Transthyretin levels in the vitreous correlate with change in visual acuity after vitrectomy.

Abstract

Little is known about biochemical markers related to change in visual acuity after vitrectomy. The potential use of transthyretin (TTR), a carrier of the retinol/retinol-binding protein, as a biochemical marker protein, was investigated. TTR was measured using immunonephelometry in a group of patients (n = 77) in longstanding (>1 week) retinal detachment (n = 29), fresh (<1 week) retinal detachment (n = 17), macular holes (n = 20) or diabetic retinopathy (n = 11). Vitreous samples were taken at the start of every vitrectomy procedure. For reference values, cadaver specimens (n = 73) were used. Reference values for vitreous TTR (median 18 mg/l; IQR 4 to 24 mg/l) comprised 2.2% of reference values for vitreous protein levels (median 538 mg/l; IQR 269 to 987 mg/l). Vitreous TTR values of patients were comparable in all disorders. Vitreous TTR values were higher in phakic (median 22.5 mg/l; IQR 10 to 27 mg/l) than in pseudophakic patients (median 12 mg/l; IQR 8 to 19 mg/l; p = 0.06). Postoperative change in visual acuity correlated well with vitreous TTR values found peroperatively (r(s) = 0.408; p = 0.012). Both change in visual acuity and lens status were the only variables which proved to explain the variance of TTR (multiple correlation coefficient: 0.494; phakic status: t = 2.767; p = 0.0084; and change in visual acuity t = 2.924: p = 0.0056). Vitreous fluid concentrations of TTR can be regarded as a biochemical marker for retinal function.