Gliotic opaque posterior hyaloid membrane separation: report of two cases

BACKGROUND: To report two cases with idiopathic unilateral diffuse opacification of the posterior hyaloid membrane (PHM) completely separated from the retina, the mechanism of which is possibly due to glial cell proliferation and migration. CASE PRESENTATION: Two Japanese women at age 75 and 84 with no systemic or ocular history developed diffuse opacification in one eye resembling a ground glass sheet almost all over the surface of the PHM, but not within the vitreous gel or fluid. The retinas were funduscopically normal; however, optical coherence tomography demonstrated hyperreflective icicle-like anterior protrusions from the surface of the fovea. The patients received pars plana vitrectomy, resulting in visual improvement. Cell block preparations of the vitreous in one case revealed a cluster of cells immunoreactive for glial fibrillary acidic protein in consistence with gliosis, while denying vitreoretinal lymphoma from lack of atypical cells and vitreous amyloidosis due to no staining for Congo red or direct fast scarlet. The lesions did not recur during follow-up with no new funduscopic abnormalities. CONCLUSIONS: To our knowledge, this is the first to demonstrate such peculiar cases of vitreous opacity with idiopathic and unilateral onset. Histological assessments revealed the possible pathogenesis of gliotic opaque PHM separation to cause its ground-glass-sheet appearance. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12886-021-02072-5.