Distal-scanning common path probe for optical coherence tomography

In this paper,we present a distal-scanning common path probe for optical coherence tomography(OCT)equipped with a hollow ultrasonic motor and a simple and specially designed beam-splitter.This novel probe proves to be able to effectively circumvent polarization and dispersion mismatch caused by fiber motion and is more robust to a variety of interfering factors during the imaging process,experimentally compared to a conventional noncommon path probe.Furthermore,our design counteracts the attenuation of backscattering with depth and the fall-off of the signal,resulting in a more balanced signal range and greater imaging depth.Spectral-domain OCT imaging of phantom and biological tissue is also demonstrated with a sensitivity of∼100dB and a lateral resolution of∼3μm.This low-cost probe offers simplified system configuration and excellent robustness,and is therefore particularly suitable for clinical diagnosis as one-off medical apparatus.

Predictive visual field outcomes after optic chiasm decompressive surgery by retinal vessels parameters using optical coherence tomography angiography

AIM:To evaluate the predictive value of superficial retinal capillary plexus(SRCP)and radial peripapillary capillary(RPC)for visual field recovery after optic cross decompression and compare them with peripapillary nerve fiber layer(pRNFL)and ganglion cell complex(GCC).METHODS:This prospective longitudinal observational study included patients with chiasmal compression due to sellar region mass scheduled for decompressive surgery.Generalized estimating equations were used to compare retinal vessel density and retinal layer thickness preand post-operatively and with healthy controls.Logistic regression models were used to assess the relationship between preoperative GCC,pRNFL,SRCP,and RPC parameters and visual field recovery after surgery.RESULTS:The study included 43 eyes of 24 patients and 48 eyes of 24 healthy controls.Preoperative RPC and SRCP vessel density and pRNFL and GCC thickness were lower than healthy controls and higher than postoperative values.The best predictive GCC and pRNFL models were based on the superior GCC[area under the curve(AUC)=0.866]and the tempo-inferior pRNFL(AUC=0.824),and the best predictive SRCP and RPC models were based on the nasal SRCP(AUC=0.718)and tempo-inferior RPC(AUC=0.825).There was no statistical difference in the predictive value of the superior GCC,tempo-inferior pRNFL,and tempo-inferior RPC(all P>0.05).CONCLUSION:Compression of the optic chiasm by tumors in the saddle area can reduce retinal thickness and blood perfusion.This reduction persists despite the recovery of the visual field after decompression surgery.GCC,pRNFL,and RPC can be used as sensitive predictors of visual field recovery after decompression surgery.

Visual Passive Ranging Method Based on Re-entrant Coaxial Optical Path and Experimental Verification

To overcome the shortcomings of the traditional passive ranging technology based on image, such as poor ranging accuracy, low reliability and complex system, a new visual passive ranging method based on re-entrant coaxial optical path is presented. The target image is obtained using double cameras with coaxial optical path. Since there is imaging optical path difference between the cameras, the images are different. In comparison of the image differences, the target range could be reversed. The principle of the ranging method and the ranging model are described. The relationship among parameters in the ranging process is analyzed quantitatively. Meanwhile,the system composition and technical realization scheme are also presented. Also, the principle of the method is verified by the equivalent experiment. The experimental results show that the design scheme is correct and feasible with good robustness. Generally, the ranging error is less than 10% with good convergence. The optical path is designed in a re-entrant mode to reduce the volume and weight of the system. Through the coaxial design,the visual passive range of the targets with any posture can be obtained in real time. The system can be widely used in electro-optical countermeasure and concealed photoelectric detection.

Optical coherence tomography angiography of optic disc perfusion in non-arteritic anterior ischemic optic neuropathy

AIM：To compare the optic disc blood flow of non-arteritic ischemic optic neuropathy（NAION）eyes with normal eyes.METHODS：The optic disc blood flow densities of diagnosed non-acute phase NAION eyes（21 eyes,14 individuals）and normal eyes（19 eyes,12 individuals）were detected via Optovue optical coherence tomography angiography（OCTA）.The optic disc blood flow was measured via Image J software.Correlations between optic disc perfusion and visual function variables were assessed by linear regression analysis.RESULTS：The average percentage of the optic disc nonperfusion areas in the non-acute phase NAION patients（17.84%±6.18%）was increased,when compared to the normal control eyes（8.61%±1.65%）,and the difference was statistically significant（P〈0.01）.Moreover,there was a proportional correlation between the visual field mean defect（MD）and the optic disc non-perfusion area percentage,and the relationship was statistically significant（t=3.65,P〈0.01,R2=0.4118）.In addition,the critical correlation between the best corrected visual acuity（BCVA）and the optic disc non-perfusion area percentage was statistically significant（t=4.32,P〈0.01,R2=0.4957）.CONCLUSION：The optic disc non-perfusion area percentages detected via OCTA in NAION eyes were significantly increased when compared with the normal eyes.Both the BCVA and MD were correlated with the optic disc flow detected,revealing that OCTA may be valuable in the diagnosis and estimation of NAION.

A Meta-analysis of the association between different genotypes(G11778A, T14484C and G3460A ) of Leber hereditary optic neuropathy and visual prognosis

AIM：To analyze the influences of different genotypes（G11778A,T14484 C and G3460A） of Leber hereditary optic neuropathy（LHON） on visual prognosis. METHODS： After a systematic literature search,all relevant studies evaluating the association between the three primary mutations of LHON and visual prognosis were included.All statistical tests were calculated with Revman 5.2 and STATA 12.0. RESULTS： Ten independent studies were included finally.A significant association between the three primary mutations and prognostic vision over 0.3 were found in G11778 A versus T14484 C [odds ratio（OR） =0.10,95% confidence interval（CI） =0.05-0.17,P 〈0.001],G11778 A versus G3460A（OR=0.18,95%CI=0.09-0.37,P 〈0.001） and T14484 C versus G3460A（OR =2.45,95% CI =1.10-5.48,P 〈0.05）.In addition,obtained by pairwise comparison,the vision during onset,age of onset and sex ratio of these three kinds of patients,have no statistical significance（P 〉0.05）.CONCLUSION： From pairwise comparison,we conclude that these three different genotypes of LHON are related to patients＇ visual prognosis.The T14484 C patients might have a best prognostic vision,G3460 A second,and G11778 A worst.And there is little relation between the three different genotypes and patients＇ vision,age of onset and sex ratio.

All-optical vector visual cryptography with high security and rapid decryption

Meta optics-empowered vector visual cryptography at the abundant degrees of freedom of light and spatial dislocation can open an avenue for optical information security and anti-counterfeiting with a compact footprint and rapid decryption.

Effects of optical axis direction on optical path difference and lateral displacement of Savart polariscope

A simple method is applied to calculating the optical path difference （OPD） of a plane parallel uniaxial plate with an arbitrary optical axis direction. Then, the theoretical expressions of the OPD and lateral displacement （LD） of Savart polariscope under non-ideal conditions are obtained exactly. The variations of OPD and LD are simulated, and some important conclusions are obtained when the optical axis directions have an identical tolerance of ／pm 1^{{／circ}}. An application example is given that the tolerances of optical axis directions are gained according to the spectral resolution tolerances of the stationary polarization interference imaging spectrometer （SPIIS）. Several approximate formulae are obtained for explaining some conclusions above. The work provides a theoretical guidance for the optic design, crystal processing, installation and debugging, data analysis and spectral reconstruction of the SPIIS.

Analysing the structure of the optical path length of a supersonic mixing layer by using wavelet methods

The nano-particle-based planar laser scattering （NPLS） technique is used to measure the density distribution in the supersonic mixing layer of the convective Mach number 0.12, and the optical path difference （OPL）, which is quite crucial for the study of aero-optics, is obtained by post processing. Based on the high spatiotemporal resolutions of the NPLS, the structure of the OPL is ana]ysed using wavelet methods. The coherent structures of the OPL are extracted using three methods, including the methods of thresholding the coefficients of the orthogonal wavelet transform and the wavelet packet transform, and preserving a number of wavelet packet coefficients with the largest amplitudes determined by the entropy dimension. Their performances are compared, and the method using the wavelet packet is the best. Based on the viewpoint of multifractals, we study the OPL by the wavelet transform maxima method （WTMM）, and the result indicates that its scaling behaviour is evident.

Macular thickness as a predictor of loss of visual sensitivity in ethambutol-induced optic neuropathy

Ethambutol is a common cause of drug-related optic neuropathy.Prediction of the onset of ethambutol-induced optic neuropathy and consequent drug withdrawal may be an effective method to stop visual loss.Previous studies have shown that structural injury to the optic nerve occurred earlier than the damage to visual function.Therefore,we decided to detect structural biomarkers marking visual field loss in early stage ethambutol-induced optic neuropathy.The thickness of peripapillary retinal nerve fiber layer,macular thickness and visual sensitivity loss would be observed in 11 ethambutol-induced optic neuropathy patients（22 eyes） using optical coherence tomography.Twenty-four healthy age-and sex-matched participants（48 eyes） were used as controls.Results demonstrated that the temporal peripapillary retinal nerve fiber layer thickness and average macular thickness were thinner in patients with ethambutol-induced optic neuropathy compared with healthy controls.The average macular thickness was strongly positively correlated with central visual sensitivity loss（r2=0.878,P=0.000）.These findings suggest that optical coherence tomography can be used to efficiently screen patients.Macular thickness loss could be a potential factor for predicting the onset of ethambutol-induced optic neuropathy.

Structural-visual functional relationships detected by optical coherence tomography in varying age-cohorts' patients with optic neuritis

AIM: To assess the relationships of final best-corrected visual acuity(BCVA) and the optic nerve structural loss in varying age-cohorts of optic neuritis(ON) patients.METHODS: This is a retrospective, cross-sectional study.Totally 130 ON subjects(200 eyes) without ON onset within 6mo were included, who underwent BCVA assessment,peripapillary retinal nerve fibre layer(pRNFL) and macular segmented layers evaluation by optical coherence tomography(OCT).RESULTS: For the 0-18y cohort, the final BCVA(logMAR)was significantly better and less frequent recurrences than adult cohorts(P=0.000). The final BCVA(logMAR) in all age-cohorts of the ON patients had negative and linear correlations to the pRNFL thicknesses and macular retinal ganglion cell layer(mRGCL) volumes, when the pRNFL thicknesses were reduced to the thresholds of 57.2-67.5 μm or 0.691-0.737 mm;in mRGCL volumes, respectively, with the strongest interdependence in the 19-40y cohort. The ON patients from varying age cohorts would be threatened by blindness when their pRNFL thicknesses dropped 36.7-48.3 μm or the mRGCL volumes dropped to 0.495-0.613 mm;.CONCLUSION: The paediatric ON has best prognosis and young adult ON exhibits perfectly linear correlations of final vision and structural loss. The pRNFL and the mRGCL could be potential structural markers to predict the vision prognosis for varying-age ON patients.

Correlation between optical coherence tomography, multifocal electroretinogram findings and visual acuity in diabetic macular edema

AIM:To analyze the correlation between macular morphology and function in eyes with diabetic macular edema(DME).METHODS:Fifty-five eyes with different visual acuity(VA)of 32 patients who suffered from DME were analyzed using multifocal electroretinography(mfERG)and optical coherence tomography(OCT).The parameters of mfERG including implicit times and response amplitude were compared to those of 50 normal eyes of 36 age-matched subjects.Correlation analysis was performed between VA,the parameters of mfERG including implicit times and response amplitude,and the central macular thickness(CMT).RESULTS:The amplitude of N1 and P1 were significantly decreased and their latency were significantly increased in five ring regions of the retina in patients with DME.There was statistically significant correlation between logMAR BCVA and P1 amplitude densities in rings 1-4(r=-0.306,-0.536,-0.470,-0.362;P=0.023,<0.01,<0.01,0.007 respectively),N1 amplitude in ring 2 and ring 3(r=-0.035,-0.286;P=0.019,0.034 respectively).There was poor correlation between the CMT and best-corrected visual acuity(BCVA;r=0.288,P=0.033),but there was no significant correlation between CMT and amplitude or implicit time of N1 and P1(P>0.05)in the central macular ring.Multiple stepwise regression analysis showed that P1 amplitude density in ring 2 was the only contributor to the VA.CONCLUSION:It seems to be more appropriate of combining use of mfERG with OCT for the evaluation of macular function in eyes with DME.

Measurements of Nighttime Nitrate Radical Concentrations in the Atmosphere by Long-Path Differential Optical Absorption Spectroscopy

The long-path differential optical absorption spectroscopy （LP-DOAS） technique was developed to mea- sure nighttime atmospheric nitrate radical （NO3） concentrations. An optimized retrieval method, resulting in a small residual structure and low detection limits, was developed to retrieve NO3. The time series of the NO3 concentration were collected from 17 to 24 March, 2006, where a nighttime average value of 15.8 ppt was observed. The interfering factors and errors are also discussed. These results indicate that the DOAS technique provides an essential tool for the quantification of NO3 concentration and in the study of its effects upon nighttime chemistry.

Change of Visual Acuity and Related Factors in Idiopathic Optic Neuritis

Purpose : To study the change of visual acuity and related factors in idiopathic optic neuritis. Methods: Retrospectively studying 136 cases (210 eyes) of idiopathic optic neuritis hospitalized in our department during last 5 years. The data was analyzed with the methods of multivariate stepwise regression analysis by SPSS statistic package. Results: The final visual acuity was very strongly related positively to the initial visual acuity at the time point of starting treatment and negatively to the time span beginning the treatment to the time showing improvement, age of patient and the duration from onset of the disorder to the time point of treatment beginning. Conclusions: Promptly right treatment can significantly change the natural course and the final vision of optic neuritis. Severe visual loss, old age, longer time without right therapy and slow improvement after the treatment may indicate an unfavorable final visual recovery. The different dosages of steroid applied in this study was not significant in view of the final visual acuity. Eye Sience 2001; 17: 46 ～ 49.

Development of Dual-light Path Monitoring System of Optical Thin-film Thickness

The accurate monitoring of optical thin-film thickness is a key technique for depositing optical thin-film. For existing coating equipments, which are low precision and automation level on monitoring thin-film thickness, a new photoelectric control and analysis system has been developed. In the new system, main techniques include a photoelectric system with dual-light path, a dual-lock-phase circuit system and a comprehensive digital processing-control-analysis system.The test results of new system show that the static and dynamic stabilities and the control precision of thin-film thickness are extremely increased. The standard deviation of thin-film thickness, which indicates the duplication of thin-film thickness monitoring, is equal to or less than 0.72%. The display resolution limit on reflectivity is 0.02 %. In the system, the linearity of drift is very high, and the static drift ratio approaches zero.

Development of Functional Interlaminar Pathways in the Mouse Superior Colliculus Revealed by Optical Imaging with Axonal Labeling

The superior colliculus (SC) is a laminated midbrain structure responsible for visual orientation behaviors. In the mature SC, neurons in the stratum griseum superficiale (SGS) receive visual inputs that contribute to exciting premotor neurons in the stratum griseum intermediale (SGI) through a dorsoventral pathway. SGI activation generates feedback signals to the SGS through a ventrodorsal pathway. However, the developmental changes in signal transmission within the SC around the time of eye opening are not yet well understood. We compared the functional connections between the SGS and SGI before and after eye opening by imaging the neuronal population responses using a voltage-sensitive absorption dye in mouse SC slices. Electrophoresis of a fluorescent dye from the stimulating electrodes was used to fill the cells in the stimulated site. We here show that the dorsoventral transmission is present both before and after eye opening. This is in contrast to our previous finding that the ventrodorsal transmission develops after eye opening. Functions of intrinsic inhibitory systems mediated by gamma-aminobutyric acid were also investigated with the antagonist. The processes stained by electrophoresis from stimulating electrodes before eye opening were confined within the respective stimulated layers. Whereas, after eye opening, the processes were widely extended especially dorsoventrally and ventrodorsally invading the SGI and SGS, respectively. These corresponded well to the early component of voltage responses that is known to reflect the activation of presynaptic elements, presumably the axonal arborizations and varicosities. Thus, the optically-revealed functional connections between the SGS and SGI were correlated to the morphology.

An Optical Path Length Modulator for Laser Diode Self-Mixing Interference

Transparent liquid flattening or stretching realizes optical path length modulation. A flat thin seal transparent cavity, one flank is an electromagnetic driving membrane and is filled over with transparent liquid. Vibration of the membrane makes the liquid compressing or stretching, changes the liquid layer thickness, i.e. the optical path length of light through the liquid layer. The liquid layer compressed is equivalent to increase membrane tension. The membrane has higher resonant frequency. The cavity diameter 10 mm modulation frequency is about 18 kHz.

Modified Ceiling Bounce Model for Computing Path Loss and Delay Spread in Indoor Optical Wireless Systems

This paper proposes modifications to the tradional Ceiling Bounce Model and uses it to characterize diffuse indoor optical wireless channel by analyzing the effect of transceiver position on signal propagation properties. The modified approach uses a combination of the tradional ceiling bounce method and a statistical approach. The effects of different transmitter-receiver separations and height of the ceiling on path loss and delay spread are studied in detail.

Visual Functions and TraceElement Metabolism in Tobacco-toxic Optic Neuropathy

Visual functions and nutrition metabolic characteristics werestudied in 8 subjects(16 eyes)with tobacco-toxic optic neuropathy(TTON).Their visual functions tested by psychophysical and electrophysiologicmethods showed that:1.central vision diminished in 16 eyes,2.dyschromatopsias were found in 14 tested eyes,3.bilateral symmetricalcentral or cecocentral scotomas were the visual field characteristics in allcases,4.PVEP were severe abnormal in 3 spatial frequencies in all cases and56.3% of 15' checkboard ...

Effect of Wei’s triple nine needling therapy on flash visual evoked potentials in rats with traumatic optic neuropathy

Objective:To investigate the effect of Wei’s triple nine needling therapy on the N2-P2 wave of the flash visual evoked potential(FVEP)in rats of the of the transverse directional pulling model.Methods:Thirty-six Wistar rats were randomly grouped,nine were in normal control group without any treatment,and the remaining 27 were surgically modelled in the right eyes.Eighteen of these rats were randomly divided into a Wei’s triple nine needling therapy group and a model group of nine rats each after the TON model was made using the transverse quantitative retraction method.The other 9 rats were sham-operated,and only the optic nerve was exposed without retraction.On the next day of modelling,the Wei’s triple nine needling therapy group was treated with Wei’s triple nine needling therapy for 20 minutes/1 time/1 day for 14 days.The model group,sham-operated group and normal control group were not intervened.Wei's triple nine acupoints were represented as follows:1st link:"Jingming"(BL1)and"Chengqi"(ST1);2nd link:"Sizhukong"(SJ23)penetrating"Taiyang"(EX-HN5);and the third:"Fengchi"(GB 20)and"Taichong"(LV3).The FVEP of each group was observed on 1d,7d and 14d.The FVEP of each group was observed on 1d,7d and 14d.Results:Compared with the model group,the N2 wave latency and P2 wave latency were shortened in the Wei’s triple nine needling therapy on 1d(P<0.05,P<0.01);on 7d,their N2 wave latency was shortened(P<0.01)and the N2-P2 wave amplitude was increased compared with the model group(P<0.05);on 14d,their P2 wave latency was shortened(P<0.05)and the N2-P2 wave amplitude was increased.There was no statistical difference in N2 wave latency,P2 wave latency and N2-P2 wave amplitude in the sham-operated group on 1d,7d and 14d(P>0.05).The delayed N2 and P2 wave latencies in the model group did not improve from 1d to 14d(P>0.05)and the amplitude decreased throughout,showing a significant difference on 14d compared to 1d(P<0.05).In contrast,the N2 wave latency in Wei’s triple nine needling therapy group was not significantly different until 7d to 14d(P<0.05);its P2 wave latency,although significantly delayed from 1d to 7d(P<0.05),recovered on 14d and reached a level that was not statistically different from 1d and 7d(P>0.05).There was also no significant decrease in N2-P2 wave amplitude between 1d and 14d in Wei’s triple nine needling therapy group(P>0.05).Conclusion:In this experiment,the TON rat model was successfully established by the transverse quantitative retraction method,and the treatment of TON rats with Wei’s triple nine needling therapy reduced the P2 wave delay of the FVEP electrophysiological signal and increased the N2-P2 amplitude,which had a certain positive effect on the repair of optic nerve injury,probably related to its effect of improving the conduction function of the optic nerve and protecting the retinal ganglion cells that had not been degenerated and necrosed.

Optical coherence tomography in ischemic optic neuropathy

Ischemic optic neuropathies are among the most common causes of sudden vision loss,especially in patients over age 50.The cause and prognosis of these disorders,and in particular non-arteritic anterior ischemic optic neuropathy,is poorly understood,and treatments remain poor in terms of restoring or preserving vision.Optical coherence tomography(OCT)and OCT angiography have allowed us to identify early and late structural changes in the optic nerve head and retina that may assist in predicting visual outcomes and may lead to greater understanding of pathogenesis and thus the development of effective medical interventions.