Effect of peripheral iridectomy on VEGF-A and TGF-β levels in rabbit aqueous humour

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.

Effect of SMILE-derived decellularized lenticules as an adhesion barrier in a rabbit model of glaucoma filtration surgery

Background To investigate the effects of small incision lenticule extraction (SMILE)-derived decellularized lenticules on intraocular pressure (IOP) and conjunctival scarring in a rabbit model of glaucoma filtration surgery. Methods Trabeculectomy was performed on both eyes of New Zealand rabbits. A decellularized lenticule was placed in the subconjunctival space in one eye of the rabbits (the decellularized lenticule group), and no adjunctive treatment was performed in the fellow eye (the control group). The filtering bleb features and IOP were evaluated 0, 3, 7, 14, 21, and 28 days after surgery, and histopathologic examination was performed 28 days after surgery. Results Decellularized lenticules significantly increased bleb survival and decreased IOP postoperatively in the rabbit model with no adverse side effects. The histopathologic results showed a larger subconjunctival space and less subconjunctival fibrosis in the decellularized lenticule group. Conclusions Decellularized lenticules can prevent postoperative conjunctiva-sclera adhesion and fibrosis, and they may represent a novel antifibrotic agent for trabeculectomy.

The Effect of a Triple Combination of Bevacizumab, Sodium Hyaluronate and a Collagen Matrix Implant in a Trabeculectomy Animal Model

Currently available anti-scarring treatments for glaucoma filtration surgery (GFS) have potentially blinding complications, so there is a need for alternative and safer agents. The effects of the intrableb administration of a new combination of the anti-VEGF bevacizumab, sodium hyaluronate and a collagen matrix implant were investigated in a rabbit model of GFS, with the purpose of modulating inflammation, angiogenesis, fibroblast migration and fibrogenesis in the wound healing process. A comparative-effectiveness study was performed with twenty-four rabbits, randomly assigned to the following treatments: (a) biodegradable collagen matrix implant (Olo), (b) bevacizumab-loaded collagen matrix implant (Olo-BVZ), (c) bevacizumab-loaded collagen matrix implant combined with sodium hyaluronate (Olo-BVZ-H5) and (d) sham-operated animals (control). Rabbits underwent a conventional trabeculectomy and were studied over 30 days in terms of intraocular pressure and bleb characterization (height, area and vascularity in central, peripheral and non-bleb zones). Histologic differences among groups were further evaluated at day 30 (inflammation, total cellularity and degree of fibrosis in the area of surgery). Local delivery of bevacizumab (Olo-BVZ and Olo-BVZ-H5) increased the survival of the filtering bleb by 21% and 31%, respectively, and generated a significant decrease in inflammation and cell infiltration histologically 30 days after surgery, without exhibiting any local toxic effects. Olo-BVZ-H5 showed less lymphocyte infiltration and inflammation than the rest of the treatments. Intraoperative intrableb implantation of bevacizumab, sodium hyaluronate and a collagen matrix may provide an improved trabeculectomy outcome in this model of intense wound healing. This study showed an effective procedure with few surgical complications and a novel combination of active compounds that offer new possibilities to improve the efficacy of filtration surgery.

Comparison of phaco time parameters in eyes with and without glaucoma filtration surgery due to pseudoexfoliation glaucoma

Purpose: To compare the phaco time parameters including ultrasound time (UST), effective phaco time (EPT), and average phaco power (APP) in eyes with pseudoexfoliation glaucoma (PEG) and had or had not glaucoma filtration surgery. Methods: In this retrospective comparative study, Group 1 was constructed with 84 PEG patients who had not operated previously, and Group 2 was constructed with 49 PEG patients who had glaucoma filtration surgery. The mean values of UST, EPT, and APP were compared. The preoperative clinical characteristics and surgical manipulations were also compared. Results: The mean ages and male-to-female ratios of the groups were similar ( p > 0.05, for both). There was no difference in the preoperative clinical characteristics, including biometric values between the groups ( p > 0.05, for all). Some surgical manipulations, including pupillary stretching ( p = 0.004), pupillary membrane peeling ( p = 0.021), iris hook using ( p = 0.041), and capsular tension ring implantation ( p = 0.041), were significantly performed more commonly in Group 2. Although the mean UST and EPT values were similar ( p > 0.05, for both), the mean APP value was significantly lower in Group 2 ( p = 0.011). Conclusion: The lower APP parameter was observed in PEG patients having had glaucoma filtration surgery. Needing more surgical manipulation to overcome poor pupillary dilation and weak zonular instability can be a reason for this result.

Intracameral Bevacizumab Versus Sub-Tenon’s Mitomycin C as Adjuncts to Trabeculectomy: 3-Year Results of a Prospective Randomized Study

Conjunctival wound healing determines success after filtration surgery and the quest for better antifibrotic agents remains active. This study compares intracameral bevacizumab to sub-Tenon’s mitomycin C (MMC) in trabeculectomy. Primary open-angle or exfoliative glaucoma patients were randomized to either bevacizumab (n = 50 eyes) or MMC (n = 50 eyes). The primary outcome measure was complete success, defined as Intraocular Pressure (IOP) > 5 mmHg and ≤ 21 mmHg with a minimum 20% reduction from baseline without medications. Average IOP and glaucoma medications decreased significantly in both groups at all follow-up points compared to baseline (p < 0.001), without significant difference between groups at 3 years (IOP: bevacizumab group from 29 ± 9.4 to 15 ± 3.4 mmHg, MMC group from 28.3 ± 8.7 to 15.4 ± 3.8 mmHg, p = 0.60; Medications: bevacizumab group from 3.5 ± 0.9 to 0.5 ± 1, MMC group from 3.6 ± 0.7 to 0.6 ± 1.1, p = 0.70). Complete success, although similar between groups at 3 years (66% vs. 64%), was significantly higher for bevacizumab at months 6 and 12 (96% vs. 82%, p = 0.03; 88% vs. 72%, p = 0.04, respectively) with fewer patients requiring medications at months 6, 9 and 12 (4% vs. 18%, p = 0.03; 6% vs. 20%, p = 0.04; 8% vs. 24%, p = 0.03, respectively). Complication rates were similar between groups. In conclusion, intracameral bevacizumab appears to provide similar long-term efficacy and safety results as sub-Tenon’s MMC after trabeculectomy.

Effects Of SMILE-Derived Decellularized Lenticule As An Adhesion Barrier In A Rabbit Model of Glaucoma Filtration Surgery

Background: To investigate the effects of small incision lenticule extraction (SMILE)-derived decellularized lenticule on intraocular pressure (IOP) and conjunctival scarring in a rabbit model of glaucoma filtration surgery. Methods: Trabeculectomy was performed on both eyes of New Zealand rabbits. Decellularized lenticule was placed in the subconjunctival space in one eye of the rabbits (decellularized lenticule group), and no adjunctive treatment was performed in the fellow eye (control group). The filtering bleb features and IOP were evaluated 0, 3, 7, 14, 21, and 28 days after surgery, and histopathologic examination was performed 28 days after surgery. Results: Decellularized lenticule significantly increased bleb survival and decreased IOP postoperatively in the rabbit model with no adverse side effects. Histopathologic results showed a larger subconjunctival space and less subconjunctival fibrosis in the decellularized lenticule group. Conclusions: Decellularized lenticule can prevent postoperative conjunctiva-sclera adhesion and fibrosis, and it may represent a novel antifibrotic agent for trabeculectomy.

Experience in managing glaucoma filtration surgery complications with oral doxycycline: A case series

Purpose: To report the clinical profile and effectiveness of oral doxycycline as a non-invasive treatment for glaucoma filtering surgery complications. Method: Prospective case series. Results: Doxycycline is widely used in treating corneal melts, ocular surface diseases, meibomian gland disease, recurrent epithelial cell erosion, rosacea, and keratitis sicca. This prospective case series highlights the successful treatment of five patients with leaking blebs and conjunctiva erosion from glaucoma filtration surgery with the use of oral doxycycline. There was no adverse event reported in our cases. Conclusions: This study suggests that oral doxycycline may be a feasible non-surgical treatment modality due to its ability to inhibit collagenolysis, restore the Meibomian gland function, thereby stopping breakdown and promote conjunctival tissue healing.