Atypical APMPPE with localized serous retinal detachments have been reported, which resembles Vogt–Koyanagi–Harada disease (Birnbaum et al. 2010; Garg and Jampol 2004). The occurrence of choroidal neovascularization (CNV) (Fig. 1.3) (Bowie et al. 2005), optic disc edema (Abu El-Asrar and Aljazairy 2002; Frohman et al. 1987), subhyaloid hemorrhage (De Souza et al. 1999), retinal vasculitis (De Souza et al. 1999; Abu El-Asrar and Aljazairy 2002; Thomas et al. 2012), or retinal vein occlusion has also been reported (Abu El-Asrar and Aljazairy 2002; De Souza et al. 1999).

In the acute stage of the disease, the active cream-colored lesions block the choroidal fluorescence during the early phases of FA (Fig. 1.4b). Irregular staining was observed in the lesions that had previously blocked fluorescence in the later phase of FA (Fig. 1.4c). In the late or resolved stage of the disease, the mottled RPE demonstrate window defects without leakage.

In ICGA, acute lesions show hypocyanescence in the early phase (Fig. 1.4d) and become more defined in shape in the late phase (Fig. 1.4e). These hypocyanescent lesions are numerous than the lesions observed on funduscopy and FA. Unlike FA, deep choroidal vessels are visible within the active lesion during early phase of ICGA and no hypercyanescence develops in the late phase. These findings support the hypothesis that the active APMPPE lesions result from the choriocapillaris nonperfusion presumably due to inflammation (Hedges et al. 1979). The hypocyanescence becomes less defined and smaller in the late or resolved stage of the disease, as disappearance of the outer retina or RPE swelling, which support the alternative hypothesis suggesting the primary inflammation of the outer retina and RPE (Gass 1968).

Spectral-domain optical coherence tomography (SD-OCT) reveals disruption of the outer retina early in the disease (Fig. 1.5, white arrow). As the lesions heal, RPE disruption occurs (Fig. 1.5, arrow head). Fluid associated with the placoid lesions has also shown in some patients, which is speculated as an intraretinal fluid accumulation rather than an exudative retinal detachment (Garg and Jampol 2004; Montero et al. 2011). Recent studies with optical coherence tomography angiography revealed choriocapillaris flow abnormalities extending beyond the SD-OCT lesions in acute APMPPE and reversible choroidal hypoperfusion in healed APMPPE lesions (Kinouchi et al. 2017; Burke et al. 2017). These findings suggest that the decreased blood flow consistent with choriocapillaris results in an ischemic RPE insult, rather than primary inflammatory change in RPE (Heiferman et al. 2017).

Spaide reported that the early hypofluorescent areas observed on FA did not match up precisely with the RPE changes on fundus autofluorescence (FAF), which suggests that the presence of choriocapillaris perfusion defects (Spaide 2006). Meanwhile, the staining of the lesion in the late phase FA matched the lesions observed on FAF in shape and size. These findings also support that the hypothesis that the RPE abnormalities resulted from the choroidal abnormalities (Spaide 2006). As resolving, the placoid lesions contracts centripetally and develop pigmented core with a depigmented halo. On FAF, these lesions are observed as intense hyperautofluorescence surrounded by hypoautofluorescence. These autofluorescence changes follow the clinical appearance (Spaide 2006).