Background/aims With the increased efficacy of current therapy for wet age-related macular degeneration (AMD), better ways to detect wet AMD are needed. This study was designed to test the ability of three-dimensional contrast threshold Amsler grid (3D-CTAG) testing to distinguish wet AMD from dry AMD.
Methods Conventional paper Amsler grid and 3D-CTAG tests were performed in 90 eyes: 63 with AMD (34 dry, 29 wet) and 27 controls. Qualitative comparisons were based upon the three-dimensional shapes of central visual field (VF) defects. Quantitative analyses considered the number and volume of the three-dimensional defects.
Results 25/34 (74%) dry AMD and 6/29 (21%) wet AMD eyes had no distortions on paper Amsler grid. Of these, 5/25 (20%) dry and 6/6 (100%) wet (p=0.03) AMD eyes exhibited central VF defects with 3D-CTAG. Wet AMD displayed stepped defects in 16/28 (57%) eyes, compared with only 2/34 (6%) of dry AMD eyes (p=0.002). All three volumetric indices of VF defects were two- to four-fold greater in wet than dry AMD (p<0.006). 3D-CTAG had 83.9% positive and 90.6% negative predictive values for wet AMD.
Conclusions 3D-CTAG has a higher likelihood of detecting central VF defects than conventional Amsler grid, especially in wet AMD. Wet AMD can be distinguished from dry AMD by qualitative and quantitative 3D-CTAG criteria. Thus, 3D-CTAG may be useful in screening for wet AMD, quantitating disease severity, and providing a quantitative outcome measure of therapy.
- Macular degeneration
- contrast sensitivity
- choroidal neovascularisation
- Amsler grid
- central visual fields
- field of vision
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Funding VMR Consulting, Inc., Huntington Beach, California, USA (study design; collection, analysis and interpretation of data; writing of article; decision to submit article); NIH grant EY03040 (no involvement in study design, analysis, interpretation, writing, or decision to submit).
Competing interests WF and AAS have proprietary interests in the three-dimensional computer-automated threshold Amsler grid test described in the study as patents on the technology have been issued. All remaining authors (CDR, SRB, RVJ and JS) have no proprietary or financial interest in the manuscript.
Patient consent Obtained.
Ethics approval This study was conducted with the approval of the University of Southern California Institutional Review Board, Los Angeles, California, USA.
Provenance and peer review Not commissioned; externally peer reviewed.