A Comparative Study Between Dissociative Treatment and Binocular Interactive Treatment in Amblyopia
Phase: NA
Conditions: Amblyopia
Sponsor: Ain Shams University

A Comparative Study between Dissociative 
Treatment and Binocular Interactive 
Treatment in Amblyopia 
 
 
Thesis  
Submitted to Faculty of Medicine – Ain Shams University 
In Partial Fulfillment of the Requirements of Doctorate Degree in Ophthalmology 
By 
Suha Ahmed Amin Moustafa Hussein 
M.B,B.C.h (2009) ,  M.Sc (2014) ,  
Faculty of medicine - Ain Shams University 
 
Under supervision of 
Professor Dr. Hazem Hosny Nouh  
Professor of Ophthalmology  
Faculty of medicine – Ain Shams University 
 
Professor Dr. Mohammad Ahmad Rashad 
Professor of Ophthalmology  
Faculty of medicine – Ain Shams University 
 
 
Dr. Walid Mohamed Abd El-Raouf El-Zawahry 
Lecturer of Ophthalmology 
Faculty of medicine – Ain Shams University 
 
Dr. Ahmad Taha Ismail  
Lecturer of Ophthalmology 
Faculty of medicine – Ain Shams University 
 
Faculty of medicine 
Ain Shams University 
Cairo – Egypt 
2022 

Introduction 
Amblyopia is a unilateral or, infrequently, a bilateral reduction of best 
corrected visual acuity (BCVA) which cannot be attributed to coexisting eye 
or visual pathway disease. Amblyopic eyes may have decreased contrast 
sensitivity and accommodation deficit. The fellow eye is not often normal but 
has subtle deficits. (Pediatric Eye Disease Investigator Group, 2005; 
Ophthalmology P, 2012) This can be explained by interocular suppression, 
or inhibition of the amblyopic eye by the strong eye, with psychophysical 
(Baker et al., 2008; Mansouri et al.,2008; Maehara et al.,2011; Ding et al., 
2013; Ding et al., 2014; Hess et al., 2014)  and physiological evidence ( Bi 
et al., 2011) 
 
Amblyopia can be classified as follows: 1) Strabismic occurring in early 
childhood 2) Refractive: a) Anisometropic b) High bilateral refractive errors 
3) Visual deprivation. (Attebo et al., 1998; American Academy of 
Ophthalmology Basic and Clinical Science Course Subcommittee, 2012) 
 
The prevalence of amblyopia worldwide is approximately 1%–5% 
(Ganekal et al., 2013; Fu et al., 2014; Oscar, et al., 2014; Aldebasi, 2015) 
In Egypt, a study that was held in Minia, Upper Egypt, found that the 
prevalence of amblyopia was 1.49%, which is higher in rural areas than in 
urban areas. (Abdelrazik and Khalil, 2014) 
 
Several modalities of treatment for amblyopia are available, yet 
occlusion treatment is the gold standard involving covering the good eye with 
a patch for a prescribed period of time ranging from 10 minutes daily to all 
waking hours  (Von Noorden  and Campos, 2002; Stewart et al., 2005). 
However, its effectiveness decreases in older children and adults (Pediatric 
Eye Disease Investigator Group, 2005)  
 
Disadvantages include prolonged treatment leading to poor 
compliance, patching related distress, relationship strain and stigma. In 
extreme cases, non-compliance with patching results in a costly hospital 
admission to supervise the patching treatment. In addition, wearing a patch 
eliminates any advantage of binocularity (Dixon-Woods et al., 2006).  Not to 
mention that not all patients respond to patching and of those who do, many 
have residual amblyopia after treatment is stopped regardless of compliance 
(Hess et al., 2014). More importantly, binocular vision is not automatically 
restored once the vision in the amblyopic eye has been improved. In fact, once 

the patch is removed after therapy, the amblyopic eye could be suppressed by 
the better seeing eye and can lose some of the gains achieved as a result of 
therapy. (Birch, 2013)  
 
Another modality of treatment is atropine eye drops and optical 
penalization which are usually secondary treatments to failed patching but 
carrying the same disadvantages as the ordinary patching (Foss et al., 2013)  
 
Advances in amblyopia treatment include dichoptic training, perceptual 
learning, and video gaming (Tsirlin et al., 2015). These depend on the fact 
that the adult brain has been shown to be much more plastic than it was once 
believed to be and hence have the advantage of expanding the age of response 
in adults. (Pizzorusso et al., 2002; He et al., 2006) 
 
Perceptual learning approaches have the advantage of being a dichoptic 
(binocular treatment) approach which is independent of age and type of 
amblyopia. (Polat et al., 2004; Levi and Li, 2009) Furthermore, it has been 
shown recently that therapy promotes binocular vision by strengthening 
stereopsis and reducing suppression (Hess et al., 2010; Hess et al., 2011) 
 
A step further to conventional treatment is the use of a home-based 
approach allowing remote internet monitoring of treatment between office 
visits and hence better compliance. (Hess et al., 2014) In addition a video game 
version of the treatment is developed to make it more enjoyable for improving 
compliance. (Foss et al., 2013). Moreover, dichoptic presentation can be 
achieved on the iPod device using a lenticular overlay screen. The advantage 
of using a lenticular overlay screen is that the luminance contrast is preserved 
(Hess et al.; 2014) 
 
 
 

Aim of the work: 
The aim of this work is to compare the gold standard occlusion 
therapy alone with dichoptic therapy 
 
Patients and Methods: 
Design: 
The study will be a prospective experimental controlled study. 
 
Patients of the study: 
From the vicinity of the ophthalmology outpatient clinic of Ain Shams 
University Hospital, 100 patients of both sexes with amblyopia will be 
enrolled to this study.  Informed consents will be obtained from adult patients 
and children’s parents. 
Patients will be assigned randomly into two groups:  
Group A: 50 patients will receive the gold standard occlusion therapy  
 
Group B: 50 patients will receive dichoptic treatment in the form of playing a 
video game (Lazy Eye Tetris games such as Lazy Eye Blocks ®) while 
wearing a red/green goggle. 
Each group will be subdivided according to age: 
1. From 4 to 7 years. 
2. From above 7 to 12 years. 
3. From above 12 to 30 years. 
 
Hours of occlusion will be classified according to the degree of amblyopia: 
 Mild to moderate amblyopia (Best corrected visual acuity (BCVA)< 
0.2): 2-4 hours occlusion 
 Severe (BCVA> 0.2): 4-6 hours occlusion 
Hours of dichoptic treatment in group B will be classified according to the 
degree of amblyopia: 
 Mild to moderate amblyopia (BCVA< 0.2): 2-4 hours of treatment 
 Severe (BCVA> 0.2): 4-6 hours of treatment 

 
Inclusion Criteria: 
- Any degree of amblyopia 
- Orthotropia in primary position. 
 
Exclusion Criteria: 
- Any ocular disease affecting vision 
- Angle of deviation in primary position (Heterotropia) 
- Adult patients and children’s parents unwilling to enter or 
complete the study 
- Ignorance of patients to use the video game 
 
Methods 
All patients will undergo the following: 
1) Full medical and ophthalmic history 
2) Examination: 
A) External Appearance: 
Anomalous Head Posture, globes (e.g., proptosis), lids (e.g. 
ptosis). 
B) Refraction: 
With and without cycloplegia. 
C) Visual acuity:  
With and without correction using Snellen acuity chart and 
preferential looking test for non-verbal patients. 
D) Motility: 
Ductions and versions (9 positions of gaze)  
E) Angle of deviation if any 
F) Fixation : 
Fixation behavior (fixation preference) will be tested via base 
down 10 PD fixation preference test. 
G) Quantitative Binocular vision assessment 
H) Anterior segment examination. 
I) Posterior segment examination using indirect ophthalmoscopy 
with a 20-D (diopter) lens through a dilated pupil. 

All patients in Group A will receive the gold standard occlusion 
therapy. All patients in Group B will receive dichoptic treatment 
 
Treatment assessment: 
All patients will be followed up in the following schedule: after 1 
month, after 2 months and after 6 months with regards to visual acuity. 
Patients who fail to complete the full time of the follow up period will be 
excluded from the study. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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