الفهرس 
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Abstract
Binocular vision is a type of vision in which humans are able to perceive a single 3D image of their surroundings.(4)
Amblyopia is a cause of losing BSV and degradation in its functions as fusion and stereopsis.
Anisometropia is the second most common cause of amblyopia. (5)
It occurs when unequal focus between the two eyes causes chronic blur on one retina and can occur with relatively small amounts of anisohyperopia or aniso-astigmatism and larger amounts of anisomyopia. (70)
Many studies recommended the importance of treating anisometropia as soon as it is diagnosed before the issue of amblyopia occurs and BSV functions affected as fusion and stereopsis. (77)
The aim of our study were to evaluate fusion and stereopsis in anisometropic patients with or without amblyopia.
Sixty-four patients were enrolled in our prospective analysed study with age range 6:65 years and of both genders who visited general ophthalmology clinic in Ain shams hospitals for vision check-ups between August 2018 and March 2019 and were diagnosed as being anisometropic.
The main inclusion criteria for patient enrolment in this study were first-time diagnosis of anisometropia or previously diagnosed but with no patching or spectacles or corrective surgeries.
Here we studied anisometropic patients with 2.5 D interocular difference or more in the (SE). The anisometropic patients were divided into two subgroups according to presence of amblyopia each group contained 32 patients: first group is non-amblyopic anisometropia group (NA), difference between both eyes of one Snellen line or less in BCVA, and the second one included amblyopic anisometropia group (AA), difference of two Snellens lines or more in BCVA between both eyes.
Patients with history of corrective surgeries, occlusion or patching therapy, strabismus, any congenital or acquired organic pathology of the eye, single eyed patients or previous eye surgery or neurologic disorders were excluded.
All of the selected patients underwent complete initial ophthalmologic examinations including:
1. Uncorrected VA for each eye using the Snellen VA chart.
2. Detection of refractive error.
3. Slit-lamp examination.
4. Cover–uncover test and alternating-cover test were performed at both distance (6m) and near fixation (33 cm) with accommodative targets to discover heterotropia in the primary position.
5. Fundus examination.
6. Cycloplegic refraction was performed for all patients.
7. BCVA by Glasses which were prescribed 1 week later (next visit) based on the cycloplegic refraction.
8. Sensory evaluations for assessing BSV functions including the Worth 4-dot test to assess fusion and Titmus stereotest (fly test) to assess stereopsis, were performed at the next visit by corrective trial glasses based on cycloplegic refraction.
We found that 53.1% of cases in AA group had aniso-hyperopia, 31.2% of cases had aniso- myopia and only 15.6 % had antimetropia, but in NA group 75% of cases had aniso-myopia, only 25% of cases had aniso-hyperopia and none of them were antimetropic.
The association of presence or absence of amblyopia with fusion and stereopsis in our study was that the cases with amblyopia had statistically significant suppression of vision than patients without as regard Worth four dot test, as in AA group 90.6% of cases (29 cases) had suppressed eye but only 9.4 % of this amblyopic cases (3 cases) had normal fusion. However, in NA patients only 5 patients (15.6%) had suppressed eyes but 27 patients (84.4%) had normal fusion.
As regard Titmus fly test there was statistically significant difference between both groups, as 100 % of AA cases had bad stereo acuity >100 arc second but 28.1% of patients (9cases) in NA group had defect in their stereo acuity.
Our study also showed that in NA group 77.8% of patients with normal fusion had good stereopsis and 60% of patients with suppressed eye had bad stereopsis. In AA group 100% had bad stereopsis.
We also found that 87.5% of NA group anisomyopes showedgood stereopsis and fusion than anisohyperopes which had only 2 patients (25%) with good stereopsis and 6 patients (75%) however in AA group all anisometropic patients shows bad stereopsis but 3 showed normal fusion and 29 had abnormal fusion.
We also discovered that there was no significant relation between fusion, stereopsis and age