The separation of outer retinal photoreceptors in patients with toxoplasmosis chorioretinitis was first named bacillary layer detachment (BALAD), which was manifested as a split at the level of the photoreceptor inner segment myoid creating a distinctive intraretinal cavity in optical coherence tomography.Subsequently BALAD has been reported by many researchers in different diseases.In the outer retina, the myoid is a relatively weak structure in photoreceptor inner segment.When the outward force that promotes the attachment of the photoreceptor outer segment to the retinal pigment epithelium exceeds the tensile strength of the photoreceptor inner segment myoid, the myoid zone splits and BALAD occurs.BALAD has its unique multimodal imaging characteristics, and the identification of it can provide a new idea for the diagnosis, detection and treatment of ocular diseases.This paper reviewed the development of BALAD nomenclature, its anatomical structure, pathophysiological mechanism and multimodal image features.

Objective The intention of this thesis is to present the nervous system symptoms of rare diseases with a view to raising researchers′awareness of these symptoms,providing one of bases for other relevant researches in the future. Methods Based on the classification in Orphanet database,rare neurological diseases are picked out and put into different groups.The diseases with the same neurological symptoms and signs are in the same group. Then,differences and similarities of the diseases in the same group are analyzed. Results 57 kinds of rare neurological diseases are sorted out from rare diseases list and account for 31.49% of total diseases in the list.These diseases are characterized by aspecific,complex and interlaced neurological abnormalities.Specifically, the above-mentioned neurological abnormalities include 10 kinds of neurological symptoms and signs like peripheral neuropathy,epilepsy,and neuromuscular diseases.Conclusions Rare diseases,in most cases,are featured with complex neurological abnormalities,which presents great challenges for identification and diagnosis.In view of this fact,it is helpful to analyze the connection between rare diseases and their symptoms by adopting the classification in Orphanet database,which is beneficial for promoting identification on neurological symptoms and signs of rare diseases.