Spectral Domain Optical Coherence Tomography of Vogt-Koyanagi-Harada Disease: Novel Findings and New Insights into the Pathogenesis

Objective To provide novel spectral domain optical coherence tomography (SD OCT) findings of Vogt-Koyanagi-Harada (VKH) disease as well as new insights into the pathogenesis of this disease. Methods Detailed SD OCT and fluorescein angiography (FA) findings of 18 consecutive VKH patients (11 women and 7 men) from December 2007 to April 2009 who were in acute uveitic stage at presentation were reviewed. All the patients had been followed up for at least 6 months with reevaluation(s) of SD OCT performed in 10 patients. Results Intraretinal cysts were found to be located in various layers of the outer retina. In addition to the photoreceptor layer, they could also be found between the outer plexiform layer and the outer nuclear layer, or spanning the external limiting membrane. On FA, intraretinal cysts could be hypofluorescent, normofluorescent, or hyperfluorescent. Some intraretinal cysts had a characteristic FA pattern, in which a small round hypofluorescent area was surrounded by a ring of hyperfluorescence (donut-shaped dye pooling). Subretinal fibrinoid deposit appeared in acute uveitic stage in two severe VKH patients and seemed to develop from subretinal exudates and evolved into typical subretinal fibrosis. Gradual transfiguration/migration and progressive proliferation/pigmentation of the subretinal fibrinoid deposit/subretinal fibrosis was observed in one patient. Conclusions Intraretinal cysts could form in various layers of the outer retina and may result from extension of choroidal inflammation. Subretinal fibrosis may develop from subretinal exudates in VKH patients and may cause substantial visual impairment.

Spectral domain optical coherence tomography crosssectional image of optic nerve head during intraocular pressure elevation

AIM: To analyze changes of the optic nerve head(ONH) and peripapillary region during intraocular pressure(IOP) elevation in patients using spectral domain optical coherence tomography(SD-OCT).METHODS: Both an optic disc 200×200 cube scan and a high-definition 5-line raster scan were obtained from open angle glaucoma patients presented with monocular elevation of IOP(≥30 mm Hg) using SD-OCT. Additional baseline characteristics included age, gender, diagnosis,best-corrected visual acuity, refractive error, findings of slit lamp biomicroscopy, findings of dilated stereoscopic examination of the ONH and fundus, IOP, pachymetry findings, and the results of visual field.RESULTS: The 24 patients were selected and divided into two groups: group 1 patients had no history of IOP elevation or glaucoma(n =14), and group 2 patients did have history of IOP elevation or glaucoma(n =10). In each patient, the study eye with elevated IOP was classified into group H(high), and the fellow eye was classified into group L(low). The mean deviation(MD)differed significantly between groups H and L when all eyes were considered(P =0.047) and in group 2(P =0.042), not in group 1(P =0.893). Retinal nerve fiber layer(RNFL) average thickness(P =0.050), rim area(P =0.015),vertical cup/disc ratio(P =0.011), cup volume(P =0.028),inferior quadrant RNFL thickness(P =0.017), and clockhour(1, 5, and 6) RNFL thicknesses(P =0.050, 0.012, and0.018, respectively), cup depth(P =0.008), central prelaminar layer thickness(P =0.023), mid-inferior prelaminar layer thickness(P =0.023), and nasal retinal slope(P =0.034)were significantly different between the eyes with groups H and L.CONCLUSION:RNFLaveragethickness,rim area,vertical cup/disc ratio, cup volume, inferior quadrant RNFL thickness, and clock-hour(1, 5, and 6) RNFL thicknesses significantly changed during acute IOP elevation.

Systematic review of macular ganglion cell complex analysis using spectral domain optical coherence tomography for glaucoma assessment

AIM: To review the use of spectral domain optical coherence tomography(SD-OCT) for macular retinal ganglion cells(RGC) and ganglion cell complex(GCC) measurement in glaucoma assessment, specifically for early detection and detection of disease progression. METHODS: A systematic review was performed by searching Pub Med, Medline, and Web of Science for articles published in English through July 2014 describing the various macular SD-OCT scanning strategies developed for glaucoma assessment. The review focused on papers evaluating the use of macular RGC/GCC SDOCT to detect early glaucoma and its progression. The search included keywords corresponding to the index test(macular ganglion cell/RGC/GCC/Spectral domain OCT), the target condition(glaucoma), and diagnostic performance. The RGC/GCC SD-OCT scanning strategies used to assess glaucoma of most commonly used SD-OCT instruments were described and compared. These included the Cirrus high definition-OCT(Carl Zeiss Meditec, Inc., Dublin, CA, United States), RTVue(Optovue, Inc., Fremont, CA, United States), Spectralis(Heidelberg Engineering, Heidelberg, Germany) and the 3D OCT 2000(Topcon Corporation, Tokyo, Japan). Studies focusing on the ability of RGC/GCC SD-OCT to detect early glaucomatous damage and on the correlation between glaucomatous progression and RGC/GCC measurement by SD-OCT were reviewed.RESULTS: According to the literature, macular RGC/GCC SD-OCT has high diagnostic power of preperimetric glaucoma, reliable discrimination ability to differentiate between healthy eyes and glaucomatous eyes, with good correlation with visual filed damage. The current data suggests that it may serve as a sensitive detection tool for glaucomatous structural progression even with mild functional progression as the rate of change of RGC/GCC thickness was found to be significantly higher in progressing than in stable eyes. Glaucoma assessment with RGC/GCC SD-OCT was comparable with and sometimes better than circumpapillary retinal nerve fiber layer thickness measurement.CONCLUSION: An increasing body of evidence supports using macular RGC/GCC thickness as an indicator for early glaucoma. This might be a useful tool for monitoring disease progression.

Microperimetry and spectral domain optical coherence tomography in myelinated retinal nerve fibers

Dear Sir,I write to present the correlation between microperimetric （MP） values and the density of myelinated retinal nerve fibers （MNFs） in optical coherence tomography （OCT） imaging.

Comment on “The diurnal variation pattern of choroidal thickness in macular region of young healthy female individuals using spectral domain optical coherence tomography”

Dear Editor,We have read and reviewed the article entitled＂The diurnal variation pattern of choroidal thickness in macular region of young healthy female individuals using spectral domain optical coherence tomography＂by Zhao et al^（[1]）with great interest.

Comparison of central macular thickness between two spectral-domain optical coherence tomography in elderly non-mydriatic eyes

AIM: To compare central macular thickness (CMT) measurements obtained by two spectral-domain optical coherence tomography (SD-OCT) exams, and to evaluate measurement reproducibility and agreement between these two exams, and to investigate the relationship between CMT and possible influencing factors such as age, sex, eye (OD/OS), and operators in elderly non-mydriatic eyes. METHODS: Seventy-two normal subjects were included. Every subject underwent CMT measurement twice using one of two SD-OCT (OSE-2000, Moptim, Shenzhen, China & 3-D OCT-1000, Topcon, Tokyo, Japan) instruments respectively where we randomly chose one eye in each patient for the test; these exams were performed by two operators over an hour period with a brief rest between sessions. Comparison of the OSE-2000 and 3-D OCT-1000 CMT measurements was based on paired- t test The mean difference between the CMT measurements was calculated. General linear model analyzed the relationships among eye (OD/OS), operator, sex, and CMT values using age as co-variant. All tests were considered statistically significant at P <0.05. The main outcome measures included CMT. RESULTS: When evaluated with general linear model analysis, CMT measurements were found to have high reproducibility across the two instruments between the two operators for the OSE-2000 single line scan and 3-D OCT-1000 macular scans (P=0.731; P=0.443). There was statistically significant difference in CMT values between the two instruments (P<0.001) and the mean difference was -46.83 mu m at 95% confidence limits (-49.15,-44.51). Age was positively correlated with CMT (beta coefficient =0.516, P=0.001; beta coefficient=0.453, P =0.009) and sex was correlated with CMT from the OSE-2000 (P=0.021) but not with the 3-D OCT-1000 (P=0.056). According to the actual thickness measurements, the CMT of the male was thicker than the female's but there was no statistical difference. There was interaction between sex and eye in OSE-2000 and not in 3-D OCT-1000 (P=0.02; P =0.374). No significant correlation was found between CMT and the influencing factor of eye in both of the instruments (P=0.884; P=0.492). CONCLUSION: Reproducibility of CMT measurement using the two SD-OCTs is excellent in normal eyes according to the operator factor analysis. OSE-2000 has a different posterior retinal boundary of CMT measurement, which results in the CMT value differences, compared with the 3-D OCT-1000. Age is positively correlated with CMT measurement while sex is correlated with CMT in the OSE-2000 but not in the 3-D OCT-1000 and eye (OD/OS) had no correlation with CMT values. Mydriatic drops may not be necessary for CMT measurement using high scan rate SD-OCT in normal eyes in dark room.

Choroidal Analysis of Polypoidal Choroidal Vasculopathy by Spectral Domain Optical Coherence Tomography

Purpose: This study was designed to measure the changes in the subfoveal choroidal thickness(SFCT) and choroidal maximal vessel diameter(MVD) of the affected and unaffected fellow eyes in patients with polypoidal choroidal vasculopathy(PCV) and compare them to healthy controls.Methods: In this cross-sectional observational clinical study,SFCT and MVD were measured in both eyes of 53 patients with unilateral PCV. PCV eyes were subgrouped into group A and unaffected fellow eyes into group B. All patients were diagnosed with PCV by fundus fluorescein angiography.(FFA)and indocyanine green angiography.(ICGA). Sixty age- and gender-matched healthy subjects were enrolled in the control group(group C).Results: No statistical difference was observed among groups in age and gender. Overall, SFCT was correlated with MVD in all subjects(P <0.001; correlation coefficient: 0.759). P values were < 0.001 with a correlation coefficient of 0.686,0.801, and 0.808 in groups A, B, and C, respectively. No statistical significance was noted in SFCT among groups A(266.45±99.51 μm),B(269.57 ± 105.10 μm),and C(243.83±99.68 μm)(P =0.335). However, the MVD in group A was(202.55±72.45 μm), significantly larger than that in group C(166.45 ±56.18 μm,P =0.008), while the MVD in group B(194.75±85.27 μm) was equally significantly greater than that in group C(166.45 ± 56.18 μm)(P=0.038).Conclusion: For both PCV patients and healthy subjects,SFCT was positively correlated with MVD. No statistical significance was noted in SFCT between PCV eyes and unaffected fellow / normal eyes. However, MVD was significantly larger in the PCV affected eyes than in unaffected fellow or normal control eyes, suggesting that MVD could be considered as a sensitive indicator to evaluate choroidal perfusion in PCV patients.

1310 nm Source Spectral-Domain Optical Coherence Tomography for Chinese Pigment and Jadeite Research

Optical Coherence Tomography (OCT) technique is a nondestructive optical detection technology based on low-coherence interferometer and it has become an attractive cultural heritage research method. A 1310 nm source spectral-domain optical coherence tomography (SD-OCT) system based on optical fiber Michelson interferometer and optical spectrum analyzer is proposed and demonstrated for Chinese cultural heritage research. The cross-section OCT images of Chinese pigment samples and jadeite samples can provide a lot of valuable microstructure information for the Chinese cultural heritage research and identification works.

Digital coherent detection research on Brillouin optical time domain reflectometry with simplex pulse codes

The digital coherent detection technique has been investigated without any frequency-scanning device in the Brillouin optical time domain reflectometry （BOTDR）, where the simplex pulse codes are applied in the sensing system. The time domain signal of every code sequence is collected by the data acquisition card （DAQ）. A shift-averaging technique is applied in the frequency domain for the reason that the local oscillator （LO） in the coherent detection is fix-frequency deviated from the primary source. With the 31-bit simplex code, the signal-to-noise ratio （SNR） has 3.5-dB enhancement with the same single pulse traces, accordant with the theoretical analysis. The frequency fluctuation for simplex codes is 14.01 MHz less than that for a single pulse as to 4-m spatial resolution. The results are believed to be beneficial for the BOTDR performance improvement.

Renal function and choroidal thickness using swept-source optical coherence tomography in diabetic patients

AIM: To assess the relationship between choroidal thickness and renal function in diabetic patients. METHODS: Cross-sectional retrospective clinical study of 42 eyes of 21 ocular treatment-na?ve diabetic patients. Demographic data included: age, sex, type and course of diabetes. Ocular data included: severity of diabetic retinopathy;retinal thickness at the central macular region, as well as choroidal thickness at the central and paracentral quadrants, using automatically generated maps by swept-source optical coherence tomography;presence of cystic macular edema;and ocular axial length(AXL). Lab-test parameters included: glycated hemoglobin(HbA1c), albuminuria, albumin/creatinine ratio in urine, and glomerular filtration rate. RESULTS: A significant negative correlation was mainly observed between several choroidal thicknesses, age(P<0.020) and ocular AXL(P<0.030). On the contrary, a significant positive correlation was found between all choroidal thicknesses, HbA1 c(P<0.035) and albuminuria(P<0.040). CONCLUSION: Choroidal thickness can represent an additional tool to help clinicians predicting the renal status in ocular treatment-na?ve diabetic patients.

Comparison of central corneal thickness measurements with three new optical devices and a standard ultrasonic pachymeter

AIM:To compare the RTVue spectral optical coherence tomography(SD-OCT),Sirius Scheimpflug-Placido topographer,Lenstar optical low coherence reflectometry(OLCR)and ultrasound pachymetry(USP)devices in terms of their agreement and repeatability of measuring central corneal thickness(CCT).METHODS:In this prospective study,50 eyes of 50patients were included.Three repeated measures were obtained using SD-OCT,Scheimpflug-Placido topographer and USP and five measurements were determined with the OLCR.Bland-Altman plots were used to assess agreement among the instruments,and 95%limits of agreement(LoA)for each comparison were calculated.Intra-examiner repeatability was assessed using intraclass correlation coefficients(ICCs).RESULTS:The mean CCT by SD-OCT,ScheimpflugPlacido topographer,OLCR,and USP were 525.90±34.08μm,525.92±34.10μm,530.30±35.62μm,and543.50±37.11μm respectively.All 4 modalities of CCT measurements correlated closely with each other,with Pearson correlation coefficients ranging from 0.977 to0.995.The mean differences(and upper/lower LoA)for CCT measurements were-0.05±6.77μm(13.3/-13.3)between SD-OCT and Scheimpflug-Placido topographer,4.38±3.79μm(11.8/-3.1)between OLCR and SD-OCT,4.38±6.03μm(16.2/-7.5)between OLCR and ScheimpflugPlacido topographer,13.20±6.46μm(25.9/0.5)between USP and OLCR,17.59±6.76μm(30.8/4.3)between USP and SD-OCT,and 17.58±8.13μm(33.5/1.6)between USP and Scheimpflug-Placido topographer.Intra-examiner repeatability was excellent for all devices with ICCs】0.98.CONCLUSION:For most practical purposes,CCT measurements with the RTVue,Sirius and Lenstar can be used interchangeably.Although highly correlated,CCTmeasurement differences between USP and these 3optical instruments can be significant depending on the clinical situation.

Comparing imaging capabilities of spectral domain and swept source optical coherence tomography angiography in healthy subjects and central serous retinopathy

Background:There are two forms of system implementation of optical coherence tomography angiography(OCTA)in ophthalmic imaging,i.e.,spectral domain(SD-)and swept source OCTA(SS-OCTA).The purpose of this paper is to compare the SD-OCTA and SS-OCTA for elucidating structural and vascular features associated with central serous retinopathy(CSR),and to evaluate the effects of CSR on SD-and SS-OCTA’s imaging capabilities.Methods:Normal subjects and CSR patients were imaged by SD-and SS-OCTA using 3×3 mm and 6×6 mm scan patterns.OCT signal strengths at the superficial retina,deep retina,Sattler’s layer and Haller’s layer were used to compare the ability of SD-and SS-OCTA to image structural features.In addition,the ability to acquire angiograms were discussed by evaluating retinal vessel density.Central serous volume(CSV)was measured and it was correlated with difference in signal strengths(ΔS)between two OCTA devices.Results:Seven normal eyes and seven diseased eyes were recruited.Results showed no significant differences between SD-and SS-OCT in detecting structural features of the retinal layer according to the paired t-test.However,when imaging the Sattler’s layer for normal eyes,a significant difference is found between SD-and SS-OCT(p<0.0001 for 3×3 mm scan,and p=0.0002 for 6×6 mm);while for CSR eyes,the corresponding values were p<0.0001 and p=0.0003,respectively.At Haller’s layer for normal eyes,the corresponding values were p=0.0004 and p=0.0014;and for CSR eyes,p=0.0004 and p<0.0001,respectively.A strong correlation betweenΔS and CSV was observed in the Sattler’s layer(3×3 mm–p=0.0031 and R^(2)=0.951;6×6 mm–p=0.0075 and R^(2)=0.911)and Haller’s layer(3×3 mm–p=0.0026 and R^(2)=0.955;6×6 mm–p=0.0013 and R^(2)=0.972).Conclusions:The results suggest no differences between SD-and SS-OCTA for imaging the retinal layers however,when imaging beyond retinal layers,SS-OCTA appears advantageous in detecting returning signals.In CSR cases,the CSV may have an impact on sub-CSR tissue imaging and appears to have more impact on SD-than SS-OCTA.

Importance of 3-D image reconstruction of spectraldomain OCT on outcome of grid laser photocoagulation for diffuse diabetic macular edema

AIM:To present the outcome of modified grid laser photocoagulation(GLP)in diffuse diabetic macular edema(DDME)in eyes without extrafoveal and/or vitreofoveal traction.METHODS:Inclusion criteria for the retrospective study were DDME eyes of patients with typeⅡdiabetes mellitus that had≥4 months of follow-up following GLP.Only one eye per patient was analyzed.Using 3-D spectral-domain optical coherence tomography(3-D SDOCT),eyes that had either extrafoveal or vitreofoveal traction,or had been previously treated by an intravitreal medication(s)were excluded.Treated DDME eyes were divided into 4 groups:A)"Classic"DDME that involved the central macula;B)edema did not involve the macular center;C)eyes associated with central epiretinal membrane(ERM);D)DDME that was associated with macular capillary dropout≥2 disc-diameter(DD).RESULTS:GLP outcome in 35 DDME eyes after 4-24(mean,13.1±6.9)months was as follows:Group A)18eyes with"classic"DDME.Following one or 2(mean,1.2)GLP treatments,best-corrected visual acuity(BCVA)improved by 1-2 Snellen lines in 44.4%(8/18)of eyes,and worsened by 1 line in 11.1%(2/18).Central macular thickness(CMT)improved by 7%-49%(mean,26.6%)in77.8%(14/18)of eyes.Causes of CMT worsening(n=4)were commonly explainable,predominantly(n=3)associated with emergence of extrafoveal traction,5-9months post-GLP.Group B)GLP(s)in DDME that did not involve the macular center(n=6)resulted in improved BCVA by 1-2 lines in 2 eyes.However,the central macula became involved in the edema process after the GLP in 3(50%)eyes,associated with an emergence of extrafoveal traction in one of these eyes 4months following the GLP.Group C)GLP failed in all 5eyes associated with central ERM.Group D)GLP was of partial benefit in 2 of 6 treated eyes with macular capillary dropout≥2DD.CONCLUSION:Eyes with DDME that involved the macular center were found to achieve favourable outcomes after GLP(s)during mid-term follow-up,unless complicated pre-GLP or post-GLP by vltreoretinal interface abnormalities,often extrafoveal traction or ERM,or by capillary dropout≥2DD.Prospective studies with larger cohorts are required.

Numerical Study on Spectral Domain Optical Coherence Tomography Spectral Calibration and Re-Sampling Importance

A spectral calibration technique, a data processing method and the importance of calibration and re-sampling methods for the spectral domain optical coherence tomography system were numerically studied, targeted to optical coherence tomography （OCT） signal processing implementation under graphics processing unit （GPU） architecture. Accurately, assigning the wavelength to each pixel of the detector is of paramount importance to obtain high quality images and increase signal to noise ratio （SNR）. High quality imaging can be achieved by proper calibration methods, here performed by phase calibration and interpolation. SNR was assessed employing two approaches, single spectrum moving window averaging and consecutive spectra data averaging, to investigate the optimized method and factor for background noise reduction. It was demonstrated that the consecutive spectra averaging had better SNR performance.

Macular ganglion cell complex injury in different stages of anterior ischemic optic neuropathy

BACKGROUND Anterior ischemic optic neuropathy(AION)is a group of ophthalmic diseases in which the optic nerve is injured causing blindness.However,the pathogenesis,clinical manifestations,and clinical treatments of AION are yet elusive.Only a few related experimental or clinical reports are available on the disease.In this study,spectral domain optical coherence tomography(SD-OCT)was used to examine the morphology of thickness swelling and atrophic changes of macular ganglion cell complex(mGCC)in the different stages of AION that were then compared with the visual fields.Thus,the clinical value of mGCC examination was alleged to be similar to that of the visual field.AIM To explore the mGCC injury at different stages in AION and the clinical significance.METHODS Cases with AION were analyzed in a retrospective study.SD-OCT was used to analyze the correlation between mGCC and peripapillary retinal nerve fiber layer thicknesses at different stages of AION and the changes in the corresponding stages of visual fields.RESULTS A total of 21 cases(28 eyes)presented AION.The onset time of AION was defined as early stage(within 3 wk of onset),middle stage(from 3 wk to 2 mo),and late stage(disease span>2 mo).In the early stage,the mGCC thickness of SD-OCT was within the normal high limit,and the perioptic nerve fibers thickness was more than the normal.The changes in the visual field in early stage were not consistent with the swelling changes in mGCC and peri-disc nerve fibers.In addition,atrophy and thinning appeared in mGCC,and the perioptic nerve fibers were swollen.However,the thickness was lower in the middle period than that in the early stage.The change in visual field was consistent with that of mGCC in this period.In the late stage,mGCC shrank and thinned,and the thickness of the nerve fibers around the optic disc in the corresponding region shrank and thinned.CONCLUSION The changes in mGCC thickness in patients with AION showed early,middle,and late stages of development by SD-OCT.Although the early stage visual field changes of AION were not consistent with the swelling changes of mGCC,the horizontal delimitation or annular atrophy of mGCC was consistent with that in the middle and late stage of the disease.The atrophy of peripheral nerve fibers was later than that of the mGCC atrophy.

频域OCT检测青光眼视网膜神经节细胞复合体厚度的研究

背景青光眼以视网膜神经节细胞（RGCs）丢失为主要的病理特征，频域光学相干断层扫描（SD—OCT）可以检测黄斑区视网膜神经节细胞复合体（GCC）厚度。目的探讨黄斑区视网膜GCC厚度在原发性开角型青光眼（POAG）人群的分布特征。方法采用系列病例对照研究设计。利用SD—OCT（RTVue-100）和时域OCT（TD—OCT）技术分别检测POAG患者101例101眼和年龄、屈光度相匹配的正常对照者41例41眼视网膜的黄斑区整体平均GCC厚度（GCC—Avg）、上方平均GCC厚度（GCC—Sup）和下方平均GCC厚度（GCC—Inf）及对应区域视盘旁视网膜神经纤维层（RNFL）厚度，按照POAG的程度分为视野损害前POAG组、早期POAG组、进展期POAG组和晚期POAG组，比较各POAG组与正常对照组间上述3个GCC参数的差异，分析GCC厚度和RNFL厚度的相关性以及青光眼患者视野平均缺损值（MD）与GCC厚度的相关性。结果视野损害前POAG组、早期POAG组GCC—Avg、GCC—Sup和GCC—Inf值均明显低于正常对照组，差异均有统计学意义（GCC—Avg：t：5．411、10．247，P〈0．01；GCC—Sup：t=6．171、9．484，P〈0．01；GCC—Inf：t=5．281、8．592，P〈0．01）。进展期POAG组GCC．Avg、GCC—Sup和GCC—Inf值均明显低于早期POAG组，差异均有统计学意义（GCC—Avg：t=4．246，P〈0．01；GCC—Sup：t=2．419，P=0．019；GCC—Inf：t=4．636，P〈0．01），而晚期POAG组GCC—Avg、GCC—Sup和GCC—Inf值均明显低于进展期POAG组，差异均有统计学意义（GCC—Avg：t=2．095，P=0．040：GCC—Sup：t=2．756，P〈0．01；GCC—Inf：t=2．018，P：0．040）。GCC—Sup、GCC—Inf和GCC—Avg值与对应区域平均RNFL厚度值均呈高度正相关（r=0．802、0．825、0．856，P〈0．01），青光眼患者的视野MD值与GCC—Avg值呈正相关（r=O．601，P〈0．01）。结论SD—OCT能够定量测量并区分青光眼患者与正常人群的黄斑区GCC厚度，GCC厚度随青光眼病情的进展而逐渐变薄，并与RNFL和视野的损害有较好的相关性。

基于相干光时域反射计的光纤温度传感测量

研究了基于相干光时域反射计的光纤传感技术,分析了基于相干光时域反射计的分布式温度传感机理.根据传感系统的组成和原理,建立了仿真模型,利用MATLAB对传感系统的性能进行了仿真与分析,结果表明基于相干光时域反射计的传感系统可以达到温度测量分辨率为0.01℃,空间分辨率为1m的性能指标.

频域光学相干断层扫描测量青光眼视网膜神经纤维层厚度的可重复性研究

目的利用频域光学相干断层扫描（SD-OCT）对青光眼患者盘周视网膜神经纤维层（RNFL）厚度进行观察测量,比较非Follow-up模式和Follow-up模式测量结果的可重复性。方法连续收集就诊于中国医科大学附属第一医院的青光眼患者38例,随机选择患者一侧眼进行测量。利用SD-OCT分别采用非Follow-up模式和Follow-up模式对盘周RNFL厚度进行测量,比较2种检查模式的组内标准差（Sw）、变异系数（CV）和组内相关系数（ICC）。结果非Follow-up模式测量RNFL厚度,Sw为3.67μm（视盘全周）-10.58μm（鼻侧象限）,CV为2.60%（视盘全周）-10.09%（鼻侧象限）,ICC为0.768（鼻侧象限）-0.974（视盘全周）。Follow-up模式测量RNFL厚度,Sw为1.42μm（视盘全周）-3.31μm（鼻上扇区）,CV为1.27%（视盘全周）-3.00%（鼻侧象限）,ICC为0.982（鼻侧象限）-0.996（视盘全周）。Follow-up模式测量的重复性优于非Follow-up模式。结论利用SD-OCT测量盘周RNFL厚度,Follow-up模式的可重复性优于非Follow-up模式,达到了临床应用标准,可用于临床青光眼的检查和长期随访。

频域光学相干断层扫描测量黄斑区视网膜神经节细胞层厚度

目的 利用频域光学相干断层扫描（SD-OCT）测量正常人和青光眼患者黄斑区视网膜神经节细胞层（GCL）厚度,并对测量结果进行重复性检验。方法 本研究纳入正常志愿者24例（正常对照组）、青光眼患者21例（青光眼组）,随机选择受试者一侧眼进行测量。利用海德堡Spectralis SD-OCT后极部非对称性分析软件对黄斑区视网膜进行扫描,以早期糖尿病视网膜病变治疗研究标准对黄斑区进行分区,分析比较正常对照组和青光眼组黄斑各分区视网膜GCL厚度,并计算组内标准差（Sw）、变异系数（CV）和组内相关系数（ICC）。结果 正常对照组黄斑中央区GCL厚度为（12.58±2.69）μm,内环平均GCL厚度为（48.87±3.81）μm,外环平均GCL厚度为（37.28±1.75）μm,呈开口向颞侧的“马蹄形”分布;青光眼组黄斑中央区GCL厚度为（9.57±2.06）μm,内环平均GCL厚度为（34.70±9.67）μm,外环平均GCL厚度为（28.20±5.51）μm,各区视网膜GCL均较正常对照组明显变薄。正常对照组各分区GCL厚度的Sw为0.46~0.87μm,CV为0.67%~3.71%,ICC为0.904~0.977;青光眼组Sw为0.53~1.65μm,CV为1.18%~5.75%,ICC为0.833~0.993,2组均具有良好的重复性。结论 利用Spectralis SD-OCT测量视网膜黄斑区GCL厚度在正常人和青光眼患者中均具有良好的可重复性,可用于临床青光眼的检查和长期随访。

谱域OCT成像系统在口腔组织检测中的应用

基于谱域光学相干层析术理论设计并搭建了一套便于集成化的光纤式谱域OCT系统,其纵向分辨率为7.3μm,横向分辨率为9.5μm,在空气中的成像深度为3.14 mm。该系统通过干涉光谱来获得样品的深度信息,实现数据的高速采集。利用该系统对口腔内唾液腺导管内壁的组织形态进行了研究,并将得到的OCT图像与相对应的病理切片图片进行了比较。实验结果表明,采用研制的系统可以获得腮腺导管内壁组织的层析结构。该项研究对临床医学上的口腔唾液腺疾病的无创检查和早期诊断具有指导意义。