Thiel cadaver eye as a training model for sub-Tenon's blocks: a feasibility study.

BACKGROUND: Regional anaesthesia education, especially for ocular procedures, necessitates reliable surgical training models. While cadaveric models offer anatomical fidelity, conventional embalming methods may compromise tissue integrity. We aimed to assess the effectiveness of Thiel cadavers for training in sub-Tenon's blocks by evaluating ocular tissues and measuring insertion forces. METHODS: Experimental design, using twenty eyes from ten Thiel cadaver heads. These cadavers were specifically prepared to test the administration of sub-Tenon's blocks. The research was conducted in a controlled laboratory setting appropriate for handling cadaveric materials and conducting precise measurements. Each cadaver eye underwent an initial ultrasound examination, and its axial length was noted. An intravitreal injection of heptastarch solution followed, to re-establish the eye's sphericity. After this volume injection, the axial length and intraocular pressure were measured again. Mock sub-Tenon's blocks were administered in 2 separate quadrants of the eye, with insertion forces measured using a pressure gauge. These were compared to a data set of insertion forces measured in a series of isolated pig's eyes on which STBs had been performed. Main outcome measurements were macroscopic assessment of the ocular tissue layers and the insertion forces required for the sub-Tenon's blocks. In a second set of 10 Thiel cadaver heads, 5 ml of sodium chloride were injected as sub-Tenon's blocks and the emergence of a periocular "T-sign" ascertained and measured by ultrasound. RESULTS: Four of twenty eyes (20%) retained near-natural sphericity, with the remaining requiring volume injection to approximate physiological shape and pressure. The conjunctiva and Tenon's layer were intact, and correct cannula placement was achieved in all cases. In 16 of 20 eyes where T-signs could be measured, the median thickness of the T-sign amounted to 2.72 mm (range 1.34 mm-5.28 mm). The average maximum cannula insertion force was 2.92 Newtons. Insertion forces in intact Thiel cadaver heads were consistently higher than in isolated pig's eyes (3.6 N vs 2.0 N). CONCLUSION: These findings suggest that Thiel cadavers are a promising model for training in sub-Tenon'sblocks, despite the challenge of often desiccated and involuted eyes.

FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY AS PREDICTOR OF LONG-TERM FUNCTIONAL OUTCOME IN MACULA-OFF RHEGMATOGENOUS RETINAL DETACHMENT.

PURPOSE: To assess whether macular fluorescence lifetimes may serve as a predictor for long-term outcomes in macula-off rhegmatogenous retinal detachment. METHODS: A single-center observational study was conducted. Patients with pseudophakic macula-off rhegmatogenous retinal detachment were included and evaluated 1 and 6 months after successful reattachment surgery. Fluorescence lifetime imaging ophthalmoscopy lifetimes in the central Early Treatment Diabetic Retinopathy Study grid subfield, in two distinct channels (short spectral channel and long spectral channel) were analyzed. Best-corrected visual acuity optical coherence tomography of the macula and fluorescence lifetimes were measured at month 1 and month 6. RESULTS: Nineteen patients were analyzed. Lifetimes of the previously detached retinas were prolonged compared with the healthy fellow eyes. Short lifetimes at month 1 were associated with better best-corrected visual acuity improvement (short spectral channel: r2 = 0.27, P < 0.05, long spectral channel: r2 = 0.23, P < 0.05) and with good final best-corrected visual acuity (short spectral channel: r2 = 0.43, P < 0.01, long spectral channel: r2 = 0.25, P < 0.05). Lifetimes were prolonged in some cases of outer retinal damage in optical coherence tomography scans. CONCLUSION: Fluorescence lifetime imaging ophthalmoscopy might serve as a prediction tool for functional recovery in pseudophakic macula-off rhegmatogenous retinal detachment. Retinal fluorescence lifetimes could give insight in molecular processes after rhegmatogenous retinal detachment.

Evaluation of an Artificial Intelligence-Based Detector of Sub- and Intraretinal Fluid on a Large Set of Optical Coherence Tomography Volumes in Age-Related Macular Degeneration and Diabetic Macular Edema.

INTRODUCTION: In this retrospective cohort study, we wanted to evaluate the performance and analyze the insights of an artificial intelligence (AI) algorithm in detecting retinal fluid in spectral-domain OCT volume scans from a large cohort of patients with neovascular age-related macular degeneration (AMD) and diabetic macular edema (DME). METHODS: A total of 3,981 OCT volumes from 374 patients with AMD and 11,501 OCT volumes from 811 patients with DME were acquired with Heidelberg-Spectralis OCT device (Heidelberg Engineering Inc., Heidelberg, Germany) between 2013 and 2021. Each OCT volume was annotated for the presence or absence of intraretinal fluid (IRF) and subretinal fluid (SRF) by masked reading center graders (ground truth). The performance of an already published AI algorithm to detect IRF and SRF separately, and a combined fluid detector (IRF and/or SRF) of the same OCT volumes was evaluated. An analysis of the sources of disagreement between annotation and prediction and their relationship to central retinal thickness was performed. We computed the mean areas under the curves (AUC) and under the precision-recall curves (AP), accuracy, sensitivity, specificity, and precision. RESULTS: The AUC for IRF was 0.92 and 0.98, for SRF 0.98 and 0.99, in the AMD and DME cohort, respectively. The AP for IRF was 0.89 and 1.00, for SRF 0.97 and 0.93, in the AMD and DME cohort, respectively. The accuracy, specificity, and sensitivity for IRF were 0.87, 0.88, 0.84, and 0.93, 0.95, 0.93, and for SRF 0.93, 0.93, 0.93, and 0.95, 0.95, 0.95 in the AMD and DME cohort, respectively. For detecting any fluid, the AUC was 0.95 and 0.98, and the accuracy, specificity, and sensitivity were 0.89, 0.93, and 0.90 and 0.95, 0.88, and 0.93, in the AMD and DME cohort, respectively. False positives were present when retinal shadow artifacts and strong retinal deformation were present. False negatives were due to small hyporeflective areas in combination with poor image quality. The combined detector correctly predicted more OCT volumes than the single detectors for IRF and SRF, 89.0% versus 81.6% in the AMD and 93.1% versus 88.6% in the DME cohort. DISCUSSION/CONCLUSION: The AI-based fluid detector achieves high performance for retinal fluid detection in a very large dataset dedicated to AMD and DME. Combining single detectors provides better fluid detection accuracy than considering the single detectors separately. The observed independence of the single detectors ensures that the detectors learned features particular to IRF and SRF.

IMAGING ARTIFACTS IN FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY.

PURPOSE: To investigate and quantify the influence of imaging artifacts on retinal fluorescence lifetime (FLIO) values and to provide helpful hints and tricks to avoid imaging artifacts and to improve FLIO image acquisition quality. METHODS: A systematic analysis of potential parameters influencing FLIO quality and/or fluorescence lifetime values was performed in a prospective systematic experimental imaging study in five eyes of five healthy subjects. For image acquisition, a fluorescence lifetime imaging ophthalmoscope (Heidelberg Engineering) was used. Quantitative analysis of FLIO lifetime changes due to imaging artifacts was performed. RESULTS: Imaging artifacts with significant influence on fluorescence lifetimes included too short image acquisition time, insufficient illumination, ocular surface problems, and image defocus. Prior use of systemic or topical fluorescein makes analysis of retinal fluorescence lifetimes impossible. CONCLUSION: Awareness of possible sources of imaging artifacts is important for FLIO image acquisition and analysis. Therefore, standardized imaging and analysis procedure in FLIO is crucial for high-quality image acquisition and the possibility for systematic quantitative fluorescence lifetime analysis.

LONGITUDINAL FOVEAL FLUORESCENCE LIFETIME CHARACTERISTICS IN GEOGRAPHIC ATROPHY USING FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY.

PURPOSE: Short foveal fluorescence lifetimes (fFLT) in geographic atrophy are typically found in eyes with foveal sparing (FS) but may also occur in eyes without FS. We investigated whether short fFLT could serve as a functional biomarker for disease progression in geographic atrophy. METHODS: Thirty three eyes were followed over the course of 4 to 6 years. Foveal sparing was assessed using fluorescence lifetime imaging ophthalmoscopy, optical coherence tomography, fundus Autofluorescence, and macular pigment optical density. RESULTS: Eyes with FS exhibited shorter fFLT compared with eyes without FS. Short fFLT (<600 ps) were measured in all eyes with FS and half of the eyes without FS. Eyes with FS showed a bigger increase in fFLT per year (+39/+30 ps (short spectral channel/long spectral channel) in FS versus +29/+22 ps (short spectral channel/long spectral channel) in non FS). The best-corrected distance visual acuity correlated significantly with fFLT (P = 0.018 and P = 0.005 for short spectral channel/long spectral channel). Macular pigment optical density measurements correlated significantly with fFLT but not in all spectral channels (P ranging from 0.018 to 0.077). CONCLUSION: In geographic atrophy, shorter fFLT are associated with FS but they can also be observed in eyes without FS. Our longitudinal data suggest that shorter fFLT features in eyes with loss of FS represent an earlier stage of disease and may be more prone to loss of the visual acuity.

FLUORESCENCE LIFETIME IMAGING OPHTHALMOSCOPY: Findings After Surgical Reattachment of Macula-Off Rhegmatogenous Retinal Detachment.

PURPOSE: The purpose of this study was to investigate fluorescence lifetime imaging ophthalmoscopy lifetimes after macula-off rhegmatogenous retinal detachment (RRD) repair. METHODS: Fifty-eight patients with successful macula-off RRD reattachment surgery were included. Retinal autofluorescence was excited with 470 nm, and amplitude-weighted mean fluorescence lifetimes (Tm) were measured in a short spectral channel (SSC, 498-560 nm) and a long spectral channel (LSC, 560-720 nm). Tm were obtained within a standardized Early Treatment Diabetic Retinopathy Study grid and correlated with Tm. The unaffected fellow eye served as control. RESULTS: Fifty-eight patients (age: 65 ± 1.6 years, 11 women) were imaged at median 1.5 months postoperatively. Tm were significantly prolongxxxed within areas of previously detached retina in the long spectral channel and particularly in the central subfield in the short spectral channel. Short lifetimes in the center of the Early Treatment Diabetic Retinopathy Study grid correlated with better visual acuity (short spectral channel; r = 0.18, P = 0.001, long spectral channel; r = 0.08, P = 0.03). Areas of residual subretinal fluid pockets in four RRD eyes displayed short fluorescence lifetimes. CONCLUSION: Areas of previously detached retina exhibit significant fluorescence lifetime changes. We found a significant correlation of fluorescence lifetimes within the fovea with visual acuity after successful RRD repair. Our data suggests that the prolongation of fluorescence lifetimes in the fovea is mainly driven by loss of macular pigment. Therefore, fluorescence lifetime imaging ophthalmoscopy may be useful in the prediction of long-term functional outcomes after macula-off RRD surgery.

Aflibercept for central retinal vein occlusions: long-term outcomes of a 'Treat-and-Extend' regimen.

BACKGROUND/AIMS: This study reports on the long-term functional and anatomical outcomes of patients with central retinal vein occlusion (CRVO) treated under the Bern treat-and-extend (T&E) protocol. METHODS: Observational study. Treatment-naive patients with CRVO and consecutive macular oedema treated with aflibercept were included. The T&E protocol involved 2 monthly injections followed by an extension based on individual assessments. At each visit, best-corrected visual acuity (BCVA), optical coherence tomography imaging and a 2 mg aflibercept injection were administered. Changes in BCVA, proportion of patients gaining ≥15 letters, central subfield thickness (CST) and treatment intervals were analysed. RESULTS: Out of 173 patients, 64 had a follow-up of at least 2 years. BCVA improved from 46.7±25.3 at baseline to 78.3±0.5 at year 9. The proportion of patients with ≥15 letters gained was 56%, 53%, 56%, 62%, 52%, 52%, 43%, 50% and 33% at years 1-9, respectively. CST decreased significantly from 660±242 µm at baseline to 359±63 µm at year 9. Treatment intervals extended from 4 weeks initially to an average of 13.0±4.1 weeks by year 8. CONCLUSIONS: The T&E regimen for CRVO shows sustained visual improvements and reduced CST over time. Patients maintained stable visual gains for many years, demonstrating the effectiveness of this treatment approach. However, no control group was available to compare our T&E regimen with other strategies.

Artificial intelligence derived large language model in decision-making process in uveitis.

BACKGROUND: Uveitis is the ophthalmic subfield dealing with a broad range of intraocular inflammatory diseases. With the raising importance of LLM such as ChatGPT and their potential use in the medical field, this research explores the strengths and weaknesses of its applicability in the subfield of uveitis. METHODS: A series of highly clinically relevant questions were asked three consecutive times (attempts 1, 2 and 3) of the LLM regarding current uveitis cases. The answers were classified on whether they were accurate and sufficient, partially accurate and sufficient or inaccurate and insufficient. Statistical analysis included descriptive analysis, normality distribution, non-parametric test and reliability tests. References were checked for their correctness in different medical databases. RESULTS: The data showed non-normal distribution. Data between subgroups (attempts 1, 2 and 3) was comparable (Kruskal-Wallis H test, p-value = 0.7338). There was a moderate agreement between attempt 1 and attempt 2 (Cohen's kappa, ĸ = 0.5172) as well as between attempt 2 and attempt 3 (Cohen's kappa, ĸ = 0.4913). There was a fair agreement between attempt 1 and attempt 3 (Cohen's kappa, ĸ = 0.3647). The average agreement was moderate (Cohen's kappa, ĸ = 0.4577). Between the three attempts together, there was a moderate agreement (Fleiss' kappa, ĸ = 0.4534). A total of 52 references were generated by the LLM. 22 references (42.3%) were found to be accurate and correctly cited. Another 22 references (42.3%) could not be located in any of the searched databases. The remaining 8 references (15.4%) were found to exist, but were either misinterpreted or incorrectly cited by the LLM. CONCLUSION: Our results demonstrate the significant potential of LLMs in uveitis. However, their implementation requires rigorous training and comprehensive testing for specific medical tasks. We also found out that the references made by ChatGPT 4.o were in most cases incorrect. LLMs are likely to become invaluable tools in shaping the future of ophthalmology, enhancing clinical decision-making and patient care.

Fluorescence lifetime imaging ophthalmoscopy and the influence of oral lutein/zeaxanthin supplementation on macular pigment (FLOS) - A pilot study.

BACKGROUND & AIMS: Oral lutein (L) and zeaxanthin (Z) supplementation enhances macular pigment optical density (MPOD) and plays a protective role in the development of age-related macular degeneration (AMD). Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a novel in vivo retinal imaging method that has been shown to correlate to classical MPOD measurements and might contribute to a metabolic mapping of the retina in the future. Our aim was to show that oral supplementation of L and Z affects the FLIO signal in a positive way in patients with AMD. METHODS: This was a prospective, single center, open label cohort study. Patients with early and intermediate AMD received oral L and Z supplementation during three months, and were observed for another three months after therapy termination. All visits included measurements of clinical parameters, serum L and Z concentration, MPOD measurements using heterochromatic flicker photometry, dual wavelength autofluorescence imaging, and FLIO. Correlation analysis between FLIO and MPOD were performed. RESULTS: Twenty-one patients completed the follow up period. Serum L and Z concentrations significantly increased during supplementation (mean difference 244.8 ng/ml; 95% CI: 81.26-419.9, and 77.1 ng/ml; 95% CI: 5.3-52.0, respectively). Mean MPOD units significantly increased (mean difference 0.06; 95% CI: 0.02-0.09; at 0.5°, 202; 95% CI: 58-345; at 2°, 1033; 95% CI: 288-1668; at 9° of eccentricity, respectively) after three months of supplementation with macular xanthophylls, which included L and Z. Median FLIO lifetimes in the foveal center significantly decreased from 277.3 ps (interquartile range 230.2-339.1) to 261.0 ps (interquartile range 231.4-334.4, p = 0.027). All parameters returned to near-normal values after termination of the nutritional supplementation. A significant negative correlation was found between FLIO and MPOD (r2 = 0.57, p < 0.0001). CONCLUSIONS: FLIO is able to detect subtle changes in MPOD after L and Z supplementation in patients with early and intermediate AMD. Our findings confirm the previous described negative correlation between FLIO and MPOD. Macular xanthophylls seem to contribute to short foveal lifetimes. This study is registered at ClinicalTrials.gov (identifier number NCT04761341).

Aflibercept for age-related macular degeneration: 4-year outcomes of a 'treat-and-extend' regimen with exit-strategy.

AIM: To report long-term outcomes on best-corrected visual acuity (BCVA) and treatment intervals with a treat-and-extend (T&E) regimen in patients with neovascular age-related macular degeneration (nAMD). METHODS: This observational study included treatment-naïve patients with nAMD, treated with aflibercept. A specific T&E protocol without a loading phase and predefined exit criteria was administered. After reaching predefined 'exit-criteria', the treatment period was complete, and patients were observed three monthly. RESULTS: Eighty-two patients with a follow-up period of ≥2 years were included. BCVA (mean±SD, ETDRS letters) increased from 51.9±25.2 at baseline to 63.7±17.7 (p<0.0001) at 1 year, 61.7±18.5 (p<0.0001) at 2 years, 62.4±19.5 (p<0.0001, n=61) at 3 years and remained insignificantly higher than baseline at 4 years at 58.5±24.3 (p=0.22). Central subfield thickness (mean±SD, µm) decreased significantly from 387.5±107.6 (p<0.0001) at baseline to 291.9±65.5 (p<0.0001) at 1 year, and remained significantly lower until 4 years at 289.0±59.4 (p<0.0001). Treatment intervals (mean±SD, weeks) could be extended up to 9.3±3.1 weeks at 1 year and remained at 11.2±3.5 weeks at 4 years. Twenty-nine (35%) patients reached exit criteria and continued with three monthly observation only. CONCLUSIONS: After 4 years of treatment, initial vision gains were maintained with a reasonable treatment burden, even without an initial loading phase. Our results on functional outcomes are comparable with large controlled studies.

The Influence of Cataract on Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO).

Purpose: To investigate the influence of lens opacifications on fluorescence lifetime imaging ophthalmoscopy (FLIO). Methods: Forty-seven eyes of 45 patients were included. Mean fluorescence lifetimes (Tm) were recorded with a fluorescence lifetime imaging ophthalmoscope in a short spectral channel (SSC) and a long spectral channel (LSC). Retinal and lens autofluorescence lifetimes were measured in subjects before and after cataract surgery. Lens opacification was graded using the Lens Opacities Classification System III (LOCS III) classification. Results: The retinal Tm decreased significantly after cataract surgery in both spectral channels (SSC: -53%, P < 0.0001; LSC: -26%, P = 0.0041). The lens Tm differed significantly between the crystalline and the artificial lens in both spectral channels (P < 0.0001). The "nuclear opacity" and "nuclear color" score of the LOCS III classification correlated significantly with the mean Tm difference in both spectral channels (P < 0.0001). Conclusions: Lens opacification results in significantly longer retinal Tm. Therefore the lens status has to be considered when performing cross-sectional fluorescence lifetime analysis. Cataract-formation and cataract-surgery needs to be considered when conducting longitudinal studies. Grading of nuclear opacity following the LOCS III classification provides an approximate conversion formula for the mean change of lifetimes, which can be helpful in the interpretation of data in patients with lens opacities. Translational Relevance: FLIO is significantly influenced by lens opacities. Using a lens opacity grading scheme and measuring fluorescence lifetimes before and after cataract surgery, an approximative conversion formula can be calculated, which enables the comparison of lifetimes after cataract surgery or over the course of time.

Understanding the Interactions Between the Ocular Surface Microbiome and the Tear Proteome.

Purpose: The purpose of this study was to explore the interplay between the ocular surface microbiome and the tear proteome in humans in order to better understand the pathogenesis of ocular surface-associated diseases. Methods: Twenty eyes from 20 participants were included in the study. The ocular surface microbiome was sequenced by whole-metagenome shotgun sequencing using lid and conjunctival swabs. Furthermore, the tear proteome was identified using chromatography tandem mass spectrometry. After compositional and functional profiling of the metagenome and functional characterization of the proteome by gene ontology, association studies between the ocular microbiome and tear proteome were assessed. Results: Two hundred twenty-nine taxa were identified with Actinobacteria and Proteobacteria being the most abundant phyla with significantly more Propionibacterium acnes and Staphylococcus epidermidis in lid compared to conjunctival swabs. The lid metagenomes were enriched in genes of the glycolysis lll and adenosine nucleotides de novo and L-isoleucine biosynthesis. Correlations between the phylum Firmicutes and fatty acid metabolism, between the genus Agrobacterium as well as vitamin B1 synthesis and antimicrobial activity, and between biosynthesis of heme, L-arginine, as well as L-citrulline and human vision were detected. Conclusions: The ocular surface microbiome was found to be associated with the tear proteome with a role in human immune defense. This study has a potential impact on the development of treatment strategies for ocular surface-associated diseases.

Relationship Between Presumptive Inner Nuclear Layer Thickness and Geographic Atrophy Progression in Age-Related Macular Degeneration.

PURPOSE: To analyze inner retinal changes in patients with geographic atrophy (GA) secondary to age-related macular degeneration and identify morphological cues for progression. METHODS: A total of 100 eyes with GA were assessed in this longitudinal, observational case series. Patients with GA and absent confounding pathology were compared with age-matched controls. The retinal layers on spectral-domain optical coherence tomography, acquired in tracking mode, were segmented manually on central scans through the fixation point. Zones of GA were defined based on choroidal signal enhancement from retinal pigment epithelium loss. An area of unaffected temporal retina was used for comparison. Progression of GA was quantified with fundus autofluorescence. RESULTS: We analyzed 41 eyes of 41 patients (mean age 79.2 ± 6.7 years). In areas of GA, the layer representing the inner nuclear layer (INL) in healthy retina was increased in thickness. Thickness of this presumptive INL was inversely correlated with best-corrected visual acuity (r = -0.48, P < 0.01). The presumptive INL thickness increase in atrophic areas was less marked in eyes with foveal sparing. Increased INL thickness in areas adjacent to GA was associated with a higher progression rate. CONCLUSIONS: Optical coherence tomography findings demonstrate that atrophy of the retinal pigment epithelium-photoreceptor complex in GA is associated with an increase of thickness of the presumptive INL, presumably caused by remodeling of the degenerating retina. Similar alterations in the retina adjacent to areas clinically affected by GA were associated with higher atrophy progression rates.