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Anita Chan, Tin Aung TUN, Sai Bo Bo Tun, John C Allen, Veluchamy A Barathi, Michael J A Girard, Tin Aung; Characterising the Microbead induced Chronic Experimental Glaucoma (EG) Model using optic coherence tomography (OCT) in non-human primates (NHP). Invest. Ophthalmol. Vis. Sci. 2017;58(8):4027.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize a Microbead induced Chronic experimental glaucoma (EG) model using optic coherence tomography (OCT) to determine the longitudinal optic nerve head (ONH) structural changes.
Bilateral eyes of 8 Cynomolgus macaque monkeys (macaca fascicularis) were imaged with slit lamp, gonioscopy, funduscopy and OCT (Spectralis) monthly from Baseline to 7 months. The IOP was measured with Tonovet and chronic IOP elevation was achieved unilaterally by repeated 15um polystyrene microbeads (Triton technologies) injections into the anterior chamber (AC). Presence of intraocular inflammation, cataract and angle changes were documented. Changes in depth of anterior lamina cribrosa surface (LCdepth) and the minimum rim width (MRW) from Bruch’s membrane opening (BMO) were calculated and compared between EG and control eyes during Phase 1 (Ph1) defined as month 1-3 IOP elevation from baseline to >30mmgHg and Phase 2 (Ph2) defined as month 4-7 when IOP elevation was consistently maintained (30-50 mmHg).
All monkeys were female, aged 5 years. There was no difference of IOP, LC depth and MRW between EG and control eyes at baseline and month 1. No cataract, PAS (>1 clock hour), or AC inflammation was documented. 8 weekly injections over 2 months with <1 additional injection/monkey was required for sustained IOP >30mmHg (month 3-7). The mean IOP was higher (36+6SD mmHg, P<0.001), the mean LCdepth was deeper (P=0.006), the MRW was thinner (P<0.001) and the CD ratio higher (mean 0.6, P<0.001) in EG eyes significantly from month 2 to 7 when compared to control eyes (mean CD ratio 0.2, mean IOP 16+3SD mmHg). Consistent and significant differences between the rate of change in LCdepth and MRW difference between all EG and control eyes were detected in Ph1 when compared to Ph2 (P<0.01).
This chronic microbead EG model produces IOP and structural changes comparable to the laser EG models without trabecular meshwork damage or inflammation. An increased rate of LC depth and MRW change corresponded to a higher rate of IOP change (Ph 1) whilst a slower rate of change in LC depth and MRW in Ph2 corresponded to a chronic IOP elevation (lower rate of IOP change) suggesting that early and adequate IOP control may be more useful in delaying structural damage.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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