Does the lens diameter increase or decrease during accommodation? Human accommodation studies: a new technique using infrared retro-illumination video photography and pixel unit measurements.

PURPOSE: To describe a new technique for viewing and measuring the lens diameter during accommodation.

METHODS

The accommodative lens activity, in a young female carrier of ocular albinism, was evaluated using retro-illumination infrared video photography and pixel unit measurements.

RESULTS

Right and left lens diameter measurements were 498 pu and 501 pu, respectively, during natural accommodation. In pharmacologic non-accommodation (Tropicamide), the average lens diameter was 524 pu (range 518-528) while in accommodation (Pilocarpine), the average lens diameter was 485 pu (range 479-491).

CONCLUSIONS

Right and left lens measurements were essentially identical. All measurements were reliable, repeatable and extremely accurate. The lens diameter consistently reduced during accommodation and enlarged during non-accommodation. The theories, similar to Tscherning's, which imply that the lens diameter increases in accommodation, are clearly disproven.