Purpose
To develop a reproducible surgical technique for the induction of choroidal neovascularization (CNV) in the subretinal space
of porcine eyes and to analyse the resulting CNV clinically and histologically.
Methods
Two different modifications of a surgical technique previously described were compared with the original method. In ten porcine
eyes retinal pigment epithelial (RPE) cells were removed using a silicone tipped cannula, in ten porcine eyes Bruch’s membrane
was perforated once with a retinal perforator without prior RPE removal and in ten eyes RPE removal was followed by a single
perforation of Bruch’s membrane. Fifteen of the eyes, five from each group, were enucleated 30 minutes after surgery, while
the remaining eyes were enucleated after 14 days. Prior to enucleation, at day 14, fundus photographs and fluorescein angiograms
were obtained. Eyes were examined by light microscopy and by immunohistochemical staining. In addition to these 30 eyes, two
eyes underwent surgery with the purpose of subsequent scanning electron microscopic (SEM) examination.
Results
In eyes enucleated immediately after surgery neuroretinas overlying the induced lesions were intact without apparent atrophy
of cells regardless of the surgical technique applied. The process of RPE removal was found to induce breaks in Bruch’s membrane
and both the size and the number of breaks varied between eyes. CNV membranes were identified in 15 of 15 eyes enucleated
after 14 days. CNV membranes induced by perforation of Bruch’s membrane without prior RPE removal were significantly thicker
than membranes from eyes undergoing both RPE removal and Bruch’s perforation (p = 0.03) and also thicker than membranes from
eyes with only RPE-removal (p < 0.01). CNV membranes from eyes with perforation of Bruch’s membrane without prior RPE removal
had a higher cellular content and were more richly vascularized and also exhibited the highest propensity to leak in fluorescense
angiograms.
Conclusion
All three surgical techniques were capable of inducing CNV, but the one applying perforation of Bruch’s membrane without RPE
removal was easier to reproduce and involved fewer variables than the techniques utilizing RPE removal. The presence of RPE
cells seems to affect both the morphology and cellular composition of induced CNV.
Keywords Choroidal neovascularization - Animal model - Subretinal surgery - Retinal pigment epithelium - Age related macular degeneration
The authors have no commercial interest in this study or in funding organizations. Full control of all primary data remains
with the authors, and we agree to allow Graefe’s Archive for Clinical and Experimental Ophthalmology to review these data
if requested.