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Keunheung Park, Jiwoong Lee; Correlation of Bruch's Membrane Opening-Minimum Rim Width (BMO-MRW) and Visual Function Loss in Glaucoma Using Broken Stick Model. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5809.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the Bruch’s membrane opening minimum rim width (BMO-MRW) tipping point where corresponding visual field damages become detectable.
One hundred fifty-eight subjects were recruited for the study: 79 healthy and 79 glaucoma subjects. All patients had visual field exam, Swedish Interactive Threshold Algorithm (SITA) 24-2 and spectral-domain optical coherence tomography (SD-OCT, Spectralis, Heidelberg) to measure BMO-MRW. 52 testing points of visual field total deviation values were allocated to the corresponding sector according to the Garway-Heath distribution map. To analysis correlation between visual field values and BMO-MRW, a ‘broken-stick’ statistical model was used. The tipping point was estimated at which visual field values start to sharply decreases with BMO-MRW thinning and then the slopes above and below this tipping point were evaluated.
Globally, BMO-MRW thinning, approximately 27.8% loss from normal thickness, was required for visual field to be detectable. Sectorally, relatively larger BMO-MRW thinning in inferior sectors (35.5%, 39.2%; inferotemporal, inferonasal respectively) and relatively smaller in superior sectors, 13.3%, 33.8% (superotemporal, superonasal respectively) was necessary for visual field to be detectable. In temporal sector, only 7.0% of BMO-MRW thinning was required. The slopes above these tipping points were almost zero throughout all sectors and visual field damages were unrelated to BMO-MRW thinning. The slopes below tipping points were steeper than above and visual field damages well associated with BMO-MRW thinning.
We identified the existence of tipping point between BMO-MRW and visual field test. Especially in early glaucoma, the functional test like visual field exam can be masked until the significant structural damage progresses and the tipping point of it is approximately 27.8% loss from normal BMO-MRW.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Healthy (H) and glaucoma (G) BMO-MRW in the global mean with corresponding (A) visual field threshold values and (B) visual field mean deviation(MD). 95% confidence interval is shown as dashed line. The tipping point / adjusted R2 is (A) 185.6 µm / 0.4173 and (B) 185.8 µm / 0.5330.
Healthy (H) and glaucoma (G) BMO-MRW in each sector with corresponding visual field threshold values. 95% confidence interval is shown as dashed line.
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