Although persistent placoid maculopathy (PPM) has several characteristics similar to APMPPE and macular serpiginous choroiditis (SC), it also has numerous distinguishing characteristics. The term PPM was coined in 2006, when six individuals aged 50 to 68 years were diagnosed with macular placoid lesions and a high rate of CNV development.
Patients with PPM may have a prodrome phase, including influenza-like symptoms, and the majority of patients report bilateral vision impairment, photopsia, and scotomas upon presentation.
Clinical examination reveals the lack of anterior uveitis and, in a minority of cases, uncommon vitreal cells, with the posterior pole being the primary location of inflammation.
- On fundus examination, patients often present with vague placoid lesions affecting mostly the macula and sparing the peripapillary area. Although involvement of the second eye might develop after presentation, placoid lesions in PPM are often bilateral, can be unifocal or multifocal, and exhibit certain morphological alterations with time.
The condition is typically self-resolving and monophasic in nature, and it always takes far longer to recover than APMPPE.
- While bilateral CNV is common, in roughly 60% of patients, the normal course of PPM may potentially progress to macular atrophy.
FAF results vary according on the level of RPE involvement. FA and ICGA exhibit early hypofluorescence in the active phase, remaining on ICGA and becoming hyperfluorescent on FA in the late phases, similar to the other placoids (FA–ICGA dissociation).
OCTA was used to demonstrate and validate perfusion deficiencies at the choriocapillaris level. Cross-sectional OCT results are phase-dependent and are often comparable to but less severe than those reported in APMPPE.
Cerebral vasculitis, like APMPPE, may exacerbate PPM. Thus, if any neurologic symptoms are present, neuro-imageing studies should be considered. PPM-like findings have also been found in two individuals aged 74 and 85 years with giant cell arteritis. These data imply that before to labelling a patient as PPM, systemic symptoms should be carefully considered.
- PPM is uncommon and may be mistaken for other placoids. Bilaterality, foveal-centered lesions, and occasionally mild to moderate visual deterioration in the absence of CNV or atrophy may help differentiate PPM from serpiginous choroiditis, which frequently involves the peripapillary area and more frequently presents with a single or a few geographically active lesions, usually resulting in severe visual loss in the case of foveal involvement.
Unlike APMPPE, which has multifocal lesions dispersed across the retina and often affects younger patients with a low risk of CNV, placoid lesions in PPM are exclusively situated at the posterior pole, the mean age of the patients is older, and CNV is common.
In contrast to tuberculous serpiginous-like choroiditis (SLC), where placoid lesions are often more prominent and extensive, PPM active lesions are typically more ill-defined with less opaque active margins, giving the appearance of a weaker inflammatory response driving the illness. This might explain the relatively mild influence on the outer retinal layers and hence on visual acuity initially.
Corticosteroid or other immunosuppressive therapy has been used to hasten illness recovery but does not seem to be effective in avoiding CNV over time. Intravitreal antivascular endothelial growth factor (VEGF) injections have been shown to improve results and minimise neovascular exudation in the presence of CNV. Early therapy seems to be beneficial, with return of CNV or atrophy after quiescence sometimes seen. Despite frequent injections, the formation of fibrosis may occur.