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The relation between accommodative facility and general binocular dysfunction
Ophthal. Physiol. Opt. Vol. 20, No. 2, pp. 98±104, 2000 # 2000 The College of Optometrists. Published by Elsevier Science Ltd All rights reserved. Printed in Great Britain 0275-5408/00/$20.00 + 0.00 www.elsevier.com/locate/ophopt
PII: S0275-5408(99)00034-4
The relation between accommodative facility and general binocular dysfunction AÂngel GarcõÂa,1 Pilar Cacho,1 Francisco Lara2 and RamoÂn MegõÂas2 1
 ptica, Universidad de Alicante, Spain and 2Departamento Departamento Interuniversitario de O de OftalmologõÂa, A.P. y O.R.L., Universidad de Murcia, Spain
Summary This study was designed to evaluate the relation between accommodative facility and accommodative and binocular dysfunctions. We determined whether failure to achieve 8 cycles per minute of binocular accommodative facility or 11 cycles per minute of monocular accommodative facility tends to be associated with these dysfunctions. Forty eight subjects, ages 10±30 years were examined and classified into four groups: 13 subjects with accommodative dysfunctions, 11 patients with binocular dysfunctions, 12 subjects with accommodative and binocular dysfunctions and 12 control subjects with refractive errors but no accommodative or binocular anomalies. Monocular and binocular accommodative facility was conducted using 22.00 D flip lenses. In general, statistical analysis indicates that subjects with binocular and accommodative (ocular motor) anomalies performed significantly poorer than subjects of normal group on monocular and binocular facility tests. Monocular accommodative facility results showed more information about the dysfunction of the patient compared with the results of the binocular accommodative facility. In general data supported a relation between reduced accommodative facility and a general binocular dysfunction (accommodative or binocular) which demonstrates the importance of the accommodative facility test in diagnosing an accommodative or binocular anomaly. # 2000 The College of Optometrists. Published by Elsevier Science Ltd. All rights reserved.
Introduction
of the relation between accommodation and vergence and should be referred to as interactive facility (Siderov and Johnston, 1990). Many studies have reported normative data for both monocular and binocular accommodative facility. Two studies, both monitored for suppression during the binocular phase of accommodative facility testing, provide good normative data. Burge (1979) using 30 subjects, 6±30 years old, correctable to 6/6 and known to be nonstrabismic and prepresbyopic, found the mean monocular accommodative facilities to be 12.6 cycles per minute (cpm) 24.6 (SD) and 11.6 cpm 24.25 (SD) for right and left eyes, respectively, with 22.00 D ¯ippers. The mean binocular accommodative facility was 7.05 cpm 24.25 (SD) while using a vectographic slide
Patients presenting for optometric examination bene®t from a thorough evaluation of their near-point visual skills. Accommodative facility is an important aspect of accommodative function, so that the monocular testing provides a direct evaluation of the dynamics of accommodative responses (Liu et al., 1979), and binocular testing of accommodative facility provides similar information but also re¯ects the interactive nature
Correspondence and reprint requests to: Pilar Cacho E-mail address: [email protected] (P. Cacho). Received: 28 January 1999 Revised form: 22 April 1999
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The relation between accomodative facility and general binocular dysfunction: AÂ. GarcõÂa et al. to monitor for suppression and 9.5 cpm without its use. Zellers et al., (1984) used a procedure similar to Burge. They studied 100 subjects, age 18±30 years, with at least 40 sec arc of stereopsis and found the mean monocular accommodative facility with 22.00 D ¯ippers to be 11.6 cpm 25.0 (SD) and 11.1 cpm 25.3 (SD) for right and left eye, respectively, and 7.7 cpm 25.2 (SD) with both eyes open (while monitoring for suppression). These norms allow practioners to compare their subject's accommodative facility rates against those of the general population. The literature contains evidence concerning the relation between accommodative infacility, i.e., failure to meet accommodative norms established by Zellers et al. (1984), and symptoms. It has been shown (Hennessey et al., 1984) that low accommodative facility, measured with 22.00 D ¯ip lenses, to be reliably associated with symptoms in young children. In this study the authors found that subjects whose accommodative facility is 1 SD below the mean binocularly (3 cpm) or monocularly (6 cpm) are predisposed to have asthenopic symptoms. Even when expanded to include the suspect category (between 3 and 8 cpm binocularly or between 6 and 11 cpm monocularly), they found that there is evidence that symptoms will likely be present. They conclude that a clinician who encounters a patient with asthenopic symptoms should explore the monocular and binocular accommodative facility as a potential causative factor. Levine et al. (1985) performed accommodative facility testing in asymptomatic and symptomatic populations and found a trend for cycles per minute values to decrease as symptom level increases. The clinical assessment of accommodative facility has also been extended into the age range just before presbyopia. Siderov and DiGuglielmo (1991) measured interactive facility in a sample of prepresbyopic adults (over 30 years of age) and compared the results with studies of young adults to determine whether low interactive facility was associated with symptoms in that age group. Using 21.00 D ¯ip lenses they were unable to ®nd a relation between low interactive accommodative facility and symptoms. Accommodative facility has also been considered to give useful information in relation to accommodative and binocular dysfunctions (Russell and Wick, 1993; Daum, 1983). It has been related to these dysfunctions (Wick and Hall, 1987) but there are few studies concerning the direct relation between accommodative and binocular dysfunctions and a marked reduction in the average number of cpm performed with the 22.00 D ¯ip test. In this study we measured monocular and binocular accommodative facility in a sample of young adults with refractive, accommodative and nonstrabismic binocular dysfunctions. We wanted to evaluate whether
99
these parameters can be used in the diagnosis of each of these dysfunctions. We hypothesized that a patient with an accommodative problem would have problems with monocular accommodative facility whereas if a patient fails the binocular test, a binocular problem should be deduced.
Methods We examined male and female subjects aged 10±30 years (mean value 21.7926.30). They were 48 subjects with refractive, accommodative and nonstrabismic binocular dysfunctions who were consecutively presenting to an optometric clinic. All subjects had normal ocular and systemic health and no one used contact lenses. The monocular visual acuities of all patients was at least 6/6. To diagnose accommodative and binocular dysfunctions we tested the patient's accommodative and binocular state with the following tests; patient history, assessment of direction and magnitude of the distance and near lateral and vertical phoria with cover test and prism bar, static retinoscopy, subjective refractive exam with crossed-cylinder, dynamic retinoscopy by MEM (Monocular Estimate Method) method, monocular accommodative amplitude, positive and negative relative accommodations, distance and near positive and negative fusional vergences, AC/A ratio, monocular and binocular accommodative facility (with suppression control) by means of 22.00 D ¯ipper lenses and stereopsis with Wirt's lights (Titmus stereopsis test). The results of each of the tests performed were compared ®rst with the population norms (Scheiman and Wick, 1994a) and then were grouped according to their deviation from the normal values. The anomalies were then identi®ed following the criteria of Scheiman and Wick (1994b). Table 1 lists the classi®cation criteria for general binocular dysfunctions used in this study. According to these criteria we classi®ed our patients into four groups: 13 subjects with accommodative dysfunctions, 11 subjects with binocular dysfunctions, 12 subjects with simultaneous accommodative and binocular dysfunctions and 12 subjects with only refractive dysfunctions (classed as the normal group). Groups 1, 2 and 3 were classi®ed entirely in accordance to their accommodative or binocular problem, regardless of whether or not the subject had a refractive anomaly. In this way normal subjects (group 4) only included subjects who had no accommodative or binocular disorder but who had a refractive error. Accommodative facility testing was conducted following the procedure of Zellers et al. (1984). The subject, wearing full distance correction, was seated and
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Table 1. Classification criteria for general binocular dysfunctions Accommodative anomalies Accommodative excess 1. Symptoms associated with reading. Sometimes blurred distance vision worse after reading or other close work and toward the end of the day. 2. Signs: Variable visual acuity findings. Variable static and subjective. Difficulty clearing +2.00 D with monocular and binocular accommodative facility. Low MEM finding. Reduced negative relative accommodation. Accommodative insufficiency 1. Symptoms associated with reading. Blurred near vision. 2. Signs: Push-up accommodative amplitude at least 2 D below Hofstetter's calculation for minimum age-appropriate amplitude: 15± 0.25 age. Difficulty clearing ÿ2.00 D with monocular and binocular accommodative facility. High MEM finding. Decreased positive relative accommodation. Binocular anomalies Convergence excess 1. Symptoms associated with reading and near tasks. 2. Signs: Significant esophoria at near (greater than distance). Reduced negative fusional vergence at near. High AC/A ratio. Fails binocular accommodative facility with ÿ2.00 D. High MEM findings. Low positive relative accommodation. Convergence insufficiency 1. Symptoms associated with reading and near tasks. 2. Signs: Significant exophoria at near (greater than distance). Reduced positive fusional vergence at near. Reduced near point of convergence. Low AC/A ratio. Fails binocular accommodative facility with +2.00 D. Low MEM finding. Low positive relative accommodation. Divergence excess 1. Symptoms: Patient closes one eye in bright light. Occasional near point asthenopia. 2. Signs: Exophoria greater at distance than at near. High calculated AC/A ratio. Normal near point of convergence. Limited negative fusional vergence, adequate positive fusional vergence.
positioned so that the spectacle plane was 40 cm from the acuity suppression slide (Bernell card, series BC 29). The target was plane polarized using ®lters so that when the subject wore cross-polarizing glasses the top row of letters was visible to the right eye only, the bottom row to the left eye only, and the middle row to both eyes. This allowed the subject to monitor for central suppression. We tested monocular and binocular facility at a 40 cm test distance using 22.00 D ¯ip lenses. We used this method of ¯ip lenses because is the most accepted one clinically (Rouse et al., 1991) although there are authors who have supported that the hand held ¯ipper is not a good device for the
evaluation of accommodative facility (Kedzia et al., 1999). The task was demonstrated to each subject using the ¯ip lenses with instructions to say ``now'' when the middle line was clear and single and all the letters on all three lines were present. The subject began viewing the target through the +2.00 D lenses at time zero. The lenses were ¯ipped by the examiner after every ``now'' response from the subject. Testing continued for 1 min and the total number of cycles (clearing both plus and minus lenses of the ¯ip task) was recorded. Any report of constant blurring, suppression or diplopia, stopped the test and resulted in a score of
The relation between accomodative facility and general binocular dysfunction: AÂ. GarcõÂa et al. 0 cpm. The order of testing was right eye, left eye, and then binocularly. It has been shown (Zellers et al., 1984) that the order of testing have no signi®cant eect on the results. Normal clinical lighting (overhead room lights on) was maintained throughout testing session.
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with accommodative dysfunctions; between normal group and subjects with binocular dysfunction, and between normal group and patients with accommodative and binocular dysfunctions, but there was no dierence between dysfunctions (Table 4). Monocular accommodative facility
Results Of the 48 examined subjects, 13 of them had accommodative dysfunctions (5 with accommodative insuciency, 8 with accommodative excess), 11 had binocular dysfunctions (10 with convergence excess and 1 with convergence insuciency), 12 had accommodative and binocular problems (4 with convergence and accommodative excess, 4 with convergence excess and accommodative insuciency, 1 with convergence and accommodative insuciency, 2 with convergence insuciency and accommodative excess and 1 with divergence and accommodative excess). The last group, 12 patients, had only refractive dysfunctions (normal subjects). The data for each subject were compared to the norms established by Zellers et al., (1984). If a subject had an accommodative facility score which was 3 cpm or less binocularly or 6 cpm monocularly, (i.e., 1 SD or more below the mean) they were considered to have failed. A score which was below the mean (8 cpm) binocularly or (11 cpm) monocularly but less than 1 SD below the mean was considered as suspect. Inability to clear either the plus or minus lenses, suppression or diplopia was considered as zero cycles and those subjects were said to have failed. Data for the four groups of subjects may be found in Table 2. Binocular accommodative facility Table 3 presents the results of failure or pass binocular accommodative facility testing of all patients. An analysis of variance (two-way ANOVA) was performed designating the binocular accommodative facility values as the dependent variable and each dysfunction as the independent variable. This analysis revealed a highly signi®cant dierence between dysfunctions (F = 11.40; df=3; p = 0.0000). A multiple range analysis using the method of 95% Fisher's Least Signi®cant Dierence (LSD) was completed. This analysis applies a multiple comparison procedure to determine which means are signi®cantly dierent from which others. An asterisk has been placed next to pairs, indicating that these pairs show statistically signi®cant dierences at the 95% con®dence level. This multiple analysis showed statistically signi®cant dierences between normal group of subjects and patients
Data of monocular accommodative facility come from the right eye of subjects as there were no signi®cant dierences between the results of both eyes ( p> > 0.05). Results of number of subjects who passed or failed the monocular (right eye) accommodative facility testing are presented in Table 5. A two way analysis of variance (ANOVA) was performed. Monocular accommodative facility values were the dependent variable and each dysfunction was the independent variable. ANOVA results showed a highly signi®cant dierence between dysfunctions (F = 11.31; df=3; p = 0.0000). A multiple comparison procedure was done to determine which means were signi®cantly dierent from which others (Table 6). The results showed statistically signi®cant dierences between all groups except between subjects with binocular dysfunctions and normal subjects.
Discussion and conclusions Accommodative facility was one of the selection criteria for diagnosing accommodative and binocular anomalies. Their results and data from other tests were used to diagnose the dierent dysfunctions, so that the classi®cation of each subject into accommodative or binocular disorder was made according to the symptoms and signs described previously. Therefore, our results of accommodative facility should corroborate the diagnosis of each anomaly, so that according to the hypothesis made at the beginning of our study, a subject who failed binocular accommodative facility testing would have a binocular disorder and a patient who failed monocular accommodative facility testing would have an accommodative anomaly. Our data partly corroborate the hypothesis proposed. ANOVA results for binocular accommodative facility testing indicates that when a cut-o value of 3 cpm is used we can dierentiate between normal patients and those with a dysfunction. Results suggest that when a subject fails the binocular accommodative facility testing with a 3 cpm cut-o, the patient is more likely to have an ocular motor dysfunction, although according with our results we are not able to con®rm if the dysfunction is accommodative, binocular or a combined accommodative and binocular.
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Table 2. Accommodative facility data of subjects with mean and SD for each dysfunction Dysfunction Accommodative dysfunction
Mean Binocular dysfunction
Mean Accommodative and binocular dysfunction
Mean Normal group
Mean
Right eye (cpm)
Left eye (cpm)
Binocular (cpm)
10 0 5 10 7 6 5 5 1 6 7 8 4 5.6922.95 13 15 12 12 14 12 23 10 6 10 11 12.5524.20 13 18 10 10 6 11 1 9 7 12 10 0 8.9224.96 10 12 11 12 15 15 11 16 16 14 13 16 13.4222.19
10 0 5 10 7 6 5 5 1 6 6 8 4 5.6222.93 13 15 12 12 14 12 22 8 10 10 12 12.7223.64 13 16 9 9 5 11 2 6 7 12 10 0 8.3324.60 10 12 10 12 15 15 12 14 14 16 10 16 13.022.3
10 7 10 12 6 9 8 3 2 8 10 9.5 2.5 7.4623.21 8 6 6 2.5 1.5 2 2 11 8 0 10 5.1823.77 13 11 11 5 6 10 1 4.5 8.5 5 10 0 7.0824.14 12 11 10 15 16 17 12 16 12 11 10 15 13.0822.54
According to monocular accommodative facility testing, the ANOVA results suggest that when a subject fails the monocular accommodative facility testing with a 6 cpm cut-o the patient is quite likely to have an accommodative dysfunction or a
combined accommodative and binocular anomaly as de®ned in Table 1. Thus, if the patient passes the monocular test then it is likely that they are either normal or have a binocular dysfunction, but unlikely that they will have an accommodative dysfunc-
The relation between accomodative facility and general binocular dysfunction: AÂ. GarcõÂa et al.
103
Table 3. Number of subjects who passed or failed the binocular accommodative facility testing Subject Accommodative dysfunction Binocular dysfunction Accommodative and binocular dysfunction Normal group
Pass
Fail
Suspect
Total
8 4 6 12
3 5 2 0
2 2 4 0
13 11 12 12
Table 4. Mean differences for binocular accommodative facility by dysfunction with 95% percent of Fisher's least significant difference ( denotes a statistically significant difference) Method: 95% Fisher's least significant difference (LSD) Contrast of means
Difference2limits
Normal group vs Accommodative dysfunction Normal group vs Binocular dysfunction Normal group vs Accommodative and binocular Accommodative vs Binocular dysfunction Accommodative and Binocular vs Binocular dysfunction Accommodative and Binocular vs Accommodative dysfunction
2.7874 2.9064 2.8426 2.8525 2.9064 2.7874
ÿ5.62179 ÿ7.90152 ÿ6.0 2.27972 ÿ1.90152 0.378205
Table 5. Number of subjects who passed or failed the monocular (right eye) accommodative facility testing Subject Accommodative dysfunction Binocular dysfunction Accommodative and binocular dysfunction Normal group
Pass
Fail
Suspect
Total
0 8 4 11
8 1 3 0
5 2 5 1
13 11 12 12
Table 6. Mean differences for monocular (right eye) accommodative facility by dysfunction with 95% percent of Fisher's least significant difference ( denotes a statistically significant difference) Method: 95% Fisher's least significant difference (LSD) Contrast of means Normal group vs Accommodative dysfunction Normal group vs Binocular dysfunction Normal group vs Accommodative and binocular Accommodative vs Binocular dysfunction Accommodative and Binocular vs Binocular dysfunction Accommodative and Binocular vs Accommodative dysfunction
tion. This result is logical because patients presenting with binocular dysfunctions will probably not fail the monocular accommodative facility test due to poor vergence ranges only aecting binocular performance. An important and general conclusion from the results of our study is that the monocular test gives more speci®c diagnostic information than the binocular test. This assumption comes from the results
Difference2limits ÿ7.72436 ÿ0.87121 ÿ4.5 ÿ6.85315 ÿ3.62879 ÿ3.22436
2.99249 3.12034 3.05175 3.0624 3.12034 2.99249
of ANOVA testing which shows that monocular accommodative facility can distinguish between dysfunctions, but can not dierentiate between them when it is performed in binocular way. In general, the data support a relation between accommodative infacility and a dysfunction. These results suggest that performing accommodative facility may play a useful role in the diagnosis of accommodative and binocular dysfunctions, although other areas
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of the investigation should not be neglected to diagnose a general binocular dysfunction.
References Burge, S. (1979). Suppression during binocular accommodative rock. Opt. Monthly 79, 867±872. Daum, K. M. (1983). Accommodative dysfunction. Documenta Ophthalmologica 55, 177±198. Hennessey, D., Iosue, R. A. and Rouse, M. W. (1984). Relation of symptoms to accommodative infacility of school-aged children. Am. J. Optom. Physiol. Opt. 61, 177± 183. Kedzia, B., Pieczyrak, D., Tondel, G., et al. (1999). Factors aecting the clinical testing of accommodative facility. Ophthal. Physiol. Opt. 19, 12±21. Levine, S., Ciureda, K., Selenow, A., et al. (1985). Clinical assessment of accommodative facility in symptomatic and asymptomatic individuals. J. Am. Optom. Assoc. 56, 286± 290. Liu, J., Lee, M., Jang, J., et al. (1979). Objective assessment of accommodation orthoptics I. Dynamic insuciency. Am. J. Optom. Physiol. Opt. 56, 285±294. Rouse, M. W., Freestone, G. M., Weiner, B. A., et al.
(1991). Comparative study of computer-based and standard clinical accommodative facility testing methods. . Optom. Visual Sci. 68, 88±95. Russell, G. and Wick, B. (1993). A prospective study of treatment of accommodative insuciency. Optom. Visual Sci. 70, 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. Siderov, J. and DiGuglielmo, L. (1991). Binocular accommodative facility in prepresbyopic adults and its relation to symptoms. Optom. Visual Sci. 68, 49±53. Siderov, J. and Johnston, A. (1990). The importance of the test parameters in the clinical assessment of accommodative facility. Optom. Visual Sci. 67, 551±557. Wick, B. and Hal, P. (1987). Relation among accommodative facility, lag and amplitude in elementary school children. Optom. Visual Sci. 64, 593±598. Zellers, J. A., Alpert, T. L. and Rouse, M. W. (1984). A review of the literature and a normaltive study of accommodative facility. J. Am. Optom. Assoc. 55, 31±37.
PII: S0275-5408(99)00034-4
The relation between accommodative facility and general binocular dysfunction AÂngel GarcõÂa,1 Pilar Cacho,1 Francisco Lara2 and RamoÂn MegõÂas2 1
 ptica, Universidad de Alicante, Spain and 2Departamento Departamento Interuniversitario de O de OftalmologõÂa, A.P. y O.R.L., Universidad de Murcia, Spain
Summary This study was designed to evaluate the relation between accommodative facility and accommodative and binocular dysfunctions. We determined whether failure to achieve 8 cycles per minute of binocular accommodative facility or 11 cycles per minute of monocular accommodative facility tends to be associated with these dysfunctions. Forty eight subjects, ages 10±30 years were examined and classified into four groups: 13 subjects with accommodative dysfunctions, 11 patients with binocular dysfunctions, 12 subjects with accommodative and binocular dysfunctions and 12 control subjects with refractive errors but no accommodative or binocular anomalies. Monocular and binocular accommodative facility was conducted using 22.00 D flip lenses. In general, statistical analysis indicates that subjects with binocular and accommodative (ocular motor) anomalies performed significantly poorer than subjects of normal group on monocular and binocular facility tests. Monocular accommodative facility results showed more information about the dysfunction of the patient compared with the results of the binocular accommodative facility. In general data supported a relation between reduced accommodative facility and a general binocular dysfunction (accommodative or binocular) which demonstrates the importance of the accommodative facility test in diagnosing an accommodative or binocular anomaly. # 2000 The College of Optometrists. Published by Elsevier Science Ltd. All rights reserved.
Introduction
of the relation between accommodation and vergence and should be referred to as interactive facility (Siderov and Johnston, 1990). Many studies have reported normative data for both monocular and binocular accommodative facility. Two studies, both monitored for suppression during the binocular phase of accommodative facility testing, provide good normative data. Burge (1979) using 30 subjects, 6±30 years old, correctable to 6/6 and known to be nonstrabismic and prepresbyopic, found the mean monocular accommodative facilities to be 12.6 cycles per minute (cpm) 24.6 (SD) and 11.6 cpm 24.25 (SD) for right and left eyes, respectively, with 22.00 D ¯ippers. The mean binocular accommodative facility was 7.05 cpm 24.25 (SD) while using a vectographic slide
Patients presenting for optometric examination bene®t from a thorough evaluation of their near-point visual skills. Accommodative facility is an important aspect of accommodative function, so that the monocular testing provides a direct evaluation of the dynamics of accommodative responses (Liu et al., 1979), and binocular testing of accommodative facility provides similar information but also re¯ects the interactive nature
Correspondence and reprint requests to: Pilar Cacho E-mail address: [email protected] (P. Cacho). Received: 28 January 1999 Revised form: 22 April 1999
98
The relation between accomodative facility and general binocular dysfunction: AÂ. GarcõÂa et al. to monitor for suppression and 9.5 cpm without its use. Zellers et al., (1984) used a procedure similar to Burge. They studied 100 subjects, age 18±30 years, with at least 40 sec arc of stereopsis and found the mean monocular accommodative facility with 22.00 D ¯ippers to be 11.6 cpm 25.0 (SD) and 11.1 cpm 25.3 (SD) for right and left eye, respectively, and 7.7 cpm 25.2 (SD) with both eyes open (while monitoring for suppression). These norms allow practioners to compare their subject's accommodative facility rates against those of the general population. The literature contains evidence concerning the relation between accommodative infacility, i.e., failure to meet accommodative norms established by Zellers et al. (1984), and symptoms. It has been shown (Hennessey et al., 1984) that low accommodative facility, measured with 22.00 D ¯ip lenses, to be reliably associated with symptoms in young children. In this study the authors found that subjects whose accommodative facility is 1 SD below the mean binocularly (3 cpm) or monocularly (6 cpm) are predisposed to have asthenopic symptoms. Even when expanded to include the suspect category (between 3 and 8 cpm binocularly or between 6 and 11 cpm monocularly), they found that there is evidence that symptoms will likely be present. They conclude that a clinician who encounters a patient with asthenopic symptoms should explore the monocular and binocular accommodative facility as a potential causative factor. Levine et al. (1985) performed accommodative facility testing in asymptomatic and symptomatic populations and found a trend for cycles per minute values to decrease as symptom level increases. The clinical assessment of accommodative facility has also been extended into the age range just before presbyopia. Siderov and DiGuglielmo (1991) measured interactive facility in a sample of prepresbyopic adults (over 30 years of age) and compared the results with studies of young adults to determine whether low interactive facility was associated with symptoms in that age group. Using 21.00 D ¯ip lenses they were unable to ®nd a relation between low interactive accommodative facility and symptoms. Accommodative facility has also been considered to give useful information in relation to accommodative and binocular dysfunctions (Russell and Wick, 1993; Daum, 1983). It has been related to these dysfunctions (Wick and Hall, 1987) but there are few studies concerning the direct relation between accommodative and binocular dysfunctions and a marked reduction in the average number of cpm performed with the 22.00 D ¯ip test. In this study we measured monocular and binocular accommodative facility in a sample of young adults with refractive, accommodative and nonstrabismic binocular dysfunctions. We wanted to evaluate whether
99
these parameters can be used in the diagnosis of each of these dysfunctions. We hypothesized that a patient with an accommodative problem would have problems with monocular accommodative facility whereas if a patient fails the binocular test, a binocular problem should be deduced.
Methods We examined male and female subjects aged 10±30 years (mean value 21.7926.30). They were 48 subjects with refractive, accommodative and nonstrabismic binocular dysfunctions who were consecutively presenting to an optometric clinic. All subjects had normal ocular and systemic health and no one used contact lenses. The monocular visual acuities of all patients was at least 6/6. To diagnose accommodative and binocular dysfunctions we tested the patient's accommodative and binocular state with the following tests; patient history, assessment of direction and magnitude of the distance and near lateral and vertical phoria with cover test and prism bar, static retinoscopy, subjective refractive exam with crossed-cylinder, dynamic retinoscopy by MEM (Monocular Estimate Method) method, monocular accommodative amplitude, positive and negative relative accommodations, distance and near positive and negative fusional vergences, AC/A ratio, monocular and binocular accommodative facility (with suppression control) by means of 22.00 D ¯ipper lenses and stereopsis with Wirt's lights (Titmus stereopsis test). The results of each of the tests performed were compared ®rst with the population norms (Scheiman and Wick, 1994a) and then were grouped according to their deviation from the normal values. The anomalies were then identi®ed following the criteria of Scheiman and Wick (1994b). Table 1 lists the classi®cation criteria for general binocular dysfunctions used in this study. According to these criteria we classi®ed our patients into four groups: 13 subjects with accommodative dysfunctions, 11 subjects with binocular dysfunctions, 12 subjects with simultaneous accommodative and binocular dysfunctions and 12 subjects with only refractive dysfunctions (classed as the normal group). Groups 1, 2 and 3 were classi®ed entirely in accordance to their accommodative or binocular problem, regardless of whether or not the subject had a refractive anomaly. In this way normal subjects (group 4) only included subjects who had no accommodative or binocular disorder but who had a refractive error. Accommodative facility testing was conducted following the procedure of Zellers et al. (1984). The subject, wearing full distance correction, was seated and
100
Ophthal. Physiol. Opt. 2000 20: No 2
Table 1. Classification criteria for general binocular dysfunctions Accommodative anomalies Accommodative excess 1. Symptoms associated with reading. Sometimes blurred distance vision worse after reading or other close work and toward the end of the day. 2. Signs: Variable visual acuity findings. Variable static and subjective. Difficulty clearing +2.00 D with monocular and binocular accommodative facility. Low MEM finding. Reduced negative relative accommodation. Accommodative insufficiency 1. Symptoms associated with reading. Blurred near vision. 2. Signs: Push-up accommodative amplitude at least 2 D below Hofstetter's calculation for minimum age-appropriate amplitude: 15± 0.25 age. Difficulty clearing ÿ2.00 D with monocular and binocular accommodative facility. High MEM finding. Decreased positive relative accommodation. Binocular anomalies Convergence excess 1. Symptoms associated with reading and near tasks. 2. Signs: Significant esophoria at near (greater than distance). Reduced negative fusional vergence at near. High AC/A ratio. Fails binocular accommodative facility with ÿ2.00 D. High MEM findings. Low positive relative accommodation. Convergence insufficiency 1. Symptoms associated with reading and near tasks. 2. Signs: Significant exophoria at near (greater than distance). Reduced positive fusional vergence at near. Reduced near point of convergence. Low AC/A ratio. Fails binocular accommodative facility with +2.00 D. Low MEM finding. Low positive relative accommodation. Divergence excess 1. Symptoms: Patient closes one eye in bright light. Occasional near point asthenopia. 2. Signs: Exophoria greater at distance than at near. High calculated AC/A ratio. Normal near point of convergence. Limited negative fusional vergence, adequate positive fusional vergence.
positioned so that the spectacle plane was 40 cm from the acuity suppression slide (Bernell card, series BC 29). The target was plane polarized using ®lters so that when the subject wore cross-polarizing glasses the top row of letters was visible to the right eye only, the bottom row to the left eye only, and the middle row to both eyes. This allowed the subject to monitor for central suppression. We tested monocular and binocular facility at a 40 cm test distance using 22.00 D ¯ip lenses. We used this method of ¯ip lenses because is the most accepted one clinically (Rouse et al., 1991) although there are authors who have supported that the hand held ¯ipper is not a good device for the
evaluation of accommodative facility (Kedzia et al., 1999). The task was demonstrated to each subject using the ¯ip lenses with instructions to say ``now'' when the middle line was clear and single and all the letters on all three lines were present. The subject began viewing the target through the +2.00 D lenses at time zero. The lenses were ¯ipped by the examiner after every ``now'' response from the subject. Testing continued for 1 min and the total number of cycles (clearing both plus and minus lenses of the ¯ip task) was recorded. Any report of constant blurring, suppression or diplopia, stopped the test and resulted in a score of
The relation between accomodative facility and general binocular dysfunction: AÂ. GarcõÂa et al. 0 cpm. The order of testing was right eye, left eye, and then binocularly. It has been shown (Zellers et al., 1984) that the order of testing have no signi®cant eect on the results. Normal clinical lighting (overhead room lights on) was maintained throughout testing session.
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with accommodative dysfunctions; between normal group and subjects with binocular dysfunction, and between normal group and patients with accommodative and binocular dysfunctions, but there was no dierence between dysfunctions (Table 4). Monocular accommodative facility
Results Of the 48 examined subjects, 13 of them had accommodative dysfunctions (5 with accommodative insuciency, 8 with accommodative excess), 11 had binocular dysfunctions (10 with convergence excess and 1 with convergence insuciency), 12 had accommodative and binocular problems (4 with convergence and accommodative excess, 4 with convergence excess and accommodative insuciency, 1 with convergence and accommodative insuciency, 2 with convergence insuciency and accommodative excess and 1 with divergence and accommodative excess). The last group, 12 patients, had only refractive dysfunctions (normal subjects). The data for each subject were compared to the norms established by Zellers et al., (1984). If a subject had an accommodative facility score which was 3 cpm or less binocularly or 6 cpm monocularly, (i.e., 1 SD or more below the mean) they were considered to have failed. A score which was below the mean (8 cpm) binocularly or (11 cpm) monocularly but less than 1 SD below the mean was considered as suspect. Inability to clear either the plus or minus lenses, suppression or diplopia was considered as zero cycles and those subjects were said to have failed. Data for the four groups of subjects may be found in Table 2. Binocular accommodative facility Table 3 presents the results of failure or pass binocular accommodative facility testing of all patients. An analysis of variance (two-way ANOVA) was performed designating the binocular accommodative facility values as the dependent variable and each dysfunction as the independent variable. This analysis revealed a highly signi®cant dierence between dysfunctions (F = 11.40; df=3; p = 0.0000). A multiple range analysis using the method of 95% Fisher's Least Signi®cant Dierence (LSD) was completed. This analysis applies a multiple comparison procedure to determine which means are signi®cantly dierent from which others. An asterisk has been placed next to pairs, indicating that these pairs show statistically signi®cant dierences at the 95% con®dence level. This multiple analysis showed statistically signi®cant dierences between normal group of subjects and patients
Data of monocular accommodative facility come from the right eye of subjects as there were no signi®cant dierences between the results of both eyes ( p> > 0.05). Results of number of subjects who passed or failed the monocular (right eye) accommodative facility testing are presented in Table 5. A two way analysis of variance (ANOVA) was performed. Monocular accommodative facility values were the dependent variable and each dysfunction was the independent variable. ANOVA results showed a highly signi®cant dierence between dysfunctions (F = 11.31; df=3; p = 0.0000). A multiple comparison procedure was done to determine which means were signi®cantly dierent from which others (Table 6). The results showed statistically signi®cant dierences between all groups except between subjects with binocular dysfunctions and normal subjects.
Discussion and conclusions Accommodative facility was one of the selection criteria for diagnosing accommodative and binocular anomalies. Their results and data from other tests were used to diagnose the dierent dysfunctions, so that the classi®cation of each subject into accommodative or binocular disorder was made according to the symptoms and signs described previously. Therefore, our results of accommodative facility should corroborate the diagnosis of each anomaly, so that according to the hypothesis made at the beginning of our study, a subject who failed binocular accommodative facility testing would have a binocular disorder and a patient who failed monocular accommodative facility testing would have an accommodative anomaly. Our data partly corroborate the hypothesis proposed. ANOVA results for binocular accommodative facility testing indicates that when a cut-o value of 3 cpm is used we can dierentiate between normal patients and those with a dysfunction. Results suggest that when a subject fails the binocular accommodative facility testing with a 3 cpm cut-o, the patient is more likely to have an ocular motor dysfunction, although according with our results we are not able to con®rm if the dysfunction is accommodative, binocular or a combined accommodative and binocular.
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Table 2. Accommodative facility data of subjects with mean and SD for each dysfunction Dysfunction Accommodative dysfunction
Mean Binocular dysfunction
Mean Accommodative and binocular dysfunction
Mean Normal group
Mean
Right eye (cpm)
Left eye (cpm)
Binocular (cpm)
10 0 5 10 7 6 5 5 1 6 7 8 4 5.6922.95 13 15 12 12 14 12 23 10 6 10 11 12.5524.20 13 18 10 10 6 11 1 9 7 12 10 0 8.9224.96 10 12 11 12 15 15 11 16 16 14 13 16 13.4222.19
10 0 5 10 7 6 5 5 1 6 6 8 4 5.6222.93 13 15 12 12 14 12 22 8 10 10 12 12.7223.64 13 16 9 9 5 11 2 6 7 12 10 0 8.3324.60 10 12 10 12 15 15 12 14 14 16 10 16 13.022.3
10 7 10 12 6 9 8 3 2 8 10 9.5 2.5 7.4623.21 8 6 6 2.5 1.5 2 2 11 8 0 10 5.1823.77 13 11 11 5 6 10 1 4.5 8.5 5 10 0 7.0824.14 12 11 10 15 16 17 12 16 12 11 10 15 13.0822.54
According to monocular accommodative facility testing, the ANOVA results suggest that when a subject fails the monocular accommodative facility testing with a 6 cpm cut-o the patient is quite likely to have an accommodative dysfunction or a
combined accommodative and binocular anomaly as de®ned in Table 1. Thus, if the patient passes the monocular test then it is likely that they are either normal or have a binocular dysfunction, but unlikely that they will have an accommodative dysfunc-
The relation between accomodative facility and general binocular dysfunction: AÂ. GarcõÂa et al.
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Table 3. Number of subjects who passed or failed the binocular accommodative facility testing Subject Accommodative dysfunction Binocular dysfunction Accommodative and binocular dysfunction Normal group
Pass
Fail
Suspect
Total
8 4 6 12
3 5 2 0
2 2 4 0
13 11 12 12
Table 4. Mean differences for binocular accommodative facility by dysfunction with 95% percent of Fisher's least significant difference ( denotes a statistically significant difference) Method: 95% Fisher's least significant difference (LSD) Contrast of means
Difference2limits
Normal group vs Accommodative dysfunction Normal group vs Binocular dysfunction Normal group vs Accommodative and binocular Accommodative vs Binocular dysfunction Accommodative and Binocular vs Binocular dysfunction Accommodative and Binocular vs Accommodative dysfunction
2.7874 2.9064 2.8426 2.8525 2.9064 2.7874
ÿ5.62179 ÿ7.90152 ÿ6.0 2.27972 ÿ1.90152 0.378205
Table 5. Number of subjects who passed or failed the monocular (right eye) accommodative facility testing Subject Accommodative dysfunction Binocular dysfunction Accommodative and binocular dysfunction Normal group
Pass
Fail
Suspect
Total
0 8 4 11
8 1 3 0
5 2 5 1
13 11 12 12
Table 6. Mean differences for monocular (right eye) accommodative facility by dysfunction with 95% percent of Fisher's least significant difference ( denotes a statistically significant difference) Method: 95% Fisher's least significant difference (LSD) Contrast of means Normal group vs Accommodative dysfunction Normal group vs Binocular dysfunction Normal group vs Accommodative and binocular Accommodative vs Binocular dysfunction Accommodative and Binocular vs Binocular dysfunction Accommodative and Binocular vs Accommodative dysfunction
tion. This result is logical because patients presenting with binocular dysfunctions will probably not fail the monocular accommodative facility test due to poor vergence ranges only aecting binocular performance. An important and general conclusion from the results of our study is that the monocular test gives more speci®c diagnostic information than the binocular test. This assumption comes from the results
Difference2limits ÿ7.72436 ÿ0.87121 ÿ4.5 ÿ6.85315 ÿ3.62879 ÿ3.22436
2.99249 3.12034 3.05175 3.0624 3.12034 2.99249
of ANOVA testing which shows that monocular accommodative facility can distinguish between dysfunctions, but can not dierentiate between them when it is performed in binocular way. In general, the data support a relation between accommodative infacility and a dysfunction. These results suggest that performing accommodative facility may play a useful role in the diagnosis of accommodative and binocular dysfunctions, although other areas
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of the investigation should not be neglected to diagnose a general binocular dysfunction.
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(1991). Comparative study of computer-based and standard clinical accommodative facility testing methods. . Optom. Visual Sci. 68, 88±95. Russell, G. and Wick, B. (1993). A prospective study of treatment of accommodative insuciency. Optom. Visual Sci. 70, 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. Siderov, J. and DiGuglielmo, L. (1991). Binocular accommodative facility in prepresbyopic adults and its relation to symptoms. Optom. Visual Sci. 68, 49±53. Siderov, J. and Johnston, A. (1990). The importance of the test parameters in the clinical assessment of accommodative facility. Optom. Visual Sci. 67, 551±557. Wick, B. and Hal, P. (1987). Relation among accommodative facility, lag and amplitude in elementary school children. Optom. Visual Sci. 64, 593±598. Zellers, J. A., Alpert, T. L. and Rouse, M. W. (1984). A review of the literature and a normaltive study of accommodative facility. J. Am. Optom. Assoc. 55, 31±37.