Serum and vitreous herpes simplex antibodies in noninfected eyes

Recently, vitreous Herpes simplex virus [HSV] antibody titers have been reported from patients with presumed herpetic retinitis. To help understand the significance of these data, we evaluated the HSV type 1 vitreous and serum antibodies in eight patients undergoing pars plana vitrectomy for diabetic vitreous hemorrhage, diabetic traction detachment, or rhegmatogenous retinal detachment. Undiluted vitreous and diluted serum specimens were tested for HSV IgG antibodies using the fluorescence immunoassay (FIAX) technique. Two patients had undetectable vitreous and serum titers. In the other six patients, the serum (diluted) results ranged from 59 to 191 FIAX units (1:40-1:160 titer), and the vitreous (undiluted) levels ranged from 15 to 56 FIAX units (1:20-1:80 titer). The serum: vitreous ratio corrected for dilution ranged from 220 to 1120. We have shown that an isolated, undiluted vitreous HSV type 1 titer as high as 1:80 occurs without evidence of intraocular herpetic infection. When detectable, the serum titer is, on average, 400 times greater than the vitreous. Further investigation is needed to determine if intraocular HSV antibody production occurs in retinitis and results in a lower serum: vitreous ratio.