Ocular Lichen Planus: A clinicopathologic review.

Lichen planus is a chronic inflammatory dermatosis that can affect the skin, mucous membranes and nails. Cutaneous lichen planus lesions are best described by the "six Ps" - purple pruritic polygonal planar papules and plaques. Mucous membrane lesions are commonly associated with cutaneous lichen planus. Ocular involvement with lichen planus is rare and conjunctival involvement usually predominates, it can however be visually devastating. Ocular lichen planus often progresses to extensive conjunctival scarring which can be impossible to distinguish clinically from other cicatrising conjunctivitis, requiring histopathological confirmation. Here we review the ocular pathology of this condition.

Systematic review of clinical practice guidelines for uveitis.

To facilitate the integration of eye care into universal health coverage, the WHO is developing a Package of Eye Care Interventions (PECI). Development of the PECI involves the identification of evidence-based interventions from relevant clinical practice guidelines (CPGs) for uveitis.A systematic review of CPGs published on uveitis between 2010 and March 2020 was conducted. CPGs passing title and abstract and full-text screening were evaluated using the Appraisal of Guidelines for Research and Evaluation II (AGREE II) tool and data on recommended interventions extracted using a standard data extraction sheet.Of 56 CPGs identified as potentially relevant from the systematic literature search, 3 CPGs underwent data extraction following the screening stages and appraisal with the AGREE II tool. These CPGs covered screening for, monitoring and treating juvenile idiopathic arthritis (JIA)-associated uveitis, the use of adalimumab and dexamethasone in treating non-infectious uveitis, and a top-level summary of assessment, differential diagnosis and referral recommendations for uveitis, aimed at primary care practitioners. Many of the recommendations were based on expert opinion, though some incorporated clinical study and randomised controlled trial data.There is currently sparse coverage of the spectrum of disease caused by uveitis within CPGs. This may partially be due to the large number of conditions with diverse causes and clinical presentations covered by the umbrella term uveitis, which makes numerous sets of guidelines necessary. The limited pool of CPGs to select from has implications for clinicians seeking guidance on clinical care strategies for uveitis.

The Cellular Composition of the Uveal Immune Environment.

The uveal tract consists of the iris, the ciliary body and the choroid; these three distinct tissues form a continuous layer within the eye. Uveitis refers to inflammation of any region of the uveal tract. Despite being grouped together anatomically, the iris, ciliary body and choroid are distinct functionally, and inflammatory diseases may affect only one part and not the others. Cellular structure of tissues direct their function, and understanding the cellular basis of the immune environment of a tissue in health, the "steady state" on which the perturbations of disease are superimposed, is vital to understanding the pathogenesis of those diseases. A contemporary understanding of the immune system accepts that haematopoietic and yolk sac derived leukocytes, though vital, are not the only players of importance. An array of stromal cells, connective tissue cells such as fibroblasts and endothelial cells, may also have a role in the inflammatory reaction seen in several immune-mediated diseases. In this review we summarise what is known about the cellular composition of the uveal tract and the roles these disparate cell types have to play in immune homeostasis. We also discuss some unanswered questions surrounding the constituents of the resident leukocyte population of the different uveal tissues, and we look ahead to the new understanding that modern investigative techniques such as single cell transcriptomics, multi-omic data integration and highly-multiplexed imaging techniques may bring to the study of the uvea and uveitis, as they already have to other immune mediated inflammatory diseases.