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W. Wittich, O. Overbury, M.A. Kapusta, D.H. Watanabe; Rate of Functional Recovery After Macular Hole Surgery: Hierarchical Linear Modeling for Visual Acuity Change Over Time . Invest. Ophthalmol. Vis. Sci. 2006;47(13):936.
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© ARVO (1962-2015); The Authors (2016-present)
Functional outcome of Macular Hole (MH) surgery is generally evaluated in the context of pre/post–surgical comparison of visual acuity. This type of evaluation, however, results in the loss of valuable information about change over time as data must be collapsed into discrete time categories. In addition, comparison of two time points does not allow for an evaluation of the rate of observed functional recovery, which may differ among patients, depending on individual characteristics that affect acuity, such as MH diameter or status of the lens.
Visual acuity (ETDRS & Landolt–C) was measured in 22 consecutive patients, who underwent successful MH surgery between June 2004 and July 2005. Pre–operative MH diameter and post–operative surgical success was confirmed with OCT scans. Follow–up time for repeated acuity measurement ranged from 6 to 18 months.
Using a linear and curvilinear growth–curve analysis approach with Hierarchical Linear Modeling, coefficients for rate of acuity recovery were calculated. Pre–operative MH diameter was a significant predictor of pre–operative acuity (intercept) as well as outcome over time; rate of recovery (slope) differed significantly in a curvilinear fashion depending on the patient's lens status but was independent of pre–operative MH diameter. Patients who had undergone cataract extraction prior to MH surgery demonstrated smooth and rapid acuity recovery, whereas most phakic patients' recovery rate was delayed by cataract formation during the follow–up period.
This analysis provides important insight into the observed functional recovery process after MH surgery. Specifically, it more closely represents the visual experience of the patient. The limitation of this approach, however, lies in the need for frequent repeated acuity measurement.
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