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Kevin M Ivers, Hongli Yang, Lirong Qin, Reyes Luke, Heather Lovelace, Juan Reynaud, Stuart Keith Gardiner, Brad Fortune, Claude F Burgoyne; Does the Effect of Acute Intraocular Pressure (IOP) Elevation on Minimum Rim Width (MRW) at Baseline Predict Future Onset of Change and/or Rate of Change in an Experimental Model of Glaucoma?. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1011.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether changes in the optic nerve head (ONH) parameter minimum rim width (MRW) in response to acute intraocular pressure (IOP) elevation at baseline are predictive of locations of earliest onset or fastest rate of subsequent chronic changes in MRW in a non-human primate model of experimental glaucoma (EG).
Five animals had ONH imaging by Spectral Domain Optical Coherence Tomography (SDOCT) 5-10 times at baseline and biweekly following laser-induced, unilateral chronic IOP elevation until onset of retinal ganglion cell functional loss measured by electroretinography was confirmed in the EG eye. ONH scans were acquired 30 min after IOP was manometrically fixed to 10 mmHg and 30 min after elevation to 30 mmHg. ONH landmarks were delineated in 40 SDOCT B-scans and MRW was calculated globally and locally in twelve 300 sectors. Time of eye-specific event-based chronic change onset was evaluated for MRW within each 300 sector. Sectoral MRW change between 10 and 30 mmHg at baseline (acute 10/30 effect), longitudinal MRW change onset and rate of change at 10 mmHg were color mapped and ranked by sector.
Globally and across sectors, the acute 10/30 effect at baseline in MRW ranged from -7.2 to -3.0% and -18.8 to 19.7%, respectively. On average, sectors 4 and 10 showed the largest acute 10/30 effect in MRW (-11.7 and -13.2%, respectively), sectors 5 and 6 showed the earliest onset of longitudinal change (142 and 137 days, respectively), and sectors 5 and 7 showed the fastest rate of change (-0.426 and -0.476 μm/day, respectively). Acute IOP-induced MRW thinning was largest in superotemporal and inferonasal sectors in all 5 eyes (Fig 1). In 4 eyes (M1,3,4,5), sectors with the largest acute IOP-induced MRW thinning qualitatively matched sectors with the fastest rate of change (Figs. 1,2). Patterns between acute IOP-induced MRW thinning and onset time were more weakly correlated (only M1,2,4 matched qualitatively).
A superotemporal-inferonasal band was observed (Figs. 1,2) between acute 10/30 change in sectoral MRW at baseline and subsequent longitudinal rates of change, which suggests acute IOP change at baseline in MRW may predict locations of faster longitudinal change in MRW and therefore could be a potential tool for clinical diagnosis and susceptibility assessment.
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