A New Distance Stereotest by Autostereoscopic Display Using an Eye-Tracking Method.

Objectives: This research aimed to present a novel glasses-free distance random-dot stereotest system (GFDRDSS) using an eye-tracking method. Methods: A single-view autostereoscopic display applying a backlight control system combined with an eye-tracking method and the corresponding random-dot stereotest software were developed to create a GFDRDSS with a viewing distance of 5 m. The stereoacuity of 12 subjects with normal eye position was evaluated using the Randot Stereotest, Stereoscopic Test Charts vol. 3 (Yan's Charts), Distance Randot® Stereotest, and GFDRDSS. Results: The GFDRDSS could provide distinct and stable glasses-free stereoscopic perception even while the subject was moving their head. It could evaluate binocular disparities of 40-2,400 arcsec. Eleven subjects with normal near visual acuity had fine near stereovision (20-60 arcsec) using the Randot stereotest and Yan's Charts. Under refractive correction, 10 subjects had fine stereovision (≤60 arcsec) using the GFDRDSS at a distance of 5 m, and 9 had fine stereovision using the Distance Randot® Stereotest at 3 m. Other subjects described the 100 arcsec-level stereograms correctly. The results exhibited a concordance of stereoacuity within one degrade between the two distance stereotests. Conclusion: The proposed GFDRDSS can alternately project a couple of random-dot stereograms to the subjects' eyes and provide a glasses-free distance stereotest, which showed good concordance with the Distance Randot® Stereotest. More data are needed for statistical studies.

[Effect of repeated horizontal acceleration exposure on cardiac structure in New Zealand rabbits].

Objective: To observe the effects of repeated horizontal -Gx acceleration exposure on cardiac structure in New Zealand rabbits. Methods: Twenty New Zealand rabbits were divided into 2 groups (n=10): control group and -Gx acceleration exposure group. The rabbits in -Gx acceleration exposure group were exposed to -3. 6 Gx with 2 s, at intervals of 5 min, repeated 20 times daily, with a total of 30 d; the control group didn't undergo the acceleration stress. After the last -Gx acceleration exposure, the animals were killed by intravenous injection of air, and two small pieces of myocardium were immediately dissected from the left ventricles for structure examination using optical microscope and transmission electron microscope. Results: There was no significant difference in the myocardial cell morphology and arrangement observed under the optical microscope between the -Gx acceleration exposure group and the control group; the myocardial fibers arranged in disorder, myocardial cell edema, nuclear membrane expansion, vascular endothelial basement membrane separation were observed in the -Gx acceleration exposure group under transmission electron microscope, compared with the control group. Conclusion: -Gx acceleration exposure can lead to ultrastructural damage in rabbit cardiac myocytes. It suggested that the more attention should be paid to the effect and protection of long-term horizontal -Gx acceleration exposure on the cardiac function of carrier fighter pilots.

[Clinical features of hypoperfusion retinopathy induced neovascular glaucoma].

OBJECTIVE: To analyze the clinical features of hypoperfusion retinopathy induced neovascular glaucoma METHODS: This retrospective case series included 18 cases (18 eyes) with hypoperfusion retinopathy induced neovascular glaucoma Among them, there were 15 male and 3 female; 10 right eye and 5 left eye. The average age was 40-year-old (ranged from 18- to 78-year-old). Visual acuity and fundus were examined using fundus fluorescein angiography (FFA), Color Doppler Flow Imaging (CDFI), magnetic resonance angiography (MRA), and Digital subtraction angiography (DSA) etc in all patients. RESULTS: The visual acuity was ranged from light perception to 0. 8 in all patients. The clinical features in hypoperfusion retinopathy induced neovascular glaucoma were characterized by midperipheral intraretinal hemorrhages, narrowed retinal arteries, dilated retinal veins, neovascularisation in iris and anterior chamber angle, ocular hypertension, excavation and atrophy of optic disk, and visual field defects when glaucoma progressed. All eyes have either ipsilateral common carotid artery obstruction or severe bilateral obstruction of the internal carotid arteries. CONCLUSIONS: Neovascular glaucoma is a rare and severe complication of hypoperfusion retinopathy associated with either ipsilateral common carotid artery obstruction or severe bilateral obstruction of the internal carotid arteries. Fundus degeneration is commonly involved in one eye. The characteristic clinical features are presented during the process of the disease.