CPF-550 vs. C-Lite: a comparison study

We conducted a two-part study to evaluate patient satisfaction with the Corning CPF-550 lenses and to determine whether or not the success of these lenses can be attributed to their selective attenuation of the short wave-lengths of light. In the first part of our investigation we asked nine low vision patients who were currently wearing CPF-550 lenses to evaluate the performance of the tint. Their responses were generally very favorable. In the second part of the study, seven of those patients were given identical prescriptions made of C-Lite material with a solid gray tint on the back surface and a photo-gray extra front surface. They were asked to compare the two filters. To our surprise, six of the seven preferred the more neutral density C-Lite lenses over the CPF-550 filter. Although we have been encouraged by the results of the first part of the study to continue prescribing the CPF-550 lenses, the second part of the study has caused us to question the theory behind the success of these lenses and has alerted us to the fact that some individuals may be even more satisfied with a neutral gray photochromic tint.