Gene therapy of the human retina levels of light. What follows often is the death of cone cells, responsible for color vision and acuity, at light levels present during the day. Loss of cones leads to full blindness as early as five years old, but may not onset until many years later. There have been multiple hypotheses about how the lack of rod cells can lead to the death of cone cells. Pinpointing a mechanism for RP is difficult because there are more than 39 genetic loci and genes correlated with this disease. In an effort to find the cause of RP, there have been different
Kodak Retina Ausf. II Retina IIc, which is later mounted on the Type 019 Ausf. II Retina IB and Type 028 Retina IIIC. The second generation Type 034 Retina Reflex S of 1959 shared "S" type lenses with the Type 027 Retina IIIS (below), and offered fully coupled metering. With these the entire lens detached allowing for a wider range of focal lengths, 28mm to 200mm. At this point economical Japanese SLRs were becoming available and the Nikon F of 1959 would set the standard for future camera system. The Reflex III of 1961 and Reflex IV of 1964 brought minor improvements