Experimental support for Schachar's hypothesis of accommodation.

To determine the physical effect of a change in the equatorial lenticular diameter on optical power, sclera-ciliary bodies of bovine eyes were stretched radially. The effective optical power and lenticular equatorial diameter were measured. We found that an increase in the equatorial diameter of the bovine lens produced an increase in its effective optical power. Our results directly contradict Helmholtz's hypothesis of accommodation and its modifications. These results support Schachar's hypothesis of accommodation, which states that there is increased zonular tension during accommodation.