Blue light versus green light fundus autofluorescence in normal subjects and in patients with retinochoroidopathy secondary to retinal and uveitic diseases

Fundus autofluorescence in uveitis: from pathogenesis to imaging interpretation

PURPOSE

This review aims to summarize the current fundus autofluorescence (FAF) ailment for diagnosis and follow-up of uveitis.

METHODS

A thorough literature search was performed in the PubMed database.

RESULTS

FAF maps the retinal pigment epithelium's (RPE) health. Therefore, several posterior infectious and non. This fast, easy-to-perform, noninvasive technique can detect and manage infectious uveitis.

CONCLUSIONS

FAF serves to understand pathophysiologic mechanisms of uveitis and is a valuable prognostic indicator of themselves.

Peripheral Retinal Involvement in Extensive Macular Atrophy with Pseudodrusen-Like Deposits

PURPOSE

To describe the alterations of the peripheral retina in extensive macular atrophy with pseudodrusen-like deposits (EMAP) by means of ultrawidefield fundus photography (UWFFP) and ultrawidefield fundus autofluorescence (UWF-FAF).

STUDY DESIGN

Prospective, observational case series.

PARTICIPANTS

Twenty-three patients affected by EMAP.

METHODS

Each patient underwent best-corrected visual acuity (BCVA) measurement, UWFFP, and UWF-FAF. The area of macular atrophy, as well as the pseudodrusen-like deposits and peripheral degeneration, were assessed using UWF images, at baseline and over the follow-up.

MAIN OUTCOME MEASURES

The assessment of the clinical patterns of both pseudodrusen-like deposits and peripheral retinal degeneration. Secondary outcomes included assessing macular atrophy by means of UWFFP and UWF-FAF, and tracking progression over the follow-up.

RESULTS

Twenty-three patients (46 eyes) were included, of whom 14 (60%) were female. Mean age was 59.0 ± 5 years. Mean BCVA at baseline was 0.4 ± 0.4, declining at a mean rate of 0.13 ± 0.21 logarithm of the minimum angle of resolution/year. Macular atrophy at baseline was 18.8 ± 14.2 mm2 on UWF-FAF, enlarging at a rate of 0.46 ± 0.28 mm/year, after the square root transformation. Pseudodrusen-like deposits were present in all cases at baseline, and their detection decreased over the follow-up. Three main types of peripheral degeneration were identified: retinal pigment epithelium alterations, pavingstone-like changes, and pigmented chorioretinal atrophy. Peripheral degeneration progressed in 29 eyes (63.0%), at a median rate of 0.7 (interquartile range, 0.4-1.2) sectors/year.

CONCLUSIONS

Extensive macular atrophy with pseudodrusen-like deposits is a complex disease involving not only the macula, but also the midperiphery and the periphery of the retina.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Functional Imaging of Mitochondria in Age-Related Macular Degeneration Using Flavoprotein Fluorescence

PURPOSE

Oxidative stress-induced mitochondrial dysfunction is implicated in the pathogenesis of age-related macular degeneration (AMD). Oxidized mitochondrial flavoprotein fluorescence (FPF) may serve as a quantifiable biomarker of oxidative stress, reported as either mean score for the entire image (intensity) or variability (heterogeneity). This study examines FPF intensity and heterogeneity across a large patient cohort of various Beckman stages of AMD.

METHODS

This study enrolled patients with isolated AMD and healthy control patients with no retinopathy between 2018 and 2021. Multivariate logistic regression analysis included stage of AMD, age, gender, ethnicity, and smoking status. Analysis of Variance test compared mean FPF intensity and heterogeneity between disease states.

RESULTS

Four hundred fifty-six eyes (228 AMD eyes, 228 age-matched control eyes) were included in the final multivariate analysis. Intermediate, geographic atrophy (GA), and neovascular AMD correlated with significantly increased FPF intensity (P < 0.001, respectively), while all AMD stages correlated with increased FPF heterogeneity (P < 0.001, respectively). FPF intensity and heterogeneity were significant negative predictors of visual acuity (P = 0.018 and 0.024, respectively).

CONCLUSIONS

This prospective observational study further implicates mitochondrial damage in AMD pathophysiology. Long-term clinical trials will be needed to examine the predictive role of FPF imaging in patients over time. [Ophthalmic Surg Lasers Imaging Retina 2023;54:24-31.].

Semi-Automated Live Tracking of Microglial Activation in CX3CR1GFP Mice During Experimental Autoimmune Encephalomyelitis by Confocal Scanning Laser Ophthalmoscopy

Confocal scanning laser ophthalmoscopy (cSLO) is a non-invasive technique for real-time imaging of the retina. We developed a step-by-step protocol for the semi-automatic evaluation of myeloid cells in cSLO images from CX3CR1GFP mice, expressing green fluorescent protein (GFP) under control of the endogenous CX3C chemokine receptor 1 locus. We identified cSLO parameters allowing us to distinguish animals with experimental autoimmune encephalomyelitis (EAE) from sham-treated/naïve animals. Especially cell count (CC) and the total microglial area (SuA) turned out to be reliable parameters. Comparing the cSLO results with clinical parameters, we found significant correlations between the clinical EAE score and the SuA and of the inner retinal layer thickness, measured by optical coherence tomography, with the CC as well as the SuA. As a final step, we performed immunohistochemistry to confirm that the GFP-expressing cells visualized by the cSLO are Iba1 positive and validated the step-by-step protocol against manual counting. We present a semi-automatic step-by-step protocol with a balance between fast data evaluation and adequate accuracy, which is optimized by the option to manually adapt the contrast threshold. This protocol may be useful for numerous research questions on the role of microglial polarization in models of inflammatory and degenerating CNS diseases involving the retina.

Multimodal Imaging Features of Optic Disc Drusen

PURPOSE

To identify key en face multimodal imaging features of optic disc drusen (ODD).

DESIGN

Retrospective cross-sectional study.

METHODS

Setting: a single academic center. Patient orStudyPopulation: 786 patients (10-82 years of age) with diagnostic codes for optic disc drusen (ODD) in clinical notes extracted using natural language processing. Intervention orObservationProcedures: color fundus imaging, green-light and blue-light fundus autofluorescence (FAF), near-infrared reflectance (NIR), and enhanced-depth imaging optical coherence tomography (EDI-OCT). MainOutcomeMeasurements: Ophthalmic imaging characteristics and sensitivity of en face imaging compared with EDI-OCT.

RESULTS

A total of 38 patients (61 eyes) had high-quality EDI-OCT scans and en face multimodal imaging. Green-light FAF imaging had the highest diagnostic sensitivity (96.8%) for ODD and showed homogeneous hyperautofluorescence, whereas blue-light FAF imaging had heterogeneous brightness, which helped differentiate superficial from deep ODD. Blue-light FAF (93.5%) and NIR (91.8%) imaging were also sensitive tests and revealed papillary and peripapillary features that were not well seen on green-light FAF, including the size and depth of ODD, morphology of the optic disc, and common ODD-associated structures such as horizontal hyper-reflective lines and peripapillary hyper-reflective ovoid mass-like structures (PHOMS). Color fundus imaging had the lowest sensitivity (82%). There was good inter-rater reliability for all en face imaging modalities (P < .0001 for all).

CONCLUSIONS

In en face imaging, green-light FAF had the highest sensitivity for the diagnosis of ODD, whereas blue-light FAF and NIR images provided more information regarding the severity, location, depth, and size of ODD. In eyes that are negative on green-light FAF, EDI-OCT should be performed and provides the highest-resolution characterization of the entire optic disc to assess or rule out ODD.

Fundus autofluorescence in premature infants

To describe fundus autofluorescence (FAF) patterns in premature infants and to determine whether FAF increases gradually with increasing post-gestational age. This was a cross-sectional, observational and descriptive case series. FAF images were obtained from patients screened for Retinopathy of Prematurity. The presence of the following hypo-autofluorescence areas/structures was graded and ranked: macular pigment (foveal centre), optic nerve head, peripapillary vessels/vascular arcade (PP/VA), and equatorial vessels (EqV). Ranks were attributed to the number of structures visualized from the posterior pole towards the periphery. The rank of FAF could then be analysed by Spearman’s correlation against age. Additionally, patients were divided by age into group 1 (< 40 weeks of corrected gestational age (WCGA)) and group 2 (> 40 WCGA). Differences between groups were tested with the Mann–Whitney U test. Thirteen patients were analysed. The mean WCGA at examination was 47.85 weeks. Spearman’s correlation showed a strong positive correlation (r = 0.714) (P = 0.006) of FAF and WCGA. The Mann–Whitney U test revealed that the PP/VA and EqV were significantly more visible at > 40 WCGA than at < 40 WCGA (8.0 [P = 0.016] and 7.5 [P = 0.03], respectively). Patterns of FAF are described for the first time in premature infants. FAF increases gradually with age and centrifugally from the posterior pole towards the equator in premature infants.

Blue-Light Fundus Autofluorescence Imaging following Ruthenium-106 Brachytherapy for Choroidal Melanoma

PURPOSE

To describe changes in blue-light fundus autofluorescence (FAF) and corresponding alterations in optical coherence tomography (OCT) within the irradiation field after ruthenium-106 brachytherapy (RBT) for choroidal melanoma.

METHODS

Consecutive patients with choroidal melanoma were included in a retrospective case series. Patients were treated with RBT at a single institution. As part of their routine examination patients underwent multimodal imaging including ultrasonography, fundus photography, OCT, and FAF imaging (excitation = 488 nm). FAF images were analysed for changes within the irradiation field.

RESULTS

31 patients (mean age 65.7 years) were treated with RBT for unilateral choroidal melanoma. Mean tumour height before therapy was 2.7 mm (SD 1.0). Mean follow-up time was 23.3 months (SD 13.3). Main FAF characteristics attributable to RBT emerged as increased FAF with speckled decreased FAF (FAF mottling) within the irradiation field and a rim of increased FAF at its border. OCT scans demonstrated loss of the ellipsoid zone and the external limiting membrane, thinning of the neurosensory retina, and alterations of the retinal pigment epithelium like clumping, migration, and atrophy.

CONCLUSIONS

FAF changes in the irradiation field after RBT of choroidal melanomas follow a characteristic pattern that correlates with distinct OCT alterations. FAF and OCT imaging give additional information to monitor effects of RBT and, therefore, complement multimodal imaging techniques after plaque therapy.