Purpose:
To quantify changes in corneal neovascularisation following treatment in patients with keratitis using indocyanine green (ICG) and fluorescein angiography (FA) with novel image analysis sotware.
Methods:
Prospective, interventional and consecutive case series of patients with active keratitis in whom corneal neovascularisation was present. Baseline colour, ICG and FA images were taken at the initiation of therapy and at follow up using a standardised protocol. Areas of corneal neovascularisation (mm2) and vessel parameters of diameter (mm), tortuosity and time (secs) to first appearance of FA dye leakage were analysed using automated custom designed software within Matlab(TM) and the paired students t-test.
Results:
Twelve patients with corneal neovascularisation were studied. Follow-up duration ranged from one to six months. The etiologies were herpes simplex keratitis or bacterial keratitis (Figure 1). There were significant decreases in area (FA mean reduction 2.3mm2, **p<0.01, ICG mean reduction 2.07mm2, **p<0.01) and vessel diameter (FA mean reduction 0.02mm, **p<0.01, ICG mean reduction 0.02mm, **p<0.01) in post-treatment follow up. Time to first appearance of FA vessel dye leakage time was also significantly greater (12secs, *p<0.05) in post-treatment follow-up. Tortuosity was not significantly reduced following treatment. Changes in corneal neovascularisation were also more evident on FA and ICG than on color imaging.
Conclusions:
Automated quantification of trajectories of change in corneal neovascularisation on FA and ICG, as demonstrated here, is a a powerful clinical metric for monitoring response to treatment and improving prognostic accuracy.
Keywords: cornea: clinical science • imaging/image analysis: clinical • neovascularization