RESUMO
Background Sweep pattern visual evoked potential (SVEP) is an objective method of visual test.There is a clear correlation between SVEP acuity and subjective vision,but they are not identical.Recent studies showed that new regression method can improve the accuracy of SVEP acuity. Objective This trial was to investigate and compare the outcome between amplitude-spatial frequency (A-SP) regression method and amplitudelogVA (A-logVA) regression method in extrapolating the SVEP acuity.Methods SVEP was recorded in 113 eyes of 64 subjects using GT-2000 ( Guo Te,China) with the gratings of 10 different spatial frequency from 0.99 to 12.89 cpd as stimulus.The 1 13 eyes included cataract,glaucoma,corneal disease,optical neuropathy,retinal disease,ocular trauma,refractive error and normal eyes.The correlation were analyzed of SVEP acuity,decimal visual acuity and LogMAR visual acuity.The response were averaged and DFT on the monitor display.SVEP acuity was calculated by extrapolating 0 response amplitude.Results The correlation indices of decimal visual acuity curves obtained by the A-logVA function was 0.663,and that obtained by the A-SP function was 0.705.The positive correlation was seen between subjective decimal visual acuity and A-logVA decimal visual acuity (r =0.540,P＜ 0.01 ) and between subjective decimal acuity and decimal acuity calculated by the A-SP regression method (r=0.620,P＜0.01 ).SVEP decimal acuity calculated by the A-SP function regression method was significantly different from the that calculated by the A-logVA function regression method (Z =-8.688,P＜0.01 ).And the correlation indices of LogMAR visual acuity curves obtained by the A-logVA function was 0.733 and that obtained by the A-SP function was 0.715.The positive correlation was found between the subjective LogMAR acuity and that calculated by the A-SP regression method (r=0.700,P＜ 0.01 ) and between the subjective LogMAR acuity and LogMAR acuity calculated by the A-logVA regression method (r=0.710,P＜0.01 ).SVEP LogMAR acuity from A-SP function regression method was significantly different from the LogMAR acuity from A-logVA function regression method (Z=-8.748,P＜0.01 ).No significant differences of VA LogMAR were found in gender,eyes,type of disease and age(x2 =2.171,P=0.338;x2 =0.976,P=0.614;x2 =6.032,P=0.420;x2 =14.720,P=0.257 ).Conclusions SVEP can obtain the visual outcome in human.The amplitude-logVA function regression method is more accurate in extrapolating SVEP acuity.