a 59-year - old asymptomatic diabetic male was referred to our retinal service with presumed diagnosis of asteroid hyalosis .
the patient had undergone laser treatment and intravitreal preserved triamcinolone acetonide injection for clinically significant diabetic macular edema in the right eye 4 years previously .
the right eye showed focal laser scars in the macula and several shiny refractile crystalline deposits [ fig . 1 ] .
optical coherence tomography localized these deposits to the posterior hyaloid [ fig . 2 ] .
these deposits were isofluorescent and not associated with specific angiographic abnormalities [ fig . 3 ] .
the patient has been followed for two additional years without any change in the visual acuity or status of the macula .
although a posterior vitreous separation has not developed , the crystals have been observed to migrate slowly in distribution . a fundus photograph of the right eye demonstrating small pre - retinal crystals concentrated in the macula , although peripheral crystals are noted ( arrow ) para - foveal optical coherence tomography scan of the right eye demonstrating triamcinolone crystal deposits on the posterior hyaloid surface ( arrow ) fluorescein angiogram of the right eye revealing several micro - aneurysms and focal laser scars , but no crystals , which are isofluorescent
triamcinolone has been shown to aggregate into crystalline structures that may resist the washout process and accumulate over the macula .
a recent study has identified intra - vitreal triamcinolone acetonide injections , both preserved and preservative - free , as a cause of crystalline retinal deposits .
our case report also identifies triamcinolone crystal deposition , all on the posterior hyaloidal surface . with follow - up now extending greater than 6 years , no functional toxic effects have been noted in our patient .
whether the crystals retain any biological activity is unclear . in our case and the previous series no adverse visual effect or
we suggest the term  drug - induced benign hyaloidopathy and recommend this to be included as a differential diagnosis of crystalline maculopathy and asteroid hyalosis .
 we report a case of unusually long persistence of triamcinolone crystals after intra - vitreal injection . 
 crystals were noted on fundus examination predominantly confined to the posterior pole . 
 optical coherence tomography localized the crystals to the posterior hyaloidal surface . over 6 years of follow - up 
 the patient has retained good visual acuity and no observable changes in the retina . as the condition clinically resembles both crystalline maculopathy and asteroid hyalosis 
 , we suggest the term  drug - induced benign crystalline hyaloidopathy. 
Case Report
Discussion