Forensic Application of Objective Assessment on Visual Acuity by ERP / 法医学杂志

ABSTRACT

Objective T o explore the com position characteristic of event related potential (E R P ) in dif-ferent visual acuity levels, and to provide theoretical basis for the objective assessm ent of visual acuity. Methods M onocular stim ulus w as perform ed on 16 selected subjects. T he subjects w ere required to look straight at the screen ahead and count the am ount of stim uli from different directions. T he pictures of optotype stim ulus w hich corresponding to three different visual acuity levels w ere show ed in the center of the screen. The ERP results w ere recorded separately. Results (1) The P1 am plitudes of m atch stim uli recorded under the supra-threshold visual acuity level w ere higher than that of m atch stim uli recorded under the threshold and sub-threshold visual acuity levels. T here w as no significant difference betw een the P 1 am plitudes of m atch stim uli recorded under the threshold and sub-threshold visual acuity levels. T he tendency of conflict stim uli w as sim ilar to that of m atch stim uli under three visual acuity levels. (2) In the 340-500 m s post-stim ulus range, P 300 com ponent w as found under supra-threshold and threshold visual acuity levels; no P 300 com ponent w as found in corresponding tim e w indow under sub-threshold visual acuity. T he differences of P 300 am plitudes am ong three visual acuity levels w ere statistically significant. T he am plitudes from high to low w ere the supra-threshold, threshold and sub-threshold visual acuity levels. Conclusion E R P can be a potential new m ethod for the objective assessm ent of visual acuity in forensic m edicine.