Influence of mydriasis on optical coherence tomography angiography imaging in patients with age-related macular degeneration.

PURPOSE

To evaluate the effect of topical mydriatic eye drops on optical coherence tomography angiography (OCTA) parameters in patients with age-related macular degeneration (AMD).

METHODS

27 eyes of 27 patients suffering from AMD were included in this cross-sectional study. Patients with ≥-4.5 diopters spherical equivalent, corneal opacities or dense cataract preventing high-quality imaging were excluded. Whole-en-face scans of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) in the central 3x3mm foveal region as well as whole-en-face and peripapillary scans of the radial peripapillary capillaries (RPC) were generated using OCTA (AngioVue®, Optovue). Imaging was first conducted with patients' eyes in miosis, then in mydriasis after instillation of a dilating eye drop (0.5% tropicamide, 2.5% phenylephrine-HCl). Main outcome measures were flow density (FD), foveal avascular zone (FAZ), signal strength index (SSI) and motion artifact score (MAS).

RESULTS

Our results reveal that in AMD patients there is no significant difference between FD measurements taken in miosis and those taken in mydriasis around the SCP (p = 0.198), DCP (p = 0.458), RPC whole-en-face (p = 0.275) and RPC peripapillary (p = 0.503). Measurements taken in these two states appear to be equivalent for assessment of FD (90%CI within ± 0.05). No significant difference was found either in the area of the FAZ (p = 0.338) or in the SSI (p = 0.371) before and after the instillation of tropicamide/phenylephrine. MAS was significantly lower after the application of mydriatic eye drops (p = 0.003).

CONCLUSIONS

Our findings reveal that neither measurements of FD nor measurements of the FAZ area changed significantly in AMD patients after the application of tropicamide/phenylephrine. Since MAS improved significantly in dilation, mydriatic examination is recommended. Nevertheless, a comparison of OCTA metrics from images taken with different pupil states (miosis versus mydriasis) is valid for clinical trials.