Ossification of the choroid: three clinical cases and literature review of the pathogenesis of intraocular ossification.

OBJECTIVE A presentation of the clinical and pathogenic aspects of choroidal ossification. CASES PRESENTATION We report three clinical cases of choroidal ossification: choroidal osteoma, ossified choroidal hemangioma and total ossification of the choroid. The three patients underwent complete eye examination. The optical microscopy of a sample of ossified choroidal tissue revealed a spongy, osseous structure consisting of circular osseous lamellae, osteocytes, canaliculi and adipose tissue with microfoci of calcification. DISCUSSION Choroidal ossification is characterized by reduced frequency of occurrence, accessible clinical diagnosis, and unspecified pathogenesis. Several of the factors identified in the pathogenesis of intraocular ossification may play a role in the ossification of the choroid: chronic inflammatory cells, bone morphogenetic proteins, growth factors and mesenchymal stem cells. In addition to these factors, pericytes have a special role in the pathogenesis of choroidal ossification. Under the influence of bone morphogenetic proteins and growth factors, mesenchymal stem cells differentiate into osteoblasts. They secrete bone matrix (osteoid), whose regeneration and remodeling lead to the formation of bone tissue. The spongy bone structure of choroidal tissue points to a model of endoconjunctive/desmal ossification. CONCLUSIONS The knowledge of the clinical aspect of ossification of the choroids is required for the differential diagnosis with the posterior pole affections, and also for the prevention and treatment of secondary complications.