A feasibility study for objective evaluation of visual acuity based on pattern-reversal visual evoked potentials and other related visual parameters with machine learning algorithm.

BACKGROUND: To develop machine learning models for objectively evaluating visual acuity (VA) based on pattern-reversal visual evoked potentials (PRVEPs) and other related visual parameters. METHODS: Twenty-four volunteers were recruited and forty-eight eyes were divided into four groups of 1.0, 0.8, 0.6, and 0.4 (decimal vision). The relationship between VA, peak time, or amplitude of P100 recorded at 5.7°, 2.6°, 1°, 34', 15', and 7' check sizes were analyzed using repeated-measures analysis of variance. Correlations between VA and P100, contrast sensitivity (CS), refractive error, wavefront aberrations, and visual field were analyzed by rank correlation. Based on meaningful P100 peak time, P100 amplitude, and other related visual parameters, four machine learning algorithms and an ensemble classification algorithm were used to construct objective assessment models for VA. Receiver operating characteristic (ROC) curves were used to compare the efficacy of different models by repeated sampling comparisons and ten-fold cross-validation. RESULTS: The main effects of P100 peak time and amplitude between different VA and check sizes were statistically significant (all P < 0.05). Except amplitude at 2.6° and 5.7°, VA was negatively correlated with peak time and positively correlated with amplitude. The peak time initially shortened with increasing check size and gradually lengthened after the minimum value was reached at 1°. At the 1° check size, there were statistically significant differences when comparing the peak times between the vision groups with each other (all P < 0.05), and the amplitudes of the vision reduction groups were significantly lower than that of the 1.0 vision group (all P < 0.01). The correlations between peak time, amplitude, and visual acuity were all highest at 1° (rs = - 0.740, 0.438). VA positively correlated with CS and spherical equivalent (all P < 0.001). There was a negative correlation between VA and coma aberrations (P < 0.05). For different binarization classifications of VA, the classifier models with the best assessment efficacy all had the mean area under the ROC curves (AUC) above 0.95 for 500 replicate samples and above 0.84 for ten-fold cross-validation. CONCLUSIONS: Machine learning models established by meaning visual parameters related to visual acuity can assist in the objective evaluation of VA.

The comparison of sensitivity of motion sickness between retinal degeneration fast mice and normal mice.

Recent studies report that a conflict between information from the visual system and vestibular system is one of the main reasons for induction of motion sickness (MS). We may be able to clarify the integration mechanism of visual and vestibular information using an animal model with a visual defect, the retinal degeneration fast (rdf) mouse, and the role of vestibular information in the pathogenesis of MS. The rdf mice and wild-type Kunming mice were subjected to rotary stimulation to induce MS. Conditioned taste anorexia to saccharin solution and behavior score were used to observe the differences in MS sensitivity between two types of mice. The decrease in intake of saccharin solution and the behavior score in rdf mice were greater than those in normal mice. After rotatory stimulation, the reduction of intake mass and the behavior score were greater in rdf mice compared to those of normal mice. The rdf mice were more sensitive to rotation than normal mice. We conclude that visual information plays a role in the pathogenesis of MS. Visual information and vestibular information impact each other and integrate through certain channels in the central nervous system in mice.

The temporal progression of retinal degeneration and early-stage idebenone treatment in the Pde6brd1/rd1 mouse model of retinal dystrophy.

Photoreceptor cell death, primarily through apoptosis, related to retinal disorders like retinitis pigmentosa (RP), would result in vision loss. The pathological processes and crucial mutant conditions preceding photoreceptor cell demise are not well understood. This study aims to conduct an in-depth examination of early-stage changes in the widely utilized Pde6brd1/rd1 (rd1) mouse model, which has Pde6b gene mutations representing autosomal recessive RP disorder. We investigated the morphology and ultrastructure of retinal cells, including second-order neurons, during the initial phase of disease progression. Our findings revealed that mitochondrial alterations in rod photoreceptors were present as a predeath mutant state as early as postnatal day 3 (P3). The bipolar and horizontal cells from the rd1 mouse retina exhibited significant morphological changes in response to loss of photoreceptor cells, indicating that second-order neurons rely on these cells for their structures. Subsequent oral administration of idebenone, a mitochondria-protective agent, enhanced retinal function and promoted both photoreceptor cell survival and inner retinal second-order synaptogenesis in rd1 mice at P14. Our findings offer a mechanistic framework, suggesting that mitochondrial damage acts as an early driver for photoreceptor cell death in retinal degeneration.

[How to use of visual evoked potential testing technology reasonable].

Visual evoked potential testing items depend on stimuli and recording parameters. There is great variation in flash visual evoked potential (FVEP), while the pattern visual evoked potential (PVEP) is stable. The later is taken as the main objective assessment of visual function indicators in clinical. Only when PVEP cannot be recorded or the waves are hard to be recognized, the FVEP will be a reference indicator. There is less clinical meaning to do FVEP testing alone. Recommended visual evoked potential and electroretinogram in combination will be more comprehensive response visual function.If it is necessary, electrooculogram, multifocal electroretinogram, pattern electroretinogram should apply to test together in some case. Multifocal visual evoked potential (mfVEP) were developed to record local field response, such as the early field change in glaucoma. The mfVEP is not a small version of the conventional visual evoked potential, since the generated source in both is different. The waves of mfVEP are related to the stimulation (spatial, temporary and contrast), recording channel (single, double or four), and method for signal extracting and signal nose ration. It is a potential objective assessment method for retinal ganglion cell or optic nerve and still needs further improvement. There will be variable and fluctuation in any visual electrophysiological testing results, the explanation for the results should be relay on complains, symptom, signs and other laboratory examination results.

Frequency cumulative effect of subthreshold energy laser-activated remote phosphors irradiation on visual function in guinea pigs.

AIM: To explore the effects of laser-activated remote phosphors (LARP) on visual function in guinea pigs. METHODS: Electroretinogram (ERG) of guinea pigs were observed after LARP irradiation at different frequencies and irradiation times. We evaluated the expression of rhodopsin, ß-catenin, connexin36, calretinin, and calbindin in the retina of guinea pigs and measured the density of photoreceptor cells after high-frequency LARP irradiation. RESULTS: After LARP irradiation, the ERG results showed that the amplitude of the dark-adapted 3.0 b-wave of the model eye was lower than that of the control eye after high-frequency irradiation (P<0.05). The expression of rhodopsin, ß-catenin, connexin36, calretinin, and calbindin in the retina of guinea pig declined. CONCLUSION: There is frequency cumulative damage effect on the retina that relates to LARP illumination frequency. This has significance for staff visual protection policies under LARP lighting conditions.

[Short-term simulated weightlessness enhances response of L-type calcium channel to angiotensin II in cerebral vascular smooth muscle cells in rats].

Some studies suggest that the calcium channels and rennin-angiotensin system (RAS) play pivotal roles in the region-specific vascular adaptation due to simulated weightlessness. This study was designed to clarify if angiotensin II (Ang II) was involved in the adaptational change of the L-type calcium channel (Ca(L)) in the cerebral arterial vascular smooth muscle cells (VSMCs) under simulated weightlessness. Tail suspension (SUS) for 3 d was used to simulate immediate early cardiovascular changes to weightlessness. Then VSMCs in cerebral basilar artery were enzymatically isolated using papain, and Ca(L) current (barium instead of calcium as current carrier) in VSMCs was measured by whole-cell patch-clamp techniques. The results showed that 3-day simulated weightlessness significantly increased current density of Ca(L). However, I-V relationships of normalized peak current densities and steady-state activation curves of Ca(L) were not affected by simulated weightlessness. Although Ang II significantly increased current densities of Ca(L) in both SUS and control rats, the increase of Ca(L) current density in SUS rats was much more than that in control rats. These results suggest that 3-day simulated weightlessness induces the adaptational change of Ca(L) in cerebral VSMCs including increased response to Ang II, indicating that Ang II may play an important role in the adaptational change of cerebral arteries under microgravity.

Retinal neovascularization induced by mutant Vldlr gene inhibited in an inherited retinitis pigmentosa mouse model: an in-vivo study.

AIM: To explore whether the retinal neovascularization (NV) in a genetic mutant mice model could be ameliorated in an inherited retinitis pigmentosa (RP) mouse, which would help to elucidate the possible mechanism and prevention of retinal NV diseases in clinic. METHODS: The Vldlr -/- mice, the genetic mutant mouse model of retinal NV caused by the homozygous mutation of Vldlr gene, with the rd1 mice, the inherited RP mouse caused by homozygous mutation of Pde6b gene were bred. Intercrossing of the above two mice led to the birth of the F1 hybrids, further inbreeding of which gave birth to the F2 offspring. The ocular genotypes and phenotypes of the mice from all generations were examined, with the F2 offspring grouped according to the genotypes. RESULTS: The rd1 mice exhibited the RP phenotype of outer retinal degeneration and loss of retinal function. The Vldlr -/- mice exhibited the phenotype of retinal NV obviously shown by the fundus fluorescein angiography. The F1 hydrides, with the heterozygote genotype, exhibited no phenotypes of RP or retinal NV. The F2 offspring with homozygous genotypes were grouped into four subgroups. They were the F2-I mice with the wild-type Pde6b and Vldlr genes (Pde6b+/+ -Vldlr+/+ ), which had normal ocular phenotypes; the F2-II mice with homozygous mutant Vldlr gene (Pde6b+/+ -Vldlr-/- ), which exhibited the retinal NV phenotype; the F2-III mice with homozygous mutant Pde6b gene (Pde6b-/- -Vldlr+/+ ), which exhibited the RP phenotype. Specifically, the F2-IV mice with homozygous mutant Vldlr and Pde6b gene (Pde6b-/- -Vldlr-/- ) showed only the RP phenotype, without the signs of retinal NV. CONCLUSION: The retinal NV can be inhibited by the RP phenotype, which implies the role of a hyperoxic state in treating retinal NV diseases.

Therapeutic effect of a traditional Chinese medicine formulation on experimental choroidal neovascularization in mouse.

AIM: To investigate therapeutic effects of traditional Chinese medicine formulations, Hexuemingmu (HXMM) on laser-induced choroidal neovascularization (CNV) and follow-up effect in mice. METHODS: C57BL/6 mice of 8-week-old were used and CNV was induced with 577 nm laser photocoagulation. Animals were randomly divided into groups and different doses of HXMM were administered daily. One, four, and eight weeks after the intervention, the electroretinogram (ERG), fundus fluorescence angiography, choroidal flat mount and immunofluorescence staining were preformed to evaluate the function and CNV formation. The expression levels of angiogenic proteins were determined by Western blotting and immunofluorescence staining. An analysis of variance and Kruskal-Wallis test were used to test the differences among the groups. RESULTS: The results showed that HXMM effectively increased amplitude of ERG of mice (P<0.05), alleviated fundus CNV leakage (P<0.05), and reduced the area of neovascularization and the expression of angiogenic proteins (P<0.05) after laser-induced CNV. CONCLUSION: HXMM can protect the retinal function of mice after laser-induced CNV, and inhibit the CNV development.

Effects of sleep deprivation on human postural control, subjective fatigue assessment and psychomotor performance.

This study aimed to investigate the effects of sleep deprivation on postural control, subjective fatigue assessment and psychomotor performance, and to assess the efficiency of an objective posturographic test as an indicator of mental fatigue. Postural sway using static posturography (Romberg's test), subjective fatigue assessment (Stanford Sleepiness Scale) and psychomotor performance (Sternberg dual-task test) were assessed in 12 subjects before and after 24 h of sustained wakefulness. After sustained wakefulness, the Romberg test parameters of circumference area and rectangle area with the eyes-closed, and standard deviation in the anterior-posterior direction with the eyes-open were significantly higher compared with baseline values (before sustained wakefulness). Subjective fatigue assessment scores were also significantly increased, while psychomotor performance was unchanged. Sleep deprivation can arouse a feeling of fatigue and can affect postural stability, hence an objective posturographic test score may be useful as an indicator of mental fatigue.

Effects of hydrogen-rich saline on endotoxin-induced uveitis.

The therapeutic effects of hydrogen-rich saline (HRS) have been reported for a wide range of diseases mainly via selectively reducing the amount of reactive oxygen species. Oxidative stress plays an important role in the pathogenesis of uveitis and endotoxin-induced uveitis (EIU). In this study, we investigated whether HRS can mitigate EIU in rats. Sprague-Dawley rats were randomly divided into Norm group, Model group, HRS group, dexamethasone (DEX) group, and rats in the latter three groups were injected with equal amount of lipopolysaccharide (LPS) to induce EIU of different severities (by 1 mg/kg of LPS, or 1/8 mg/kg of LPS). Rats in HRS group were injected with HRS intraperitoneally at three different modes to purse an ameliorating effect of EIU (10 mL/kg of HRS immediately after injection of 1 mg/kg of LPS, 20 mL/kg of HRS once a day for 1 week before injection of 1 mg/kg of LPS and at 0, 0.5, 1, 2, 6, 8, 12 hours after LPS administration, or 20 mL/kg of HRS once a day for 1 week before injection of 1/8 mg/kg of LPS, and at 0, 0.5, 1, 2, 6, 8, 12, 24 hours and once a day for 3 weeks after LPS administration). Rats of DEX group were injected with 1 mL/kg of DEX solution intraperitoneally immediately after LPS administration. Rats in Norm and Model groups did not receive any treatment. All rats were examined under slit lamp microscope and graded according to the clinical signs of uveitis. Electroretinogram, quantitative analysis of protein in aqueous humor (AqH) and histological examination of iris and ciliary body were also carried out. Our results showed that HRS did not obviously ameliorate the signs of uveitis under slit lamp examination and the inflammatory cells infiltration around iris and cilliary body of EIU induced by 1 mg/kg or 1/8 mg/kg of LPS (P > 0.05), while DEX significantly reduced the inflammation reflected by the above two indicators (P < 0.05). The impaired retinal function of mild EIU induced by 1/8 mg/kg of LPS, showed by delay of peak time of b-wave of Dark adapted 3.0 electroretinogram, was not significantly restored by HRS (P > 0.05), while DEX had an obvious therapeutic effect (P < 0.05). However, HRS exerted an inhibition trend on elevation of protein in AqH of EIU induced by 1 mg/kg of LPS, and significantly reduced the increasing amount of protein in AqH of mild EIU induced by 1/8 mg/kg of LPS (P < 0.05). In conclusion, HRS could not obviously mitigate EIU in rats, while it could inhibit the elevation of AqH protein.

The reason for the amelioration of N-methyl-N-nitrosourea-induced retinitis pigmentosa in rats by hydrogen-rich saline.

AIM: To investigate the effects of hydrogen-rich saline (HRS) on microglia activation and Sirtuin type 1 (Sirt1) in rats with N-methyl-N-nitrosourea (MNU)-induced retinitis pigmentosa (RP). METHODS: Rats were divided into norm (N) group, model (M) group and HRS (H) group. Rats in M and H groups were given saline and HRS respectively prior to and after administration of MNU. At one day (d1) and d3 afterwards, electroretinogram and histological examination were performed to confirm the effects of HRS on retinal function and structure of MNU-induced RP. Immunofluorescence staining of anti-ionized calcium-binding adapter molecule 1 (Iba1), a maker of microglia cells, was performed, with quantitative real-time polymerase chain reaction (qRT-PCR) for its mRNA quantification. Moreover, Sirt1 mRNA and protein expression in the retinas were detected by Western blot and qRT-PCR. RESULTS: HRS preserved the retinal function and mitigated the reduction of photoreceptor degeneration in MNU-treated retinas. The presence of microglia cells was somewhat more obvious in H group than that in M group at d1. HRS suppressed the further activation of microglia cells, with the number of microglia cells less than that of M group at d3. Results of qRT-PCR of Iba1 were consistent with those of immunofluorescence staining, with the mRNA expression of Iba1 in H group more intensive than that of M group at d1 (P<0.05), while less than that of M group at d3 (P<0.05). Furthermore, the Sirt1 mRNA and protein expression decreased after MNU administration, while HRS mitigated the MNU-induced downregulation of Sirt1. CONCLUSION: HRS can effectively keep microglia activation induced by MNU to an appropriate extent, while upregulate Sirt1 in MNU-induced RP.

Hydrogen-rich Saline is ineffective in oxygen-induced retinopathy.

AIMS: Hydrogen-rich saline (HRS) is a novel protection against various oxidative disorders and almost all types of inflammation. Moreover, its toxicity and side effects are rarely reported. We sought to clarify the protective effect of HRS against the oxygen-induced retinopathy (OIR) in C57BL/6 J model. MAIN METHODS: The OIR in the HRS treated mice and the untreated controls were systematically compared. The retinas of both groups were analyzed using high-molecular-weight FITC-dextran staining of flat-mount preparations, hematoxylin and eosin (H&E) staining of cross-sections. The distribution and expression of the vascular endothelial growth factor (VEGF) were also evaluated by the immunohistochemical measurements between postnatal days 17 (P17) and P21. KEY FINDING: The leakage and non-perfusion areas of retinal blood vessels were not alleviated in the HRS treatment group. Moreover, the number of preretinal vascular endothelial cell in the HRS treatment group was similar to that in the untreated group after exposure to hyperoxia (P>0.05). The degree of OIR was positively correlated with the expression level of VEGF. Intriguingly, the preretinal vascular endothelial cell count in the retinas of pups reared in room air with HRS treatment was 15.21±2.98. The preretinal vascular endothelial cell count of the HRS treated mice was significantly higher than that of the untreated group reared in room air. SIGNIFICANCE: In summary, HRS therapy (at the dose of 10ml/day, applied between P12 and P17) did not inhibit retinal neovascularization in OIR; On the contrary, it would induce the retinal neovascularization during the development of normal retinas.

The Time Course of Deafness and Retinal Degeneration in a Kunming Mouse Model for Usher Syndrome.

Usher syndrome is a group of autosomal recessive diseases characterized by congenital deafness and retinitis pigmentosa. In a mouse model for Usher syndrome, KMush/ush, discovered in our laboratory, we measured the phenotypes, characterized the architecture and morphology of the retina, and quantified the level of expression of pde6b and ush2a between postnatal (P) days 7, and 56. Electroretinograms and auditory brainstem response were used to measure visual and auditory phenotypes. Fundus photography and light microscopy were used to measure the architecture and morphology of the retina. Quantitative real-time PCR was used to measure the expression levels of mRNA. KMush/ush mice had low amplitudes and no obvious waveforms of Electroretinograms after P14 compared with controls. Thresholds of auditory brainstem response in our model were higher than those of controls after P14. By P21, the retinal vessels of KMush/ush mice were attenuated and their optic discs had a waxy pallor. The retinas of KMush/ush mice atrophied and the choroidal vessels were clearly visible. Notably, the architecture of each retinal layer was not different as compared with control mice at P7, while the outer nuclear layer (ONL) and other retinal layers of KMush/ush mice were attenuated significantly between P14 and P21. ONL cells were barely seen in KMush/ush mice at P56. As compared with control mice, the expression of pde6b and ush2a in KMush/ush mice declined significantly after P7. This study is a first step toward characterizing the progression of disease in our mouse model. Future studies using this model may provide insights about the etiology of the disease and the relationships between genotypes and phenotypes providing a valuable resource that could contribute to the foundation of knowledge necessary to develop therapies to prevent the retinal degeneration in patients with Usher Syndrome.

Recent advances in the dark adaptation investigations.

Dark adaptation is a highly sensitive neural function and may be the first symptom of many status including the physiologic and pathologic entity, suggesting that it could be instrumental for diagnose. However, shortcomings such as the lack of standardized parameters, the long duration of examination, and subjective randomness would substantially impede the use of dark adaptation in clinical work. In this review we summarize the recent research about the dark adaptation, including two visual cycles-canonical and cone-specific visual cycle, affecting factors and the methods for measuring dark adaptation. In the opinions of authors, intensive investigations are needed to be done for the widely use of this significant visual function in clinic.

Sirtuin Type 1 Mediates the Retinal Protective Effect of Hydrogen-Rich Saline Against Light-Induced Damage in Rats.

PURPOSE: Molecular hydrogen has been used as an antioxidant to treat many diseases in clinical and animal studies. However, the therapeutic mechanism of molecular hydrogen remains unclear. We previously reported mitigation of light-induced damage in the rat retina by intraperitoneal injection of hydrogen-rich saline (HRS). In the present study, we investigated whether Sirtuin Type 1 (Sirt1), a class III histone deacetylase, mediates the retinal protective effect of HRS in rats with light-induced retinal damage. METHODS: Rats were treated with HRS for 5 days after intense light exposure, and then ERGs were performed and retinas were collected to evaluate the effect of HRS on Sirt1 expression. The necessity of Sirt1 for the retinal protective effect of HRS was investigated using the Sirt1 activator resveratrol, the Sirt1 inhibitor EX-527, and short interfering RNAs. RESULTS: In light-damaged retinas, 5 days of HRS treatment increased Sirt1 expression, mitigated a- and b-wave amplitude reduction, and decreased the reduction of outer nuclear cell layers. The Sirt1 activator resveratrol mimicked the effect of HRS in light-damaged retinas. This result supported our hypothesis that Sirt1 mediates the protective effect of HRS. Additionally, the retinal protective effect of HRS was inhibited by both the Sirt1 inhibitor EX-527 and Sirt1 targeted short interfering RNAs. Hydrogen-rich saline also increased B-cell lymphoma 2 (Bcl-2) expression and the activity of the antioxidant enzyme superoxide dismutase (SOD). Conversely, HRS decreased Bcl2-associated X protein expression, cleaved caspase-3, and oxidant-stress product malondialdehyde (MDA) in a Sirt1-dependent manner. CONCLUSIONS: Sirt1 mediates light-induced damage mitigation by HRS through inhibition of apoptosis and oxidant-stress.

Validation of the Chinese Version of ID-Migraine in Medical Students and Systematic Review with Meta-Analysis Concerning Its Diagnostic Accuracy.

AIMS: To validate the Chinese version of Migraine Screener (ID-Migraine) in medical students in mainland China and to estimate the diagnostic accuracy of ID-Migraine by means of a systematic review with meta-analysis. METHODS: A total of 555 medical university students participated in the clinical study. Of these, 190 volunteered to take part in a face-to-face consultation and 365 in a telephone interview to diagnose the presence of migraine according to the criteria of the International Classification of Headache Disorders. The correctness of the diagnosis made clinically and by telephone was assessed by Cohen's kappa statistics. Twenty-two studies were included in the meta-analysis. Sensitivity and specificity were calculated for the clinical study and the meta-analysis. RESULTS: The overall sensitivity and specificity of the Chinese version of ID-Migraine was 84.0% (95% confidence intervals [CI]: 75.0%-90.0%) and 64.0% (95% CI: 59.0%-68.0%), respectively. The Cohen's kappa value of the diagnosis obtained by the face-to-face consultation and the telephone interview was 0.85 (95% CI: 0.69-1.00). A total of 8,682 participants from the 22 studies were included in the meta-analysis. The pooled sensitivity, specificity, and diagnostic odds ratio were 81.0% (95% CI: 80.0%-82.0%), 68.0% (95% CI: 66.0%-69.0%) and 17.03 (95% CI: 9.94-29.18), respectively. CONCLUSIONS: The accurate recognition of migraine by the medical students suggests that the Chinese ID-Migraine version is a valid screening tool. In addition the meta-analysis confirmed the high diagnostic accuracy of this screening tool.

A naturally occurring rat model of X-linked cone dysfunction.

PURPOSE: To describe the electrophysiological, histologic, and hereditary features of a naturally occurring rat model of cone function loss. METHODS: Dark- and light-adapted electroretinograms (ERGs) were used to evaluate retinal function. The thickness and architecture of the retina were observed by light microscopy. The cone density was investigated by wholemount immunocytochemistry. The inheritance pattern was defined by mating with control female rats. RESULTS: In affected rats, light-adapted ERGs were nearly absent, whereas dark-adapted responses were of normal amplitude with delays in b-wave implicit time. Overall retinal structure was normal at the light microscopic level. There was no difference in cone density between control and affected rats. The cone function abnormality is inherited as an X-linked trait. CONCLUSIONS: A spontaneous rat mutant was identified that has markedly affected cone function, whereas rod-mediated function is largely spared. The presence of the normal number of cone outer segments indicates that the defect does not involve cone photoreceptor degeneration. This rat model provides a model of X-linked cone dysfunction, and may also be used to examine aspects of rod-mediated visual function in the rat. Further studies are needed to identify the gene that is involved.

[Effects of infrasound on visual electrophysiology in mice].

OBJECTIVE: To investigate the possible effects of infrasound on visual functions. METHOD: One hundred and fifty mature male Kunming-mice were divided into 5 groups, in which one was control and the other four were exposed to infrasound of 8 Hz, 90 dB; 8 Hz, 130 dB; 16 Hz, 90 dB and 16 Hz, 130 dB 2 h/d respectively. The exposure time for them were 0, 1, 4, 7, 14 and 21 d respectively, each group was divided into 6 sub-groups. Electroretinogram (ERG), oscillatory potentials (OPs), and visual evoked potential (VEP) were recorded after exposure. RESULT: The visual electrophysiological indices after 8 Hz, 90 dB and 16 Hz, 90 dB exposures were similar except for a little difference at some temporal points (P<0.05). Most of the indices in 8 Hz, 130 dB group changed after 7 d exposure, and the longer the exposure, the more obvious changes were observed (P<0.01). The indices in 16 Hz, 130 dB group changed obviously after 1 d and reversed with increase of exposure time (P<0.01). CONCLUSION: The effect of infrasound on visual functions are related to its frequency and intensity. Infrasound of different frequencies causes different levels of retinal resonance, which leads to different degrees of cellular lesion and produces different electrical potentials.

Oxygen-induced retinopathy in mice with retinal photoreceptor cell degeneration.

AIMS: It is reported that retinal neovascularization seems to rarely co-exist with retinitis pigmentosa in patients and in some mouse models; however, it is not widely acknowledged as a universal phenomenon in all strains of all animal species. We aimed to further explore this phenomenon with an oxygen-induced retinopathy model in mice with retinal photoreceptor cell degeneration. MAIN METHODS: Oxygen-induced retinopathy of colored and albino mice with rapid retinal degeneration were compared to homologous wild-type mice. The retinas were analyzed using high-molecular-weight FITC-dextran stained flat-mount preparation, hematoxylin and eosin (H&E) stained cross-sections, an immunohistochemical test for vascular endothelial growth factor (VEGF) distribution and Western blotting for VEGF expression after exposure to hyperoxia between postnatal days 17 (P17) and 21. KEY FINDINGS: Leakage and areas of non-perfusion of the retinal blood vessels were alleviated in the retinal degeneration mice. The number of preretinal vascular endothelial cell nuclei in the retinal degeneration mice was smaller than that in the homologous wild-type mice after exposure to hyperoxia (P<0.01). The degree of oxygen-induced retinopathy was positively correlated with the VEGF expression level. However, the VEGF expression level was lower in the retinal degeneration mice. SIGNIFICANCE: Proliferative retinopathy occurred in mice with rapid retinal degeneration, but retinal photoreceptor cell degeneration could partially restrain the retinal neovascularization in this rapid retinal degeneration mouse model.

Workload influence on fatigue related psychological and physiological performance changes of aviators.

OBJECTIVE: We evaluated a variety of non-invasive physiological technologies and a series of test approaches for examination of aviator performances under conditions of mental workload in order to provide a standard real-time test for physiological and psychological pilot fatigue assessments. METHODS: Twenty-one male aviators were selected for a simulated flight in a hypobaric cabin with artificial altitude conditions of 2400 meter above sea level. The simulated flight lasted for 1.5 h, and was repeated for two times with an intervening 0.5 h rest period outside the hypobaric cabin. Subjective criteria (a fatigue assessment instrument [FAI]) and objective criteria (a standing-position balance test as well as a critical flicker fusion frequency (CFF) test) were used for fatigue evaluations. RESULTS: No significant change was observed in the FAI scores before and after the simulated flight, indicating that there was no subjective fatigue feeling among the participants. However, significant differences were observed in the standing-position balance and CFF tests among the subjects, suggesting that psychophysiological indexes can reflect mental changes caused by workload to a certain extent. The CFF test was the simplest and clearly indicated the occurrence of workload influences on pilot performances after a simulated flight. CONCLUSIONS: Results showed that the CFF test was the easiest way to detect workload caused mental changes after a simulated flight in a hypobaric cabin and reflected the psychophysiological state of aviators. We suggest that this test might be used as an effective routine method for evaluating the workload influences on mental conditions of aviators.