|Year : 1987 | Volume
| Issue : 4 | Page : 207-210
Role of occlusion in treatment of intermittent exotropia
SK Vishnoi, Vinita Singh, MK Mehra
|Date of Web Publication||20-Dec-2008|
S K Vishnoi
Source of Support: None, Conflict of Interest: None
Sensory and Motor effects of occlusion in 37 patients of intermittent exotropia have been discussed 25 patients were given part time occlusion and 12 patients were given full time occlusion. Part time occlusion was found to be more effective and more acceptable than full time occlusion.
|How to cite this article:|
Vishnoi S K, Singh V, Mehra M K. Role of occlusion in treatment of intermittent exotropia. Indian J Ophthalmol 1987;35:207-10
|How to cite this URL:|
Vishnoi S K, Singh V, Mehra M K. Role of occlusion in treatment of intermittent exotropia. Indian J Ophthalmol [serial online] 1987 [cited 2022 Jan 24];35:207-10. Available from: https://www.ijo.in/text.asp?1987/35/4/207/26178
| Introduction|| |
About 85% cases of Comitant alternating exotropia are of an intermittent nature These cases are characterized by periods of manifest divergent strabismus alternated with periods of latent strabismus. The condition is thought to be due to neuromuscular incoordination of central origin [Figure 1]. A weakness of the convergence  or an excessive divergence , innervation will result in exophoria. This gradually decompensates to become intermittent exotropia During the periods of tropia the patient experiences troublesome diplopia, which is overcome by activation of strong fusional reserves When the fusional reserves fail to resolve the troublesome diplopia, the patient has to resort to facultative suppression which in turn inhibits the fusional reflexes and thereby favours the tropic phase. Thus strong fusional reflexes and good convergence favour the phoric phase, whereas facultative suppression and weak fusional reserves promote the tropic phase. Occlusion abolishes diplopia which is a strong stimulus for development of facultative suppression.
Occlusion is not a new form of treatment nor it is novel in its application It has been reported to be an effective method of treatment of intermittent exotropia ,,,,,,, . Its utility lies in eliminating suppression increasing fusional amplitudes, increasing periods of phoria and decreasing the strabismic angle.
| Materials and Methods|| |
We have assessed the effectivity of this method of treatment in 37 patients of intermittent exotropia. None of the patients had been subjected to previous strabismus surgery. The age of the patients ranged from 7 to 32 years Above 80% (31) of the patients had good corrected visual acuity in both eyes None of the eyes had a vision poorer than 6/12. 22 patients were emetropes and 15 were myopes of varying degrees.
We gave alternate occlusion to our patients The occlusion was total and adhesive in type. The patch was worn over one eye for one week and over the other eye the following week The patients wre arbitrarily divided into two groups
Group - I : Part time occlusion - 25 patients 6 hrs/day x 7 days a week
Group - II: Full time occlusion - 12 patients, 24 hrs/day x 7 days a week
The occlusion treatment was given for a period of 6 to 12 weeks Patients were subjected periodically to a detailed orthoptic check-up including corrected visual acuity cover test measurement of angle of deviation on the synoptophore and by Prism Bar and Cover test for near (with and without + 3.00 D. Sph.) and distance, convergence ocular movements, detection of suppression and measurement of fusional amplitudes Follow up was done every 15 days.
| Observations|| |
To assess the role of occlusion following sensory (Elimination of Suppression and chance in fusional amplitudes) and motor (change in mean exodeviation, conversion of intermittent tropia to phoria) effects were looked for
(1) Elimination of suppression : [Table 1]
Elimination of facultative suppression is necessary for further fusional training Out of the 37 patients 15 were found to have facultative suppression as tested on the Worth's Four Dot Test and Synoptophore. After 6 to 12 weeks of occlusion suppression was abolished in 13 patients. 2 patients who failed to overcome facultative suppression had large angle tropias more than 25 to 30 prism diopters.
72% of patients given part time occlusion and25% of the patients given full time occlusion, were found to have a better control over their deviations and were found to convert to predominent phoric phase.
(2) Change in fusional amplitudes : [Table 2]
The amplitudes of fusion as tested on the synoptophore was found to improve in 88% (22/25) cases in Group I and 50% cases of Group-II
(3) Change in Mean Exodeviation: [Table 3]
Some reduction in the amount of exodeviation was also observed, more so in patients treated by part time occlusion than those treated by full time occlusion
[Figure 2] illustrates a comparison of the results obtained after part time occlusion (Group I) vs full time occlusion (Group 11) in terms of elimination of suppression, improvement in fusional range, decrease in angle of deviation and conversion to predominant phoric phase Patients treated by part time occlusion responded better than those treated by full time occlusion.
We investigated the possible negative effects of occlusion on either (both) the sensory responses and/or motor control of the deviations We did not observe any negative sensory or motor effects The patients, who had an initial deviation of 30 prism dioptres or more did not benefit by occlusion treatment.
| Discussion|| |
Occlusion by itself, is obviously, not a complete therapy for intermittent exotropia, but it has a definite place in the treatment of intermittent exotropia.
We agree with Flynn  that particularly in that group of patients where decision to operate or treat conservatively is a borderline and difficult one, occlusion must be tried as it may also furnish information helpful in mating the decision.
We support the views of Chutter CP.  and Jampolsky  that part time occlusion is equally or more effective than full time occlusion Occlusion alternated with no occlusion prevents suppression from occuring much of the time yet allows binocular fusion to occur some of the time while disrupting any firm fixation patterns, it is also easier to carry out and more acceptable to the patients.
Though the long term result of occlusion treatment are yet to be studied, we feel that part time occlusion is a straight forward safe and effective method of treatment of intermittent exotropia, particularly of milder degree (angle less than 25 prism dioptres). It provides us with a method of actively treating this type of exodeviation with the ability to reducing the size of strabismic angle, as well as to enhance fusional amplitudes, thus obviating the need for surgery in some patients To disregard this form of treatment would be to deny the patient a better chance for a good and stable result.[Table 4]
| References|| |
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Adler, FR Ed 3. St Louis The CV. Mosby Ca, 1959, p 473.
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Chutter, CP.: Am Orthopt J. 27; pp 80-84; 1977.
Spoor, D.K and Hiles, D.A : Ophthalmology. Vol.86, No. 2, pp2152-2157, December, 1979.
Flynn. J.T.; Mc Kenney, S. and Rosenhouse, M Management of intermittent exotropia in Orthoptics Past Present and future. Moore, S. K Mein. J. Stockbridge L (Eds.), New Vorl, Grune and Stratton; 1976; pp 551-557.
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]