• Users Online: 124
  • Home
  • Print this page
  • Email this page
Home Current issue Ahead of print Search About us Editorial board Archives Submit article Instructions Subscribe Contacts Login 

 Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 107  |  Issue : 1  |  Page : 33-36

Sensory heterotropia: Which eye should be the main site of surgery, sound or amblyopic eye?


Department of Ophthalmology, Minia University, Minia, Egypt

Date of Submission11-Nov-2013
Date of Acceptance12-Dec-2013
Date of Web Publication21-Jun-2014

Correspondence Address:
Sahar Torky Abdelrazik
Department of Ophthalmology, Minia University Hospital 61111, Minia
Egypt
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2090-0686.134943

Rights and Permissions
  Abstract 

Introduction
The altered tonic vergence movement in sensory heterotropia may make the preoperative measured angle of deviation inconstant, and the surgical results are less predictable than when visual acuity is normal in each eye. Maintaining the postoperatively corrected position of the amblyopic eyes is considered difficult because the brain has lost interest in those eyes' position.
Objective
The aim of this study was to compare the postoperative results and their stability in patients undergoing surgery mainly on the sound eyes with those undergoing surgery mainly in the amblyopic eyes in case of sensory heterotropia.
Design
This prospective nonrandomized comparative study was carried out in the Ophthalmology Department, Minia University Hospital during the period from March 2011 to October 2012.
Patients and methods
Sixty patients were included in this study and were divided into two equal groups according to the type of horizontal deviations. In each group, half of the patients underwent surgery mainly on the sound eyes and the others underwent surgery mainly on the amblyopic eyes, and the results were compared.
Results
In patients of group 1 (esotropia) who underwent surgery mainly on the sound eyes, there were significantly higher and stable results than those who underwent surgery mainly on the amblyopic eyes after 1 and 6 months. Patients of group 2 (exotropia) who underwent surgery on the sound eyes had significantly higher and stable results than those who underwent surgery on the amblyopic eyes after 6 months only.
Conclusion
Surgery on the sound eyes mainly in horizontal sensory heterotropia had better and more stable results than surgery on the amblyopic eyes.

Keywords: Sensory heterotropia, amblyopic eye, sound eye


How to cite this article:
Abdelrazik ST, Khalil MF. Sensory heterotropia: Which eye should be the main site of surgery, sound or amblyopic eye?. J Egypt Ophthalmol Soc 2014;107:33-6

How to cite this URL:
Abdelrazik ST, Khalil MF. Sensory heterotropia: Which eye should be the main site of surgery, sound or amblyopic eye?. J Egypt Ophthalmol Soc [serial online] 2014 [cited 2020 Jul 12];107:33-6. Available from: http://www.jeos.eg.net/text.asp?2014/107/1/33/134943


  Introduction Top


Sensory heterotropia occurs as a result of primary sensory deficit followed by partial or complete disruption of fusion, and thus disrupts the eyeball array [1].

The frequencies of esotropia and exotropia in those patients are variable. There are many factors relevant to the direction of deviation in sensory strabismus, such as age at onset, the degree of loss or deterioration of vision, the interorbital distance, and the refractive error of the sound eye [2],[3].

The preoperative measured angle of deviation may be inconstant because of the altered tonic vergence movement in sensory heterotropia, and the surgical results are less predictable than when visual acuity is normal in each eye. Furthermore, maintaining the postoperatively corrected position of the eyeball is considered difficult because the nature of sensory heterotropia precludes restoration of binocular function and sensory fusion [4],[5].


  Objective Top


The aim of this study was to compare the postoperative results and their stability in patients undergoing surgery mainly on the sound eyes with those undergoing surgery mainly in the amblyopic eyes in case of sensory heterotropia.


  Design Top


This prospective nonrandomized comparative study was carried out in the Ophthalmology Department, Minia University Hospital during the period from March 2011 to October 2012.


  Patients and methods Top


After getting the approval of the research ethics committee of faculty of medicine, Minia University, 60 patients were chosen and enrolled in our study. All patients were above 13 years (below which amblyopia can be treated) and had a horizontal deviation with unilateral defective vision due to either amblyopia or organic lesions e.g. media opacity

The strabismic patients attending the outpatient clinic, Minia University Hospital were subjected to complete history taking, general examination, and complete ophthalmic examination including the following:

  1. Visual acuity measurement with Snellen's chart and pupillary reaction.
  2. Slit-lamp biomicroscopy for detection of any media opacity.
  3. Cycloplegic refraction and fundus examination.
  4. Complete orthoptic examination: detection of angle of deviation with prism cover test, cover tests, and ocular motility assessment.


A total of 60 patients were chosen and enrolled in our study. All patients were above 13 years of age (below which amblyopia can be treated) and had a horizontal deviation with unilateral defective vision due to either amblyopia or organic lesions, for example, media opacity.

We chose 30 esotropic patients and 30 exotropic patients. Each group was divided into two equal subgroups according to the main side of the operation, either on the amblyopic eye (the amblyopic subgroup) or on the sound eye (the sound subgroup). The amblyopic subgroups were called so as the majority of patients (27 cases) had amblyopia and only three patients had media opacity.

The patients and/or their parents were informed about surgery on the sound eye and written consents were obtained.

All surgeries were carried out under general anesthesia.

Patients were examined on the first postoperative day then every week for 1 month and then every month for the next 6 months.

Data were collected and GraphPad Prism version 4.0 programme for windows (Graph Pad Software Inc., San Diego, CA, USA 2003) was used for statistical analyses. Differences between results were assessed using the χ2 -test for trend. P value less than 0.05 was considered to be significant.


  Results Top


Demographic data of our patients were as follows: group 1 (esotropia) included 30 patients with an age of 15-35 years (mean 25.43 ± 5.538 years), 12 male and 18 female patients [Table 1], and group 2 (exotropia) included 30 patients with an age of 13-32 years (mean 23.13 ± 6.274 years), 13 male and 17 female patients [Table 2].
Table 1: Demographic data of the esotropia group

Click here to view
Table 2: Demographic data of the exotropia group

Click here to view


There was no complication in all 60 patients other than undercorrection or overcorrection.


  Discussion Top


Treatment of sensory heterotropia is directed toward improving the cosmetic appearance by means of surgical correction [1].

In sensory exotropia with a large angle of deviation, straightening the eyes with strabismus surgery is more difficult and undercorrection remains common [6].

The long-term maintenance of postsurgical alignment in sensory heterotropia is expected to be poor, and the recurrence rate is high because of the low chance of regaining stable fusion [4].

In sensory heterotropia resulted from monocular visual loss, most surgeons preferred operating only on the eye with poor vision because it is easier to persuade patients who would be reluctant to undergo surgery on their sound eye [7].

In our study, we decided to operate mainly on the amblyopic eye in half of the patients and mainly on the sound eye in the other half of the patients.

In case of the esotropia group

Comparing the results in the two subgroups revealed statistically significant results (P < 0.001).

After 1 month, the overcorrection was the same in both groups (6.67%), whereas the undercorrection in the amblyopic subgroup was five times than that in the sound subgroup (33.33 vs. 6.67%) as shown in [Table 3].
Table 3: Results of surgery in group 1 (esotropia)

Click here to view


Orthophoria was obtained in 60% patients in the amblyopic subgroup in comparison with 86.6% in the sound subgroup.

With respect to the stability of the results in the sound subgroup, the results remained the same after 6 months postoperatively, but in the amblyopic subgroup only 1/3 of the patients were orthophoric at the end of the sixth month, which means the number of orthophoric patients was reduced by 50% after 6 months. The number of overcorrected patients was tripled (6.67-20%), whereas the undercorrected patients increased by about 13% by the sixth month.

The explanation of poor orthophoria after 1 month in the amblyopic subgroup as compared with the sound subgroup is that visual acuity is better in the sound eye, which stimulates and motivates the brain to fixate both eyes using the sound eye (which had now surgically induced exotropia). Hence, according to Herring's law, equal impulses will go to the other amblyopic eye and it will be maintained straight in the primary position similar to the sound eye.

Overcorrection was tripled after 6 months in the amblyopic subgroup patients, as weakening a medial rectus muscle in amblyopic eye with simultaneous strengthening of the lateral rectus muscle will put the eye at risk for outward deviation and hence consecutive exotropia.

In case of the exotropia group

Interestingly, we reported no case of overcorrection in both subgroups neither at 1 month nor at 6 months, and this finding can be explained by the tendency of those eyes to deviate again in the divergent position not in the convergent position, especially with the age of the patient; hence, eyes have the tendency to take resting position.

With respect to the first month results, there was no statistically significant difference between the two subgroups, but after 6 months highly significant results were reported (P < 0.0001) where 26% of the patients in the amblyopic subgroup were no longer orthophoric in comparison with only 6% of the patients in the sound subgroup as shown in [Table 4]. In addition, the undercorrected patients were tripled (13.33-40%) in the amblyopic subgroup, whereas they were only doubled (6.67-13.33%) in the sound subgroup.
Table 4: Results of surgery in group 2 (exotropia)

Click here to view


This regression in orthophoria and the increase in undercorrection in the amblyopic subgroup may be due to the tendency of these eyes to deviate again in the divergent position as a result of many factors such as age of the patient and wide interpupillary distance; hence, eyes have the tendency to take resting position.

Kim et al. [8] chose to perform their reoperation for the second time on the amblyopic eye also, and they found that the surgical result of reoperation on the deviated eye of recurred, consecutive, or undercorrected sensory strabismus after the first surgery was satisfactory, despite the reduced amount of surgical correction compared with the surgical dosage recommended for the nonoperated eye.

In 1980, Mitsui et al. [9] had similar concept to ours, as they suggested that better results were obtained when the operation was limited on the dominant eye in exodeviations cases, but they did not search about esotropia cases.

However, Lennerstrand [10] in 1986 reported that there is no difference in the success when surgery was performed on the dominant versus nondominant eye.

To the best of our knowledge, this study is the first to report the results of surgery performed mainly on the sound eye compared with surgery performed mainly on amblyopic eye in patients with sensory heterotropia, and it will help in surgical decision on dealing with these cases, especially regarding the long-term results and stability.


  Conclusion Top


Surgery mainly on the sound eyes in horizontal sensory heterotropia had better and more stable results than surgery mainly on the amblyopic eyes in both esotropia and exotropia.

The results are better and stable in esotropia from the first month, whereas it showed some regression after 6 months in case of exotropia but still better than surgery on the amblyopic eye.


  Acknowledgements Top


Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.Von Noorden GK. Esodeviations. In: von Noorden GK, editor. Binocular vision and ocular motility: theory and management of strabismus. 5th ed. St Louis: Mosby; 1996;331-332.  Back to cited text no. 1
    
2. Sidikaro Y, von Noorden GK. Observations in sensory heterotropia. J Pediatr Ophthalmol Strabismus 1982; 19 :12-19.  Back to cited text no. 2
    
3. Havertape SA, Cruz OA, Chu FC. Sensory strabismus: eso or exo? J Pediatr Ophthalmol Strabismus 2001; 38 :327-330.  Back to cited text no. 3
    
4. Edelman PM, Brown MH. The stability of surgical results in patients with deep amblyopia. Am Orthopt J 1977; 27 :103-106.  Back to cited text no. 4
[PUBMED]    
5. Rosenbaum AL, Santiago AP. Clinical strabismus management. Philadelphia: W.B. Saunders Company; 1999;193-199.  Back to cited text no. 5
    
6. Owens PL, Strominger MB, Rubin PA, Veronneau-Troutman S. Large angle exotropia corrected by intraoperative botulinum toxin A and monocular recession resection surgery. J AAPOS 1998; 2 : 144-146.  Back to cited text no. 6
    
7. Wright KW, Spiegel PH. Pediatric ophthalmology and strabismus. 2nd ed. New York: Springer; 2003.  Back to cited text no. 7
    
8. Kim MJ, Khwarg SI, Kim S-J, Chang BL. Results of re-operation on the deviated eye in patients with sensory heterotropia. Korean J Ophthalmol 2008; 22 :32-36.  Back to cited text no. 8
    
9. Mitsui Y, Tamura O, Hirai K, Akazawa K, Ohga K, Masuda K. Effect on master eye surgery in exodeviations. Jpn J Ophthalmol 1980; 24 :221.  Back to cited text no. 9
    
10.1Lennerstrand G. Effects of surgery on the dominant eye in exodeviations. Acta Ophthalmol (Copenh) 1986; 64 :391-396.  Back to cited text no. 10
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
Abstract
Introduction
Objective
Design
Patients and methods
Results
Discussion
Conclusion
Acknowledgements
References
Article Tables

 Article Access Statistics
    Viewed1575    
    Printed25    
    Emailed0    
    PDF Downloaded119    
    Comments [Add]    

Recommend this journal


[TAG2]
[TAG3]
[TAG4]