Prevention of Corneal Neovascularization; a Preliminary Experimental Study in Rabbits

The purpose of this study was to compare the effects of propranolol, timolol and bevacizumab with betamethasone to prevent corneal neovascularization (CNV) in rabbits. This study was performed on 28 male rabbits. CNV was induced by three 7-0 silk sutures 2 mm long and 1 mm distal to the limbus. Animals were randomly divided into 4 groups of propranolol + betamethasone, timolol + betamethasone and bevacizumab + betamethasone and betamethasone alone. Eye drops were started from the first day of study. On 7^th, 14^th, 21^st, 28^th, 35^th and 42^nd days, vascular progression, time of neovascularization and vascular area were evaluated and compared with the control group (betamethasone alone). There was a significant reduction in the area of ​​neovascularization in the timolol and bevacizumab groups compared to the control group (P-value = 0.05, P=0.047, respectively). Also, regarding vascular progression, there was a significant decrease in the timolol and bevacizumab groups (P-value = 0.014, P=0.002, respectively). Regarding delayed onset of neovascularization, there was a significant difference in the timolol and bevacizumab group in rabbits (P-value = 0.04, P=0.00, respectively). In conclusion, the use of timolol and bevacizumab drops besides betamethasone can delay neovascularization and decrease the length of corneal vascularization in rabbits.

The Antiangiogenic Properties of Adipose-Derived Mesenchymal Stem/Stromal Cells in Corneal Neovascularization in a Rabbit Model

The purpose was to study the anti-angiogenic effect of adipose-derived mesenchymal stem/stromal cells (ADMSCs) on experimentally induced corneal injuries. Corneal neovascularization (NV) was induced by incising and subsequently suturing the corneal surface in 32 New Zealand rabbits. Following suturing, the rabbits were randomly allocated into 2 groups, and received either phosphate-buffered saline (PBS) (control) or ADMSCs, both administered via three different routes. Digital images of the cornea were obtained two weeks post-incision to measure the area of neovascularized cornea. Tumor necrosis factor (TNF) was immunohistochemically assessed in the both groups. The corneal tissue was evaluated for vascular endothelial growth factor (VEGF). The extent of corneal NV in all eyes was assessed photographically by an independent observer. Fourteen days after the incisions, the degree of corneal NV was substantially decreased in the ADMSC-treated group (1.87 ± 0.9 mm², 1.4 % ± 0.67 % of corneal surface) compared to the control and PBS-treated group (4.66 ± 1.74 mm², 3.51 % ± 1.31 %, p < 0.001). ADMSCs significantly decreased injury-induced corneal NV in New Zealand rabbits two weeks post-treatment. This strategy has potential for use in the control of corneal NV in vivo.

Topical Tacrolimus as an adjunct to Conventional Therapy for Stromal Herpetic Keratitis: a Randomized Clinical Trial

Purpose

This study investigates the effects of 0.05% topical tacrolimus as an adjunct therapy for patients with non-necrotizing herpetic stromal keratitis (HSK).

Methods

Patients with non-necrotizing HSK, referred to the Cornea Clinic at Hospital in Rasht, Iran, between September 2016 and February 2018, were randomly assigned to two groups. The case group (N = 25) and the control group (N = 25) received conventional treatment with systemic acyclovir and topical prednisolone. The case group (N = 25) additionally received 0.05% tacrolimus eye drops four times a day for one month. Complete ocular examinations, including best-corrected visual acuity (BCVA) assessment, intraocular pressure (IOP) measurement, slit lamp biomicroscopy, and photo slit lamp imaging, were performed before treatment, and 3, 7, 14, 21, and 28 days after the intervention.

Results

The mean age of the patients was 46.2 ± 12.9 years, and 70% of the patients were male. There was no difference between the groups in terms of age, sex, and baseline ocular measurements (P> 0.05). The case group had a lower mean logarithm of the minimum angle of resolution (LogMAR) for BCVA, lower grading scores, and steeper decreasing trends for corneal haziness, edema, neovascularization, and epitheliopathy compared to the control group after the second week (P< 0.05), while IOP remained unchanged between groups (P> 0.05).

Conclusion

The addition of 0.05% topical tacrolimus enhances visual acuity and reduces corneal inflammation, neovascularization, and scarring; thus, it can used as an appropriate adjunct treatment for patients with HSK.

Triamcinolone acetonide as an adjunct to bevacizumab for prevention of corneal neovascularization in a rat model

PURPOSE

To evaluate the short-term effects of a single subconjunctival injection of triamcinolone acetonide as an adjunct to subconjunctival bevacizumab for prevention of corneal neovascularization in rats.

METHODS

Chemical cauterization was performed in the central cornea of the right eye in 48 male Sprague-Dawley rats (4 eyes were excluded due to perforation and/or infection). Immediately after the injury, the rats were randomly assigned to four treatment groups: controls (n=10), received subconjunctival injection of 0.02 mL balanced salt solution; group 1 (n=12), received 0.02 mL bevacizumab (25 mg/mL); group 2 (n=11), were treated with 0.02 mL triamcinolone acetonide (40 mg/mL); and group 3 (n=11), received both bevacizumab and triamcinolone acetonide. On days 7 and 14 after cauterization, digital photographs of the corneas were taken and the area of neovascularization was calculated and compared among the study groups.

RESULTS

The area of corneal neovascularization in all three treatment groups was less than the controls (P<0.05 for all comparisons). On day 7, the corneal avascular area was largest in group 3 (63%). On day 14, the area of corneal neovascularization in groups 2 and 3 was smaller than that in group 1 (P=0.031 and 0.011, respectively), but the difference between groups 2 and 3 was not statistically significant (P=0.552). Microscopic evaluation of the cornea was compatible with gross findings; inflammation and the number of new vessels was the least in group 3.

CONCLUSION

Triamcinolone acetonide was more effective than bevacizumab in inhibiting corneal neovascularization. Its adjunctive administration to bevacizumab resulted in even better prevention of corneal neovascularization. However, the produced combined effect was less than the sum of their separate effects and did not match additive or synergistic interactions.

Photodynamic therapy with verteporfin for corneal neovascularization

Purpose:

To investigate the efficacy of photodynamic therapy (PDT) with verteporfin for the treatment of patients with corneal neovascularization.

Materials and Methods:

Retrospective interventional case series of 33 eyes of 32 patients with stable corneal neovascularization who were refractory to conventional treatment and were treated with single photodynamic therapy with verteporfin (6 mg/m²) at King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia between January 1, 2007 and December 30, 2009. The mean age was 40.7 ± 19 years (range 16-76 years). The mean follow-up for all patients was 13.1 ± 5.5 months (range 6-24 months). The average amount of corneal neovascularization was 2.7 ± 1.9 (1-10). Corneal neovascularization was deep in 19 (57.6%) eyes and superficial in 14 (42.4%) eyes. Preoperative and postoperative visual acuity and intraocular pressure, and clinical outcome of the treatment were assessed. Statistical analysis was performed to investigate the association to potential risk factors, to assess the change in data and determine the risks for failure. A P-value less than 0.05 was statistically significant.

Results:

At the last follow-up visit, 22 (66.7%) eyes showed a decrease in corneal neovascularization and evidence of vascular thrombosis. Complete vascular occlusion was achieved in 14 (42.4%) eyes, partial occlusion was achieved in 8 (24.2%) eyes, and the vessels were patent in 11 (33.3%) eyes. The corneal neovascularization score and depth of the vessels were found to be significant risk factors for failure (P = 0.0001 and 0.046, respectively). However, the diagnoses or causes of corneal neovascularisation were not statistically significant. No significant systemic or ocular complications associated with photodynamic therapy were observed.

Conclusion:

Photodynamic therapy with verteporfin was effective for the treatment of corneal neovascularization in the majority of the cases in this study.