Naso-Temporal Asymmetry of Retinal Function in Children With Strabismic Amblyopia

Purpose:Previous studies¹ have shown naso-temporal asymmetry of spatial interaction in strabismic amblyopia. The aim of this study was to compare naso-temporal hemiretinal function with pattern electroretinogram (PERG) in children with strabismic amblyopia. Methods:Ten children with a diagnosis of strabismic amblyopia (3 males, 7 females, mean age: 6 ± 1 years), with a visual acuity of 0.4-0.7 in the amblyopic and of 1.0 Snellen units in the fellow eye were analyzed. All patients had convergent strabismus 10 prismatic dioptres (D). All children were hyperopic and four were astigmatic > 1.5 D. Pattern electroretinogram (PERG) was recorded in response to transient stimuli generated on a 19" TV monitor (temporal frequency 2 Hz, check size 30’), presented to the central retinal region (22 x 22 degrees) and to nasal and temporal hemiretinal fields. Analysis was according to ISCEV guidelines. Results:In the amblyopic eyes, the central PERG was significantly reduced in mean amplitude (p < 0.01) compared to the fellow eyes. However, nasal hemiretinal amplitude losses were significantly greater than corresponding temporal losses ( - 23.2 ± 4 % versus - 4.5 ± 5.6 %, p < 0.01). Conclusions:Strabismic amblyopia shows a retinal dysfunction characterized by a naso-temporal asymmetry, suggesting a retinal genesis of the reduction of nasal hemiretinal input to the visual cortex.

Purpose: Previous studies¹ have shown naso-temporal asymmetry of spatial interaction in strabismic amblyopia. The aim of this study was to compare naso-temporal hemiretinal function with pattern electroretinogram (PERG) in children with strabismic amblyopia. Methods: Ten children with a diagnosis of strabismic amblyopia (3 males, 7 females, mean age: 6 ± 1 years), with a visual acuity of 0.4-0.7 in the amblyopic and of 1.0 Snellen units in the fellow eye were analyzed. All patients had convergent strabismus ≥ 10 prismatic dioptres (D). All children were hyperopic and four were astigmatic > 1.5 D. Pattern electroretinogram (PERG) was recorded in response to transient stimuli generated on a 19" TV monitor (temporal frequency 2 Hz, check size 30’), presented to the central retinal region (22 x 22 degrees) and to nasal and temporal hemiretinal fields. Analysis was according to ISCEV guidelines. Results: In the amblyopic eyes, the central PERG was significantly reduced in mean amplitude (p < 0.01) compared to the fellow eyes. However, nasal hemiretinal amplitude losses were significantly greater than corresponding temporal losses ( - 23.2 ± 4 % versus - 4.5 ± 5.6 %, p < 0.01). Conclusions: Strabismic amblyopia shows a retinal dysfunction characterized by a naso-temporal asymmetry, suggesting a retinal genesis of the reduction of nasal hemiretinal input to the visual corte