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General binocular disorders: prevalence in a clinic population
Ophthal. Physiol. Opt. Vol. 21, No. 1, pp. 70±74, 2001 q 2001 The College of Optometrists. Published by Elsevier Science Ltd All rights reserved. Printed in Great Britain 0275-5408/00/$20.00 www.elsevier.com/locate/ophopt
PII: S0275-5408(99)00104-0
General binocular disorders: prevalence in a clinic population Francisco Lara 2, Pilar Cacho 1, AÂngel GarcõÂa 1 and RamoÂn MegõÂas 2 1 Â ptica, Universidad de Alicante, Spain and Departamento Interuniversitario de O de OftalmologõÂa, A.P. y O.R.L., Universidad de Murcia, Spain
2
Departamento
Summary The purpose of this paper was to study the prevalence of nonstrabismic accommodative and binocular dysfunctions in a clinical population. We examined 265 symptomatic patients who were chosen from an optometric clinic. We performed several tests to diagnose any form of refractive, accommodative or binocular dysfunction. Of the 265 subjects examined, 59 patients (22.3%) had some form of accommodative or binocular dysfunction and required not just the correction of the refractive error but a speci®c treatment for each of the problems diagnosed. The remaining subjects were classed as having refractive anomalies. The frequency of binocular dysfunctions was 12.9%, and 9.4% for accommodative anomalies. Convergence excess (4.5%) was more prevalent than convergence insuf®ciency (0.8%) and accommodative excess (6.4%) more prevalent than accommodative insuf®ciency (3%). q 2000 The College of Optometrists. Published by Elsevier Science Ltd. All rights reserved.
and 80% of the 21 had accommodative problems, with a higher prevalence of accommodative insuf®ciencies. In this case he used accommodative amplitude and positive relative accommodation (PRA) results to classify the anomalies. Dwyer and Wick (1995) studied 536 patients aged under 35 and found that 58% of the subjects had some form of accommodative or binocular anomaly, a percentage which was higher when associated with some form of refractive error needing refractive correction. Scheiman et al. (1996) studied a clinical pediatric population of 2023 patients and their results showed that the most common disorders recorded (after refractive ones) were binocular (14.3%) and accommodative (5.4%). Convergence excess (7.1%) was more prevalent than convergence insuf®ciency (4.6%), while the number of patients with accommodative insuf®ciency (2%) was a little higher than those with accommodative excess (1.8%). In this report they chose a greater number of signs than the former authors for diagnosing the anomalies, such as MEM dynamic retinoscopy, accommodative facility, or AC/A ratio. In most of these studies there is a higher prevalence of accommodative insuf®ciencies among the accommodative disorders diagnosed. However, current studies, such as that of Porcar and MartõÂnez-Palomera (1997), have shown a higher percentage of accommodative excess (10.8%) in a population of 65 university students using the diagnosis criteria derived from Scheiman and Wick (1994a,b).
Introduction Many authors have suggested that anomalies of accommodation and nonstrabismic binocular dysfunctions are commonly encountered in optometric practice (Matsuo and Ohtsuki, 1992; Russell and Wick, 1993; Dwyer and Wick, 1995). Some studies have estimated the prevalence of these dysfunctions, although there are different results among those studies. Of the 114 subjects with accommodative dysfunctions studied by Daum (1983), over 80% were found to have accommodative insuf®ciencies, and only three patients had accommodative excess. He only used the lower expected amplitude for a particular age to classify patients with accommodative insuf®ciency. Hokoda (1985), studied a population of 119 symptomatic patients aged under 35 and found that accommodative dysfunction was the most commonly encountered condition. Twenty-one of the 119 subjects had binocular or accommodative disorders Received: 17 May 1999 Revised form: 8 October 1999 Accepted: 10 October 1999 Correspondence and reprint requests to: M a Pilar Cacho MartõÂnez, Â ptica, Apartado Correos 99, UniverDepartamento Interuniversitario de O sidad de Alicante, 03080 Alicante, Spain. E-mail address: [email protected] (P. Cacho).
70
General binocular disorders: prevalence in a clinic population: F. Lara et al. The different results offered by these authors may be caused by the different diagnosis criteria they used, in addition to special characteristics of the population used in some studies. Rouse et al. (1998) suggested that using a greater number of signs for diagnosing convergence insuf®ciency, the frequency of the anomaly was smaller, so according to the previous studies this assumption could be applied to the other accommodative and binocular dysfunctions. Thus, the purpose of our study was, using a greater number of signs than other studies for the diagnosis of each anomaly, to determine the prevalence of accommodative anomalies and nonstrabismic binocular dysfunctions among a representative sample of 265 subjects chosen from an optometric clinic and to compare our results to these other studies. Methods A population of 265 subjects aged 10±35, with a mean age of 20.75 ^ 5.78 SD, was chosen from an optometric clinic between December 1997 and March 1998. They were consecutive patients who presented with symptoms related to their vision. Only records for patients aged 35 years and younger were reviewed in order to reject accommodative anomalies related to normal presbyopic changes. None of subjects had an ocular or systemic pathology, and none wore contact lenses. Subjects with strabismus were also rejected. The corrected monocular visual acuity of all patients was at least 6/6 or better. A complete visual exam was conducted, including the assessment of the accommodative and binocular tests needed to diagnose accommodative and binocular disorders. The examination included the following tests: 1. A case-history, re¯ecting the full range of symptoms presented by the patient. 2. Ocular health exam with direct ophthalmoscopy and biomicroscopy. 3. Assessment of refractive error. Static retinoscopy procedure was done without lenses for the working distance while the subject was instructed to watch the 20/400 letter E on the distant chart at 6 m. A subjective exam technique was performed by means of a monocular fogging method with cross-cylinder, followed by binocular balancing to a standard endpoint of maximum plus for best visual acuity (BVA). This BVA correction will be named in this work as the result of the subjective refractive exam. 4. Accommodative and binocular tests. The assessment of accommodative and binocular tests was done with the results of the subjective refractive exam in place. The tests involved the assessment of direction and magnitude of the distance and near horizontal and vertical phoria with a cover test and prism bar, AC/A ratio measured with both calculated and gradient methods, positive and negative fusional vergence (smooth and step vergence
71
with Von Graefe and prism bar method respectively), positive and negative relative accommodation, objective and subjective near point of convergence, monocular and binocular accommodative facility with ^2.00 D ¯ip lenses using a card with acuity suppression (Bernell card, series BC 29), dynamic retinoscopy with Monocular Estimate Method (MEM) using a commercially available nearpoint card (Bernell Corporation BC 11981), monocular accommodative amplitude using both pushup and minus lenses methods, and stereopsis measurement with the Titmus stereotest. The results of each of the tests performed were ®rst compared with the population norms (Scheiman and Wick, 1994a) and then were grouped according to their deviation from the expected values. The anomalies were then diagnosed following the criteria of Scheiman and Wick (1994b) which are shown in Tables 1 and 2, where we also have speci®ed the number of signs that we used to classify the patients under each diagnosis. Results Subjects who revealed symptoms and abnormal results in the accommodative and binocular tests were classi®ed as subjects with accommodative and/or binocular disorders. When subjects suffering symptoms had normal clinical ®ndings in the accommodative±convergence tests and their problems were solved by the proper correction of their refractive error, they were considered as normal patients with only refractive dysfunctions. Of the 265 symptomatic subjects examined, 22.3% (59 subjects) showed accommodative and/or binocular disorders that might or might not be accompanied by refractive anomalies. Of these, 34 (12.9%) had binocular disorders and 25 subjects (9.4%) had accommodative dysfunctions (Figure 1). The remaining 206 patients (77.7%) were classi®ed as refractive disorders. A breakdown of these results is given in Table 3, which shows more subjects with convergence excess (9.0%) than with convergence insuf®ciency (3.5%). Of the 24 patients with convergence excess, for half of them it was associated with accommodative disorders, mainly accommodative excess. As far as patients with convergence insuf®ciency are concerned, most of them also had accommodative anomalies, usually accommodative excess. In terms of
Figure 1. Distribution of visual anomalies of 265 subjects studied.
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Ophthal. Physiol. Opt. 2001 21: No 1
Table 1. Diagnosis criteria for accommodative disorders Accommodative excess Symptoms. Most symptoms are associated with reading or other close work. Common complaints include: blurred distance vision which is worse after reading or other close work and often worse toward the end of the day, headaches and eyestrain after short periods of reading, dif®culty focusing from far to near, and sensitivity to light. Signs. Need to be present signs 1±3, and two of 4±6. (1) Variable visual acuity ®ndings. (2) Variable static retinoscopy and subjective refraction. (3) Dif®culty clearing 12.00 D with monocular accommodative facility, < 6 cpm. (4) Dif®culty clearing 12.00 D with binocular accommodative facility, < 3 cpm. (5) Low MEM ®nding, , 1 0.25 D. (6) Reduced Negative Relative Accommodation (NRA), < 1.50 D. Accommodative infacility Symptoms. Most symptoms are associated with reading or other work. Common complaints are asthenopia and intermittent blurred vision associated with near tasks; the most common symptom is dif®culty changing focus from one distance to another. Signs. Need to be present signs 1 and 2. (1) Fails binocular and monocular accommodative facility assessment using ^2.00 D lenses, monocular < 6 cpm, binocular < 3 cpm. (2) Low positive and negative relative accommodation, PRA < 1.25 D, NRA < 1.50 D. Accommodative insuf®ciency Symptoms. Blurred near vision, discomfort and strain associated with near tasks, fatigue associated with near point tasks, dif®culty with attention and concentration when reading. Signs. Need to be present signs 1 and 2, and two of 3±5. (1) Reduced amplitude of accommodation. Push-up accommodative amplitude at least 2 D below Hofstetter's calculation for minimum age-appropiate amplitude: 15±0.25 £ age. (2) Fails monocular accommodative facility with 22.00 D, < 6 cpm. (3) Fails binocular accommodative facility with 22.00 D, < 3 cpm. (4) High MEM ®nding, . 1 0.75 D. (5) Low PRA, < 1.25D.
Table 2. Diagnosis criteria for binocular disorders Convergence insuf®ciency Symptoms. Symptoms are associated with reading or other near tasks, asthenopia and headaches, intermittent blur. Signs. Need to be present signs 1±3 and two of 4±7. (1) Moderate to high exophoria at near, .6 D. (2) Reduced positive fusional vergence at near, < 11/14/3 for blur, diplopia and recovery (at least one of three). (3) Receded near point of convergence, .10 cm for loss of fusion, .17.5 cm for recovery. (4) Low calculated AC/A ratio, ,3/1. (5) Fails binocular accommodative facility testing with 12.00 D, < 3 cpm. (6) Low MEM, , 1 0.25 D. (7) Low NRA, < 1.50 D. Convergence excess Symptoms. Symptoms are associated with reading or other near tasks and generally are worse at the end of the day. The most common include asthenopia and headaches, and intermittent blur. Signs. Need to be present signs 1±2 and two of 3±6. (1) Signi®cant esophoria at near, .2 D. (2) Reduced negative fusional vergence at near, < 8/16/7 for blur, diplopia and recovery (at least one of three). (3) High calculated AC/A ratio, .7/1. (4) Fails binocular accommodative facility with 22.00 D, < 3 cpm. (5) High MEM, . 1 0.75 D. (6) Low PRA, < 1.25 D. Basic exophoria Symptoms. Asthenopia associated with distance and near tasks, intermittent blur at distance and near. Symptoms are worse at the end of the day. Signs. Need to be present signs 1±2 and two of 3±6. (1) Exophoria of approximately of equal magnitude at near and distance (within 5 D). (2) Reduced positive fusional vergence at distance and near, < 11/14/3 and < 4/8/5 for blur, diplopia and recovery for near and distance respectively. (3) Normal AC/A ratio. (4) Fails binocular accommodative facility with 12.00 D, < 3 cpm. (5) Low MEM, , 1 0.25 D (6) Reduced NRA, < 1.50 D.
General binocular disorders: prevalence in a clinic population: F. Lara et al.
73
Table 3. Prevalence of accommodative and binocular dysfunctions of subjects Dysfunction Accommodative dysfunctions Accommodative insuf®ciency Accommodative excess Binocular dysfunctions Convergence excess only Convergence excess with accommodative excess Convergence excess with accommodative insuf®ciency Convergence insuf®ciency only Convergence insuf®ciency with accommodative insuf®ciency Convergence insuf®ciency with accommodative excess Convergence insuf®ciency with accommodative infacility Basic exophoria Normal group (refractive dysfunctions) Total
accommodative dysfunction, there was a higher incidence of accommodative excess (6.4%) than accommodative insuf®ciencies (3.0%). Discussion Of the 265 subjects examined in this study, 59 patients (22.3%) presented some kind of accommodative or binocular dysfunction, with a higher prevalence of binocular disorders. The most common disorders were convergence excess and accommodative excess. Accommodative excess was the most common anomaly both for subjects with purely accommodative dysfunction and for those who also had binocular disorders (convergence excess and convergence insuf®ciency). It can be observed that our results differ from those of authors who found more accommodative insuf®ciencies in their clinical populations (Daum, 1983; Hokoda, 1985) but are closer to the ®ndings of Porcar and MartõÂnez-Palomera (1997). However it is dif®cult to make comparisons between our results and those obtained by other authors, as each study uses different populations and diagnostic de®nitions. In his study of 114 subjects with accommodative dysfunctions, Daum (1983) found that 96 subjects (80%) of the total sample had accommodative insuf®ciencies. The criterion used by Daum for diagnosing accommodative insuf®ciency was based only on the measurement of accommodative amplitude, so that when a subject had an amplitude of accommodation below the lower limit of the expected amplitude for a particular age, that patient was classi®ed as having accommodative insuf®ciency. Considering this single criterion, some disorders with reduced accommodative amplitude might well have been classi®ed differently if other signs had been taken into account. For instance, convergence excess or convergence insuf®ciency may be associated with accommodative insuf®ciency and so they may be considered as mixed accommodative and binocular dysfunction. Moreover,
Number of subjects
Prevalence (%)
25 8 17 34 12 7 5 2 1 5 1 1 206 265
9.4 3.0 6.4 12.9 4.5 2.6 1.9 0.8 0.4 1.9 0.4 0.4 77.7 100
the population used in that study was preselected so that the data should not be considered exactly representative of the general population. Hokoda (1985) analyzed a sample of 119 subjects aged from 4 to 35. The results showed 25 patients (21%) having general binocular disorders, a similar proportion to our results. However, the most common disorder was accommodative insuf®ciency, found in 11 subjects, ®ve of whom had also a binocular dysfunction. The criteria used in that study for diagnosing accommodation insuf®ciency were the amplitude of accommodation and positive relative accommodation (PRA) ®ndings, so that having an amplitude of accommodation 2 D below the minimum established by Hofstetter's formula (Borish, 1975) and a PRA value <1.50 D gave a diagnosis of accommodative insuf®ciency. In a more recent study, Scheiman et al. (1996) examined 2023 patients of ages up to 18, ®nding that 19.7% had accommodative and/or nonstrabismic binocular dysfunctions. They used more tests for diagnosing accommodative insuf®ciency. They considered that a patient with a low amplitude of accommodation, who also failed two of the following tests: PRA (positive relative accommodation), monocular accommodative facility, binocular accommodative facility and MEM retinoscopy, had an accommodative insuf®ciency. With these criteria, they found that, of the total sample used, 2% of the subjects had accommodative insuf®ciency, while those with accommodative excess represented 1.8% of the total patients studied. It can be observed that the prevalence of accommodative insuf®ciency is not particularly large. Moreover, they showed a higher incidence of convergence excess than convergence insuf®ciency. Even though the population examined in that study was younger than ours, the results obtained were more similar to those re¯ected in our study with similar diagnostic criteria. Considering the former studies it is observed that the greater number of signs used to diagnose a disorder, the lower the observed frequency of the anomaly. This fact is
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Ophthal. Physiol. Opt. 2001 21: No 1
evident in the study of Porcar and MartõÂnez-Palomera (1997), who used similar criteria for diagnosing general binocular disorders to those used in our study. They studied a whole range of accommodative and binocular tests to reach a diagnosis, although they did not clearly report how many signs had to be present to be classi®ed under each dysfunction. They examined 65 university students aged around 22, 32.3% of whom proved to have accommodative and/or binocular disorders. This percentage is higher than that obtained in our study, but they are not strictly comparable. The subjects used in their study were all university students, a population inclined to visual dysfunction due to their occupational demands. In contrast, the patients tested in our study belonged to a wider age-range sample, with several occupations, and they would be more representative of the general population. However their study found a higher prevalence of accommodative excess than accommodative insuf®ciency, a ®nding that coincides with the results obtained in ours. It would appear that the differences between our results and those of other authors, suggesting that accommodative excess is more common than accommodative insuf®ciency in a pre-presbyopia population, results from the criteria adopted for diagnosing each dysfunction. When few tests are used as the basis for detecting disorders, the result may be an inappropriate diagnosis. Thus, for instance, an accommodative insuf®ciency can be confused with an undetected latent hyperopia because a large proportion of the subject's accommodation is being used. So, the fact that just a few results and not the full range of accommodative and binocular tests are taken, could explain the major prevalence of, for example, accommodative insuf®ciency in some of the studies discussed. In summary, this and other studies reveal a clear presence of accommodative and binocular dysfunctions in the general clinic population. Only a full assessment of accommodative and binocular functions, in addition to refraction, will ensure that such disorders do not go unnoticed in the routine eye examination. Conclusions Of the 265 symptomatic subjects examined, 22.3% (59 patients) showed accommodative and/or binocular dysfunctions. Convergence excess (9%) was more prevalent than
convergence insuf®ciency (3.5%), as was accommodative excess (6.4%) compared with accommodative insuf®ciency (3%). A diagnosis of accommodative and/or binocular disorder depends not only on a few clinical ®ndings of some accommodative and binocular investigations but on a whole battery of tests, in order to produce diagnosis of the type of dysfunction of the subject. It should be noticed that a refractive examination excludes the majority of binocular and accommodative dysfunctions which we would expect in about one-quarter of the clinic population. For this reason optometrists should systematically complement their routine examination with a whole battery of accommodative and binocular tests that would help to avoid the non-detection of these anomalies in daily optometric practice. References Borish, I. M. (1975). Clinical Refraction, 3rd ed., Professional Press, Chicago, p. 170. Daum, K. M. (1983). Accommodative dysfunction. Documenta Ophthalmologica 55, 177±198. Dwyer, P. and Wick, B. (1995). The in¯uence of refractive correction upon disorders of vergence and accommodation. Optom. Vis. Sci. 72 (3), 224±232. Hokoda, S. C. (1985). General binocular dysfunctions in an urban optometry clinic. J. Am. Optom. Assoc. 56 (7), 560±562. Matsuo, T. and Ohtsuki, H. (1992). Follow-up results of a combination of accommodation and convergence insuf®ciency in school-age children and adolescents. Graefe's Arch. Clin. Exp. Ophthalm. 230, 166±170. Porcar, E. and MartõÂnez-Palomera, A. (1997). Prevalence of general binocular dysfunctions in a population of university students. Optom. Vis. Sci. 74 (2), 111±113. Rouse, M. W., Hyman, L. and Hussein, M., et al. (1998). Frequency of convergence insuf®ciency in optometry clinic settings. Optom. Vis. Sci. 75 (2), 88±96. Russell, G. E. and Wick, B. (1993). A prospective study of treatment of accommodative insuf®ciency. Optom. Vis. Sci. 70 (2), 131±135. Scheiman, M. and Wick, B. (1994a). Clinical management of binocular vision. In: Heterophoric, Accommodative and Eye Movement Disorders, Lippincott, Philadelphia, pp. 3±31. Scheiman, M. and Wick, B. (1994b). Clinical management of binocular vision. In: Heterophoric, Accommodative and Eye Movement Disorders, Lippincott, Philadelphia, pp. 41±81. Scheiman, M., Gallaway, M. and Ciner, E., et al. (1996). Prevalence of visual anomalies and ocular pathologies in a clinic pediatric population. J. Am. Optom. Assoc. 67 (4), 193±201.
PII: S0275-5408(99)00104-0
General binocular disorders: prevalence in a clinic population Francisco Lara 2, Pilar Cacho 1, AÂngel GarcõÂa 1 and RamoÂn MegõÂas 2 1 Â ptica, Universidad de Alicante, Spain and Departamento Interuniversitario de O de OftalmologõÂa, A.P. y O.R.L., Universidad de Murcia, Spain
2
Departamento
Summary The purpose of this paper was to study the prevalence of nonstrabismic accommodative and binocular dysfunctions in a clinical population. We examined 265 symptomatic patients who were chosen from an optometric clinic. We performed several tests to diagnose any form of refractive, accommodative or binocular dysfunction. Of the 265 subjects examined, 59 patients (22.3%) had some form of accommodative or binocular dysfunction and required not just the correction of the refractive error but a speci®c treatment for each of the problems diagnosed. The remaining subjects were classed as having refractive anomalies. The frequency of binocular dysfunctions was 12.9%, and 9.4% for accommodative anomalies. Convergence excess (4.5%) was more prevalent than convergence insuf®ciency (0.8%) and accommodative excess (6.4%) more prevalent than accommodative insuf®ciency (3%). q 2000 The College of Optometrists. Published by Elsevier Science Ltd. All rights reserved.
and 80% of the 21 had accommodative problems, with a higher prevalence of accommodative insuf®ciencies. In this case he used accommodative amplitude and positive relative accommodation (PRA) results to classify the anomalies. Dwyer and Wick (1995) studied 536 patients aged under 35 and found that 58% of the subjects had some form of accommodative or binocular anomaly, a percentage which was higher when associated with some form of refractive error needing refractive correction. Scheiman et al. (1996) studied a clinical pediatric population of 2023 patients and their results showed that the most common disorders recorded (after refractive ones) were binocular (14.3%) and accommodative (5.4%). Convergence excess (7.1%) was more prevalent than convergence insuf®ciency (4.6%), while the number of patients with accommodative insuf®ciency (2%) was a little higher than those with accommodative excess (1.8%). In this report they chose a greater number of signs than the former authors for diagnosing the anomalies, such as MEM dynamic retinoscopy, accommodative facility, or AC/A ratio. In most of these studies there is a higher prevalence of accommodative insuf®ciencies among the accommodative disorders diagnosed. However, current studies, such as that of Porcar and MartõÂnez-Palomera (1997), have shown a higher percentage of accommodative excess (10.8%) in a population of 65 university students using the diagnosis criteria derived from Scheiman and Wick (1994a,b).
Introduction Many authors have suggested that anomalies of accommodation and nonstrabismic binocular dysfunctions are commonly encountered in optometric practice (Matsuo and Ohtsuki, 1992; Russell and Wick, 1993; Dwyer and Wick, 1995). Some studies have estimated the prevalence of these dysfunctions, although there are different results among those studies. Of the 114 subjects with accommodative dysfunctions studied by Daum (1983), over 80% were found to have accommodative insuf®ciencies, and only three patients had accommodative excess. He only used the lower expected amplitude for a particular age to classify patients with accommodative insuf®ciency. Hokoda (1985), studied a population of 119 symptomatic patients aged under 35 and found that accommodative dysfunction was the most commonly encountered condition. Twenty-one of the 119 subjects had binocular or accommodative disorders Received: 17 May 1999 Revised form: 8 October 1999 Accepted: 10 October 1999 Correspondence and reprint requests to: M a Pilar Cacho MartõÂnez, Â ptica, Apartado Correos 99, UniverDepartamento Interuniversitario de O sidad de Alicante, 03080 Alicante, Spain. E-mail address: [email protected] (P. Cacho).
70
General binocular disorders: prevalence in a clinic population: F. Lara et al. The different results offered by these authors may be caused by the different diagnosis criteria they used, in addition to special characteristics of the population used in some studies. Rouse et al. (1998) suggested that using a greater number of signs for diagnosing convergence insuf®ciency, the frequency of the anomaly was smaller, so according to the previous studies this assumption could be applied to the other accommodative and binocular dysfunctions. Thus, the purpose of our study was, using a greater number of signs than other studies for the diagnosis of each anomaly, to determine the prevalence of accommodative anomalies and nonstrabismic binocular dysfunctions among a representative sample of 265 subjects chosen from an optometric clinic and to compare our results to these other studies. Methods A population of 265 subjects aged 10±35, with a mean age of 20.75 ^ 5.78 SD, was chosen from an optometric clinic between December 1997 and March 1998. They were consecutive patients who presented with symptoms related to their vision. Only records for patients aged 35 years and younger were reviewed in order to reject accommodative anomalies related to normal presbyopic changes. None of subjects had an ocular or systemic pathology, and none wore contact lenses. Subjects with strabismus were also rejected. The corrected monocular visual acuity of all patients was at least 6/6 or better. A complete visual exam was conducted, including the assessment of the accommodative and binocular tests needed to diagnose accommodative and binocular disorders. The examination included the following tests: 1. A case-history, re¯ecting the full range of symptoms presented by the patient. 2. Ocular health exam with direct ophthalmoscopy and biomicroscopy. 3. Assessment of refractive error. Static retinoscopy procedure was done without lenses for the working distance while the subject was instructed to watch the 20/400 letter E on the distant chart at 6 m. A subjective exam technique was performed by means of a monocular fogging method with cross-cylinder, followed by binocular balancing to a standard endpoint of maximum plus for best visual acuity (BVA). This BVA correction will be named in this work as the result of the subjective refractive exam. 4. Accommodative and binocular tests. The assessment of accommodative and binocular tests was done with the results of the subjective refractive exam in place. The tests involved the assessment of direction and magnitude of the distance and near horizontal and vertical phoria with a cover test and prism bar, AC/A ratio measured with both calculated and gradient methods, positive and negative fusional vergence (smooth and step vergence
71
with Von Graefe and prism bar method respectively), positive and negative relative accommodation, objective and subjective near point of convergence, monocular and binocular accommodative facility with ^2.00 D ¯ip lenses using a card with acuity suppression (Bernell card, series BC 29), dynamic retinoscopy with Monocular Estimate Method (MEM) using a commercially available nearpoint card (Bernell Corporation BC 11981), monocular accommodative amplitude using both pushup and minus lenses methods, and stereopsis measurement with the Titmus stereotest. The results of each of the tests performed were ®rst compared with the population norms (Scheiman and Wick, 1994a) and then were grouped according to their deviation from the expected values. The anomalies were then diagnosed following the criteria of Scheiman and Wick (1994b) which are shown in Tables 1 and 2, where we also have speci®ed the number of signs that we used to classify the patients under each diagnosis. Results Subjects who revealed symptoms and abnormal results in the accommodative and binocular tests were classi®ed as subjects with accommodative and/or binocular disorders. When subjects suffering symptoms had normal clinical ®ndings in the accommodative±convergence tests and their problems were solved by the proper correction of their refractive error, they were considered as normal patients with only refractive dysfunctions. Of the 265 symptomatic subjects examined, 22.3% (59 subjects) showed accommodative and/or binocular disorders that might or might not be accompanied by refractive anomalies. Of these, 34 (12.9%) had binocular disorders and 25 subjects (9.4%) had accommodative dysfunctions (Figure 1). The remaining 206 patients (77.7%) were classi®ed as refractive disorders. A breakdown of these results is given in Table 3, which shows more subjects with convergence excess (9.0%) than with convergence insuf®ciency (3.5%). Of the 24 patients with convergence excess, for half of them it was associated with accommodative disorders, mainly accommodative excess. As far as patients with convergence insuf®ciency are concerned, most of them also had accommodative anomalies, usually accommodative excess. In terms of
Figure 1. Distribution of visual anomalies of 265 subjects studied.
72
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Table 1. Diagnosis criteria for accommodative disorders Accommodative excess Symptoms. Most symptoms are associated with reading or other close work. Common complaints include: blurred distance vision which is worse after reading or other close work and often worse toward the end of the day, headaches and eyestrain after short periods of reading, dif®culty focusing from far to near, and sensitivity to light. Signs. Need to be present signs 1±3, and two of 4±6. (1) Variable visual acuity ®ndings. (2) Variable static retinoscopy and subjective refraction. (3) Dif®culty clearing 12.00 D with monocular accommodative facility, < 6 cpm. (4) Dif®culty clearing 12.00 D with binocular accommodative facility, < 3 cpm. (5) Low MEM ®nding, , 1 0.25 D. (6) Reduced Negative Relative Accommodation (NRA), < 1.50 D. Accommodative infacility Symptoms. Most symptoms are associated with reading or other work. Common complaints are asthenopia and intermittent blurred vision associated with near tasks; the most common symptom is dif®culty changing focus from one distance to another. Signs. Need to be present signs 1 and 2. (1) Fails binocular and monocular accommodative facility assessment using ^2.00 D lenses, monocular < 6 cpm, binocular < 3 cpm. (2) Low positive and negative relative accommodation, PRA < 1.25 D, NRA < 1.50 D. Accommodative insuf®ciency Symptoms. Blurred near vision, discomfort and strain associated with near tasks, fatigue associated with near point tasks, dif®culty with attention and concentration when reading. Signs. Need to be present signs 1 and 2, and two of 3±5. (1) Reduced amplitude of accommodation. Push-up accommodative amplitude at least 2 D below Hofstetter's calculation for minimum age-appropiate amplitude: 15±0.25 £ age. (2) Fails monocular accommodative facility with 22.00 D, < 6 cpm. (3) Fails binocular accommodative facility with 22.00 D, < 3 cpm. (4) High MEM ®nding, . 1 0.75 D. (5) Low PRA, < 1.25D.
Table 2. Diagnosis criteria for binocular disorders Convergence insuf®ciency Symptoms. Symptoms are associated with reading or other near tasks, asthenopia and headaches, intermittent blur. Signs. Need to be present signs 1±3 and two of 4±7. (1) Moderate to high exophoria at near, .6 D. (2) Reduced positive fusional vergence at near, < 11/14/3 for blur, diplopia and recovery (at least one of three). (3) Receded near point of convergence, .10 cm for loss of fusion, .17.5 cm for recovery. (4) Low calculated AC/A ratio, ,3/1. (5) Fails binocular accommodative facility testing with 12.00 D, < 3 cpm. (6) Low MEM, , 1 0.25 D. (7) Low NRA, < 1.50 D. Convergence excess Symptoms. Symptoms are associated with reading or other near tasks and generally are worse at the end of the day. The most common include asthenopia and headaches, and intermittent blur. Signs. Need to be present signs 1±2 and two of 3±6. (1) Signi®cant esophoria at near, .2 D. (2) Reduced negative fusional vergence at near, < 8/16/7 for blur, diplopia and recovery (at least one of three). (3) High calculated AC/A ratio, .7/1. (4) Fails binocular accommodative facility with 22.00 D, < 3 cpm. (5) High MEM, . 1 0.75 D. (6) Low PRA, < 1.25 D. Basic exophoria Symptoms. Asthenopia associated with distance and near tasks, intermittent blur at distance and near. Symptoms are worse at the end of the day. Signs. Need to be present signs 1±2 and two of 3±6. (1) Exophoria of approximately of equal magnitude at near and distance (within 5 D). (2) Reduced positive fusional vergence at distance and near, < 11/14/3 and < 4/8/5 for blur, diplopia and recovery for near and distance respectively. (3) Normal AC/A ratio. (4) Fails binocular accommodative facility with 12.00 D, < 3 cpm. (5) Low MEM, , 1 0.25 D (6) Reduced NRA, < 1.50 D.
General binocular disorders: prevalence in a clinic population: F. Lara et al.
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Table 3. Prevalence of accommodative and binocular dysfunctions of subjects Dysfunction Accommodative dysfunctions Accommodative insuf®ciency Accommodative excess Binocular dysfunctions Convergence excess only Convergence excess with accommodative excess Convergence excess with accommodative insuf®ciency Convergence insuf®ciency only Convergence insuf®ciency with accommodative insuf®ciency Convergence insuf®ciency with accommodative excess Convergence insuf®ciency with accommodative infacility Basic exophoria Normal group (refractive dysfunctions) Total
accommodative dysfunction, there was a higher incidence of accommodative excess (6.4%) than accommodative insuf®ciencies (3.0%). Discussion Of the 265 subjects examined in this study, 59 patients (22.3%) presented some kind of accommodative or binocular dysfunction, with a higher prevalence of binocular disorders. The most common disorders were convergence excess and accommodative excess. Accommodative excess was the most common anomaly both for subjects with purely accommodative dysfunction and for those who also had binocular disorders (convergence excess and convergence insuf®ciency). It can be observed that our results differ from those of authors who found more accommodative insuf®ciencies in their clinical populations (Daum, 1983; Hokoda, 1985) but are closer to the ®ndings of Porcar and MartõÂnez-Palomera (1997). However it is dif®cult to make comparisons between our results and those obtained by other authors, as each study uses different populations and diagnostic de®nitions. In his study of 114 subjects with accommodative dysfunctions, Daum (1983) found that 96 subjects (80%) of the total sample had accommodative insuf®ciencies. The criterion used by Daum for diagnosing accommodative insuf®ciency was based only on the measurement of accommodative amplitude, so that when a subject had an amplitude of accommodation below the lower limit of the expected amplitude for a particular age, that patient was classi®ed as having accommodative insuf®ciency. Considering this single criterion, some disorders with reduced accommodative amplitude might well have been classi®ed differently if other signs had been taken into account. For instance, convergence excess or convergence insuf®ciency may be associated with accommodative insuf®ciency and so they may be considered as mixed accommodative and binocular dysfunction. Moreover,
Number of subjects
Prevalence (%)
25 8 17 34 12 7 5 2 1 5 1 1 206 265
9.4 3.0 6.4 12.9 4.5 2.6 1.9 0.8 0.4 1.9 0.4 0.4 77.7 100
the population used in that study was preselected so that the data should not be considered exactly representative of the general population. Hokoda (1985) analyzed a sample of 119 subjects aged from 4 to 35. The results showed 25 patients (21%) having general binocular disorders, a similar proportion to our results. However, the most common disorder was accommodative insuf®ciency, found in 11 subjects, ®ve of whom had also a binocular dysfunction. The criteria used in that study for diagnosing accommodation insuf®ciency were the amplitude of accommodation and positive relative accommodation (PRA) ®ndings, so that having an amplitude of accommodation 2 D below the minimum established by Hofstetter's formula (Borish, 1975) and a PRA value <1.50 D gave a diagnosis of accommodative insuf®ciency. In a more recent study, Scheiman et al. (1996) examined 2023 patients of ages up to 18, ®nding that 19.7% had accommodative and/or nonstrabismic binocular dysfunctions. They used more tests for diagnosing accommodative insuf®ciency. They considered that a patient with a low amplitude of accommodation, who also failed two of the following tests: PRA (positive relative accommodation), monocular accommodative facility, binocular accommodative facility and MEM retinoscopy, had an accommodative insuf®ciency. With these criteria, they found that, of the total sample used, 2% of the subjects had accommodative insuf®ciency, while those with accommodative excess represented 1.8% of the total patients studied. It can be observed that the prevalence of accommodative insuf®ciency is not particularly large. Moreover, they showed a higher incidence of convergence excess than convergence insuf®ciency. Even though the population examined in that study was younger than ours, the results obtained were more similar to those re¯ected in our study with similar diagnostic criteria. Considering the former studies it is observed that the greater number of signs used to diagnose a disorder, the lower the observed frequency of the anomaly. This fact is
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evident in the study of Porcar and MartõÂnez-Palomera (1997), who used similar criteria for diagnosing general binocular disorders to those used in our study. They studied a whole range of accommodative and binocular tests to reach a diagnosis, although they did not clearly report how many signs had to be present to be classi®ed under each dysfunction. They examined 65 university students aged around 22, 32.3% of whom proved to have accommodative and/or binocular disorders. This percentage is higher than that obtained in our study, but they are not strictly comparable. The subjects used in their study were all university students, a population inclined to visual dysfunction due to their occupational demands. In contrast, the patients tested in our study belonged to a wider age-range sample, with several occupations, and they would be more representative of the general population. However their study found a higher prevalence of accommodative excess than accommodative insuf®ciency, a ®nding that coincides with the results obtained in ours. It would appear that the differences between our results and those of other authors, suggesting that accommodative excess is more common than accommodative insuf®ciency in a pre-presbyopia population, results from the criteria adopted for diagnosing each dysfunction. When few tests are used as the basis for detecting disorders, the result may be an inappropriate diagnosis. Thus, for instance, an accommodative insuf®ciency can be confused with an undetected latent hyperopia because a large proportion of the subject's accommodation is being used. So, the fact that just a few results and not the full range of accommodative and binocular tests are taken, could explain the major prevalence of, for example, accommodative insuf®ciency in some of the studies discussed. In summary, this and other studies reveal a clear presence of accommodative and binocular dysfunctions in the general clinic population. Only a full assessment of accommodative and binocular functions, in addition to refraction, will ensure that such disorders do not go unnoticed in the routine eye examination. Conclusions Of the 265 symptomatic subjects examined, 22.3% (59 patients) showed accommodative and/or binocular dysfunctions. Convergence excess (9%) was more prevalent than
convergence insuf®ciency (3.5%), as was accommodative excess (6.4%) compared with accommodative insuf®ciency (3%). A diagnosis of accommodative and/or binocular disorder depends not only on a few clinical ®ndings of some accommodative and binocular investigations but on a whole battery of tests, in order to produce diagnosis of the type of dysfunction of the subject. It should be noticed that a refractive examination excludes the majority of binocular and accommodative dysfunctions which we would expect in about one-quarter of the clinic population. For this reason optometrists should systematically complement their routine examination with a whole battery of accommodative and binocular tests that would help to avoid the non-detection of these anomalies in daily optometric practice. References Borish, I. M. (1975). Clinical Refraction, 3rd ed., Professional Press, Chicago, p. 170. Daum, K. M. (1983). Accommodative dysfunction. Documenta Ophthalmologica 55, 177±198. Dwyer, P. and Wick, B. (1995). The in¯uence of refractive correction upon disorders of vergence and accommodation. Optom. Vis. Sci. 72 (3), 224±232. Hokoda, S. C. (1985). General binocular dysfunctions in an urban optometry clinic. J. Am. Optom. Assoc. 56 (7), 560±562. Matsuo, T. and Ohtsuki, H. (1992). Follow-up results of a combination of accommodation and convergence insuf®ciency in school-age children and adolescents. Graefe's Arch. Clin. Exp. Ophthalm. 230, 166±170. Porcar, E. and MartõÂnez-Palomera, A. (1997). Prevalence of general binocular dysfunctions in a population of university students. Optom. Vis. Sci. 74 (2), 111±113. Rouse, M. W., Hyman, L. and Hussein, M., et al. (1998). Frequency of convergence insuf®ciency in optometry clinic settings. Optom. Vis. Sci. 75 (2), 88±96. Russell, G. E. and Wick, B. (1993). A prospective study of treatment of accommodative insuf®ciency. Optom. Vis. Sci. 70 (2), 131±135. Scheiman, M. and Wick, B. (1994a). Clinical management of binocular vision. In: Heterophoric, Accommodative and Eye Movement Disorders, Lippincott, Philadelphia, pp. 3±31. Scheiman, M. and Wick, B. (1994b). Clinical management of binocular vision. In: Heterophoric, Accommodative and Eye Movement Disorders, Lippincott, Philadelphia, pp. 41±81. Scheiman, M., Gallaway, M. and Ciner, E., et al. (1996). Prevalence of visual anomalies and ocular pathologies in a clinic pediatric population. J. Am. Optom. Assoc. 67 (4), 193±201.