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  • What Degree of Visual Field Damage Causes Disability for Glaucoma Patients?

    By Lynda Seminara
    Selected By: Richard K. Parrish II, MD
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    Journal Highlights

    American Journal of Ophthalmology, January 2019

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    Jammal et al. used latent class analysis (LCA) to classify patient-reported glaucoma outcomes and to quantify the amount of visual field damage that results in disability. They found that this model, which is rarely used in oph­thalmology, is useful for both purposes, and they noted that early visual field loss in the better eye can cause substan­tial disability.

    Participants in this cross-sectional study were required to have open an­gles on gonioscopy. The 263 enrollees completed the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25), after which an LCA model was applied to analyze the data. Patients were grouped into mutually exclusive classes according to question­naire responses. Differences between the classes were documented, including standard automated perimetry mean deviations (SAP MD) and integrated binocular mean sensitivity values. The optimal number of classes was defined based on goodness-of-fit criteria, inter­pretability, and clinical utility.

    The model containing two latent classes (disabled and nondisabled) had the best fit, demonstrating Lo-Mendell-Rubin test values superior to those of the one-class model and not signifi­cantly different from those of models with more classes. The two-class final LCA model had a high entropy value (0.965), denoting excellent distinction between the classes. Forty-eight patients (18%) were classified as disabled, and 215 (82%) were classified as nondis­abled. The average SAP MD of the better eye was –5.98 dB in the disabled group and –2.51 dB in the nondisabled group (p < .001). Corresponding values for the worse eye were –13.36 dB and –6.05 dB (p < .001).

    This study showed that damage of approximately –6 dB for SAP MD, denoting relatively early visual field loss, may signal significant disability if present in the better eye. The research suggests that LCA may be a valuable tool to analyze patients’ concerns about quality of life.

    The original article can be found here.