A 3-year-old child with esotropia has a cycloplegic refraction of +7.00 D in the right eye and +1.00 D in the left eye. Visual acuity is 6/60 in the right eye and 6/6 in the left eye. There is no ocular misalignment. The amblyopia is classified as:

• A Strabismic amblyopia
• B Stimulus deprivation amblyopia
• C Anisometropic amblyopia ✓
• D Combined strabismic and anisometropic amblyopia

Explanation

Anisometropic amblyopia results from a significant refractive difference between the two eyes causing the brain to favor the clearer image. Here the 6 D difference in hypermetropia (with no manifest squint) causes amblyopia in the more ametropic eye. Strabismic amblyopia requires manifest deviation. Stimulus deprivation requires an obstruction like cataract or ptosis. The absence of misalignment excludes strabismic amblyopia as the primary mechanism.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

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Written and medically reviewed by the StethoPrep medical team.