Intrastromal versus subconjunctival anti-VEGF agents for treatment of corneal neovascularization: a rabbit study

Abstract

Objective: To determine whether subconjunctival or intrastromal administration of anti-VEGF agents is more effective on suture-induced corneal neovascularization (CoNV) in rabbits.

Methods: CoNV was induced in 48 eyes of 24 New Zealand white rabbits by using an 8/0 silk suture. On the 7th day after suturing, the rabbits were divided into four treatment groups as follows: six rabbits received subconjunctival bevacizumab (group 1), six rabbits received subconjunctival aflibercept (group 2), six rabbits received intrastromal bevacizumab (group 3) and six rabbits received intrastromal aflibercept (group 4). On the 7th and 14th days after suturing, the CoNV area was calculated by standardised analysis of photographs using the Image-J program. On the 14th day after suturing, all rabbits were sacrificed and then corneal tissue was harvested for the analysis of vascular endothelial growth factor (VEGF)-A, VEGF-B and placental growth factor (PIGF) levels.

Results: On the 7th day after suturing, CoNV areas were 17.10 ± 2.98, 18.88 ± 3.78, 17.36 ± 4.52, 18.57 ± 4.16 and 17.31 ± 2.81 mm² in the groups 1-4 and control group, respectively. On the 7th day after intervention and removal of suture, CoNV areas were 4.85 ± 1.99, 6.66 ± 1.73, 2.83 ± 1.08, 2.63 ± 1.16 and 11.93 ± 2.64 mm² in the group 1-4 and control group, respectively. CoNV area was reduced by 88.1% and 82.5% in eyes receiving intrastromal aflibercept and bevacizumab, respectively (both p < 0.001), and by 64.5% and 69.9% in eyes receiving subconjunctival aflibercept and bevacizumab, respectively (both p = 0.001).

Conclusion: Intrastromal anti-VEGF therapy regressed CoNV more effectively than subconjunctival therapy regardless of the type of anti-VEGF agent.

Fig. 1. Interventions to the cornea and measurement of CoNV area.

A 8/0 silk suture placement on the superior part of the cornea. B Subconjunctival administration technique. C Intrastromal administration technique. D Standard imaging of CoNV area and adjacent ruler. E Magnified CoNV area without marking. F Magnified CoNV area surrounded by manual marking.

Fig. 2. Representative images of each group before and 1 week after the treatment.

A, B CoNV areas in the control group before and 1 week after the saline injection. C, D CoNV areas in the subconjunctival bevacizumab group before and 1 week after the injection. E, F CoNV areas in the subconjunctival aflibercept group before and 1 week after the injection. G, H CoNV areas in the intrastromal bevacizumab group before and 1 week after the injection. I, J CoNV areas in the intrastromal aflibercept group before and 1 week after the injection.

Fig. 3. Percent reductions in CoNV areas in different treatment groups.

Percent reductions in CoNV area were 30.3% in the control group, 69.9% in the subconjuctival bevacizumab group, 64.5% in the subconjunctival aflibercept group, 82.5% in the intrastromal bevacizumab group and 88.1% in the intrastromal aflibercept group (p* = 0.007). In pairwise comparison of each group with the control group, p^# = 0.010 for subconjunctival bevacizumab vs. control, p^# = 0.005 for subconjuctival aflibercept vs. control, p^# = 0.003 for intrastromal bevacizumab vs. control, and p^# < 0.001 for intrastromal aflibercept vs. control. A Percent reductions in CoNV area were 76.2% in the bevacizumab group, and 76.3% in the aflibercept group, regardless of the administration route (p* = 0.001), p^# = 0.002 for bevacizumab vs. control, p^# = 0.001 for aflibercept vs. control, p^# = 0.609 for bevacizumab vs. aflibercept). B Percent reductions in CoNV area were 67.2% in the subconjunctival group, and 85.3% in the intrastromal group, regardless of the type of anti-VEGF. (p* < 0.001). In pairwise comparison, p^# = 0.005 for subconjunctival injection vs. control, p^# < 0.001 for intrastromal injection vs. control, p^# = 0.039 for subconjunctival injection vs. aflibercept injection). *Kruskal–Wallis test, ^#Mann–Whitney U test.