .look at the words naturally. . .") and Instruction 3 (". . .carefully focus. . .") baseline instruction ("pick a word in the middle of the block of text and look at it"). In a sample including most subjects, mean responses for Badal and real space targets are identical. However, it appears that some subjects have difficulty accommodating for Badal targets. ::: Conclusions. The authors recommend the use of Instructions 2 and 3 for investigation of the static accommodative response, with a number of provisos. Accommodative responses to Badal and real space targets are generally equivalent, but researchers should take care to identify those persons who have difficulties accommodating for Badal target.
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paper_title: Myopic children show insufficient accommodative response to blur.

paper_content:

Abstract The study was performed to establish the relationship between the slope of the accommodative response function and refractive error in children. Using an autorefractor, accommodative responses were measured in children under the following conditions. The subjects wore their best subjective refraction to view targets (a 3 x 3 array of 20/100 letters) displayed at seven distances (4.0 to 0.25 m). They viewed letters placed at 4.0 m through a series of negative lenses and letters placed at 0.25 m through a series of positive lenses. Myopic children accommodate significantly less than emmetropic children for real targets at near distances. Compared with emmetropic subjects, myopic children use blur poorly to increase accommodation, as shown by shallow slopes of the accommodative response functions for negative lenses. However, with positive lenses, requiring relaxation of accommodation, there is no significant difference in slope between myopic and emmetropic children. Blur is not an effective stimulus for accommodation in myopic children.
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paper_title: MEASUREMENT OF ACCOMMODATIVE AMPLITUDE IN AMBLYOPIA

paper_content:

Monocular accommodative amplitudes were measured in amblyopic individuals by the subjective minus lens and push-up techniques and by objective dynamic retinoscopy. Accommodative amplitudes were always reduced in amblyopic eyes using the minus lens and retinoscopy techniques, but not with the push-up technique which inflated this measure. Owing to difficulty in detecting defocused stimuli with the amblyopic eye, it is suggested that the objective retinoscopic technique be used by clinicians for accurate assessment of accommodative amplitude in these patients.
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paper_title: The amplitude of accommodation in 6-10-year-old children - not as good as expected!

paper_content:

The aim of this study was to measure the amplitude of accommodation for junior level school children and to compare it with age-expected values. A junior level school in Göteborg, Sweden, was randomly chosen and the amplitude of accommodation among 76 children aged 6-10 years was examined using Donders' push-up method. The results showed lower amplitude than expected in a large group of children. Results also showed lower amplitude than previously reported for this age group, especially under monocular conditions, which revealed an average dioptric difference from the expected value of -3.60 dioptres (D) right eye (mean 12.40 D, median 12.00 D, S.D. 3.7 D) and -3.50 D left eye (mean 12.50 D, median 12.70 D, S.D. 3.8 D) (p < 0.001 for both eyes). Consequently, we conclude that it cannot be assumed that the amplitude of accommodation is in the expected amplitude range for all children of these ages.
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paper_title: Effect of target distance on accommodative amplitude measured using the minus lens technique.

paper_content:

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.
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paper_title: Critical subjective measurement of amplitude of accommodation

paper_content:

ABSTRACT The use of fixed print size to measure amplitude of accommodation by the push-up method will result in a range of angular sizes of the print at the nearpoint for patients with different amplitudes. We investigated the effect of this on measured amplitude of accommodation in 60 subjects aged 25 to 45 years. We designed a near-vision chart, based on the Bailey- Lovie near-vision charts, but for which the letter sizes on adjacent lines are varied so that the difference between the inverse of letter sizes is constant (dioptric scale) rather than the geometric ratio between letters on adjacent lines being constant (logarithmic scale). Using this new chart, we compared the amplitudes obtained using N5 print (N5 Blur method) and with two critical methods for which the print of interest was always close to threshold acuity. This was achieved by having patients' attention drawn to a smaller line of letters every time the chart was moved closer in half-diopter steps. The N5 Blur method gave considerably higher amplitude measures than the two critical methods, but the mean differences decreased markedly as age increased: 1.8 to 2.2 D for a 25- to 29-year-old group to 0.7 to 0.8 D for a 40- to 45-yearold group. We believe that the use of fixed size print for measuring amplitude of accommodation by the push-up method gives overestimations that are more marked the higher the amplitude. This occurs because smaller measuring distances that accompany the higher amplitudes will increase angular size and consequently depth-of-focus (in dioptric terms). A critical method of measuring amplitude of accommodation in clinical practice is described. A comparison of our results with those of previous, large scale studies leads to the conclusion that these studies overestimated amplitude in young subjects relative to those of older subjects.
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paper_title: Accommodation functions: Co-dependency and relationship to refractive error

paper_content:

We assessed the extent to which different accommodative functions are correlated and whether accommodative functions predict the refractive error or the progression of myopia over a 12 month period in 64 young adults (30 myopes and 34 non-myopes). The functions were: amplitude of accommodation; monocular and binocular accommodative facility (6 m and 40 cm); monocular and binocular accommodative response to target distance; AC/A and CA/C ratios, tonic accommodation (dark focus and pinhole), accommodative hysteresis, and nearwork-induced transient myopia. Within groups of related accommodative functions (such as facility measures or open-loop measures) measurements on individuals were generally significantly correlated, however correlations between functions from different groups were generally not significant. Although accommodative amplitude and pinhole (open loop) accommodation were significantly different in myopes than in non-myopes, these functions were unrelated to myopia progression. Facility of accommodation and accommodative lag was independent predictors of myopia progression.
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Title: A Review of Depth of Focus in Measurement of the Amplitude of Accommodation

Section 1: Introduction
Description 1: Briefly introduce the purpose of clinical refraction, the concept of Depth of Focus (DoF), and its importance in measuring the Amplitude of Accommodation (AoA).

Section 2: Factors Influencing the Effect of DoF on the Measurement of AoA
Description 2: Discuss various factors that influence DoF and how these factors affect the measurement of AoA, including test-object parameters, pupil size, end-point criterion, and perceptual discrimination.

Section 3: Research Showing that DoF Affects Measurement of AoA
Description 3: Present empirical studies and research showing how DoF impacts the measurement of AoA and compare different methods used to measure AoA with considerations for DoF.

Section 4: Effect of the Method of Measurement
Description 4: Examine how different methods of measurement affect results due to DoF, comparing techniques such as the push-up method and the minus lens method, and discuss findings from various studies.

Section 5: Reduction of the Error Due to DoF in AoA Measurement
Description 5: Explore strategies for reducing error due to DoF in the measurement of AoA, including the utilization of high spatial frequency test objects and other proposed methods.

Section 6: Conclusions
Description 6: Summarize the main findings regarding the impact of DoF on AoA measurement errors and propose the need for improved measurement methods that eliminate or reduce DoF for clinical use.