ABSTRACT
Myopia is the most common type of refractive error. At present, the characteristics of the low age and rapid growth of myopia in our country are obvious, and the myopia of adolescents and children has become a public health problem of concern to the whole society. Visual experience guides the development of children's refractive state and emmetropization. The occurrence and development of myopia is accompanied by changes in the structure of the eyeball, and the choroid has a thinning trend. The thickness change of the choroid may be determined by blood flow perfusion. Decreased choroidal blood flow perfusion may lead to scleral ischemia and hypoxia, and hypoxia induces scleral matrix remodeling and axial length growth. This article reviews the relationship between choroidal blood flow and myopia, and suggests the significance of paying attention to choroidal changes in the prevention and control of myopia.
ABSTRACT
Background Congenital fibrosis of extraocular muscles (CFEOM) affects patient' s appearance and quality of life,and no effective treatment for this disease is available.Imaging study is helpful for exploring the pathogenesis of CFEOM.Objective This study was to describe the characteristics of CFEOM associated with limb movement disorder using magnetic resonance imaging (MRI).Methods A family with CFEOM associated with limb movement disorder was investigated in Renmin Hospital of Wuhan University.Disease history was collected and the pedigree was investigated.Ophthalmologic examinations,including corrected visual acuity,refractive error,slitlamp examination,ophthalmoscopic examination,force of levator palpebrae superioris,ocular movement,eye position,forced duction test,and bell phenomenon examination,were performed.Ocular orbital and cranial MRI was performed in 4 CFEOM patients and 10 normal subjects to compare the structures of the extraocular muscles,motor nerve and cranium.Oral informed consent was obtained from each patient prior to any medical examination.Results A total of 1 1 members from 3 generations were investigated in this study,presenting with 4 cases of disease.The mode of inheritance of this family complied with the Mendelian autosomal dominant inheritance law.Clinical signs included disturbance of eye movement,deviation of eye position,ptosis,lack of Bell sign and positive reaction of passive pull test.In addition,unstable gait,improper body limb alignment,dysphasia and mental retardation were ohserved in 1 patient,which coincided with the diagnostic criteria of type 3 CFEOM.MRI results demonstrated that the levator palpebrae superioris,superior rectus and superior oblique muscle were clearly thinner,and the medial rectus,lateral rectus,inferior rectus muscle were thinning in the patients,showing significant differences in comparison with the normal controls(P＜O.05).The oculomotor and abducens nerves became thinner and even absent in the patients.Cranial MRI showed that Ⅲ-3 in the pedigree with callosum was shorter than that of the normal controls,suggesting that patient suffered from corpus callosum hypoplasia.Meanwhile,cranial MRI indicated the presence of cerebellar hypoplasia and the expansion of the fourth ventricle.Conclusions MRI demonstrates consistent abnormalities of the oculomotor nerves and abducens nerves in the affected individuals in this CFEOM 3 family,and some affected members exhibit two types of central nervous system abnormalities-corpus callosum and cerebellar hypoplasia.These findings suggest that CFEOM 3 is primarily a neuronal disease.