Purchase this article with an account.
A. Selenow, H. Ying, K.J. Ciuffreda, S.R. Ali, L.W. Spencer; Point of Regard in an Ophthalmic Lens . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4078.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Progressive addition spectacle lenses (PALs) have made tremendous gains in patient acceptance over the past decade. However, these complexly designed lenses have inherent peripheral, non-uniform optical blur and magnification distortion that effectively reduces the usable visual field at all distances. To keep the line-of-sight within a zone of visual resolution for optimal target recognition, the individual is required to execute frequent and precise eye and head movements. Reconfiguration of a conventional eye/head movement system (ISCAN; POLHEMUS) has allowed us to develop a new objective method of determining the precise point on the spectacle lens that the line-of-sight intersects (i.e., point of regard, POR) during gaze changes. Methods: Two-dimensional recordings of POR, eye movements, and head movements were compared for single vision lenses (SVL) and PALs for three visual tasks. (1) Fixation: Subjects fixated upon a threshold letter at 40, 64, and 325 cms. along the midline, through a point in the lens that for them provided maximum clarity. (2) Reading: Subjects read a 30 deg. wide text at 64 cm. 3) Zone of clarity: Subjects maintained the head fixed while shifting their gaze horizontally (left and right), until threshold targets first became blurred through the lens at 64 and 325 cms. Results: The POR was different for SVL versus PALs for both fixation and reading, with a greater range for the SVL than the PAL. Similarly, the subjective zone of clarity was narrower for the POR criterion than for a comon industry standard of 1D optical cylinder defocus. Conclusions: Lens design affected the POR. For the first time, objective recordings of POR have been made under naturalistic conditions. The primary finding that the empirically derived POR range was different than predicted based on theoretical optical calculations provides valuable information to modify and improve PAL lens design in the future to increase patient acceptance, comfort, and visual efficiency.
This PDF is available to Subscribers Only