Unified deep learning model for predicting fundus fluorescein angiography image from fundus structure image

The prediction of fundus fluorescein angiography(FFA)images from fundus structural images is a cutting-edge research topic in ophthalmological image processing.Prediction comprises estimating FFA from fundus camera imaging,single-phase FFA from scanning laser ophthalmoscopy(SLO),and three-phase FFA also from SLO.Although many deep learning models are available,a single model can only perform one or two of these prediction tasks.To accomplish three prediction tasks using a unified method,we propose a unified deep learning model for predicting FFA images from fundus structure images using a supervised generative adversarial network.The three prediction tasks are processed as follows:data preparation,network training under FFA supervision,and FFA image prediction from fundus structure images on a test set.By comparing the FFA images predicted by our model,pix2pix,and CycleGAN,we demonstrate the remarkable progress achieved by our proposal.The high performance of our model is validated in terms of the peak signal-to-noise ratio,structural similarity index,and mean squared error.

Fundus photography,fundus fluorescein angiography,and optical coherence tomography of healthy cynomolgus monkey,New Zealand rabbit,Sprague Dawley rat,and BALB/c mouse retinas

Background:A variety of experimental animal models are used in basic ophthalmological research to elucidate physiological mechanisms of vision and disease pathogenesis.The choice of animal model is based on the measurability of specific parameters or structures,the applicability of clinical measurement technologies,and the similarity to human eye function.Studies of eye pathology usually compare optical parameters between a healthy and altered state,so accurate baseline assessments are critical,but few reports have comprehensively examined the normal anatomical structures and physiological functions in these models.Methods:Three cynomolgus monkeys,six New Zealand rabbits,ten Sprague Dawley(SD)rats,and BALB/c mice were examined by fundus photography(FP),fundus fluorescein angiography(FFA),and optical coherence tomography(OCT).Results:Most retinal structures of cynomolgus monkey were anatomically similar to the corresponding human structures as revealed by FP,FFA,and OCT.New Zealand rabbits have large eyeballs,but they have large optic disc and myelinated retinal nerve fibers in their retinas,and the growth pattern of retinal vessels were also different to the human retinas.Unlike monkeys and rabbits,the retinal vessels of SD rats and BALB/c mice were widely distributed and clear.The OCT performance of them were similar with human beings except the macular.Conclusions:Monkey is a good model to study changes in retinal structure associated with fundus disease,rabbits are not suitable for studies on retinal vessel diseases and optic nerve diseases,and rats and mice are good models for retinal vascular diseases.These measures will help guide the choice of model and measurement technology and reduce the number of experimental animals required.

Fundus photography,fluorescein angiography,optical coherence tomography and electroretinography of preclinical animal models of ocular diseases

The eye is an immune-privileged and sensory organ in humans and animals.Anatomical,physiological,and pathobiological features share significant similarities across divergent species(1).Each compartment of the eye has a unique structure and function.The anterior and posterior compartments of the eye contain endothelium(cornea),epithelium(cornea,ciliary body,iris),muscle(ciliary body),vitreous and neuronal(retina)tissues,which make the eye suitable to evaluate efficacy and safety of tissue specific drugs(2).

Fundus autofluorescence in central serous chorioretinopathy: association with spectral-domain optical coherence tomography and fluorescein angiography

and FA for identifying pathological abnormalities in CSC. The characteristics of IA AF in CSC were attributable to the modification of melanin in the RPE. IR- AIM: To evaluate the correlation among changes in fundus autofluorescence (AF) measured using infrared fundus AF (IR -AF) and short-wave length fundus AF (SW -AF) with changes in spectral -domain optical coherence tomography (SD -OCT) and fluorescein angiography (FA) in central serous chorioretinopathy (CSC). METHODS: Two hundred and twenty consecutive patients with CSC were included. In addition to AF, patients were assessed by means of SD -OCT and FA. Abnormalities in images of IA -AF, SW -AF, FA were analyzed and correlated with the corresponding outer retinal alterations in SD-OCT findings. RESULTS: Eyes with abnormalities on either IR-AF or SW-AF were found in 256 eyes (58.18%), among them 256 eyes (100%) showed abnormal IR -AF, but SW-AF abnormalities were present only in 213 eyes (83.20%). The hypo-IR-AF corresponded to accumulation of subretinal liquid, collapse of retinal pigment epithelium (APE) or detachment of APE with or without RPE leakage point in the corresponding area. The hyper -IR -AF corresponded to the area with loss of the ellipsoid portion of the inner segments and sub -sensory retinal deposits or focal melanogenesis under sensory retina. The hypo-SW-AF corresponded to accumulation of subretinal liquid or atrophy of RPE. The hyper -SW -AF associated with sub -sensory retinal deposits, detachment of RPE and focal melanogenesis. CONCLUSION: IR-AF was more sensitive than SW-AF AF should be used as a common diagnostic tool for identifying pathological lesion in CSC.

Fluorescein angiography of retinal vascular involution after intravitreal injection of ranibizumab for retinopathy of prematurity

AIM: To describe the involution patterns of vessel growth of retina through fluorescein angiography(FA) of children, who had been under treatment up to 1 y previously intravitreal ranibizumab(IVR) as monotherapy for retinopathy of prematurity(ROP). METHODS: This is a retrospective study. The medical information and FA of 17 children(34 eyes) whose area of avascular retina from the ora serrata was more than two disc diameters(DD) were analyzed. RESULTS: Among 34 eyes, all were the presence of finger-shaped vessels and arteriolar-venular shunts(100%,34/34 eyes). Popcorn abnormalities were found in most of the eyes(94.1%, 32/34 eyes). Furthermore, in many cases(23.5%, 8/34 eyes), there were leakage persisting in the region of the junction between avascular and vascular retina. In contrast, just 2 eyes(5.9%) showed damage of retinal capillary bed and 3 eyes(8.8%) showed large area of retinal pigment epithelium(RPE) atrophy. CONCLUSION: Although IVR can be very effective in ROP, we should remain cautious as infants may remain avascular peripheral retinas and abnormal vessel. FA allows accurate visualization of vessel abnormalities in eyes with ROP, which will be helpful to affect assessment of disease activity and therapeutic effect.

Simultaneous Determination of Fluorescein, Rhodamine 6G and Rhodamine B in Turbid Solution by Polarization Variable-Angle Synchronous Fluorescence Spectrometry

Polarization variable-angle synchronous fluorescence spectrometry was proposed to determine samples in turbid solution. A mixture of fluorescein, rhodamine 6G and rhodamine B was used to evaluate the technique. The background caused by scattering light was decreased remarkably. The limits of detection were 0.6 ng/ml for fluorescein, 2.3 ng/ml for rhodamine 6G and 4.1 ng/ml for rhodamine B, respectively.

Fractal analysis of retinal vasculature in normal subjects on ultra-wide field fluorescein angiography

AIM: To evaluate the fractal feature of the retinal vasculature of normal eyes on a stereographic projected and montaged ultra-wide field(UWF) fluorescein angiography(FA).METHODS: Prospective, observational, cross-sectional study. Totally 59 eyes of 31 normal subjects were imaged using the Optos 200 Tx. Images obtained at different gaze angles stereographically projected and montaged. The early-phase UWF FA frames were processed to segment the retinal vasculature and the results were exported as binary masks. The fractal dimension(FD) was calculated using the box-counting method.RESULTS: The global FD for the entire retina was 1.6±0.04, with no difference between males and females(1.59±0.04 vs 1.61±0.04, P=0.084) or between right and left eyes(1.6±0.04 vs 1.6±0.05, P=0.61). FD was nonuniformly distributed among four quadrants(P<0.001) and decreased as the distance from the fovea increased(P<0.001). A negative association was observed between FD and age(R=-0.37, P=0.006), and this relationship was observed in the posterior and mid-peripheral retina(P<0.05) but absent in far-periphery(P>0.05).CONCLUSION: Fractal geometry is non-uniformly distributed across the retina in normal eyes and decreases from the fovea to the far-periphery. Subjects with an older age tend to have a smaller FD, however, the FD in the farperiphery does not appear to be influenced by age.

Quantitative analysis of retinal vasculature in normal eyes using ultra-widefield fluorescein angiography

AIM:To quantify the area and density of retinal vascularity by ultra-widefield fluorescein angiography(UWFA).METHODS:In a retrospective study,UWFA images were obtained using an ultra-widefield imaging device in 42 normal eyes of 42 patients.Central and peripheral steered images were used to define the edge of retinal vasculature by a certified grader.The length from the center of the optic disc to the edge of retinal vascularity(RVL)in each quadrant and the total retinal vascular perfusion area(RVPA)were determined by the grader using OptosAdvance software.The density of retinal vascularity(RVD)was quantified in different zones of central-steered images using Image J software.RESULTS:Among 42 healthy eyes,the values for mean RVL in each quadrant were 19.007±0.781 mm(superior),18.467±0.869 mm(inferior),17.738±0.622 mm(nasal)and 24.241±1.336 mm(temporal).The mean RVPA was 1140.117±73.825 mm^(2).The mean RVD of the total retina was 4.850%±0.638%.RVD varied significantly between different retina zones(P<0.001),and significant differences existed in the RVD values for total retinal area in patients over 50 years old compared to those under 50 years old(P=0.033).No gender difference was found.CONCLUSION:The UWFA device can be a promising tool for analyzing the overall retinal vasculature and may provide a better understanding of retinal vascular morphology in normal eyes.Aging may be related to lower RVD.

Comparison of 24×20 mm^(2) swept-source OCTA and fluorescein angiography for the evaluation of lesions in diabetic retinopathy

AIM: To compare ultra-widefield(24×20 mm^(2)) sweptsource optical coherence tomography angiography(SSOCTA) and fluorescein angiography(FA) in the evaluation of diabetic retinopathy(DR) lesions. METHODS: Forty-six eyes of 23 patients with treatmentna?ve DR were included at Peking University People’s Hospital from September 1, 2021, until December 31, 2021, as well as 23 age and gender matched healthy controls. Quantitative assessments of DR lesions on FA and SS-OCTA(superficial capillary plexus, SCP, 24×20 mm^(2)) were performed.RESULTS: Area of fovea avascular zone(FAZ) was larger in DR cases than controls(0.34±0.069 mm^(2) vs 0.287±0.108 mm^(2), P=0.006). In DR eyes, the mean FAZ area was 0.34±0.069 and 0.334±0.087 mm^(2) on SS-OCTA and FA, respectively(P=0.428), while the median FAZ perimeter was 2.382(IQR, 2.201-2.59) and 2.333(IQR, 2.138-2.6) mm on SS-OCTA and FA images(P=0.733). There was no significant difference in the size of the non-perfusion area(NPA) between the images on SS-OCTA and FA(12.389, IQR 4.96-28.3 and 11.125, IQR 5-28.31 mm^(2), P=0.197). The median total microaneurysm(MA) count was 35(IQR, 19-46) and 73(IQR, 43-93) on SS-OCTA and FA(P<0.001), respectively. No significant difference in intra-retinal microvascular abnormality(IRMA) and neovascularization (NV) count was found between the two techniques. The intraclass coefficient(ICCs) of all the parameters above indicated stable repeatability.CONCLUSION: Ultra-widefield SS-OCTA represents a reliable, noninvasive, and quantitative imaging technique in the assessment of microvasculature in DR, which offers a potential substitute for FA in DR evaluation.

Comparison of fundus fluorescein angiography and fundus photography grading criteria for early diabetic retinopathy

AIM:To compare the assessment outcomes of the characteristics of mild to moderate non-proliferative diabetic retinopathy(NPDR) established by fundus photography and fundus fluorescein angiography(FFA).METHODS:The fundus photos and FFA results of 260 patients with diabetes mellitus were reviewed.Diabetic retinopathy(DR) severity was graded based on the international classification standard.The microaneurysms,hemorrhages,and intraretinal microvascular abnormalities(IRMA) in FFA images of patients with mild to moderate NPDR were observed.The differences between the fundus photos and the FFA results were summarized,analyzed,and compared.RESULTS:The counting of intraretinal hemorrhages identified by FFA revealed that only 9 eyes(1.9%) had more than 20 intraretinal hemorrhages in all four quadrants;15 eyes(3.1%) had more than 20 intraretinal hemorrhages in three quadrants;26 eyes(5.4%) had over 20 intraretinal hemorrhages in two quadrants;and 37 eyes(7.7%) had more than 20 intraretinal hemorrhages in only one quadrant.Furthermore,the number of IRMAs appeared ≥4 in 17 eyes,3 in 35 eyes,2 in 69 eyes,and 1 in 93 eyes.CONCLUSION:FFA has higher detection accuracy of retinal angiopathy than fundus photography.FFA grading results are helpful for timely detection and proper treatment of lesions easily missed by fundus photography.

Transdermal delivery of fluorescein isothiocyanate-dextrans using the combination of microneedles and low-frequency sonophoresis

This study aimed to evaluate the patient-friendly methods that are used in the delivery of hydrophilic macromolecules into deep skin layers,in particular,the combination of microneedles patch(MNs patch)and low-frequency sonophoresis(SN).The hydrophilic macromolecule drug fluorescein isothiocyanate(FITC)-dextrans(FD-4:MW 4.4 kDa)was used as the model drug in our experimental design.In this study,excised porcine skin was used to investigate and optimize the key parameters that determine effective MNs-and SNfacilitated FD-4 delivery.In vitro skin permeation experiments revealed that the combination of MNs patch with SN had a superior enhancing effect of skin permeation for FD-4 compared to MNs alone,SN alone or untreated skin,respectively.The optimal parameters for the combination of MNs and SN included the following:10 N insertion force of MNs,4 W/cm^(2)SN intensity,6 mm radiation diameter of the SN probe,2 min application time,and the continuous mode duty cycle of SN.In addition,vertical sections of skin,clearly observed under a confocal microscope,confirmed that the combination of MNs and SN enhanced permeation of FD-4 into the deep skin layers.These studies suggest that the combination of MNs and SN techniques could have great potential in the delivery of hydrophilic macromolecules into deep skin.

Dynamic versus static ultra-widefield fluorescein angiography in eyes with diabetic retinopathy:a pilot prospective cross-sectional study

AIM:To analyze differences in ultra-widefield fluorescein angiography(UWFA)findings between dynamic and static images of eyes with diabetic retinopathy(DR).METHODS:This cross-sectional study included 28 eyes of 28 patients with DR undergoing UWFA.A series of UWFA images acquired from each patient were converted into a time-lapse video and used as a dynamic image.A single,clear,arteriovenous phase image was chosen as a static image.Non-perfusion index(NPI)and its correlation with vascular abnormalities in different zones were compared between dynamic and static UWFA imaging.RESULTS:NPI appeared to increase from the center to the far-periphery in both groups.Dynamic NPI was lower in the total retinal area(0.26 vs 0.29,P=0.009)and farperiphery(0.33 vs 0.36,adjusted P=0.042),which was contrary to the static NPI.Far-peripheral NPI was associated with intraretinal microvascular abnormality in the posterior area in both groups.CONCLUSION:Time-lapse dynamic UWFA imaging is a useful modality to differentially diagnose hypofluorescence in the most peripheral region.This modality could provide a reliable method for NPI measurement.

Sensitive Colorimetric and Fluorescent Detection of Mercury Using Fluorescein Derivations

A colorimetric and fluorometric dual-model probe for mercury (II) ion was developed employing fluorescein hydrazide (FH) in ethanol-HEPES solution (1:1, v/v, pH 8.0). The probe exhibited high selectivity and sensitivity for Hg2+ detection using UV/Vis and fluorescence spectroscopy. Addition of Hg2+ caused a visual color change from colorless to coloured and a fluorescence change from colorless to bright green. Other metal ions did not interfere with the detection of Hg2+.

Preparation and Performance of Fluorescein Isothiocyanate⁃Labeled Fluorescent Starch and Polyvinyl Alcohol for Warp Sizing

In order to solve the problems of low accuracy and poor variety adaptability of the current measurement method of the permeability and coating property of sizing paste in textile industry, taking starch and polyvinyl alcohol(PVA) as the representatives of the most commonly used textile sizes, various concentrations of fluorescent molecules fluorescein isothiocyanate(FITC) were used to label starch and PVA to prepare fluorescein(F)-starch and F-PVA fluorescent sizes with different degrees of labeling(DLs) for the first time, respectively. Then the starch and PVA derivatives were employed to size pure cotton warp yarns. After preparing the sections of the sized yarns, the permeability and coating percentage of starch and PVA paste to the yarns were calculated by using a fluorescence microscope and the Photoshop software, respectively. The results demonstrate that F-starch and F-PVA with appropriate DL of 0.791% and 0.161%, respectively, exhibit good fluorescence property and similar sizing performance to the sizing performance of unlabeled starch and PVA. It is considered that fluorescence labeling of sizing agents with fluorescein units can provide an innovative way for the accurate determination of the permeability and coating property of sizing paste to warp yarns.

Histopathological confirmation of similar intramucosal distribution of fluorescein in both intravenous administration and local mucosal application for probebased confocal laser endomicroscopy of the normal stomach

Probe-based confocal laser endomicroscopy(p CLE) is capable of acquiring in vivo magnified cross-section images of the gastric mucosa. Intravenous injection of fluorescein sodium is used for confocal imaging. However, it is still under debate if local administration of the dye to the mucosa is also effective for confocal imaging as it is not yet clear if topical application also reveals the intramucosal distribution of fluorescein. The objective of this study was to evaluate the intramucosal distribution of fluorescein sodium after topical application and to compare the distribution to the conventional intravenous injection used for confocal imaging. p CLE of the stomach uninfected with Helicobacter pylori was performed in a healthy male employing intravenous administration and local mucosal application of fluorescein. The mucosa of the lower gastric body was biopsied 1 min and 5 min after intravenous administration or local mucosal application of fluorescein, and the distribution of fluorescein in the biopsy samples was examined histologically. Green fluorescence was already observed in the cytoplasm of fundic glandular cells in the biopsied deep mucosa 1 min after local mucosal application of fluorescein. It was also observed in the foveolar lumen and inter-foveolar lamina propria, although it was noted at only a few sites. In the tissue biopsied 5 min after the local mucosal application of fluorescein, green fluorescence was more frequently noted in the cytoplasm of fundic glandular cells than in that 1 min after the local mucosal application of fluorescein, although obvious green fluorescence was not identified in the foveolar lumen or inter-foveolar lamina propria. The distribution of intravenously administered fluorescein in the cytoplasm of fundic glandular cells was also clearly observed similarly to that after local mucosal application of fluorescein. Green fluorescence in more cells was observed in many cells 5 min after intravenous administration compared with that after 1 min. The presence of fluorescein in the mucosa was observed within a short time after local mucosal application of fluorescein, suggesting that pC LE images similarly to those after intravenous fluorescein administration can be acquired by local mucosal application of fluorescein.

Syntheses and Crystal Structures of a Series of Coordination Complexes Derived from the Fluorescein Ligand

Solvothermal reaction of lanthanide（Ⅲ） salts with fluorescein （2-（6-hydroxy3-oxo-3H-xanthen-9-yl）benzoic acid） led to a series of new coordination polymers {[Ln（C 20 H 11 O 5）（C 20 H 10 O 5）（H 2 O）]·DMF} n （Ln=Er,Eu,Gd,Tb,Tm,Yb）.The PXRD patterns of the complexes indicate they are isomorphous.The structure of complex {[Er（C 20 H 11 O 5）（C 20 H 10 O 5）（H 2 O）]·DMF} n has been determined by single-crystal X-ray diffraction,revealing a 2D framework in which DMF molecules were filled between the layers.The crystal structure belongs to the triclinic system,space group P1,with a=12.107（4）,b=12.232（4）,c=13.273（4）,α=68.005（7）,β=88.024（11）,γ=77.451（8）°,V=1776.7（9） 3,Z=2,D c=1.720 g/cm 3,μ=2.434 mm-1,F（000）=918,R int=0.0584,T=293（2） K,the final R=0.0621 and wR=0.1501.

Effect of 2% fluorescein on Scheimpflug central corneal thickness measurements

AIM： To assess central corneal thickness （CCT） changes measured with Scheimpflug device following instillation of 2% fluorescein in normal subjects. ~ METHODS： This was a prospective randomized study of 60 hospital volunteers. After baseline CCT measurements of both eyes of 40 subjects were obtained using Scheimpflug system, a drop of preservative-free 2% fluorescein, was instilled in one eye and in other eye, one drop of normal saline （control）. Measurements were repeated after 1, 2, 5, 10, 20, 30, 40, 50 and 60min （continuous assessment group）. Twenty subjects had baseline CCT taken, then fluorescein was instilled in one eye and measurements were taken at lmin. Ten eyes had saline rinse after lmin and 10 other eyes did not, measurements were repeated at 2min （eye rinse group）. RESULTS： The mean baseline CCT for continuous assessment group was 546.2±32.1um （range, 489.0-606.0）, control eyes was 546.6~±30.7 um （range, 489.0-602.0）. At lmin after fluorescein instillation, CCT significantly increased by 37.0±34.0um （P〈0.001）, then decreased gradually, reaching baseline at 60min. CCT variations were not significant in control group （P〉0.05）. For eye rinse group, CCT mean differences between baseline and 2min were 18.2um （95 % Ch -54.7 to 18.3） with rinse and 26.5um （95% CI： -62.9 to 9.9） without rinse; paired sample tests were not significant （P〉0.05）. CONCLUSION： The presence of fluorescein increased CCT value to a clinically relevant level of 6.8%. Eye rinse did not significantly reduce the effect at 2min post fluorescein timepoint.

Synthesis and pH Sensitive Fluorescent Performance of 2'-Chloroseminaphthofluorescein with Dual Bands

A novel unsymmetrical fluorescein derivative substituted by chlorine and naphthol, 2 '-chloroseminaphthofluorescein, was prepared by the two-step synthetic method. This method can effectively control the reactive process,so the pure unsymmetrical fluorescein derivative can be obtained in high yield. The new fluorophore exhibited dual absorption bands,dual excitation bands and dual emission bands with long-wavelength,selectively exciting the acidic and basic forms of the fluorophore. Compared with the similar symmetrical fluorescein derivatives such as 2 ', 7 '-dichlorofluorescein and dinaphtofluorescein, this fluorophore was found to have larger Stokes shift,especially in the basic form. Based on the properties above,this unsymmetrical fluorescein derivative is expected as a good fluorescent probe to be used where the interference exists due to the presence of endogenous fluorescers.