Children with Down syndrome benefit from bifocals as evidenced by increased compliance with spectacle wear Rohit Adyanthaya, MD, Sheena Isenor, CO, Brinda Muthusamy, FRCOphth, Kristina Irsch, PhD, and David L. Guyton, MD BACKGROUND
In our experience, children with Down syndrome were noncompliant with spectacle wear, often attributed to their inability to appreciate benefit from the glasses. Studies show that up to 80% of children with Down syndrome have reduced accommodation. The purpose of this study was to evaluate whether the use of bifocals increased compliance with spectacle wear.
METHODS
A retrospective review of medical records from 1983 to 2007 identified 86 children with Down syndrome who were prescribed either bifocal or single vision spectacles. Compliance with spectacle wear was assessed by telephone and was available for 57 children: 27 with bifocals and 30 with single-vision spectacles. Accommodative ability had been assessed by dynamic retinoscopy in 39 of these children.
RESULTS
In the 27 bifocal children, all had poor accommodation on dynamic retinoscopy. Of these 27 children, 24 were compliant with spectacle wear (89%), whereas only 15 of the 30 singlevision spectacle children were compliant (50%). Of the 30 single-vision spectacle children, 18 had not had dynamic retinoscopy, and accommodative ability was thus unknown. Of the 12 who had undergone dynamic retinoscopy, 5 showed poor accommodation. The remaining 7 had good accommodation but showed compliance of only 43% in wearing singlevision glasses. The association between type of spectacle prescribed and compliance with wear was statistically significant by c2 testing (P 5 0.002). In our study cohort, the addition of bifocal segments improved compliance with spectacle wear in children with Down syndrome. ( J AAPOS 2014;18:481-484)
CONCLUSIONS
R
ecent studies have documented that 55%-80% of children with Down syndrome have reduced accommodation.1-3 This accommodative deficiency poses a crucial problem, especially in school-age children’s performance with near tasks, by creating a constant near blur, especially in children with hypermetropia, and may even lead to low levels of amblyopia.4,5 Studies have shown that whereas spectacle wear can correct the distance refractive error caused by the hyperopia seen in many of these patients, it does not improve accommodation at near.6 In fact, these children consistently maintained the same amount of hypoaccommodation with and without single-vision spectacles. In their longitudinal study, Cregg and colleagues6 have shown that the accommodative deficiency in children with
Author affiliations: The Krieger Children’s Eye Center at The Wilmer Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland Submitted May 26, 2013. Revision accepted July 18, 2014. Published online September 26, 2014. Correspondence: David L. Guyton, MD, The Wilmer Institute 233, The Johns Hopkins Hospital, Baltimore, MD 21287 (email: [email protected]). Copyright Ó 2014 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/$36.00 http://dx.doi.org/10.1016/j.jaapos.2014.07.158
Journal of AAPOS
Down syndrome differs from adults with presbyopia. Adults who are presbyopic will attempt to use all their accommodative reserve in order to focus on a target; as a target is brought in from a distance, presbyopic adults will gradually increase their accommodation until they reach their maximum ability. Children with Down syndrome, however, have been shown not to demonstrate this increasing effort as the viewing target is brought closer or varied. Children with Down syndrome hypoaccommodate regardless of the target distance, and this hypoaccommodation is not affected by correcting their refractive error.6 Cregg and colleagues6 postulate that this may be due to a higher tolerance for blur, and that these children only accommodate to “achieve a perceptually clear image.” In 1984 the senior author (DLG) began prescribing high, flat-top bifocals to many patients who showed little or no accommodation on dynamic retinoscopy,7 including children with Down syndrome. Other clinicians in our division were not performing dynamic retinoscopy at that time and only prescribed spectacles with distance correction. The purpose of the present study was to evaluate whether the use of bifocals increased spectacle compliance in children with Down syndrome.
481
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Methods This study was approved by the Johns Hopkins Institutional Review Board and adhered to the US Health Insurance Portability and Accountability Act of 1996. The medical records of Down syndrome patients seen at the Krieger Children’s Eye Center at the Wilmer Institute of the Johns Hopkins University School of Medicine from 1983 to 2007 were retrospectively reviewed to identify those who were prescribed either single-vision spectacles or high, flat-top bifocal segments between 12.50 D and 13.00 D in power. The choice of the add strength was dependent on the child’s habitual reading distance. The following data were recorded: patient age, visual acuity, cycloplegic refraction, ocular alignment, accommodative ability, spectacle correction, and any mention of compliance with spectacles. Accommodation was assessed by a simple and rapid version of dynamic retinoscopy.7,8 A near fixation target such as a toy or other attention-attracting object with fine detail is held as close as possible to the retinoscope peephole without occluding the peephole or the light source. With distance correction in place, the patient is asked to fixate on a distant target. The retinoscopic reflex is assessed in both eyes, and strong “with” motion should be observed. The patient’s attention is then drawn to the near target, with the retinoscope and target held approximately at the normal reading distance. The “with” motion will rapidly change to neutralization (no motion) or even slight “against” motion if accommodative ability is good. If the accommodative ability is poor, the examiner will still see “with” movement even when the subject is looking at the near object. In our experience, most patients with Down syndrome show no detectable accommodation at all when switching fixation from distance to near (the “with” movement remains the same), so the distinction between good and poor accommodation is usually straightforward. An attempt was made to locate and contact the parents of each patient by telephone to determine their child’s compliance with spectacle wear. Compliance with spectacle wear was defined as essentially full-time wear of the glasses, as part-time wear was rarely if ever encountered. For the purpose of analysis, patients were divided into two groups: those who were prescribed bifocal spectacles and those who were prescribed single-vision spectacles. Some children presented to us already wearing single-vision glasses, and bifocals were prescribed based on the dynamic retinoscopy findings. These patients were included in the bifocal group and were not included in the single-vision glasses group so as not to include the same patient twice. We also analyzed the data based on the presence or absence of accommodation on dynamic retinoscopy. Statistical comparisons were performed using the c2 test, the Fisher exact test, and the Mann-Whitney U test, as appropriate. A P value of \0.05 was considered statistically significant. Continuous variables are reported as mean standard deviation.
Results A total of 86 Down syndrome patients were identified. Compliance information was obtained for 57 children (age range, 22 months to 13 years when first prescribed glasses; average, 7.5 years). The telephone contact was an
Volume 18 Number 5 / October 2014 average of 51 months after first prescription of the respective spectacles. There were 27 children in the bifocal spectacles group and 30 in the single-vision spectacles group. All children had undergone cycloplegic refraction. Overall, 8 children (14%) were myopic and 49 (86%) were hyperopic. Of the 27 children prescribed bifocal lenses, 1 was myopic, with spherical equivalent refractions of 1.00 D and –0.75 D; 26 were hyperopic, with an average spherical equivalent in the right eye of 13.01 1.39 D and in the left eye of 13.13 1.48 D. The maximum anisometropia for the children in bifocals was 11.75 D, and the average anisometropia was 10.32 0.47 D. For the children in single-vision spectacles, 7 were myopic and 23 were hyperopic. The average spherical equivalent for the myopic group in single vision glasses was 5.07 4.37 D in the right eye and 4.68 4.06 D in the left eye. The average spherical equivalent for the hyperopic group in single vision glasses was 13.29 1.77 D in the right eye and 13.11 1.75 D in the left eye. The maximum anisometropia for the children in single vision spectacles was 11.00 D, with an average of 10.27 0.28 D. Of the 30 patients in the single-vision spectacle group, 16 (53%) had strabismus; of the 27 in the bifocal spectacle group, 18 (67%) had strabismus. This difference was not statistically significant (P 5 0.306). Dynamic retinoscopy had been performed on 39 of the 57 patients to assess accommodation. Of these, 7 showed good accommodation (18%) and 32 showed poor accommodation (82%). The 7 children with good accommodation on dynamic retinoscopy were prescribed single-vision spectacles but only had a 43% compliance with spectacle wear. Of the 32 patients demonstrating poor accommodation on dynamic retinoscopy, 27 were prescribed bifocal spectacles, and the remaining 5 were still prescribed single-vision spectacles (prescribed by colleagues of the senior author). The compliance with spectacle wear of the 27 children with poor accommodation in bifocals was 89% (24/27) while the compliance rate of the 5 children with poor accommodation in single-vision spectacles was 40% (2/5). Analysis of the cycloplegic refraction results and ability to accommodate showed that of the 32 patients with poor accommodation, 29 (91%) were hyperopic, whereas of the 7 children with good accommodation, 6 (86%) were hyperopic. The average spherical equivalent in the group with good accommodation was 1.96 1.97 D in the right eye and 1.86 1.70 D in the left eye. In the group with poor accommodation, the average spherical equivalent was 2.24 3.21 D in the right eye and 2.36 3.12 D in the left eye. These differences in spherical equivalent were not statistically significant (P . 0.05). All 18 patients with unknown ability to accommodate (no dynamic retinoscopy examination) were prescribed single-vision spectacles based on their distance refraction. In these, the compliance with spectacle wear was 56% (10/18). Overall, the children in bifocal spectacles had better compliance with spectacle wear than the children with
Journal of AAPOS
Volume 18 Number 5 / October 2014 single-vision spectacles. Of the 27 bifocal children, 24 (89%) were compliant with spectacle wear, whereas only 15 (50%) of the 30 nonbifocal children were compliant. Of these 30 children in single-vision glasses, 7 had good accommodation on dynamic retinoscopy, 5 had poor accommodation on dynamic retinoscopy, and the remaining 18 children had unknown accommodative ability. The association between type of spectacle prescribed and compliance with wear was statistically significant by c2 testing (P 5 0.002). Even among the 7 children with known good accommodation on dynamic retinoscopy, the compliance was only 43% in single-vision glasses. During the interviews and case note review we noted that 9 parents voluntarily noted a dramatic improvement in compliance when the spectacles were switched from initial single-vision spectacles to bifocal spectacles in the bifocal group.
Discussion Children with Down syndrome often have ophthalmologic anomalies, including lens opacities, refractive errors, accommodative insufficiency, strabismus, and nystagmus.1,2,9 Woodhouse and colleagues have shown using dynamic retinoscopy that 80% of children with Down syndrome have decreased accommodative ability compared with agematched, developmentally normal children.2 Other studies have shown the prevalence of accommodative weakness in children with Down syndrome to be between 55% and 68%.1,3 We report a similar prevalence (82%) of poor accommodation in patients with Down syndrome, as assessed by dynamic retinoscopy. Hyperopia is the predominant refractive error in children with Down syndrome, and this was our finding as well. In our practice, we had noted that children with Down syndrome did not tolerate their single-vision glasses well, often refusing to wear them continuously. This lack of compliance was presumed to be due to a lack of perceived benefit by the child. The functional environment for most children involves the use of near vision and accommodation, perhaps especially for those children with intellectual disabilities because of more indoor confinement and closer supervision. Based on the findings on dynamic retinoscopy, the senior author began prescribing high, flat-top bifocal spectacles to Down syndrome patients in 1984. The concept was to provide these patients with clear near vision, and hopefully thereby treat any bilateral amblyopia that might have been present. Stewart and colleagues10 found a higher incidence of hypermetropia in those patients with Down syndrome who had poor accommodation. We could not confirm this statistically, for among our patients with poor accommodation, 91% were hypermetropic, and among those with good accommodation 86% were hypermetropic. The numbers of myopic children in the two groups were too small to determine any real difference in behavior from the hyperopic children. The study by Stewart and
Journal of AAPOS
Adyanthaya et al
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colleagues10 also showed a higher incidence of strabismus in the hypoaccommodative group; our study did not find a statistically significant difference in prevalence of strabismus between the two groups (P 5 0.306). This may reflect the nature of the referral patterns to our practice. An interventional study conducted by Stewart and colleagues11 over a 5-month period showed that the compliance with bifocal spectacle wear compared with distance correction alone was high and comparable in both interventional groups. The present study found that compliance was better with bifocal spectacles in the longer term. Stewart and colleagues10,11 did, however, demonstrate, with further retrospective analysis of their records, that children with Down syndrome showed an improvement in their accommodative ability following use of bifocal lenses. Longitudinal studies by Nandakumar and colleagues12,13 have demonstrated that the use of bifocal spectacles in children with Down syndrome improved compliance, reduced their accommodative lag, improved their near vision, and was associated with an improvement in their early literacy scores. Our study further suggests that if a universal policy of prescribing single-vision spectacles to correct only distance acuity is adopted, then compliance with spectacle wear will be in the 56% range. Unexpectedly, in our 7 patients who showed good accommodation on dynamic retinoscopy, compliance with single-vision spectacle wear was only 43%. This was slightly, but not statistically significantly better (based on the Fisher exact test), than the 40% compliance with single-vision spectacles in our 5 patients with poor accommodation on dynamic retinoscopy (P 5 0.057). Based on this, we cannot reject the null hypothesis that there is no difference in compliance with wearing single-vision glasses between those with good or poor accommodation. We speculate that even those children with Down syndrome who can demonstrate accommodation in the clinic on dynamic retinoscopy may not be able to sustain such accommodation for long and may be more comfortable with the “crutch” provided by the bifocals and therefore show increased compliance with bifocal wear over single-vision spectacle wear. The primary limitation of our study is that the data are largely retrospective, although information regarding spectacle wear compliance was routinely collected. The study is also limited by its not analyzing such factors as intellectual disability and behavioral disorders that may further affect compliance beyond the benefit of improved vision. Additionally, dynamic retinoscopy was not performed in a quantitative manner, as was the case in other longitudinal studies,6,10,11 Our aim was only to determine clinically whether a child did or did not accommodate to a near detailed target. Dynamic retinoscopy data were not available on more than half of the children who were prescribed single-vision glasses; thus no strong conclusions can be made with regard to the relationship between accommodative ability and spectacle compliance in this group.
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With over 80% of Down syndrome patients demonstrating poor accommodation, the results of our study support our hypothesis that bifocal spectacles offer a significant advantage over single-vision spectacles. Prescribing bifocals improves compliance with spectacle wear, strongly suggesting that the extra power for near is appreciated and used, with the potential advantages of improving reading ability and performance in school. Because we found relatively poor compliance with spectacle wear in all of our Down syndrome patients who were prescribed single vision glasses, even in those 7 single-vision glasses patients with good accommodation by dynamic retinoscopy, we cannot state that dynamic retinoscopy can reliably distinguish between those who will and will not accept glasses well. It is still our practice, however, to assess accommodation by dynamic retinoscopy in all children with decreased vision, including all patients with Down syndrome, before cycloplegia, and for those with little or no accommodation we prescribe 12.50 to 13.00 D flat-top bifocals, based on the patient’s age and reading distance. Our data suggest that even if Down syndrome patients with demonstrable accommodation show poor compliance with single-vision glasses, bifocal spectacles should be prescribed. We feel that dynamic retinoscopy is an important part of evaluating patients with Down syndrome, because poor accommodation is a specific deficiency that should be made known to parents, care-providers, and educators. We encourage clinicians to use dynamic retinoscopy as an objective assessment of accommodation, to prescribe treatment as per this assessment, and not to adopt a policy of prescribing expensive bifocal glasses in a universal fashion in order to benefit the majority. The child’s ability to accommodate should ideally be documented at the initial evaluation. This will allow the physician to monitor the effect that the bifocal glasses have on the patient’s ongoing ability to accommodate. Stewart and colleagues10,11 and Al-Bagdady and colleagues14 have shown that bifocals can improve accommodation over time. Thus in addition
Volume 18 Number 5 / October 2014 to improving compliance with spectacle wear, bifocal glasses may promote more normal development of accommodation, and it may eventually be possible to wean the child off the bifocal adds. References 1. Haugen OH, Høvding G, Lundstr€ om I. Refractive development in children with Down’s syndrome: a population based, longitudinal study. Br J Ophthalmol 2001;85:714-19. 2. Woodhouse JM, Meades JS, Leat SJ, Saunders KJ. Reduced accommodation in children with Down syndrome. Invest Ophthalmol Vis Sci 1993;34:2382-7. 3. Woodhouse JM, Cregg M, Gunter HL, et al. The effect of age, size of target and cognitive factors on accommodative responses of children with Down syndrome. Invest Ophthalmol Vis Sci 2000;41:2479-85. 4. Courage ML, Adams RJ, Reyno S, Kwa PG. Visual acuity in infants and children with Down syndrome. Dev Med Child Neurol 1994; 36:586-93. 5. Nandakumar K, Leat SJ. Bifocals in Down Syndrome Study (BiDS): Design and baseline visual function. Optom Vis Sci 2009;86:196-207. 6. Cregg M, Woodhouse JM, Pakeman VH, et al. Accommodation and refractive error in children with Down syndrome: Cross-sectional and longitudinal studies. Invest Ophthalmol Vis Sci 2001;42:55-63. 7. Guyton DL, O’Connor GM. Dynamic retinoscopy. Curr Opin Ophthalmol 1991;2:78-80. 8. Hunter DG. Dynamic retinoscopy: the missing data. Surv Ophthalmol 2001;46:269-74. 9. Cregg M, Woodhouse JM, Stewart RE, et al. Development of refractive error and strabismus in children with Down syndrome. Invest Ophthalmol Vis Sci 2003;44:1023-30. 10. Stewart RE, Woodhouse JM, Cregg M, Pakeman VH. Association between accommodative accuracy, hypermetropia, and strabismus in children with Down’s syndrome. Optom Vis Sci 2007;84:149-55. 11. Stewart RE, Margaret Woodhouse J, Trojanowska LD. In focus: the use of bifocal spectacles with children with Down’s syndrome. Ophthalmic Physiol Opt 2005;25:514-22. 12. Nandakumar K, Leat SJ. Bifocals in children with Down syndrome (BiDS)-visual acuity, accommodation and early literacy skills. Acta Ophthalmol 2010;88:196-204. 13. Nandakumar K, Evans MA, Briand K, Leat SJ. Bifocals in Down syndrome study (BiDS): Analysis of video recorded sessions of literacy and visual perceptual skills. Clin Exp Optom 2011;94(6):575-85. 14. Al-Bagdady M, Stewart RE, Watts P, Murphy PJ, Woodhouse JM. Bifocals and Down’s syndrome: Correction or treatment? Ophthalmic Physiol Opt 2009;29:416-21.
Journal of AAPOS
In our experience, children with Down syndrome were noncompliant with spectacle wear, often attributed to their inability to appreciate benefit from the glasses. Studies show that up to 80% of children with Down syndrome have reduced accommodation. The purpose of this study was to evaluate whether the use of bifocals increased compliance with spectacle wear.
METHODS
A retrospective review of medical records from 1983 to 2007 identified 86 children with Down syndrome who were prescribed either bifocal or single vision spectacles. Compliance with spectacle wear was assessed by telephone and was available for 57 children: 27 with bifocals and 30 with single-vision spectacles. Accommodative ability had been assessed by dynamic retinoscopy in 39 of these children.
RESULTS
In the 27 bifocal children, all had poor accommodation on dynamic retinoscopy. Of these 27 children, 24 were compliant with spectacle wear (89%), whereas only 15 of the 30 singlevision spectacle children were compliant (50%). Of the 30 single-vision spectacle children, 18 had not had dynamic retinoscopy, and accommodative ability was thus unknown. Of the 12 who had undergone dynamic retinoscopy, 5 showed poor accommodation. The remaining 7 had good accommodation but showed compliance of only 43% in wearing singlevision glasses. The association between type of spectacle prescribed and compliance with wear was statistically significant by c2 testing (P 5 0.002). In our study cohort, the addition of bifocal segments improved compliance with spectacle wear in children with Down syndrome. ( J AAPOS 2014;18:481-484)
CONCLUSIONS
R
ecent studies have documented that 55%-80% of children with Down syndrome have reduced accommodation.1-3 This accommodative deficiency poses a crucial problem, especially in school-age children’s performance with near tasks, by creating a constant near blur, especially in children with hypermetropia, and may even lead to low levels of amblyopia.4,5 Studies have shown that whereas spectacle wear can correct the distance refractive error caused by the hyperopia seen in many of these patients, it does not improve accommodation at near.6 In fact, these children consistently maintained the same amount of hypoaccommodation with and without single-vision spectacles. In their longitudinal study, Cregg and colleagues6 have shown that the accommodative deficiency in children with
Author affiliations: The Krieger Children’s Eye Center at The Wilmer Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland Submitted May 26, 2013. Revision accepted July 18, 2014. Published online September 26, 2014. Correspondence: David L. Guyton, MD, The Wilmer Institute 233, The Johns Hopkins Hospital, Baltimore, MD 21287 (email: [email protected]). Copyright Ó 2014 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/$36.00 http://dx.doi.org/10.1016/j.jaapos.2014.07.158
Journal of AAPOS
Down syndrome differs from adults with presbyopia. Adults who are presbyopic will attempt to use all their accommodative reserve in order to focus on a target; as a target is brought in from a distance, presbyopic adults will gradually increase their accommodation until they reach their maximum ability. Children with Down syndrome, however, have been shown not to demonstrate this increasing effort as the viewing target is brought closer or varied. Children with Down syndrome hypoaccommodate regardless of the target distance, and this hypoaccommodation is not affected by correcting their refractive error.6 Cregg and colleagues6 postulate that this may be due to a higher tolerance for blur, and that these children only accommodate to “achieve a perceptually clear image.” In 1984 the senior author (DLG) began prescribing high, flat-top bifocals to many patients who showed little or no accommodation on dynamic retinoscopy,7 including children with Down syndrome. Other clinicians in our division were not performing dynamic retinoscopy at that time and only prescribed spectacles with distance correction. The purpose of the present study was to evaluate whether the use of bifocals increased spectacle compliance in children with Down syndrome.
481
482
Adyanthaya et al
Methods This study was approved by the Johns Hopkins Institutional Review Board and adhered to the US Health Insurance Portability and Accountability Act of 1996. The medical records of Down syndrome patients seen at the Krieger Children’s Eye Center at the Wilmer Institute of the Johns Hopkins University School of Medicine from 1983 to 2007 were retrospectively reviewed to identify those who were prescribed either single-vision spectacles or high, flat-top bifocal segments between 12.50 D and 13.00 D in power. The choice of the add strength was dependent on the child’s habitual reading distance. The following data were recorded: patient age, visual acuity, cycloplegic refraction, ocular alignment, accommodative ability, spectacle correction, and any mention of compliance with spectacles. Accommodation was assessed by a simple and rapid version of dynamic retinoscopy.7,8 A near fixation target such as a toy or other attention-attracting object with fine detail is held as close as possible to the retinoscope peephole without occluding the peephole or the light source. With distance correction in place, the patient is asked to fixate on a distant target. The retinoscopic reflex is assessed in both eyes, and strong “with” motion should be observed. The patient’s attention is then drawn to the near target, with the retinoscope and target held approximately at the normal reading distance. The “with” motion will rapidly change to neutralization (no motion) or even slight “against” motion if accommodative ability is good. If the accommodative ability is poor, the examiner will still see “with” movement even when the subject is looking at the near object. In our experience, most patients with Down syndrome show no detectable accommodation at all when switching fixation from distance to near (the “with” movement remains the same), so the distinction between good and poor accommodation is usually straightforward. An attempt was made to locate and contact the parents of each patient by telephone to determine their child’s compliance with spectacle wear. Compliance with spectacle wear was defined as essentially full-time wear of the glasses, as part-time wear was rarely if ever encountered. For the purpose of analysis, patients were divided into two groups: those who were prescribed bifocal spectacles and those who were prescribed single-vision spectacles. Some children presented to us already wearing single-vision glasses, and bifocals were prescribed based on the dynamic retinoscopy findings. These patients were included in the bifocal group and were not included in the single-vision glasses group so as not to include the same patient twice. We also analyzed the data based on the presence or absence of accommodation on dynamic retinoscopy. Statistical comparisons were performed using the c2 test, the Fisher exact test, and the Mann-Whitney U test, as appropriate. A P value of \0.05 was considered statistically significant. Continuous variables are reported as mean standard deviation.
Results A total of 86 Down syndrome patients were identified. Compliance information was obtained for 57 children (age range, 22 months to 13 years when first prescribed glasses; average, 7.5 years). The telephone contact was an
Volume 18 Number 5 / October 2014 average of 51 months after first prescription of the respective spectacles. There were 27 children in the bifocal spectacles group and 30 in the single-vision spectacles group. All children had undergone cycloplegic refraction. Overall, 8 children (14%) were myopic and 49 (86%) were hyperopic. Of the 27 children prescribed bifocal lenses, 1 was myopic, with spherical equivalent refractions of 1.00 D and –0.75 D; 26 were hyperopic, with an average spherical equivalent in the right eye of 13.01 1.39 D and in the left eye of 13.13 1.48 D. The maximum anisometropia for the children in bifocals was 11.75 D, and the average anisometropia was 10.32 0.47 D. For the children in single-vision spectacles, 7 were myopic and 23 were hyperopic. The average spherical equivalent for the myopic group in single vision glasses was 5.07 4.37 D in the right eye and 4.68 4.06 D in the left eye. The average spherical equivalent for the hyperopic group in single vision glasses was 13.29 1.77 D in the right eye and 13.11 1.75 D in the left eye. The maximum anisometropia for the children in single vision spectacles was 11.00 D, with an average of 10.27 0.28 D. Of the 30 patients in the single-vision spectacle group, 16 (53%) had strabismus; of the 27 in the bifocal spectacle group, 18 (67%) had strabismus. This difference was not statistically significant (P 5 0.306). Dynamic retinoscopy had been performed on 39 of the 57 patients to assess accommodation. Of these, 7 showed good accommodation (18%) and 32 showed poor accommodation (82%). The 7 children with good accommodation on dynamic retinoscopy were prescribed single-vision spectacles but only had a 43% compliance with spectacle wear. Of the 32 patients demonstrating poor accommodation on dynamic retinoscopy, 27 were prescribed bifocal spectacles, and the remaining 5 were still prescribed single-vision spectacles (prescribed by colleagues of the senior author). The compliance with spectacle wear of the 27 children with poor accommodation in bifocals was 89% (24/27) while the compliance rate of the 5 children with poor accommodation in single-vision spectacles was 40% (2/5). Analysis of the cycloplegic refraction results and ability to accommodate showed that of the 32 patients with poor accommodation, 29 (91%) were hyperopic, whereas of the 7 children with good accommodation, 6 (86%) were hyperopic. The average spherical equivalent in the group with good accommodation was 1.96 1.97 D in the right eye and 1.86 1.70 D in the left eye. In the group with poor accommodation, the average spherical equivalent was 2.24 3.21 D in the right eye and 2.36 3.12 D in the left eye. These differences in spherical equivalent were not statistically significant (P . 0.05). All 18 patients with unknown ability to accommodate (no dynamic retinoscopy examination) were prescribed single-vision spectacles based on their distance refraction. In these, the compliance with spectacle wear was 56% (10/18). Overall, the children in bifocal spectacles had better compliance with spectacle wear than the children with
Journal of AAPOS
Volume 18 Number 5 / October 2014 single-vision spectacles. Of the 27 bifocal children, 24 (89%) were compliant with spectacle wear, whereas only 15 (50%) of the 30 nonbifocal children were compliant. Of these 30 children in single-vision glasses, 7 had good accommodation on dynamic retinoscopy, 5 had poor accommodation on dynamic retinoscopy, and the remaining 18 children had unknown accommodative ability. The association between type of spectacle prescribed and compliance with wear was statistically significant by c2 testing (P 5 0.002). Even among the 7 children with known good accommodation on dynamic retinoscopy, the compliance was only 43% in single-vision glasses. During the interviews and case note review we noted that 9 parents voluntarily noted a dramatic improvement in compliance when the spectacles were switched from initial single-vision spectacles to bifocal spectacles in the bifocal group.
Discussion Children with Down syndrome often have ophthalmologic anomalies, including lens opacities, refractive errors, accommodative insufficiency, strabismus, and nystagmus.1,2,9 Woodhouse and colleagues have shown using dynamic retinoscopy that 80% of children with Down syndrome have decreased accommodative ability compared with agematched, developmentally normal children.2 Other studies have shown the prevalence of accommodative weakness in children with Down syndrome to be between 55% and 68%.1,3 We report a similar prevalence (82%) of poor accommodation in patients with Down syndrome, as assessed by dynamic retinoscopy. Hyperopia is the predominant refractive error in children with Down syndrome, and this was our finding as well. In our practice, we had noted that children with Down syndrome did not tolerate their single-vision glasses well, often refusing to wear them continuously. This lack of compliance was presumed to be due to a lack of perceived benefit by the child. The functional environment for most children involves the use of near vision and accommodation, perhaps especially for those children with intellectual disabilities because of more indoor confinement and closer supervision. Based on the findings on dynamic retinoscopy, the senior author began prescribing high, flat-top bifocal spectacles to Down syndrome patients in 1984. The concept was to provide these patients with clear near vision, and hopefully thereby treat any bilateral amblyopia that might have been present. Stewart and colleagues10 found a higher incidence of hypermetropia in those patients with Down syndrome who had poor accommodation. We could not confirm this statistically, for among our patients with poor accommodation, 91% were hypermetropic, and among those with good accommodation 86% were hypermetropic. The numbers of myopic children in the two groups were too small to determine any real difference in behavior from the hyperopic children. The study by Stewart and
Journal of AAPOS
Adyanthaya et al
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colleagues10 also showed a higher incidence of strabismus in the hypoaccommodative group; our study did not find a statistically significant difference in prevalence of strabismus between the two groups (P 5 0.306). This may reflect the nature of the referral patterns to our practice. An interventional study conducted by Stewart and colleagues11 over a 5-month period showed that the compliance with bifocal spectacle wear compared with distance correction alone was high and comparable in both interventional groups. The present study found that compliance was better with bifocal spectacles in the longer term. Stewart and colleagues10,11 did, however, demonstrate, with further retrospective analysis of their records, that children with Down syndrome showed an improvement in their accommodative ability following use of bifocal lenses. Longitudinal studies by Nandakumar and colleagues12,13 have demonstrated that the use of bifocal spectacles in children with Down syndrome improved compliance, reduced their accommodative lag, improved their near vision, and was associated with an improvement in their early literacy scores. Our study further suggests that if a universal policy of prescribing single-vision spectacles to correct only distance acuity is adopted, then compliance with spectacle wear will be in the 56% range. Unexpectedly, in our 7 patients who showed good accommodation on dynamic retinoscopy, compliance with single-vision spectacle wear was only 43%. This was slightly, but not statistically significantly better (based on the Fisher exact test), than the 40% compliance with single-vision spectacles in our 5 patients with poor accommodation on dynamic retinoscopy (P 5 0.057). Based on this, we cannot reject the null hypothesis that there is no difference in compliance with wearing single-vision glasses between those with good or poor accommodation. We speculate that even those children with Down syndrome who can demonstrate accommodation in the clinic on dynamic retinoscopy may not be able to sustain such accommodation for long and may be more comfortable with the “crutch” provided by the bifocals and therefore show increased compliance with bifocal wear over single-vision spectacle wear. The primary limitation of our study is that the data are largely retrospective, although information regarding spectacle wear compliance was routinely collected. The study is also limited by its not analyzing such factors as intellectual disability and behavioral disorders that may further affect compliance beyond the benefit of improved vision. Additionally, dynamic retinoscopy was not performed in a quantitative manner, as was the case in other longitudinal studies,6,10,11 Our aim was only to determine clinically whether a child did or did not accommodate to a near detailed target. Dynamic retinoscopy data were not available on more than half of the children who were prescribed single-vision glasses; thus no strong conclusions can be made with regard to the relationship between accommodative ability and spectacle compliance in this group.
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Adyanthaya et al
With over 80% of Down syndrome patients demonstrating poor accommodation, the results of our study support our hypothesis that bifocal spectacles offer a significant advantage over single-vision spectacles. Prescribing bifocals improves compliance with spectacle wear, strongly suggesting that the extra power for near is appreciated and used, with the potential advantages of improving reading ability and performance in school. Because we found relatively poor compliance with spectacle wear in all of our Down syndrome patients who were prescribed single vision glasses, even in those 7 single-vision glasses patients with good accommodation by dynamic retinoscopy, we cannot state that dynamic retinoscopy can reliably distinguish between those who will and will not accept glasses well. It is still our practice, however, to assess accommodation by dynamic retinoscopy in all children with decreased vision, including all patients with Down syndrome, before cycloplegia, and for those with little or no accommodation we prescribe 12.50 to 13.00 D flat-top bifocals, based on the patient’s age and reading distance. Our data suggest that even if Down syndrome patients with demonstrable accommodation show poor compliance with single-vision glasses, bifocal spectacles should be prescribed. We feel that dynamic retinoscopy is an important part of evaluating patients with Down syndrome, because poor accommodation is a specific deficiency that should be made known to parents, care-providers, and educators. We encourage clinicians to use dynamic retinoscopy as an objective assessment of accommodation, to prescribe treatment as per this assessment, and not to adopt a policy of prescribing expensive bifocal glasses in a universal fashion in order to benefit the majority. The child’s ability to accommodate should ideally be documented at the initial evaluation. This will allow the physician to monitor the effect that the bifocal glasses have on the patient’s ongoing ability to accommodate. Stewart and colleagues10,11 and Al-Bagdady and colleagues14 have shown that bifocals can improve accommodation over time. Thus in addition
Volume 18 Number 5 / October 2014 to improving compliance with spectacle wear, bifocal glasses may promote more normal development of accommodation, and it may eventually be possible to wean the child off the bifocal adds. References 1. Haugen OH, Høvding G, Lundstr€ om I. Refractive development in children with Down’s syndrome: a population based, longitudinal study. Br J Ophthalmol 2001;85:714-19. 2. Woodhouse JM, Meades JS, Leat SJ, Saunders KJ. Reduced accommodation in children with Down syndrome. Invest Ophthalmol Vis Sci 1993;34:2382-7. 3. Woodhouse JM, Cregg M, Gunter HL, et al. The effect of age, size of target and cognitive factors on accommodative responses of children with Down syndrome. Invest Ophthalmol Vis Sci 2000;41:2479-85. 4. Courage ML, Adams RJ, Reyno S, Kwa PG. Visual acuity in infants and children with Down syndrome. Dev Med Child Neurol 1994; 36:586-93. 5. Nandakumar K, Leat SJ. Bifocals in Down Syndrome Study (BiDS): Design and baseline visual function. Optom Vis Sci 2009;86:196-207. 6. Cregg M, Woodhouse JM, Pakeman VH, et al. Accommodation and refractive error in children with Down syndrome: Cross-sectional and longitudinal studies. Invest Ophthalmol Vis Sci 2001;42:55-63. 7. Guyton DL, O’Connor GM. Dynamic retinoscopy. Curr Opin Ophthalmol 1991;2:78-80. 8. Hunter DG. Dynamic retinoscopy: the missing data. Surv Ophthalmol 2001;46:269-74. 9. Cregg M, Woodhouse JM, Stewart RE, et al. Development of refractive error and strabismus in children with Down syndrome. Invest Ophthalmol Vis Sci 2003;44:1023-30. 10. Stewart RE, Woodhouse JM, Cregg M, Pakeman VH. Association between accommodative accuracy, hypermetropia, and strabismus in children with Down’s syndrome. Optom Vis Sci 2007;84:149-55. 11. Stewart RE, Margaret Woodhouse J, Trojanowska LD. In focus: the use of bifocal spectacles with children with Down’s syndrome. Ophthalmic Physiol Opt 2005;25:514-22. 12. Nandakumar K, Leat SJ. Bifocals in children with Down syndrome (BiDS)-visual acuity, accommodation and early literacy skills. Acta Ophthalmol 2010;88:196-204. 13. Nandakumar K, Evans MA, Briand K, Leat SJ. Bifocals in Down syndrome study (BiDS): Analysis of video recorded sessions of literacy and visual perceptual skills. Clin Exp Optom 2011;94(6):575-85. 14. Al-Bagdady M, Stewart RE, Watts P, Murphy PJ, Woodhouse JM. Bifocals and Down’s syndrome: Correction or treatment? Ophthalmic Physiol Opt 2009;29:416-21.
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