Wide-field indocyanine green fluorescein angiography findings in inferior posterior staphyloma.

Inferior posterior staphyloma (IPS) is a rare disease typically associated with tilted disc syndrome, characterized by posterior staphyloma within the inferior fundus, without pathological myopia. Subretinal fluid (SRF) occurs in about 30-40% of IPS cases. This study investigated choroidal circulation and morphological changes in IPS using widefield indocyanine green angiography (ICGA). The study included 14 eyes of 8 Japanese patients (mean age: 65.1 years) with treatment-naïve IPS and utilized ICGA and optical coherence tomography. Exclusion criteria were high myopia, macular diseases, prior treatments, and contrast media allergy. The main ICGA findings were a downward shift of the watershed (85.7% of eyes), asymmetric dilated vortex vein (ADVV) (85.7%), anastomosis between the superior and inferior choroidal veins (57.1%), and delayed choroidal filling (100%). SRF was present in seven eyes. No statistical differences were found in the ratio of downward shift, ADVV, or delayed filling between eyes with or without SRF. However, anastomosis was significantly higher in eyes without SRF. The study concluded that IPS shows high prevalence of watershed shift, ADVV, anastomosis, and choroidal filling delay, with anastomosis potentially resolving SRF by reducing choroidal blood flow congestion, similar to pachychoroid spectrum diseases. KEY MESSAGES : WHAT IS KNOWN : Inferior posterior staphyloma (IPS) sometimes occurs subretinal fluid (SRF), however the mechanism of its appearance and disappearence is unknown. WHAT IS NEW : Indocyanine green angiography (ICGA) findings in IPS showed the downward shift in the watershed, asymmetric dilated vortex vein (ADVV), and choroidal filling delay, which was also found in pachychoroid spectrum diseases (PDS). Anastomosis between the superior and inferior choroidal veins across watershed contributes to the resolution of SRF in that it reduces the overload as the anastomosis progresses. We suggest that the mechanism for the appearance and disappearance of SRF in IPS may be due to the same mechanism that an imbalance in macular choroidal blood flow and localized hyperperfusion as in PDS.