A 70-year-old female presented with a full-thickness macular hole in her right eye and underwent vitrectomy (Fig. 1). Adaptive optics imaging was performed at baseline and 6 months postoperatively with 4 degrees of superior, inferior, nasal, and temporal eccentricity (Fig. 2). Preoperatively (Fig. 2A), cones were detectable in the superior and inferior quadrants and in all 4 quadrants at 6 months (Fig. 2B). Mean (±SD) cone density was 12,640.1 ± 1939 cells/mm2 and 7797.8 ± 3320 cells/mm2, and mean spacing was 10 ± 1.3 µm and 11.9 ± 2.5 µm at baseline and at 6 months, respectively. This case demonstrates how the parafoveal retina may be stretched centripetally to close the macular hole leading to the lower corresponding cone densities. View Large Image Figure Viewer Download Hi-res image

Vitreous substitutes are clinically used to maintain retinal apposition and preserve retinal function; yet the most used substitutes are gases and oils which have disadvantages including strict face-down positioning post-surgery and the need for subsequent surgical removal, respectively. We have engineered a vitreous substitute comprised of a novel hyaluronan-oxime crosslinked hydrogel. Hyaluronan, which is naturally abundant in the vitreous of the eye, is chemically modified to crosslink with poly(ethylene glycol)-tetraoxyamine via oxime chemistry to produce a vitreous substitute that has similar physical properties to the native vitreous including refractive index, density and transparency. The oxime hydrogel is cytocompatible in vitro with photoreceptors from mouse retinal explants and biocompatible in rabbit eyes as determined by histology of the inner nuclear layer and photoreceptors in the outer nuclear layer. The ocular pressure in the rabbit eyes was consistent over 56 d, demonstrating limited to no swelling. Our vitreous substitute was stable in vivo over 28 d after which it began to degrade, with approximately 50% loss by day 56. We confirmed that the implanted hydrogel did not impact retina function using electroretinography over 90 days versus eyes injected with balanced saline solution. This new oxime hydrogel provides a significant improvement over the status quo as a vitreous substitute.