Search

Background: Peripheral iridectomy (PI), routinely performed during glaucoma filtration surgery, may contribute to scarring. This study aims to determine whether PI alters the concentrations of VEGF-A and TGF-β isoforms in the rabbit aqueous humour., Methods: Anterior chamber paracentesis (ACP) was performed in both eyes of six New Zealand white rabbits, with additional surgical PI performed in the right eyes. Eyes were examined on postoperative days (PODs) 1, 7, 30 and 60 by means of the tonopen, slit-lamp biomicroscopy, and bead-based cytokine assays for TGF-β and VEGF-A concentrations in the aqueous humor., Results: ACP caused a significant reduction in intraocular pressure (IOP) from mean preoperative 11.47 ± 1.01 mmHg to 5.67 ± 1.63 mmHg on POD 1 while PI did not cause further IOP reduction. Limbal conjunctival vasculature appeared slightly increased on POD 1 in both ACP and PI eyes with PI also causing mild bleeding from damaged iris vessels. Two PI eyes developed fibrinous anterior chamber reaction and/ or peripheral anterior synechiae. Aqueous VEGF-A levels were not significantly different between eyes treated with ACP and PI. Aqueous TGF-β concentrations distributed in the ratio of 4:800:1 for TGF-β1:TGF-β2:TGF-β3 respectively. While aqueous TGF-β2 was not significantly induced by either procedure at any time point, TGF-β1 and TGF-β3 were significantly induced above baseline levels by PI on POD 1., Conclusion: PI increases the risk of inflammation. The combined induction of aqueous TGF-β1 and TGF-β3 by PI in glaucoma surgery may impact surgery success in glaucoma subtypes sensitive to these isoforms., (© 2022. The Author(s).)

[This corrects the article DOI: 10.1186/s40662-018-0128-8.].

Background: Optical coherence tomography angiography (OCTA) is a novel non-invasive angiography technology that has recently been extensively studied for its utility in anterior segment imaging. In this study, we compared a split-spectrum amplitude decorrelation angiography (SSADA) OCTA and an Complex OCT signal difference angiography [corrected] (CODAA SD) [corrected] OCTA system to current angiographic technique, indocyanine green angiography (ICGA), to assess corneal vascularisation in an animal model., Methods: We imaged 16 rabbits, (one eye per animal) with corneal vascularisation using SSADA OCTA (AngioVue; Optovue Inc., USA), CODAA OCTA [corrected] (Angioscan; RS-3000 Nidek Co. Ltd., Japan) and ICGA in the same region of interest of the cornea at successive time-points. We then analysed all scanned images for vessel density measurements and used paired t-tests and Bland-Altman plots to examine for significant differences. The en-face segmentation images from each of the OCTA scans were also extracted and were matched at every 50 μm segmentation to be compared for vessel density at the respective depths., Results: Bland-Altman plots revealed a good agreement between all three imaging techniques ( P  > 0.05) for all vessel density measurements computed, and the ranges of 95% limit of agreement were acceptable from a clinical perspective. No significant difference was reported, with ICGA (μ = 16.52 ± 8.94%) being more comparable to the CODAA [corrected] OCTA (μ = 16.23 ± 9.51%; p  = 0.50) than the SSADA OCTA (μ = 17.09 ± 7.34%; p  = 0.33) system. Also, a good correlation value ( r  > 0.9) was obtained when comparing the vessel density measurements of the en-face segmentations between the OCTA systems., Conclusions: Comparable vessel density quantification between the two OCTA systems, and with ICGA was obtained. Segmentation analysis of the vasculature at different depths showed varied performance in the two OCTA systems relative to each other. The implications of the study may help to aid in the development of better OCTA algorithms for the anterior segment and its use in clinical translational research., Competing Interests: The work was carried out with prior approval from the Institutional Animal Care and Use Committee of SingHealth. All experimental procedures were carried out in accordance with the guidelines of the Association for Research in Vision and Ophthalmology for the use of animals in ophthalmic and vision research.Not applicable.The authors declare that they have no competing interests.