En face optical coherence tomography and angiography of talc retinopathy (2015)

A 60-year-old African American male with known HIV, hepatitis C and history of intravenous drug use presented for routine ophthalmic evaluation and glasses check. He denied any visual disturbance, flashes or floaters. The patient's past ocular history was significant for granulomatous anterior uveitis, myopia with lattice degeneration, and laser retinopexy of atrophic holes in both eyes (OU). On examination, patient had 20/20-2 visual acuity OU with glasses correction. Pupils were equal, round and reactive to light. There was no afferent pupillary defect. Intraocular pressures were 13 mmHg OU. His anterior segment examination was quiet OU without evidence of keratic precipitates or cell/flare. The patient had age-appropriate trace nuclear sclerosis OU. Dilated fundus examination revealed fine crystal deposits in the macula (Fig. 1), lattice degeneration and laser retinopexy of atrophic holes OU. There was no evidence of retinal whitening or neovascularization. Spectral domain optical coherence tomography (SD-OCT) (Spectralis HRA+OCT; Heidelberg Engineering, Heidelberg, Germany) showed punctate areas of hyperreflectivity distributed along the vasculature of the inner retina OU consistent with the fine crystal deposits seen on dilated fundus examination (Fig. 2A). En face OCT and angiography (OCT-A) was performed using the prototype AngioVue system on the commercially available Avanti SD-OCT device (Optovue Inc., Fremont, CA, USA). Orthogonal registration and merging of two consecutive scans were used to obtain volumetric scans of a central 3 × 3 mm area of the macula (Fig. 2B). En face OCT imaging of the central macula at the level of superficial vascular network showed hyperreflective punctate spots inside the perifoveal arterioles corresponding to the fine crystals of talc retinopathy (Fig. 2C). These areas were seen as hyporeflective spots at the deep vascular network as well as the outer retina, presumably due to the shadowing caused by overlying talc particles (Fig. 2D,E). Of note, there was no abnormal hyperreflectivity at the level of the deep capillary plexus. OCT-A of the superficial retinal vasculature appeared relatively normal with no disruption of blood flow (Fig. 2F). Similar to the en face OCT at that level, the OCT-A of the deep capillary plexus demonstrated areas of hyporeflectivity without signal caused by shadowing (Fig. 2G). OCT-A of the outer retina also appeared normal, as expected (Fig. 2H). En face OCT and the recently emerging OCT-A represent two of the most cutting-edge developments in retinal imaging and are increasingly becoming more widespread. This provides the unique ability to evaluate en face OCT and angiography images separately across different cross sections through the retina and choroid. The ability to distinguish between superficial and deep retinal vascular networks enabled further evaluation for clinical signs in our diagnosis and management of retinal pathology (Spaide et al. 2015). Observing the distribution of talc particles across the retina through the multilayer images described in this case provides an opportunity to revisit retinal vascular anatomy. The branches from the central retinal artery dive deep into the retina forming the superficial network within the ganglion cell layer and the deep network in the inner nuclear layer. These two vascular networks end as the ganglion cell and inner nuclear layer disappear in the foveal slope. The deep network arises from the superficial network, is composed of vessels of smaller calibre and has a lower density of capillaries (Yu et al. 2010). Talc enters the eye from the systemic circulation and therefore deposits along retinal arterioles (Tarantola et al. 2010). In this case study, the talc particles distributed along only the superficial vasculature with sparing of the deep capillary plexus. Although it is not proven, this imaging finding indicates that talc particles may be too large to penetrate the finer calibre vessels of the deep capillary network. This is the first description of crystalline retinopathy findings on OCT-A and suggests that conditions involving retinal perfusion may affect the two retinal vascular layers to different extents.