Near-infrared Autofluorescence Imaging Research Articles

Combined Angiography for High-Quality Near-Infrared Autofluorescence Images

To describe an innovative imaging technique to obtain high-quality near-infrared autofluorescence (NIA) images. Simultaneous fluorescein angiography + indocyanine green angiography (FA + ICGA) acquisition mode (without dye injection) of Spectralis HRA + OCT (Heidelberg Retina Angiograph; Heidelberg Engineering, Heidelberg, Germany), setting maximum level of illuminance, and Automatic Real-time (ART) Module (Heidelberg Engineering) to increase signal-to-noise ratio. The combined confocal scanning laser ophthalmoscope technique allows the Spectralis HRA + OCT device to create high-quality NIA ART images. This innovative imaging technique, consisting of simultaneous FA + ICGA acquisition mode, setting maximum level of illuminance, and ART, allows the Spectralis HRA + OCT device to create high-quality NIA ART images, without requiring the need for the HRA2 (Heidelberg Retina Angiograph; Heidelberg Engineering) device.

Near-infrared and Short-wavelength Autofluorescence in Resolved Central Serous Chorioretinopathy: Association With Outer Retinal Layer Abnormalities

To evaluate the correlation between changes in fundus autofluorescence (AF) measured using 2 different sources (near-infrared fundus autofluorescence from melanin and short-wavelength fundus autofluorescence from lipofuscin) with changes in spectral-domain optical coherence tomography (SD OCT) and fluorescein angiography in resolved central serous chorioretinopathy (CSC). Retrospective, observational case study. A total of 91 eyes from 86 patients with a history of resolved CSC and abnormal AF imaging findings were included. In addition to AF, patients were assessed by means of SD OCT and fluorescein angiography. Outer retinal layer alterations in OCT images and abnormalities in fluorescein angiography were analyzed and correlated with the corresponding AF data. All eyes with abnormal near-infrared AF showed a hyperfluorescent angiography window defect in the corresponding area. There was a significant association between the OCT and short-wavelength AF findings. An abnormal short-wavelength AF signal was significantly associated with loss of the ellipsoid portion of the inner segments (EPIS, previously known as the junction between the inner and outer segments of the photoreceptors) on SD OCT (χ(2) test; P < .0001). Near-infrared AF could not predict the status of EPIS without the short-wavelength AF image. Outer retinal layer changes in OCT images can be predicted by analyzing both short-wavelength AF and near-infrared AF images. Abnormal changes in the short-wavelength AF image were predictive of EPIS damage.

Comparison of Near-Infrared and Short-Wavelength Autofluorescence in Retinitis Pigmentosa

To compare near-infrared autofluorescence (NIR-AF) and short-wavelength (SW) AF in retinitis pigmentosa (RP) and assess their relationships to underlying retinal structure and visual function. SW-AF, NIR-AF, and spectral domain optical coherence tomography (SD-OCT) images were acquired from 31 patients (31 eyes) with RP and registered to each other. Microperimetry was performed on a subset of 12 patients. For both SW-AF and NIR-AF images, three independent observers measured the area enclosed by the outer border of the hyperautofluorescent ring and the distance from the fovea to the outer and inner border of the ring. For SD-OCT images, the distance from the fovea to the location where the inner segment ellipsoid (ISe) band became undetectable was measured. All eyes had a hyperautofluorescent ring on both SW-AF and NIR-AF. The position of the outer border of the ring was similar for both modalities. On NIR-AF the signal outside the ring was lower than inside the ring, resulting in a high contrast between the two areas. Also, the inner border of the ring was closer to the fovea on NIR-AF than SW-AF, corresponding to a location on SD-OCT where the ISe band was at least partially intact. Visual sensitivity was relatively preserved within the ring, reduced across the ring, and markedly decreased or nonrecordable outside the ring. SW-AF and NIR-AF are both useful for monitoring disease progression in RP; however, NIR-AF may have advantages clinically and could unveil a process that precedes the formation of fluorophores that emit the SW-AF signal.

RETINAL PIGMENT EPITHELIAL ATROPHY IN PATIENTS WITH EXUDATIVE AGE-RELATED MACULAR DEGENERATION UNDERGOING ANTI–VASCULAR ENDOTHELIAL GROWTH FACTOR THERAPY

To evaluate the occurrence of retinal pigment epithelial atrophy in patients with age-related macular degeneration undergoing anti-vascular endothelial growth factor therapy. The study is a retrospective review. Eligible were patients with age-related macular degeneration and choroidal neovascular membranes treated with anti-vascular endothelial growth factor between October 2007 and February 2011; they were followed for >3 months, with fundus photographs and fluorescein angiography at baseline and with autofluorescence and near-infrared autofluorescence images at baseline and follow-up. Demographics, visual acuity, the type of choroidal neovascular membranes, the number of treatments performed, and the length of follow-up were recorded. Autofluorescence and near-infrared autofluorescence images were evaluated for the presence or absence of areas of reduced signal. A multilevel logistic regression model was used to investigate the factors that may be associated with "progression of atrophy" at follow-up, which was the primary outcome of this study. Sixty-three patients (72 eyes) were followed for a median of 16 months (range, 3-36 months). Atrophy at baseline was observed in 47% (34/72) of eyes; progression of atrophy occurred in 62% (45/72) of eyes at the last visit. The number of anti-vascular endothelial growth factor injections received was statistically significantly associated with the progression of atrophy at follow-up (odds ratio, 1.35; 95% confidence interval, 1.05-1.73; P = 0.02). Atrophy was frequently observed in patients with age-related macular degeneration and choroidal neovascular membranes undergoing anti-vascular endothelial growth factor therapy.

Foveal sparing in patients with Japanese Stargardt’s disease and good visual acuity

Patients with Stargardt's disease usually have a poor visual prognosis. However, in our clinical practice we have observed some patients with dark-red foveal pigmentation (sparing) who had good best corrected visual acuity (BCVA) despite the presence of a late-stage disease. The purpose of this study was to investigate the BCVA outcomes in Japanese patients with Stargardt's disease with foveal sparing. Eighteen consecutive patients (36 eyes) with Stargardt's disease underwent ophthalmoscopy, fluorescein angiography, fundus autofluorescence imaging, and near-infrared fundus autofluorescence (NIA) imaging. The patients were divided into two groups based on the presence or absence of foveal sparing. The presence of foveal sparing was determined based on ophthalmoscopy and NIA imaging results. The association between foveal sparing and BCVA was assessed statistically by Students' t test. Of the 36 eyes, ten (27.8 %) had dark-red foveal sparing. The mean BCVA of the group with sparing was 0.16 ± 0.31, expressed in logarithm of the minimum angle of resolution (logMAR) units, and that of the group without sparing was 1.03 ± 0.39 logMAR units, which is a significant difference (p = 0.0000002507). A subgroup of Japanese patients with late-stage Stargardt's disease and dark-red foveal sparing maintained a relatively good BCVA. The pigmentation was clearly observed using NIA and proved useful for assessing the BCVA prognosis.

In vivo near‐infrared autofluorescence imaging of pigmented skin lesions: methods, technical improvements and preliminary clinical results

Fluorescence emission from in vivo cutaneous melanin was recently detected under near-infrared (NIR) excitation by our group. We then built a prototype NIR autofluorescence imaging system to observe and characterize the melanin distribution in human skin. In this article, we reported a new setup of NIR fluorescence imaging system and calibration methods to optimize the system for better clinical feasibility and clearer image. The imaging system was designed to perform both fluorescence and reflectance imaging with a 785-nm fiber-coupled laser source. The illumination light was purified by a 785-nm bandpass filter for fluorescence excitation; while the spontaneous components were selected by a longpass filter for NIR reflectance imaging. A hand-controlled filter wheel was used to switch these two filters for different imaging modes. A dichroic filter was used to guide the illuminating light onto the skin surface for excitation. Reflectance and fluorescence signals were collected sequentially by a NIR optimized CCD camera. The captured images were calibrated by the reflectance images of a standard reflectance disk for non-uniform illuminations and light collection efficiencies. The clinical results demonstrated that NIR fluorescence intensities and distribution patterns vary among lesion types. It was also confirmed that pigmented skin lesions emitted higher NIR fluorescence than the surrounding normal skin due to the presentation of higher concentrations of cutaneous melanin within the lesions. NIR autofluorescence imaging system could be utilized as a powerful tool for visualizing melanin distribution in pigmented skin lesions and as a potential method for aiding melanoma detection.

Centrifugal Expansion of Fundus Autofluorescence Patterns in Stargardt Disease Over Time

To study the longitudinal changes in autofluorescence in Stargardt disease to reveal aspects of disease progression not previously evident. Changes in autofluorescence reflect changing fluorophore compositions of lipofuscin and melanin in retinal pigment epithelial cells, which has been hypothesized to contribute to Stargardt disease pathogenesis. We examined the temporospatial patterns of fundus autofluorescence with excitation at both 488 nm (standard fundus autofluorescence) and 795 nm (near-infrared autofluorescence) in a longitudinal case series involving 8 eyes of 4 patients (range of follow-up, 11-57 months; mean, 39 months). Image processing was performed to analyze spatial and temporal cross-modality associations. Longitudinal fundus autofluorescence imaging of fleck lesions revealed hyperautofluorescent lesions that extended in a centrifugal direction from the fovea with time. Patterns of spread were nonrandom and followed a radial path that left behind a trail of diminishing autofluorescence. Longitudinal near-infrared autofluorescence imaging also demonstrated centrifugal lesion spread but with fewer hyperautofluorescent lesions, suggestive of more transient hyperautofluorescence and more rapid decay at longer wavelengths. Fundus autofluorescence and near-infrared autofluorescence abnormalities were spatially correlated with each other, and together they reflect systematic progressions in fleck distribution and fluorophore composition occurring during the natural history of the disease. Stargardt disease fleck lesions do not evolve randomly in location but instead follow consistent patterns of radial expansion and a systematic decay of autofluorescence that reflect changing lipofuscin and melanin compositions in retinal pigment epithelial cells. These progressive foveal-to-peripheral changes are helpful in elucidating molecular and cellular mechanisms underlying Stargardt disease and may constitute potential outcome measures in clinical trials.

GEOGRAPHIC ATROPHY IN RETINAL ANGIOMATOUS PROLIFERATION

To describe the occurrence of geographic atrophy in patients with retinal angiomatous proliferation (RAP). Demographics, visual acuity, color fundus photographs, fluorescein and indocyanine green angiograms, and fundus autofluorescence and near-infrared autofluorescence images were reviewed in 53 patients (66 eyes) with RAP. Of 53 treatment-naive eyes, 19 (36%) had atrophy at baseline. Of 66 eyes, 57 (86%) developed de novo atrophy or enlargement of preexisting areas of atrophy during the follow-up (median, 17 months; range, 3-53 months) after treatment. Areas of atrophy were observed at the site of the RAP (58 of 66 eyes, 88%) of a previously existing pigment epithelial detachment (18 of 44 eyes; 41%) and elsewhere (43 of 66 eyes, 65%). At presentation, RAP was found to be frequently associated with increased autofluorescence at the fovea because of cystoid macular edema (36 of 53 eyes, 68%) and reduced autofluorescence because of hard exudation (38 of 53 eyes, 72%) and intraretinal hemorrhages (32 of 53 eyes, 60%). Background reticular (39%) and homogeneous (36%) autofluorescence were most commonly observed. Geographic atrophy occurs frequently in patients with RAP after treatment. This information, if confirmed in other cohorts, would be valuable for the counseling of patients with this disease and for the understanding of the pathogenesis of this condition and its progression after treatment.

Fundus Autofluorescence and Spectral Domain OCT in Central Serous Chorioretinopathy

Background. To describe the standard autofluorescence (FAF), the near infrared autofluorescence (NIA) and optical coherence tomography (OCT) patterns in central serous chorioretinopathy, correlating them with fluorescein angiography. Methods. Cross-sectional observational study, in which patients with at least seven months of CSC underwent ophthalmologic examination, fundus photography, FAF, NIA, fluorescein angiography (FA), and spectral-domain OCT. Results. Seventeen eyes of thirteen patients were included. The presentation features were a mottled hyperFAF in the detached area and areas with pigment mottling. NIA images showed areas of hyperNIA similar to FAF and localized areas of hypoNIA, which correlated with the points of leakage in the FA. OCT showed pigment epithelium detachment at the location of these hypoNIA spots. Discussion. FAF showed increased presence of fluorophores in the area of retinal detachment, which is believed to appear secondary to lipofuscin accumulation in the RPE or the presence of debris in the subretinal fluid. NIA has been related to the choroidal melanin content and there were areas of both increased and decreased NIA, which could be explained by damage ahead the retina, basically RPE and choroid. These findings, along with the PEDs found in the areas of hypoNIA, support the notion of a primary choroidal disease in CSC.

Polarized near-infrared autofluorescence imaging combined with near-infrared diffuse reflectance imaging for improving colonic cancer detection

We evaluate the diagnostic feasibility of the integrated polarized near-infrared (NIR) autofluorescence (AF) and NIR diffuse reflectance (DR) imaging technique developed for colonic cancer detection. A total of 48 paired colonic tissue specimens (normal vs. cancer) were measured using the integrated NIR DR (850-1100 nm) and NIR AF imaging at the 785 nm laser excitation. The results showed that NIR AF intensities of cancer tissues are significantly lower than those of normal tissues (p<0.001, paired 2-sided Student's t-test, n=48). NIR AF imaging under polarization conditions gives a higher diagnostic accuracy (of ~92-94%) compared to non-polarized NIR AF imaging or NIR DR imaging. Further, the ratio imaging of NIR DR to NIR AF with polarization provides the best diagnostic accuracy (of ~96%) among the NIR AF and NIR DR imaging techniques. This work suggests that the integrated NIR AF/DR imaging under polarization condition has the potential to improve the early diagnosis and detection of malignant lesions in the colon.

In Vivo Near-Infrared Auto-Fluorescence Imaging of Pigmented Skin Lesions: Methods and Preliminary Clinical Results

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Autofluorescence findings in Vogt-Koyanagi-Harada disease

To report shortwave autofluorescence (SW-AF) and near infrared autofluorescence (NIR-AF) findings in a case of Vogt-Koyanagi-Harada (VKH) disease. A 22-year-old man presented with a 2-week history of headache, moderate hearing loss, discolored hair, and bilateral gradually decreased vision (20/800 bilaterally). Ophthalmologic examinations revealed bilateral granulomatous anterior uveitis and multiple patchy bullous retinal detachments. Fundus fluorescein angiography (FFA), SW-AF, and NIR-AF imaging were performed with a confocal scanning laser ophthalmoscope at the beginning and after resolution. The patient responded well to systemic prednisolone treatment. Visual acuity and hearing loss improved quickly (visual acuity 16/20 bilaterally). Multilobular dye pooling with a dark rim was observed in serous detached retinal areas on late-phase FFA. These areas were observed as hypoAF in SW-AF and NIR-AF mode due to the blockage. After resolution of serous detachment, numerous hypoAF granular dots were observed scattered over the previously serous detached areas in SW-AF and NIR-AF mode. These hypoAF granular dots were seen as window defect lesion in FFA and interpreted as retinal pigment epithelial damage or atrophy. SW-AF and NIR-AF imaging confirmed granular retinal pigment epithelium atrophy which corresponds to FFA findings. SW-AF and NIR-AF imaging methods are noninvasive and useful techniques for documentation of fundus changes in VKH disease.

Added value of infrared, red-free and autofluorescence fundus imaging in pseudoxanthoma elasticum

PurposePseudoxanthoma elasticum (PXE) is an autosomal recessive disorder caused by mutations in the ABCC6 gene and primarily affects the oculocutaneous and cardiovascular systems. However, the phenotype, including the ophthalmological manifestations,...

Multimodal Imaging Including Spectral Domain OCT and Confocal Near Infrared Reflectance for Characterization of Outer Retinal Pathology in Pseudoxanthoma Elasticum

To investigate the value of multimodal confocal scanning laser ophthalmoscopy (cSLO) for phenotyping fundus lesions in patients with pseudoxanthoma elasticum (PXE) and to correlate these findings with morphologic alterations detected by spectral domain optical coherence tomography (SD-OCT). Imaging was performed with a combined SD-OCT-cSLO system (Spectralis HRA-OCT; Heidelberg Engineering, Heidelberg, Germany). OCT scans were placed at locations of interest on near-infrared (NIR) reflectance, fundus autofluorescence (FAF), and fluorescein angiography (FA) images. The instrument allowed for exact topographic correlation of findings on OCT and cSLO images. NIR reflectance imaging showed the highest sensitivity to detect angioid streaks and peau d'orange compared to FAF or FA. On OCT scans, angioid streaks reliably showed breaks in Bruch's membrane. Peau d'orange was associated with alternating reflectivity within Bruch's membrane. Characteristic mid-peripheral chorioretinal atrophies showed hyporeflective spaces involving the outer neurosensory retina. In eyes with pattern dystrophy like alterations, subneurosensory accumulation of material was observed within areas of increased FAF. SD-OCT in combination with cSLO imaging using NIR light locates the primary pathologic formations of angioid streaks and peau d'orange in Bruch's membrane. NIR reflectance imaging may be superior for detecting PXE-related fundus lesions at the level of Bruch's membrane, because the blue laser light that is used in FAF and FA is markedly absorbed by the pigment epithelium and therefore may only detect alterations if this cell layer is also affected. The findings indicate that multimodal cSLO and SD-OCT imaging of the outer retina allows for screening of PXE related retinal alterations.

Near-infrared autofluorescence imaging of cutaneous melanins and human skin in vivo

In recent years, near-infrared (NIR) autofluorescence imaging has been explored as a novel technique for tissue evaluation and diagnosis. We present an NIR fluorescence imaging system optimized for the dermatologic clinical setting, with particular utility for the direct characterization of cutaneous melanins in vivo. A 785-nm diode laser is coupled into a ring light guide to uniformly illuminate the skin. A bandpass filter is used to purify the laser light for fluorescence excitation, while a long-pass filter is used to block the main laser wavelength but pass the spontaneous components for NIR reflectance imaging. A computer-controlled filter holder is used to switch these two filters to select between reflectance and fluorescence imaging modes. Both the reflectance and fluorescence photons are collected by an NIR-sensitive charge-coupled device (CCD) camera to form the respective images. Preliminary results show that cutaneous melanin in pigmented skin disorders emits higher NIR autofluorescence than surrounding normal tissue. This confirmed our previous findings from NIR fluorescence spectroscopy study of cutaneous melanins and provides a new approach to directly image the distributions of cutaneous melanins in the skin. In-vivo NIR autofluorescence images may be useful for clinical evaluation and diagnosis of pigmented skin lesions, including melanoma.

Near-infrared and short-wavelength autofluorescence imaging in central serous chorioretinopathy

Aims:The aim of the study was to compare the results of short-wavelength (SW) and near-infrared (NIR) autofluorescence (AF) in acute central serous chorioretinopathy (CSC).Methods:Twenty-six eyes of the 26 patients diagnosed...

Near-Infrared Autofluorescence Imaging of the Fundus: Visualization of Ocular Melanin

To evaluate the origin of the near-infrared autofluorescence (AF) of the fundus detected by scanning laser ophthalmoscopy and compare the distribution of this AF with that of lipofuscin. AF [787] fundus images (excitation [Exc.] 787 nm; emission [Emi.] >800 nm) were recorded with a confocal scanning laser ophthalmoscope, in 85 normal subjects (ages: 11-77 years) and in 25 patients with AMD and other retinal diseases. Standard AF [488] images (Exc. 488 nm; Emi. >500 nm) were recorded in a subset of the population. The fovea exhibits higher AF[787] than the perifovea in an area approximately 8 degrees in diameter, roughly equivalent to the area of higher RPE melanin seen in AF[488] and color images. The ratio of foveal to perifoveal AF[787] decreases with age (P < 0.0001) and is higher in subjects with light irides (P = 0.04). Higher AF[787] emanates from hyperpigmentation, from the choroidal pigment (nevi, outer layers) and from the pigment epithelium and stroma of the iris. Low AF[787] is observed in geographic atrophy particularly in subjects with light irides. AF[787] originates from the RPE and to a varying degree from the choroid. Oxidized melanin, or compounds closely associated with melanin, contributes substantially to this AF, but other fluorophores cannot be excluded at this stage. Confocal AF[787] imaging may provide a new modality to visualize pathologic features of the RPE and the choroid, and, together with AF[488] imaging, offers a new tool to study biological changes associated with aging of the RPE and pathology.

Investigation of near-infrared autofluorescence imaging for the detection of breast cancer

Detection of breast cancer in fresh tissue obtained from surgery is investigated using near-infrared autofluorescence imaging under laser excitation at 532 and 632.8 nm. The differences in intensity between the three main components of breast tissue (cancer, fibrous, and adipose) are estimated and compared to those obtained from cross-polarized light scattering images recorded under polarized illumination at 700 nm. The optical spectroscopic images for each tissue sample were subsequently compared with the histopathology slides. The experimental results indicate that the intensity of the near-infrared emission is considerably different in breast cancer compared to that of the adjacent nonneoplastic tissues (adipose and fibrous tissue). The experimental results suggest that 632.8-nm excitation offers key advantages compared to 532 nm excitation.