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Modified cataract surgery with telescopic magnification for patients with age-related macular degeneration
Megumi Iizuka1, John Gorfinkel, Mark Mandelcorn
1Low Vision Service, University Health Network Hospitals, Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON.
Background:
The most desirable effect following cataract surgery in the presence of age-related macular degeneration (AMD) is to obtain an improvement in distance resolution acuity, and the only optical solution to this is the use of telescopic magnification. The purpose of the study was to develop and verify the clinical utility of inducing low-grade telescopic magnification (<33%) at the time of cataract surgery by the choice of an appropriate intraocular lens power and spectacle glasses in patients with AMD and cataract.
Methods:
The design was a prospective, nonrandomized, interventional case series involving 6 patients aged 74-86 (mean 80; SD 4) years with AMD and cataract. Participants were males and females, equal in number, who had visual acuity of less than 20/400 in the weaker eye. Standard cataract surgery was performed in the weaker eye. The power of the intraocular lens was derived from the reduced Gullstrand model of the eye in such a way that at the intraocular lens plane a minus lens was created, which, together with a plus lens in matching glasses, formed a Galilean telescopic system with magnification of up to 33%. Outcome measures were visual acuity, contrast sensitivity, and activities of daily living (ADL) scores.
Results:
The mean power of the implanted intraocular lenses was 6.31 (SD 2.42) diopters and, according to the theoretical derivations, achieved magnification between 20% and 30% (mean 26%; SD 4.92%). Visual acuity improved for the group from a mean of 20/525 (logMAR 1.48; SD 0.13) to a mean of 20/290 (logMAR 1.20; SD 0.21). Contrast sensitivity improved significantly (p < 0.001) only in the lower spatial frequencies. Postoperatively, ADL scores improved significantly in all patients except one. At the end of the follow-up period, 3 patients reported that they would like to proceed with similar surgery for the other eye.
Interpretation:
An optimal surgical telescopic device based on low-grade telescopic magnification may improve functional vision for usage in all tasks in AMD patients. All patients from this study were satisfied following surgery and viewed study outcomes as positive and beneficial, and some patients responded with enthusiasm. Surgeons are encouraged to use this modified technique of cataract surgery in low-vision patients with AMD and cataract.
