Early Vitreous Changes in Experimental Proliferative Vitreoretinopathy

• Proton magnetic resonance imaging (MRI) was employed to obtain information on early vitreal changes preceding ophthalmoscopically visible proliferative vitreoretinopathy. Rabbits were injected close to the posterior pole with a suspension of 250 000 cultured homologous fibroblasts. The MRI was carried out using a 1.4-tesla (T) superconducting imager (at a proton frequency of 61.4 MHz). The images were obtained over a span of six days, prior to any detection of proliferative vitreoretinopathy with ophthalmoscopy. As early as two days after injection, an area of increased spin-spin relaxation time (T₂) corresponding to the vitreal injection site became visible. The MRI observations paralleled in vitro changes in proton relaxation times (T₁ [spin-lattice relaxation time] and T₂) after addition of β-N-acetylglucosaminidase to the vitreous. Our data suggest that hyaluronate disruption due to the activity of fibroblastic enzymes may result in fibroblast dispersion and movement in the vitreous and that MRI can provide early signs of vitreal changes that lead to retinal detachment.