Adaptation (eye) opsin photopigment. The various cone cells are maximally sensitive to either short wavelengths (blue light), medium wavelengths (green light), or long wavelengths (red light). Rod photoreceptors only contain one type of photopigment, rhodopsin, which has a peak sensitivity at a wavelength of approximately 530 nanometers which corresponds to blue-green light. A minor mechanism of adaptation is the pupillary light reflex, adjusting the amount of light that reaches the retina. In response to varying ambient light levels, rods and cones of eye function both in isolation and in tandem to adjust the visual system. Changes in the sensitivity of rods and
Gene therapy of the human retina Thus overall, subretinal AAV is 5-10 times more efficient than delivery using the intravitreal route. One important factor in gene delivery is developing altered cell tropisms to narrow or broaden rAAV-mediated gene delivery and to increase its efficiency in tissues. Specific properties like capsid conformation, cell targeting strategies can determine which cell types are affected and also the efficiency of the gene transfer process. Different kinds of modification can be undertaken. For example, modification by chemical, immunological or genetic changes that enables the AAV2 capsid to interact with specific cell surface molecules. Initial studies with AAV in the retina have