Comparison of anterior section parameters using anterior segment optical coherence tomography and ultrasound biomicroscopy in myopic patients after ICL implantation

AIM：To compare the agreement of anterior chamber depth（ACD）and central vault measurements obtained by anterior segment optical coherence tomography（AS-OCT）and ultrasound biomicroscopy（UBM）of post surgical high myopic eyes with posterior chamber phakic intraocular lens（Visian ICL;STAAR Surgical）implantation.·METHODS：Fifty-two phakic eyes of 28 high myopic patients who underwent implantable Collamer lens（ICL）surgery for the correction of high myopia were studied.The postoperative ACD,the distance between the corneal endothelium and the anterior surface of ICL（cornea-ICL）and the central vault were measured with the AS-OCT system and the UBM system.Intraclass correlation coefficient（ICC）and the Bland-Altman plot were used to evaluate the repeatability and agreement of two devices.·R ESULTS：The mean ACD,cornea-ICL and central vault in the 52 phakic eyes after ICL surgery was 3.19±0.28 mm,2.47±0.28 mm,0.50±0.19 mm by AS-OCT and3.13±0.25 mm,2.49±0.25 mm,0.44±0.19 mm by UBM,respectively.Pairwise comparison of ACD and central vault measurements showed significant differences between AS-OCT and UBM（〈0.05）.However,no statistically significant difference was found between these imaging techniques in cornea-ICL（〉0.05）.The Pearson correlation coefficient（）between AS-OCT and UBM measurements for ACD,cornea-ICL and vault was0.88,0.80 and 0.89,respectively（〈0.001）.The ICC was0.89-0.94 for the measurements of AS-OCT and UBM.Bland-Altman analysis showed the 95%limits of agreement of ACD,cornea-ICL,central vault measurements between these two devices were-0.20 to 0.32 mm,-0.36to 0.32 mm and-0.12 to 0.24 mm,respectively.58·CONCLUSION：Central ACD and vault measurements using AS-OCT demonstrated a slight significantly higher value than using UBM in phakic eyes after ICL surgery.These two devices should not be used interchangeably for measurements of central ACD and vault in patients after phakic intraocular lens implantation.

Macular changes of neuromyelitis optica through spectral-domain optical coherence tomography

AIM： To evaluate the thickness of the retinal layers in the macula using spectral-domain optical coherence tomography（SD-OCT） in patients with neuromyelitis optica（NMO）. METHODS： Spectralis SD-OCT, utilizing automated macular layer segmentation, was performed in 26 NMO patients and 26 healthy controls. Visual function including visual field tests and pattern visual evoked potential were recorded in study subjects.RESULTS： Forty-one eyes from 26 NMO patients and52 eyes from 26 age- and sex-matched healthy controls were included. Besides total macular volume, peri-paipillary retinal nerve fiber layer（RNFL） thickness, the thickness of macular RNFL, ganglion cell layer（GCL） and inner plexiform layer（IPL） were also significantly reduced in NMO patients compared to those inhealthy controls（P 〈0.000）. No differences were found in the thickness of macular inner nuclear layer（INL）, outer plexiform layer（OPL）, and outer nuclear layer（ONL） between the two groups. Reversely, the outer retinal layer（ORL） was shown to be thicker in NMO than controls（P 〈0.05）.Compared with the peri-papillary RNFL thickness, the GCL thickness was demonstrated to correlate with visual function better.CONCLUSION： The study provides in vivo evidence of retinal neural loss in NMO patients and demonstrates abetter structure-function correlation between retinal ganglion cell and visual function than peri-papillary RNFL does. In addition, no evidence of primary neural damage is found. Besides, the photoreceptor cells and retinal pigments epithelial（RPE） cells presumably proliferated in compensation in NMO after retinal neural loss.

Reflectivity and thickness analysis of epiretinal membranes using spectral-domain optical coherence tomography

AIM：To compare thickness and reflectivity spectral domain optical coherence tomography（SD-OCT）findings in patients with idiopathic epiretinal membranes（ERMs）,before and after ERM peeling surgery,with normal controls.·METHODS：A retrospective study analyzing SD-OCTs of eyes with ERMs undergoing ERM peeling surgery by one surgeon from 2008 to 2010 and normal control eyes.SD-OCTs were analyzed using a customized algorithm to measure reflectivity and thickness.The relationship between the SD-OCT findings and best corrected visual acuity（BCVA）outcomes was also studied.·RESULTS：Thirty-four ERM eyes and 12 normal eyes were identified.Preoperative eyes had high reflectivity and thickness of the group of layers from the internal limiting membrane（ILM）to the retinal pigment epithelium（RPE）and the group of layers from the ILM to the external limiting membrane（ELM）.The values of reflectivity of these two groups of layers decreased postoperatively,but were still higher than normal eyes.In contrast,preoperative eyes had lower reflectivity of two10×15 pixel regions of interest（ROIs）incorporating：1）ELM＋outer nuclear layer（ONL）and 2）photoreceptor layer（PRL）＋RPE,compared to controls.The values of reflectivity of these ROIs increased postoperatively,but were still lower than normal controls.A larger improvement in BCVA postoperatively was correlated with a greater degree of abnormal preoperative reflectivity and thickness findings.·C ONCLUSION：Quantitative differences in reflectivity and thickness between preoperative,postoperative,and normal SD-OCTs allow assessment of changes in the retina secondary to ERM.Our study identified hyperreflective inner retina changes and hyporeflective outer retina changes in patients with ERMs.SD-OCT quantitative measures of reflectivity and/or thickness of specific groups of retinal layers and/or ROIs correlate with improvement in BCVA.

Brain derived neurotrophic factor keep pattern electroretinogram from dropping after superior colliculus lesion in mice

AIM： To determine if brain-derived neurotrophic factor （BDNF） could offer protention to retinal ganglion cells following a superior colliculus （SC） lesion in mice using pattern electroretinogram （PERG） and optical coherence tomography （OCT） as a measures of ganglion cell response and retinal health. METHODS： Seven C57BIJ6J mice with BDNF protection were tested with PERG and OCT before and after SC lesions, RESULTS： Compared with baseline PERG, the amplitude of PERG decreased 11.7% after SC lesions, but not significantly（P〉0.05）. Through fast Fourier transform （FFT） analysis of the PERGs before and after SC lesions, it was found that dominant frequency of PERGs stayed unchanged, suggesting that the ganglion cells of the retina remained relatively healthy inspite of damage to the ends of the ganglion cell axons. Also, OCT showed no changes in retinal thickness after lesions. CONCLUSION： It was concluded that BDNF is essential component of normal retinal and helps retina keeping normal function. While retina lack of BDNF, ex vivo resource of BDNF provides protection to the sick retina. It implies that BDNF is a kind therapeutic neurotrophic factor to retina neurodegeneration diseases, such as glaucoma, age related macular degeneration.

A new strategy to interpret OCT posterior pole asymmetry analysis for glaucoma diagnosis

AIM：To detect early glaucoma by optical coherence tomography（OCT） posterior pole asymmetry analysis.METHODS：Totally 39 eyes from 39 healthy subjects,40 eyes from 40 mild glaucoma patients,33 eyes from 33 moderate glaucoma patients and 41 eyes from severe glaucoma patients were included in this study.All subjects underwent posterior pole asymmetry analysis（PPAA） of OCT and the posterior pole area was divided into three zones.Means,standard deviations and 95% confidence intervals of each zone asymmetry in control group were assessed.Retina thickness asymmetry（RTA） of different stage of glaucoma were compared for each zone,and receiver operating characteristic（ROC） curves were made to test the efficacy of strategies using different zones to discriminate glaucomatous eyes from the healthy ones.RESULTS：In a healthy population,RTA of the centre zone showed the minimal mean value（3.085 μm）,standard deviation（1.756）,and the narrowest 95% confidence interval（from 2.360 to 3.810 μm）.It was only in the center zone that RTA exhibited significant difference between control and moderate glaucoma group（P〈0.01）,as well as control and severe glaucoma group（P〈0.00001）.The strategy utilized in the center zone had the strongest diagnostic capability（zone 3 AUROC=0.816,P=0.0016） in comparison to that of the periphery area（zone 1 AUROC=0.675,P=0.0016;zone 2 AUROC=0.623,P=0.0197）,the whole posterior pole involved interpreting strategy showed inferior diagnostic power than the centre zone dependent strategy（z=2.851,P=0.0044）.CONCLUSION：Utilizing the posterior pole centre zone to interpret OCT PPAA results are more effective than making use of the whole posterior pole map.

Gold nanoshells： Contrast agents for cell imaging by cardiovascular optical coherence tomography

Optical coherence tomography （OCT） has gained considerable attention in interventional cardiovascular medicine and is currently used in clinical settings to assess atherosclerotic lesions and to optimize stent placement. Artery imaging at the cellular level constitutes the first step towards cardiovascular molecular imaging, which represents a major advance in the development of personalized noninvasive therapies. In this work we demonstrate that cardiovascular OCT can be used to detect individual cells suspended in biocompatible fluids. Importantly, the combination of this catheter-based clinical technique with gold nanoshells （GNSs） as intracellular contrast agents led to a substantial enhancement in the backscattered signal produced by individual cells. This cellular contrast enhancement was attributed to the large backscattering cross-section of GNSs at the OCT laser wavelength （1,300 nm）. A simple intensity analysis of OCT cross-sectional images of suspended cells makes it possible to identify the sub-population of living cells that successfully incorporated GNSs. The generalizability of this method was demonstrated using two different cell lines （HeLa and Jurkat cells）. This work provides novel insights into cardiovascular molecular imaging using specifically modified GNSs.