VEGF-C and 5-Fluorouracil Improve Bleb Survival in a Rabbit Glaucoma Surgery Trabeculectomy Model.

Purpose: To evaluate VEGF-C-induced lymphoproliferation in conjunction with 5-fluorouracil (5-FU) antimetabolite treatment in a rabbit glaucoma filtration surgery (GFS) model. Methods: Thirty-two rabbits underwent GFS and were assigned to four groups (n = 8 each) defined by subconjunctival drug treatment: (a) VEGF-C combined with 5-FU, (b) 5-FU, (c) VEGF-C, (d) and control. Bleb survival, bleb measurements, and IOP were evaluated over 30 days. At the end, histology and anterior segment OCT were performed on some eyes. mRNA was isolated from the remaining eyes for RT-PCR evaluation of vessel-specific markers (lymphatics, podoplanin and LYVE-1; and blood vessels, CD31). Results: Qualitatively and quantitatively, VEGF-C combined with 5-FU resulted in blebs which were posteriorly longer and wider than the other conditions: vs. 5-FU (P = 0.043 for longer, P = 0.046 for wider), vs. VEGF-C (P < 0.001, P < 0.001) and vs. control (P < 0.001, P < 0.001). After 30 days, the VEGF-C combined with 5-FU condition resulted in longer bleb survival compared with 5-FU (P = 0.025), VEGF-C (P < 0.001), and control (P < 0.001). Only the VEGF-C combined with 5-FU condition showed a negative correlation between IOP and time that was statistically significant (r = -0.533; P = 0.034). Anterior segment OCT and histology demonstrated larger blebs for the VEGF-C combined with 5-FU condition. Only conditions including VEGF-C led to increased expression of lymphatic markers (LYVE-1, P < 0.001-0.008 and podoplanin, P = 0.002-0.011). Expression of CD31 was not different between the groups (P = 0.978). Conclusions: Adding VEGF-C lymphoproliferation to standard antimetabolite treatment improved rabbit GFS success and may suggest a future strategy to improve human GFSs.

A Versatile Hydrogel with Antibacterial and Sequential Drug-Releasing Capability for the Programmable Healing of Infectious Keratitis.

Hydrogels have attracted tremendous attention as favorable corneal substitutes for treating severe infectious keratitis (IK). However, current hydrogel-based corneal substitutes were majorly designed to promote the single stage of corneal regeneration, which falls short in meeting the clinical management needs of severe IK including the multiple phases of corneal wound healing. Herein, we introduce a versatile hybrid hydrogel (SQPV) composed of silk fibroin and chitosan, which exhibits spatiotemporal properties for drug release. The SQPV is fabricated by incorporating verteporfin-loaded poly(lactic-co-glycolic)-polyethylene glycol-o-nitrobenzene micelles into a hydrogel network, which is formed from methacrylate silk fibroin and glycidyl methacrylate functionalized quaternized chitosan containing polydeoxyribonucleotide. This double network approach results in a material with exceptional anti-inflammatory, antibacterial, and proliferative stimulation and tissue remodeling regulation capabilities. Furthermore, SQPV showcases mechanical strength and transparency akin to those of native cornea. Extensive in vitro and in vivo studies validate SQPV's ability to effectively eliminate residual bacteria, mitigate inflammation, foster regeneration of corneal epithelium and stroma, prevent corneal scarring, and ultimately expedite wound healing. In summary, the SF/CS-based hybrid hydrogel may represent a promising substitute for comprehensive corneal repair and regeneration in severe IK.

Assessment of iris volume in glaucoma patients with type 2 diabetes mellitus by AS-OCT.

AIM: To examine the change of iris volume measured by CASIA2 anterior segment optical coherence tomography (AS-OCT) in glaucoma patients with or without type 2 diabetes mellitus (T2DM) and explore if there is a correlation between hemoglobin A1c (HbA1c) level and iris volume. METHODS: In a cross-sectional study, 72 patients (115 eyes) were divided into two groups: primary open angle glaucoma (POAG) group (55 eyes) and primary angle-closure glaucoma (PACG) group (60 eyes). Patients in each group were separately classified into patients with or without T2DM. Iris volume and glycosylated HbA1c level were measured and analyzed. RESULTS: In the PACG group, diabetic patients' iris volume was significantly lower than those of non-diabetics (P=0.02), and there was a significant correlation between iris volume and HbA1c level in the PACG group (r=-0.26, P=0.04). However, diabetic POAG patients' iris volume was noticeably higher than those of non-diabetics (P=0.01), and there was a significant correlation between HbA1c level and iris volume (r=0.32, P=0.02). CONCLUSION: Diabetes mellitus impact iris volume size, as seen by increased iris volume in the POAG group and decreased iris volume in the PACG group. In addition, iris volume is significantly correlated with HbA1c level in glaucoma patients. These findings imply that T2DM may compromise iris ultrastructure in glaucoma patients.

Subconjunctival Lymphatics Respond to VEGFC and Anti-Metabolites in Rabbit and Mouse Eyes.

Purpose: To characterize and pharmacologically influence subconjunctival lymphatics in rabbit and mouse eyes. Methods: Rabbits received subconjunctival injections of trypan blue or fixable fluorescent dextrans. Bleb-related outflow pathways were quantified. Immunofluorescence for vessel-specific markers (lymphatics [podoplanin and LYVE-1] and blood vessels [CD31]) were performed in native rabbit conjunctiva and after fixable fluorescent dextran injection. Vascular endothelial cell growth factor-C (VEGFC) was injected subconjunctivally in rabbits. mRNA and protein were assessed for the above markers using RT-PCR and Western blot. Alternatively, mouse studies used Prox1-tdTomato transgenic reporter mice. Subconjunctival injection conditions included: no injection, balanced salt solution (BSS), VEGFC, 5-fluorouracil (5FU) and two concentrations of mitomycin-C (MMC). Two mouse injection protocols (short and long) with different follow-up times and number of injections were performed. Mouse eyes were enucleated, flat mounts created, and subconjunctival branching and length assessed. Results: Rabbit eyes demonstrated clear bleb-related subconjunctival outflow pathways that were distinct from blood vessels and were without nasal/temporal predilection. Immunofluorescence against vessel-specific markers showed lymphatics and blood vessels in rabbit conjunctiva, and these lymphatics overlapped with bleb-related subconjunctival outflow pathways. Subconjunctival VEGFC increased lymphatic (P = 0.004-0.04) but not blood vessel (P = 0.77-0.84) mRNA or protein in rabbits. Prox1-tdTomato transgenic reporter mice demonstrated natively fluorescent lymphatics. Subconjunctival VEGFC increased murine lymphatic branching and length (P ≤ 0.001-0.004) while antimetabolites (P ≤ 0.001-0.043) did the opposite for the long protocol. Discussion: Subconjunctival lymphatics are pharmacologically responsive to both VEGFC and antimetabolites in two animal models studied using different methodologies. These results may be important for bleb-forming glaucoma surgeries or ocular drug delivery.

Associations of lens thickness and axial length with outcomes of laser peripheral iridotomy.

AIM: To investigate the association of axial length (AL), lens thickness (LT), and lens vault (LV) with postoperative anterior chamber angle metrics after laser peripheral iridotomy (LPI). METHODS: Prospective observational study of 69 patients (97 eyes) were diagnosed as primary angle-closure suspect (PACS), primary angle closure (PAC) or primary angle-closure glaucoma (PACG). AL, LT, anterior central chamber depth (ACD), angle opening distance (AOD), trabecular iris angle (TIA), and angle recess area (ARA) were measured before and 1wk after LPI. The association between AL, LT, LV with ACD, AOD, TIA, ARA were analyzed by comparing the differences between preoperative and postoperative measurements for anterior segment biometric parameters. RESULTS: ACD, AOD, TIA, and ARA were significantly increased after LPI (all P<0.05). Greater LT was significantly associated with greater postoperative increases in ACD, AOD, TIA, and ARA (all P<0.05). AL was not significantly associated with changes of anterior segment biometric parameters. Greater LV was significantly associated with greater postoperative increases in ACD, AOD, and TIA (all P<0.05), but was not significantly associated with changes of ARA. CONCLUSION: Greater baseline LT and LV measurements are associated with greater increases in anterior segment biometric parameters after laser peripheral iridotomy. AL are not associated with the change of anterior segment biometric parameters.

Effects of lens extirpation with anterior vitrectomy on vitreous three-dimensional mesh structure.

AIM: To investigate the changes in vitreous gel structure after lens extirpation combined with anterior vitrectomy in rabbit eyes. METHODS: Twenty-eight chinchilla rabbits were divided into three groups. The control group (Group I) included 16 eyes from eight rabbits who did not receive any treatment. Group II included 20 eyes from 10 rabbits that underwent lens aspiration only. Group III included 20 eyes from 10 rabbits that underwent lens aspiration combined with posterior capsulotomy and anterior vitrectomy. Eyes were harvested on the 30th and 60th day postoperatively, respectively. Changes in vitreous gel stretch length due to gravity and the rate of vitreous liquefaction were observed. The collagen content in the vitreous body was examined using the L-hydroxyproline test. Electronic microscopic images were obtained from each eyeball. RESULTS: On both the 30th and 60th day postoperatively, the vitreous gel length of group III was significantly shorter than group I and group II (P<0.05), while the rate of liquefaction of the vitreous body in group III was significantly higher than group I and group II (P<0.05). The collagen content in group III was also higher than that in group I and group II (P<0.05). CONCLUSION: Loss of vitreous gel mass is more likely to occur in the eyes of rabbits receiving anterior vitrectomy. Lensectomy combined with anterior vitrectomy may damage the stable three-dimensional mesh structure of collagen, which could aggravate vitreous gel liquefaction.

Chemical and material communication between the optic nerves in rats.

BACKGROUND: To examine interactions between optic nerves. METHODS: A total of 24 Sprague-Dawley rats received unilateral intravitreal injections. The rats were equally divided into four groups: group A was administered an adeno-associated virus (AAV) carrying an exogenous gene (ND4; rAAV-ND4); group B, AAV carrying a green fluorescent protein (GFP; rAAV-GFP); group C, fluorogold (FG) nerve tracer dye; and group D, phosphate-buffered saline (PBS) as a control. Two weeks later, GFP expression was evaluated in both retinas and optic nerves of group B rats after frozen sectioning. The presence of FG was also evaluated in group C optic nerves by fluorescent microscopy after frozen sectioning. Four weeks after injection, ND4 expression was evaluated in both eyes of groups A and D using western blotting and immunofluorescence. RESULTS: FG was observed in the optic chiasm posterior segment along the optic nerve of injected eyes. Some FG reached the anterior optic nerve of the non-injected eye. GFP fluorescence was observed only in the retina of the injected eye but not in the contralateral retina or either optic nerve. ND4 expression was significantly different between injected and non-injected eyes but not between the non-injected eyes in groups A and D. CONCLUSION: Unilaterally injected material can reach the contralateral optic nerve through axoplasmic transport. It is possible that this the only mechanism by which the optic nerves directly communicate.