Analysis of the pachychoroid phenotype in an Asian population: methodology and baseline study population characteristics.

Aim: To describe the clinical characteristics in a cohort of patients with the pachychoroid phenotype and to evaluate the association of ocular and systemic factors with type of complications observed.

Methods: We report baseline findings from a prospective observational study which recruited subjects with subfoveal choroidal thickness (SFCT) of ≥300 µm on spectral-domain optical coherence tomography (OCT). Multimodal imaging was used to classify eyes as uncomplicated pachychoroid (UP) or pachychoroid disease with pachychoroid pigment epitheliopathy (PPE), central serous chorioretinopathy (CSC) or pachychoroid neovasculopathy (PNV) subtypes.

Results: Among 181 eyes of 109 participants (mean age 60.6 years, 33 (30.3%) female, 95 (7.2%) Chinese), 38 eyes (21.0%) had UP. Of 143 eyes (79.0%) with pachychoroid disease, 82 (45.3%), 41 (22.7%) and 20 (11.0%) had PPE, CSC and PNV, respectively. Addition of autofluorescence and OCT angiography to structural OCT led to reclassification of 31 eyes to a more severe category. Systemic and ocular factors evaluated, including SFCT, were not associated with disease severity. Comparison of PPE, CSC and PNV eyes showed no significant difference in OCT features of retinal pigment epithelial (RPE) dysfunction, but disruption of the ellipsoid zone (PPE 30.5% vs CSC 70.7% vs PNV 60%, p<0.001) and thinning of inner nuclear/inner plexiform layers (PPE 7.3% vs CSC 36.6% vs PNV 35%, p<0.001) were more frequent in CSC and PNV eyes.

Conclusions: These cross-sectional associations suggest pachychoroid disease manifestations may reflect progressive decompensation from the choroid to the RPE then retinal layers. Planned follow-up of this cohort will be beneficial in clarifying the natural history of the pachychoroid phenotype.