Abstract
Purpose:
To evaluate effects of procedural complications on retinal function and structure following subretinal delivery in mice
Methods:
AAV2-CMV-GFP was delivered via subretinal injection (1 uL) at 1.0 x 109 vg to the right eyes of 60 female C57BL/6NTac mice via a transcorneal route. Left eyes were untreated. Fluorescein (0.1%) was included in the formulation to evaluate successful delivery. Slit lamp biomicroscopy and indirect ophthalmoscopy were performed 1 and 4 weeks postdose. Optical coherence tomography (OCT), scotopic and photopic electroretinography (ERG) luminance-response series, and light-adapted flicker ERG were performed 4 weeks postdose.
Results:
Procedure-related findings at 1 week postdose included: incipient cortical or complete cataracts, retinal, subretinal, or vitreal hemorrhage, white vitreous floaters, and red vitreous cell. Elevated retinas with or without presence of blood under the retina were also noted. The incidence of findings decreased by 4 weeks postdose, with the exception of cataracts which did not change in incidence or severity. Incipient cataracts had minimal or no impact on ERG or OCT imaging whereas the presence of complete cataracts prevented imaging of the retina and almost completely reduced ERG amplitude as compared to the untreated contralateral eye. The observation of elevated injection site with hemorrhages postdose was associated with mild to moderate reductions of scotopic and photopic ERG signal and poor visualization of retinal layers on OCT compared to eyes with minimal procedural complications or contralateral eyes. Scotopic and photopic ERG were reduced negligibly in eyes given AAV when only minimal procedural complications were noted during ophthalmic examination. OCT findings seen in other species and considered to be injection-related included accumulations of reflective material in the bacillary layer, disorganized/thinned/thickened layers (e.g. IS/OS and ONL) often seen near the injection site and persistent small areas of detachment.
Conclusions:
Subretinal delivery is sometimes associated with procedure-related complications that impact functional testing and imaging of the retina. Ophthalmic examination can be used to identify these complications and aid in selection of suitable animals for further evaluation on research studies.