Objective Assessment of Visual Field Defects Caused by Optic Chiasm and Its Posterior Visual Pathway Injury / 法医学杂志

OBJECTIVES@#To investigate the characteristics and objective assessment method of visual field defects caused by optic chiasm and its posterior visual pathway injury.@*METHODS@#Typical cases of visual field defects caused by injuries to the optic chiasm, optic tracts, optic radiations, and visual cortex were selected. Visual field examinations, visual evoked potential (VEP) and multifocal visual evolved potential (mfVEP) measurements, craniocerebral CT/MRI, and retinal optical coherence tomography (OCT) were performed, respectively, and the aforementioned visual electrophysiological and neuroimaging indicators were analyzed comprehensively.@*RESULTS@#The electrophysiological manifestations of visual field defects caused by optic chiasm injuries were bitemporal hemianopsia mfVEP abnormalities. The visual field defects caused by optic tract, optic radiation, and visual cortex injuries were all manifested homonymous hemianopsia mfVEP abnormalities contralateral to the lesion. Mild relative afferent pupil disorder (RAPD) and characteristic optic nerve atrophy were observed in hemianopsia patients with optic tract injuries, but not in patients with optic radiation or visual cortex injuries. Neuroimaging could provide morphological evidence of damages to the optic chiasm and its posterior visual pathway.@*CONCLUSIONS@#Visual field defects caused by optic chiasm, optic tract, optic radiation, and visual cortex injuries have their respective characteristics. The combined application of mfVEP and static visual field measurements, in combination with neuroimaging, can maximize the assessment of the location and degree of visual pathway damage, providing an effective scheme for the identification of such injuries.

Prenatal ultrasonic research of fetal optic chiasma / 中华超声影像学杂志

Objective To research fetal optic nerve,optic chiasma and optic tract size using high resolution prenatal ultrasound,establish a scan method and the reference range of optic nerve,optic chiasma and optic tract in normal fetus.Methods Based on the section of circulus arteriosus cerebri,the probe were rotated to get the chiasma section for measuring the diameter of bilateral optic nerve,optic tract and area of optic chiasma in 453 normal fetus respectively.Used gestation age and corresponding biological parameters as independent variables,the regression equation was established analyse the gender differences.Results 26-33 weeks was the preferable gestational age to visualize the chiasma section.It had good repeatability except chiasma area.The bilateral optic nerve and optic tract diameter,optic chiasma diameter and area had an increased along with the gestational age reposefully.There was no significant difference between the two sides of optic nerve and the gender.Conclusions Prenatal ultrasound can assess the size and shape of fetal optic nerve,optic chiasma and optic tract.The normal reference range,established by ultrasound,is helpful to diagnose the abnormality of optic chiasma.

Anatomy of the optic chiasma and its surrounding structures in saddle area operation / 中国综合临床

Objective To provide morphological evidences for visual field defect caused by the compression of the saddle area tumors.Methods The shape and position of the optic chiasma and its surrounding saddle diaphragm,pituitary,internal carotid artery,and perforating arteries of optic chiasma were studied from 80 adult.Results Its maximum angle was 100° in anterior horn with prechiasmatic space, and minimum angle was 40° with postfixed optic chiasma.The area of optic chiasma averaged(1.32±0.04)cm2,the thickness of saddle diaphragm was 0.58 mm,and about 5% of saddie diaphragm did not exist.The foramen of saddle diaphragm pushed into the opposite side was 52.5%,and the maximum diameter was 7.8 mm×9.8 mm.The pituitary was found inferior to the saddle diaphragm foramen in 78%(62/80).In 76.3%(61/80) brains,the carotid artery touched chiasm opticum.Conclusions Visual field defect caused by compression from pituitary tumor and craniopharyngioma is directly related with the shape of the optic chiasma and its surrounding structures.