The laser burns seal the edges of the retinal hole and prevent retinal detachment from developing. The retina is a thin, transparent membrane surrounding the vitreous body. It is the part of the eye that actually sees. Light is absorbed by the sensory cells in the outer layers of the retina. There are two kinds of sensory cells, cones and rods .
Cones function best in daylight, rods in twilight and dark.
We see colors through cone function. Rods do not react to different colors. They see only different shades of grey. That is why we do not see colors when the dusk becomes sufficiently dark. Retinal blood vessels are very thin vessels.