Figure 1.

The frequency distributions of change in ocular length (front of cornea to back of sclera) in negative lens–wearing eyes (A), all the fellow eyes (B), positive lens–wearing eyes (C), all measured 3 days apart, and untreated eyes measured repeatedly within an hour from another group (D), in chicks. Arrows indicate the average of each group. It is clear that, while negative lenses increased the rate of ocular elongation, positive lenses decreased it, with 38.5% of the positive lens–wearing eyes shortening during the course of the experiment (on the left side of zero). Furthermore, data from eyes measured repeatedly (D) show the error of biometry measurements in ocular length. When very little eye growth was expected within an hour, most of the points are close to zero.