Purchase this article with an account.
Laura Wilsey, Juan Reynaud, Claude F Burgoyne, Brad Fortune; Macular structure and function in non-human primate (NHP) experimental glaucoma (EG). Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):638.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To evaluate structure and function of macular retinal layers in early and late stages of NHP EG.
A total of 21 NHP (17F/4M, mean ± SD age: 11 ± 8 yr) had longitudinal imaging of macular structure by SDOCT (Spectralis); N=16 also had recordings of macular function by multifocal electroretinography (mfERG, VERIS) during baseline (BL) and on alternating weeks after induction of chronic unilateral IOP elevation. SDOCT scans consisted of a radial star pattern centered on the fovea (48 radials, N=7; 80 radials, N=21). Image segmentations were corrected where errant and the average thickness over 15 deg was derived for 7 individual layers (L): nerve fiber (NFL), RGCL, inner plexiform (IPL), inner nuclear (INL), outer plexiform (OPL), outer nuclear+inner segment (ONL+IS), outer segment (OS). Peripapillary retinal nerve fiber layer thickness (ppRNFLT) was also measured from a single circular B-scan with 12 deg diameter. Responses to a slow-sequence mfERG stimulus (7F) were filtered (at 75 Hz) into low- and high-frequency components (LFC, HFC). The peak-to-trough amplitude of LFC features N1, P1, N2 and the RMS amplitude of HFC represent outer retinal function and retinal ganglion cell (RGC) function, respectively. Change from BL was assessed by Wilcoxon test with p≤0.001 criterion given multiple comparisons.
Study duration was 15 ± 6 months. In EG eyes, average post-laser IOP was 21 ± 6 mmHg; peak IOP was 42 ± 11 mmHg. At final follow-up, significant structural loss occurred only in EG eyes and only for ppRNFLT (-28 ± 24%), macular NFL (-16 ± 14%), RGCL (23 ± 17%) and IPL (-20 ± 15%); though there was also a small increase in ONL+IS (4 ± 4%) and similar tendency for INL and OPL (Figs 1A & 2). Significant functional loss occurred only for HFC and N2 in EG eyes (Fig 1B). Significant longitudinal structure-function correlations (p<0.01) were observed only in EG eyes and only for mfERG HFC and N2: HFC was correlated with ppRNFLT (R=0.67), macular NFL (R=0.50), RGCL (R=0.75) and IPL (R=0.73); N2 was correlated with RGCL (R=0.56) and IPL (R=0.52). Macular structural loss was correlated with ppRNFLT only for the NFL, RGCL and IPL (R=0.84, 0.86 and 0.94, respectively, p<0.0001).
Macular retinal structural and functional losses are correlated and specific to RGCs over a wide range of EG severity. Subtle outer retinal changes may be due in part to artifact from loss of inner retina.
This PDF is available to Subscribers Only