Evaluation and interpretation of VEP changes before and after treatment of amblyopia in children

Aim: To assess prognosis of Amblyopia by evaluating and interpreting visual evoked potential changes before and after treatment. Objective: To identity a relation between VEP changes in amblyopic patients before and after treatment. To identify the relation between VEP changes (latency and amplitude) and visual outcome. Materials and Methods: This is a prospective interventional study conducted at the department of paediatric ophthalmology, Sarojini Devi Eye Hospital, Regional Institute of Ophthalmology, Hyderabad. The study was conducted from June 2009-Dec 2011. 30 amblyopic patients of age group 4-12 years with different etiologies presenting at Sarojini Devi Eye Hospital, Hyderabad were selected for the study. The etiology was 8 Strabismic amblyopia, 11 Anisometropic amblyopia, 11 Isometropic amblyopia. Sex ratio was 21 female to 9 male. The patients who were not treated earlier for refractive error, amblyopia or ocular disease were considered for study. Clear media and normal fundus on ophthalmoscopic examination was a prerequisite for selection. Children below 3 years of age, Non Co-operative and children with toxic amblyopia were excluded from study. All cases were thoroughly evaluated by an experienced Ophthalmologist by using, Torch and Loupe, Slit lamp, Direct and indirect Ophthalmoscope, Prism bars. Visual acuity was recorded by using Snellen's chart or Allen's Pictorial chart. Cycloplegic refraction was done in all cases. Post mydriatic test was done to prescribe glasses. All subjects were subjected to VEP test using Nicolet Viking Select Neuro diagnostic system Version 10. Occlusive amblyopia therapy was given for six month taking care about normal eye by avoiding occlusion for 2 days in a week. Post patch VEP was done and visual acuity recorded and conclusions were drawn. Results: Mean age of the patients is 7.46 + 1.98 years. 44 amblyopic eye of 30 patients underwent occlusion amblyopia therapy for six months. All amblyopic patients had decreased visual acuity, increased VEP latency decreased VEP amplitude, and had improvement following patching indicates increased response of higher centres. All cases showed more than two Snellen's lines visual acuity improvement Conclusion: Paired T-Test was done with sample collections comparing pre patch and post patch VEP P100 values and found statistically very significant (RE and LE P values 0.003 and 0.031 respectively). On curve fit analysis the pre and post patch VEP P100values of right eye showed F value 10.335 and P value 0.003 on curve fit analysis post and pre patch VEP P100values of left eye showed F value 5.692 and P value 0.024 both of which are highly significant.