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   Table of Contents      
ORIGINAL ARTICLE
Year : 2006  |  Volume : 54  |  Issue : 4  |  Page : 257-260

Efficiency of occlusion therapy for management of amblyopia in older children


Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh, Punjab, India

Correspondence Address:
Gagandeep S Brar
Department of Ophthalmology, PGIMER, Chandigarh - 160 012
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0301-4738.27951

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  Abstract 

Materials and Methods: This was a retrospective consecutive case series analysis of children treated for amblyopia at a tertiary care center. All children received full time occlusion (FTO) for the dominant eye.
Results: Eighty-eight children older than 6 years at the time of initiation of therapy were included. Age at initiation of therapy ranged from 6 to 20 years (9.45 ± 3.11 years). Forty-two children (47.7%) had strabismic amblyopia, 37 (42.0%) had anisometropic amblyopia and 9 (10.2%) had a combination of strabismic and anisometropic amblyopia. Eighty out of 88 eyes (90.0%) had improvement in visual acuity following FTO. Visual acuity (VA) improved from 0.82 ± 0.34 at presentation to 0.42 ± 0.34 ( P < 0.001) after FTO. In children with strabismic amblyopia, VA improved from 0.81 ± 0.42 to 0.42 ± 0.39 ( P < 0.001). In children with anisometropic amblyopia, visual acuity of the amblyopic eye improved from 0.82 ± 0.24 to 0.36 ± 0.29 ( P < 0.001) following FTO. Out of 13 children older than 12 years, only 6 children (46.1%) had improvement in VA. Mean follow-up after complete stoppage of occlusion was 8.37 ± 1.78 months.
Conclusion: Occlusion therapy yields favorable results in strabismic and/or anisometropic amblyopia, even when initiated for the first time after 6 years of age. After 12 years of age, some children may still respond to occlusion of the dominant eye.

Keywords: Amblyopia, occlusion


How to cite this article:
Brar GS, Bandyopadhyay S, Kaushik S, Raj S. Efficiency of occlusion therapy for management of amblyopia in older children. Indian J Ophthalmol 2006;54:257-60

How to cite this URL:
Brar GS, Bandyopadhyay S, Kaushik S, Raj S. Efficiency of occlusion therapy for management of amblyopia in older children. Indian J Ophthalmol [serial online] 2006 [cited 2019 Nov 17];54:257-60. Available from: http://www.ijo.in/text.asp?2006/54/4/257/27951

Table 2:  Results of full time occlusion in all the three groups

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Table 2:  Results of full time occlusion in all the three groups

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Table 1: Demographic characteristics in the three groups

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Table 1: Demographic characteristics in the three groups

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Occlusion of the non-amblyopic eye is the most commonly used treatment for children with amblyopia.[1] The response to amblyopia therapy is related to type of amblyogenic stimulus, initial depth and duration of amblyopia, age at initiation of therapy, method of amblyopia treatment and compliance.[2] Reports of children treated for anisometropic and strabismic amblyopia continue to suggest that occlusion therapy yields better response to treatment up to 6 to 7 years of age.[3],[4] Flynn et al. reviewed the results of amblyopia therapy using pooled data from 961 children described in 23 published studies between 1965 and 1994[5] and observed that the single factor that most clearly related to a successful outcome was age at initiation of therapy.[5] Epelbaum et al. found that efficiency of treatment for strabismic amblyopia decreases with age and it is null by 12 years of age.[6] Children with anisometropic amblyopia have been found to respond to therapy even at a late age.[6]-[8] The purpose of this consecutive patient series studied retrospectively was to analyze results of occlusion therapy for strabismic and anisometropic amblyopia in children above 6 years of age.


  Materials and Methods Top


This was a retrospective consecutive case series analysis of children treated for amblyopia in the strabismus clinic of the department of ophthalmology at a tertiary care center from January 2001 to December 2002. A difference of 1 line or more on Snellen visual acuity chart was used as diagnostic criterion for amblyopia. A difference between the spherical equivalents of the two eyes exceeding 1.50 diopter (D) was considered anisometropia. Strabismic amblyopes who had constant esotropia or exotropia were included in this consecutive patient series. Children who had been treated with occlusion or had undergone any eye muscle surgery in the past were excluded.

All children had complete ocular examination and orthoptic work-up prior to treatment. A cycloplegic refraction was carried out using atropine 1% (children younger than 10 years) or cyclopentolate 1% (older than 10 years) in the first visit. Best-corrected visual acuity (BCVA) (line acuity) was measured in all children. Visual acuity (VA) was measured on the Carl Zeiss SZP 350 chart projector, which projects two letters each for the 20/200 and 20/160 line, three letters for the 20/125 line and four letters for each subsequent line. Children were deemed to have read the line if they read all letters of 20/200, 20/160 and 20/125 lines and at least three out of four letters for all subsequent lines. The chart has a regular doubling of the visual angle between different lines; so a log Mar conversion was done to facilitate calculation of mean acuity and to compare VA between different groups.

All children were advised to undergo occlusion of the better eye with adhesive patch applied for at least 80% of all waking hours/day and this was termed 'full time occlusion' (FTO). Children were followed up monthly to document improvement and record compliance. The parents were asked to maintain a daily diary detailing the number of hours of occlusion achieved each day. At each follow-up visit, the same examiner used the same method to assess BCVA. This treatment was continued till there was no further improvement for at least three consecutive visits or attainment of VA equal to that of the initially dominant eye. Thereafter, maintenance patching (6 h/day) was used for further 6 months to prevent recidivism. After completion of maintenance patching, children were followed up at 3 to 6-month intervals to record visual activity.


  Results Top


This study included 88 eyes of 88 consecutive children who were treated with occlusion between January 2001 and December 2002 and were compliant with FTO. During the same period, there were another 26 children (22.8%) of amblyopia in the same age group who either refused to undergo trial of FTO or were noncompliant. The age at initiation of amblyopia therapy ranged from 6 years to 20 years with a mean age of 9.45 ± 3.11 years. There were 58 males (61.5%) and 30 females (38.4%). Forty-two children (47.7%) had strabismic amblyopia and 37 (42.0%) had anisometropic amblyopia. Nine children (10.2%) had a combination of strabismic and anisometropic amblyopia. Follow-up ranged from 10 to 28 months, with a mean follow-up of 15.76 ± 4.08 months. The demographic profile and clinical characteristics of the children are given in [Table - 1].

Eighty out of 88 eyes had improvement in VA (90.0%) following FTO. The initial VA of the amblyopic eye ranged from 3/200 to 20/40, with mean log Mar of 0.82 ± 0.34. Following therapy, the mean VA of the amblyopic eye improved to 0.42 ± 0.34 ( P < 0.001). The mean time taken for vision to start improving was 1.80 ± 0.88 months, whereas time taken to achieve final improvement was 5.59 ± 2.78 months. There were eight children (9.1%) who did not have any improvement in VA of the amblyopic eye following FTO. Out of these eight children, seven (87.5%) were older than 12 years at the initiation of amblyopia therapy.

In children with strabismic amblyopia, BCVA acuity at presentation ranged from 3/200 to 20/40, with mean log Mar acuity of 0.81 ± 0.42. The final BCVA ranged from 3/200 to 20/40, with mean log Mar acuity of 0.42 ± 0.39 ( P < 0.001). Cycloplegic retinoscopic values of the amblyopic eye ranged from +7.0 to -1.75 D, with mean of 1.99 ± 1.88 D. Thirty-one children (73.8%) had esotropia whereas 11 children (26.2%) had exotropia. Thirty-eight eyes (90.5%) had more than 1 line improvement in Snellen acuity and 27 eyes (64.3%) had more than 2 lines improvement in Snellen acuity. The mean time taken for VA to start improving in the amblyopic eye was 1.67 ± 0.88 months (range 1 to 5 months). The time taken to achieve final improvement ranged from 2 to 14 months, with mean time of 5.56 ± 2.31 months. Follow-up ranged from 10 to 28 months, with mean of 16.38 ± 4.40 months.

In children with anisometropic amblyopia, VA of the amblyopic eye ranged from 10/200 to 20/40, mean log Mar acuity being 0.82 ± 0.24. The final BCVA ranged from 20/200 to 20/20, with mean log Mar value of 0.36 + 0.29 ( P < 0.001). Out of 37 children, 32 (89.7%) were hypermetropic and 5 (10.3%) were myopic. The initial cycloplegic retinoscopic values ranged from +10.50 to -13.00 D, with a mean value of 3.39 ± 4.33 D. The mean anisometropia was 2.53 ± 2.59 D. Mean cycloplegic retinoscopic value for children with hypermetropia was +5.01 ± 1.07 D for the amblyopic eye and +1.75 ± 0.33 D for the dominant eye. Similarly, mean cycloplegic retinoscopic value for children with myopia was -5.70 ± 0.80 D for the amblyopic eye and -1.10 ± 0.31 D for the dominant eye. Thirty-five eyes (94.5%) had at least 1 Snellen line improvement in VA, whereas 28 eyes (75.3%) improved by 2 lines or more. Mean time taken for VA to start improving was 1.94 ± 1.13 months (range 1 to 4 months) and mean time taken to achieve final improvement was 5.38 ± 2.12 months (range 2 to 9 months).

In nine children with mixed type of amblyopia (anisometropic and strabismic), the mean cycloplegic retinoscopic value was 6.81 ± 1.37 D (range +4.50 to -9 D) and mean anisometropia was 3.08 ± 2.11 D. Six children had esotropia whereas three children had exotropia. The VA at initiation of therapy ranged from 10/200 to 20/60, mean log Mar acuity being 0.88 ± 0.24. Following occlusion therapy, the VA improved to 0.66 ± 0.27 (range 17/200 to 20/30) ( P = 0.007). The mean time required for initial improvement in VA was 1.94 ± 1.13 months (range 1 to 4 months) and time taken to achieve final improvement was 6.56 ± 2.78 months (range 3 to 12 months). The amount of improvement and time taken to improve for all the three types of amblyopia are given in [Table - 2].

The oldest patient who received FTO in this study was a 20-year-old male with a combination of strabismic and anisometropic amblyopia. The patient had exotropia with anisometropia of 2.5 D (hypermetropia of 4.00 D in the amblyopic eye). VA at presentation was 20/120 and 20/20 respectively. Following FTO, the VA of the amblyopic eye improved to 20/40. The time taken for vision to improve by 1 Snellen line was 3 months and final improvement was achieved after 9 months of FTO. He subsequently underwent successful surgery for alignment and received 6 months maintenance patching, after which occlusion was stopped. The patient maintained the final vision even after 9 months of cessation of treatment.

Seventy-five (85.3%) out of total 88 children were younger than 12 years at the initiation of amblyopia therapy. Statistical analysis showed significantly better mean final VA ( P = 0.044) in children who were younger than 12 years. Mean improvement in children younger than 12 years was 3.15 ± 0.83 Snellen lines, whereas it was 1.78 ± 0.46 Snellen lines in children older than 12 years ( P = 0.037).

Out of 13 children older than 12 years, only 6 children (46.2%) had improvement in VA of the amblyopic eye following FTO: one had strabismic amblyopia, 4 had anisometropic amblyopia and one had a combination of strabismic and anisometropic amblyopia. In the 7 children who did not show any improvement, 4 had strabismic, 2 anisometropic and 1 had mixed amblyopia. Apart from the difference in type of amblyopia, there was no difference in age, initial VA, refractive error or compliance between those children who improved and those who did not. In children who improved, mean initial VA at presentation was 0.90 ± 0.11, whereas final VA achieved was 0.43 ± 0.12 ( P < 0.001). Mean time taken to achieve final improvement was 5.63 ± 0.38 months, which was comparable with children who were under 12 years of age at the initiation of amblyopia treatment ( P = 0.388).

All children were kept under follow-up even after cessation of maintenance patching. The mean follow-up after complete stoppage of occlusion was 8.37 ± 1.78 months (range 5 to 12 months). None of the eyes had any deterioration of vision following cessation of occlusion treatment.


  Discussion Top


The success of amblyopia therapy mainly depends on the age at initiation of treatment and initial depth of amblyopia in the affected eye.[5] Results of occlusion therapy have been found to be better in younger children,[5] but there is ample evidence in literature suggesting benefit of amblyopia therapy in older children.[2],[3],[7], [9],[10],[11],[12],[13],[14],[15]

In the present series, 80 (90.0%) out of 88 children had improvement in VA with FTO. The result showed that VA could be improved uniformly for strabismic, anisometropic or a combination of strabismic and anisometropic amblyopia in compliant children. We observed improvement in VA in 98.7% of children younger than 12 years and 46.2% of children older than 12 years at the time of initiation of occlusion therapy.

Oliver et al .[11] studied the results of occlusion treatment in 227 compliant children (age range 2 to 11½ years). There were 37 children (16.3%) who were above 8 years of age and 190 children (83.7%) were under 8 years at the initiation of amblyopia therapy. They noted significant improvement in VA following FTO in both the groups. The mean initial VA values at the initiation of treatment in the both the groups were comparable; corresponding to about 20/100 on the Snellen chart. At the end of the study, the mean final acuity in the younger age group was 20/30, whereas older children achieved mean final VA of 20/40. The difference approached one line of the Snellen chart and was significant. In the present series, we have analyzed the results of occlusion therapy in older children (age 6 to 20 years). Our result suggests that the children who were younger than 12 years had a significantly better chance of improvement in vision ( P < 0.001) and achieved better best-corrected final VA than older children. Even in children above 12 years of age, 6 out of 13 (46.2%) showed improvement in vision following occlusion and the amount of improvement was statistically significant when compared to presenting VA ( P < 0.001). Mintz-Hitner[2] reported the results of occlusion therapy in 36 children above 7 years of age. In their series, there were 19 children with anisometropic amblyopia, 9 with strabismic amblyopia and 8 with anisometropic and strabismic amblyopia. The initial VA ranged from 20/50 to 20/100. The final VA ranged from 20/20 to 20/30, with median of 20/25. They also noted uniform improvement in VA in the three different types of amblyopes. The oldest patient in their series was 10.3 years old, with anisometropic amblyopia. Following FTO, VA improved from 20/200 to 20/20 after 0.4 years of therapy. Our results also suggest that in compliant children, all three types of amblyopia can be treated with equal success with FTO and age is only a relative bar to offering amblyopia therapy in older children. Children who were under 12 years showed improvement of VA in almost all cases (98.7%), whereas among the 13 children who were above 12 years at the initiation of therapy, only 6 (46.2%) had improvement in VA. These 6 eyes had almost doubling of their VA following FTO ('0.90 ± 0.11' to '0.43 ± 0.12').

Vereecken and Brabant's[10] observations of improvement in vision of the amblyopic eye following the loss of the good eye in 28.5% of their patients suggest that upper age limit for response to amblyopia therapy may not be as rigid as previously understood. Recent evidence suggests that FTO leads to a significant improvement in VA of the amblyopic eye in compliant children as old as 15 years.[16] Early results from the Pediatric Eye Disease Investigator Group (PEDIG) also reveal that children, teenagers and even adults as old as 20 years may improve after occlusion therapy.[17] We had similar results whereby almost half of the children who were older than 12 years at the time of initiation of occlusion had significant and maintained improvement in VA with FTO.

Most of the published reports suggest that following occlusion therapy, VA starts improving within the first 3 months,[11],[18] and maximal benefit occurs within the first 3-6 months.[19] In the present series, mean time taken for VA to start improving was 1.80 ± 0.88 months, whereas time taken to achieve final improvement was 5.59 ± 2.78 months. Four children took more than 3 months to show at least one Snellen line improvement in VA. This is an unusual observation and needs to be analyzed. We think it may be related to the older age at the initiation of amblyopia treatment.

It is yet not clearly known, however, whether the visual improvement in older amblyopes remains so after occlusion is discontinued.[11] In our series, all children received maintenance patching for 6 months following completion of FTO. None of the children had any deterioration of vision in the amblyopic eye even after a mean follow-up of more than 8 months after stopping occlusion. We are keeping these children on further follow-up to look for late recidivism.

There is limited literature available analyzing results of amblyopia therapy initiated for the first time after 12 years of age. Most studies suggest that 12 years of age is the upper limit as far as response to amblyopia therapy is concerned. Birnbaum et al.[13] reported positive results after sustained treatment of teenagers and a few adults who were affected by amblyopia. A randomized clinical trial carried out by the PEDIG[20] analyzed 507 patients aged 7 to 17 years with amblyopia, receiving optical correction and then randomized to receive treatment in the form of 2-6 h of occlusion of the dominant eye. In the 7-12 years age group, children on occlusion also received atropine sulfate 1% one drop daily in the dominant eye. They observed an improvement (> 2 Snellen lines) with occlusion in 53% of children younger than 12 years of age and in 47% of children older than 12 years. Although the results of the present study cannot be directly compared to the randomized trial because we gave FTO to our patients, we did observe a greater chance of improvement in younger children. Fifty-eight out of 88 eyes (65.9%) in our study improved by more than 2 Snellen lines. In children younger than 12 years of age, 56 out of 75 eyes (74.6%) improved by more than 2 Snellen lines.

Our results suggest that almost half the children older than 12 years may benefit from amblyopia therapy. The retrospective nature of this study has its limitations; hence further studies are needed to analyze various parameters influencing response to therapy in these children. Although chances of success reduce with advancing age, a significant number of older amblyopes can be improved with FTO. Therefore, we recommend that a therapeutic trial of occlusion is advisable even in older children.



 
  References Top

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2.
Mintz-Hitner HA, Fernandez KM. Successful amblyopia therapy initiated after age 7 years. Arch Ophthalmol 2000;118:1535-41.  Back to cited text no. 2
    
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Flynn JT, Schiffman J, Feuer W, Corona A. The therapy of amblyopia: An analysis of the results of amblyopia therapy utilizing the pooled data of published studies. Trans Am Ophthalmol Soc 1998;96:431-53.   Back to cited text no. 5
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Epelbaum M, Milleret C Buisseret P, Dufier JL. The Sensitive Period for stabismic amblyopia in humans. Ophthalmology 1993;100:323-7.  Back to cited text no. 6
    
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Wick B, Wingard M, Cotter S, Scheiman M. Anisometropic amblyopia: Is the patient ever too old to treat? Optom Vis Sci 1992;69:866-78.  Back to cited text no. 7
    
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Kasser MD, Feldman JB. Amblyopia in adults. Treatment of those engaged in various industries. Am J Ophthalmol 1953;36:1443-6.  Back to cited text no. 9
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10.
Vereecken EP, Brabant P. Prognosis for vision in amblyopia after the loss of the good eye. Arch Ophthalmol 1984;102:220-4.  Back to cited text no. 10
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11.
Oliver M, Neumann R, Chaimovitch Y, Gottesman N, Shimshoni M. Compliance and Results of treatment for amblyopia in children more than 8 years old. Am J Ophthalmol 1986;102:340-5.  Back to cited text no. 11
    
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Bremner MH. Visual acuity in the primary school child aged four to twelve years: A review of amblyopia treatment in this age group at Princess Margaret Hospital. Aust J Ophthalmol 1984;12:395-9.  Back to cited text no. 12
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Birnbaum MH, Koslowe K, Sanet R. Success in amblyopia therapy as a function of age: A literature survey. Am J Optom Physiol Opt 1977;54:269-75.  Back to cited text no. 13
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Woodruff G, Hiscox F, Thompson JR, Smith LK. Factors affecting the outcome of children treated for amblyopia. Eye 1994;8:627-31.  Back to cited text no. 14
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Massie H. Fixing eye occlusion: Survey of approximately 1000 case histories of patients who received occlusion of the fixing eye. Trans Ophthalmol Soc Aust 1965;24:39-46.  Back to cited text no. 15
    
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Mohan K, Saroha V, Sharma A. Successful occlusion therapy for amblyopia in 11- to 15-year-old children. J Pediatr Ophthalmol Strabismus 2004;41:89-95.  Back to cited text no. 16
    
17.
Pediatric Eye Disease Investigator Group. A prospective, pilot study of treatment of amblyopia in children 10 to <18 years old. Am J Ophthalmol 2004;137:581-3.  Back to cited text no. 17
    
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Lithander J, Sjostrand J. Anisometropic and strabismic amblyopia in the age group 2 years and above: A prospective study of the results of treatment. Br J Ophthalmol 1991;75:111-6.  Back to cited text no. 18
    
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Cleary M. Efficacy of occlusion for strabismic amblyopia: Can an optimal duration be identified? Br J Ophthalmol 2000;84:572-8.  Back to cited text no. 19
    
20.
Scheiman MM, Hertle RW, Beck RW, Edwards AR, Birch E, Cotter SA, et al . Randomized trial of treatment of amblyopia in children aged 7 to 17 years. Arch Ophthalmol 2005;123:437-47.  Back to cited text no. 20
    



 
 
    Tables

  [Table - 1], [Table - 2]


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