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The lacrimal lens as an assessment factor in hard contact lens fitting
Author(s) -
Gowans M.
Publication year - 1995
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1046/j.1475-1313.1995.9500096v.x
Subject(s) - keratometer , lens (geology) , contact lens , radius of curvature , optics , optometry , cornea , ophthalmology , curvature , physics , medicine , mathematics , mean curvature , geometry , mean curvature flow
Summary The fitting of hard contact lenses relies primarily on the evaluation of the findings of ‘K’ readings, the fluorescein pattern of the tear configuration and the interpretation of the lens movement upon blinking and the lens position after blinking. All of these methods have some disadvantages in the evaluation procedure: (a) keratometer readings measure cornical radius in a small and restricted area of the central cornea not in the larger area to eventually be covered by the lens (Bennett and Rabbetts, Clinical Visual Optics . Butterworths, London, UK, pp. 420–421, 1984 1 ); (b) the fluorescein pattern is sometimes unreliable especially in the presence of excessive tear flow; (c) lens movement, arguably the most reliable of evaluation methods, nonetheless requires some alternative back‐up technique. This presentation outlines the possibility of utilising the lacrimal lens as a useful additional procedure to the above when prescribing a lens curvature of choice. It should be pointed out that the technique discussed refers to spherical or near spherical corneas.