Discovery of Clinical Manifestations in Spontaneous Glaucoma Suspect Nonhuman Primates

The primary aim of this study was to assess the longitudinal changes in retinal nerve fiber layer (RNFL) thickness and relative ONH parameters using spectral-domain optical coherence tomography (SD-OCT) in the living eyes of nonhuman primates with spontaneous glaucoma.

Totally 9 macaque subjects underwent a standard fundus photo and OCT examination, including 3 adult monkeys with stable elevated intraocular pressure (IOP) as the glaucoma suspect group and 6 normal IOP monkeys as the control group. Each eye of primates with IOP measurement was repeated three times. OCT measurements recorded RNFL, Bruch's membrane opening (BMO) minimum rim width (MRW). The follow-up scan of glaucomatous subjects was undergone in 10 months.

The mean ages of glaucoma and healthy subjects are 19.33 ± 0.33 and 20.5 ± 1.46 years. Elevated IOP was achieved in three nonhuman primate eyes with an average increase of 10 mm Hg over the study period. Elevated IOP was associated with decreased RNFL thickness in all the regions and decreased RNFL phase retardation in the superior and inferior regions. When averaged over the entire retinal area, only the whole RNFL and temporal regions showed a significant decrease. The mean IPL thicknesses are 87.17 ± 2.15 μm in glaucomatous and 93.33 ± 1.51 μm in healthy eyes (p = 0.03). Lamina cribrosa parameters are measured from the OCT images and showed significant differences between glaucoma primates and normal primates.

Of the measured parameters, decreased RNFL and MRW were correlated with glaucomatous damage. Natural glaucoma primate can be a natural glaucoma model which is closer to glaucoma in humans.