Comparison of Topical Low-Molecular-Weight Heparin-Taurocholate and Bevacizumab for Treatment and Prevention of Corneal Neovascularization

Subconjunctival aflibercept inhibits corneal angiogenesis and VEGFR-3+CD11b+ cells

PURPOSE

This study aimed to investigate the effects of subconjunctival injection of aflibercept, a soluble protein decoy for VEGFR-1 and VEGFR-2, on corneal angiogenesis and VEGFR-expressing CD11b+ cells in a mouse model of suture-induced corneal neovascularization.

METHODS

Corneal neovascularization was induced in BALB/c mice by placing three sutures on the cornea. Immediately after surgery, either 200 µg aflibercept (5 µL) or an equal volume of phosphate-buffered saline (PBS) was administered into the subconjunctival space. Seven days after later, corneal new vessels were quantified through clinical examination and measurement of the CD31-stained area in corneal flat mounts. The levels of pro-angiogenic and inflammatory markers in the cornea were evaluated using RT-qPCR. The percentages of VEGFR-2+CD11b+ cells and VEGFR-3+CD11b+ cells were analyzed in the cornea, blood, and draining cervical lymph nodes (DLNs) using flow cytometry.

RESULTS

Subconjunctival injection of aflibercept significantly reduced the growth of corneal new vessels compared to subconjunctival PBS injection. The mRNA levels of Cd31, vascular growth factors (Vegfc and Angpt1), and pro-angiogenic/inflammatory markers (Tek/Tie2, Mrc1, Mrc2, and Il6) in the cornea were downregulated by subconjunctival aflibercept. Also, the percentage of VEGFR-3+CD11b+ cells in the cornea, blood, and DLNs was decreased by aflibercept, whereas that of VEGFR-2+CD11b+ cells was unaffected.

CONCLUSION

Subconjunctival aflibercept administration inhibits inflammatory angiogenesis in the cornea and reduces the numbers of cornea-infiltrating and circulating VEGFR-3+CD11b+ cells.

Subconjunctival Aflibercept for the Treatment of Formed Corneal Neovascularization

PURPOSE

To evaluate the effect of a single subconjunctival aflibercept injection on formed corneal neovascularization.

METHODS

A prospective clinical trial, conducted at a single tertiary medical center. Included were consecutive patients with corneal pathologies complicated by corneal neovascularization, who were candidates for anti-vascular endothelial growth factor treatment at the discretion of a cornea specialist. A single subconjunctival injection of 0.08 mL of Aflibercept (Eylea 25 mg/mL) was administered near the limbus in proximity to the areas of maximal pathological neovascularization. Follow-up visits were scheduled on days 7, 30, 60, and 90 following injection. Best-corrected visual acuity (BCVA), intraocular pressure, slitlamp examination, digital cornea photography, specular microscopy, and anterior-segment optical coherence tomography were documented at each visit. The images were graded by a masked observer for density, extent, and centricity of corneal vascularization.

RESULTS

Six eyes of six patients were analyzed. No clinically significant ocular or systemic adverse events were documented. No change was noted in extent, density, or centricity of corneal blood vessels at seven, 30, and 90 days after injection (P>0.1 for all time point comparisons, Friedman test). Best-corrected visual acuity fluctuated insignificantly in 5/6 patients during follow-up time, and objective but not subjective improvement of BCVA was noted in one patient with no concurrent change of neovascularization. The recruitment has therefore halted prematurely.

CONCLUSIONS

A single subconjunctival aflibercept injection seems to be well tolerated. However, it is ineffective for regressing formed corneal neovascularization.

Efficacy of a new automated method for quantification of corneal neovascularisation

BACKGROUND/AIMS

To evaluate the efficacy of a new automated method for quantification of corneal neovascularisation (NV).

METHODS

An in-house software for automated measurement of corneal NV was developed. Anterior segment photographs (ASPs) of 81 consecutive patients with corneal NV were analysed using our newly developed software. Manual measurements were performed by three independent examiners using ImageJ software V.1.48 (National Institute of Health, Bethesda, Maryland, USA). Interobserver reliability of the automated and manual methods, and correlations between the results of both methods were evaluated.

RESULTS

The automated method showed a strong interexaminer reliability (intraclass correlation coefficient (ICC)=0.994), which was slightly better than the manual method (ICC=0.958). A significant correlation was found between the results of both methods (p<0.001 for all three examiners). The time spent for analysis of each ASP was significantly reduced in the automated method compared with the manual method (p<0.001 for all three examiners).

CONCLUSIONS

Our newly developed automated method for quantification of corneal NV was more reproducible and time-saving compared with the manual method. Our method can be useful for diagnosis and monitoring diseases causing corneal NV.

In vivo biodistribution of topical low molecular weight heparin-taurocholate in a neovascularized mouse cornea

AIM

To investigate the ocular biodistribution and clearance of topically administered 7-taurocholic acid conjugated low-molecular weight heparin (LHT7) in a neovascularized mouse cornea using an in vivo optical imaging system.

METHODS

A total of 10 eyes of 6 to 8-week-old BALB/c mice were analyzed. Corneal neovascularization (CoNV) was induced in the inferior cornea (IC) of each animal by penetrating the stroma with two interrupted sutures. The development of CoNV was verified after one week and the area of each neovascularized region was measured. A near-infrared fluorescent probe of 20 µmol/L Cy5.5 labeled LHT7 (LHT7-Cy5.5) in 0.02 mL solution was topically instilled onto the cornea in the experimental group (n=5). Free-Cy5.5 of 20 µmol/L in 0.02 mL was instilled in the control group (n=5). In vivo optical images were obtained before instillation and 5min, 2, 4, and 6h after instillation. The intensities were separately measured at the superior cornea (SC) and the IC.

RESULTS

The mean CoNV areas were 1.97±0.17 mm² and 1.92±0.96 mm² in the experimental and control groups, respectively (P=0.832). The SC remained normal in all 10 subject animals. The IC intensity of the LHT7-Cy5.5 was greater than the SC intensity at 5min (P=0.038), 2h (P=0.041), and 4h (P=0.041) after application. The IC intensity fell to less than half of its initial value (42.9%±8.6%) at 6h in the experimental group. In the control mice, here were no significant differences in the free-Cy5.5 intensity between the IC and SC.

CONCLUSION

Topically administered LHT7 shows a high biodistribution in CoNV areas for 4h and should be reapplied accordingly to maintain its effects. In vivo optical imaging can be a useful tool for evaluating the ocular biodistribution of a drug in an animal model.