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Quantification of Ghosting Produced With Presbyopic Contact Lens Correction

2012; Lippincott Williams & Wilkins; Volume: 38; Issue: 4 Linguagem: Inglês

10.1097/icl.0b013e31825aa879

1542-233X

Pete Kollbaum, BoKaye M. Dietmeier, Meredith E. Jansen, Martin E. Rickert,

Ocular Surface and Contact Lens

Objectives: The defocused portion of the image obtained in wearers of bifocal and multifocal contact lenses often appears as a "ghost." Relatively few methods exist to quantify the ghosting perceived with lenses. The purpose of this study is to validate and implement a questionnaire to help patients quantify the ghost images perceived with bifocal or multifocal corrections. Methods: Ten subjects viewed simulated bifocal vision images displayed on a monitor. Images contained a focused and a defocused (ghost) component of a specific dimension (direction, position offset, intensity, and focus). Using a test card, the subjects identified the ghosting dimension level displayed on the monitor. An additional 54 presbyopic subjects wearing a multifocal correction monocularly viewed a well-focused stimulus and then compared the perceived image to that of the other well-corrected eye looking at the ghosting test card to quantify their visual experience of the 4 proposed ghosting dimensions. Results: Regardless of ghost letter size and orientation, subject responses were within 1 rating unit of expected on >95% of all trials for all 4 dimensions when asked to directly match a single dimension of ghosting. With bifocal images containing random amounts of these 4 dimensions most response errors were also within ±1 unit. In presbyopes wearing a multifocal lens, the focus dimension was most strongly associated with overall ratings of ghosting. Conclusions: The subjects can accurately and reliably report on ghost intensity, focus, direction and position offset, and well-focused ghosts are most correlated with the overall perceptual saliency of ghosting.