Modern exploration of choroidal inflammation

Abstract

Abstract Purpose The choroid is the site of intraocular inflammation as often as the retina. Because choroidal structures were not accessible to sensitive and performing investigational procedures, analysis of inflammatory events lagged behind. This was at the origin of the inadequate appraisal of choroiditis and the use of imprecise or vague terminologies such as “White Dot Syndromes”. Thanks to indocyanine green angiography (ICGA), access to the choroidal compartment has been granted to the clinician and more precise information on inflammatory mechanisms has allowed to establish a classification based on disease behaviour as well as direct monitoring of disease evolution in the choroid. Methods With the help of ICGA, choroiditis could be subdivided into at least two inflammatory patterns touching 2 different choroidal structures are occuring. Firstly, inflammation of the choriocapillaris causing non perfusion is very well recognised by its typical ICGA features and constitutes a group of diseases that are called inflammatory choriocapillaropathies, including MEWDS, APMPPE or multifocal choroiditis. Results Secondly, there is a totally different type of choroiditis, with inflammation occurring in the choroidal stroma in form of a mostly granulomatous infiltration called stromal choroiditis. When the target is specifically in the choroid such as in VKH disease or Sympathetic Ophthalmia (SO) we speak of primary stromal choroiditis and when the choroid is just the structure where a systemic disease such as sarcoidosis elects to manifest itself we speak of secondary stromal choroiditis. Conclusion Beside the fact that ICGA has helped us classify choroiditis based on disease mechanism, it also allows proper monitoring of disease activity reaching a high degree of accuracy.