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Amblyopia. Mutez Gharaibeh,MD Assisstant professor Univ of Jordan. 2-4% of the general population. The most common cause of visual loss under 20 years of life. Amblyopia.
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Amblyopia Mutez Gharaibeh,MD Assisstant professor Univ of Jordan
2-4% of the general population. • The most common cause of visual loss under 20 years of life.
Amblyopia • Decrease in visual acuity of one eye without the presence of an organic cause that explains that decrease in visual acuity. • Cortical ignorance of one eye. • Lazy eye.
Amblyopia is NOT : • When the image is seen in front of the retina = myopia. • The opposite of emblyopia ! • The eyes in converging case = esotropia . • Decrease of light which enter the eye. • Aiming the two eyes correctly= orthotropia • When the patient sees double image= diplopia
2 dichoptic stimuli ( half images with similar features but not exactly the same).
What if images were totally different or grossly differnet ? • Diplopia. • Rivalry. • Confusion. • Suppression.
Why fusion may fail ? • significant anisometropia. • significant aniseikonia. • Strabismus. • Higher cortical problems ( e.g: head trauma, alcohol intake , drugs , … etc).
Binocular suppression • Failure to allow some monocular portion of the binocular field to contribute to the combined binocular percept.
This will lead to : • Binocular rivalry. • Binocular luster. • Binocular suppression. • Diplopia. • Amblyopia. Critical period
Critical period • The first 10 years of life • What do we mean by critical period
Types of amblyopia 1- Strabismic
Types 2- Deprivation amblyopia
Types 3- Anisometropic amblyopia ( refractive amblyopia) • More common with hypermetropic anisometropia. • ( Iso- ametropic amblyopia) = significant bilateral uncorrected refractive error. • ( Astigmatic ( Meridional) amblyopia=
Changes in amblyopia • Different visual functions have different critical periods. • Most of them are developed by the age of 9-10 years. • Photopic and scotopic sensitivity--- 0-1 yr • Pattern vision and biocular vision--- 1-2 yr • Contrast sensitivity--- 2-8 yr
Light sense --- normal • Color vision --- Normal • Contrast sensitivity --- reduced • Visual acuity --- reduced • Structure of the eye --- shold be normal .( how ???)
Table 4.1 page 97 • Thank you