Purchase this article with an account.
G. Williams, H. Yang, C. Hardin, N. G. Strouthidis, I. A. Sigal, B. Fortune, C. F. Burgoyne; Spectral Domain Optical Coherence Tomography (SD-OCT) Detected Optic Nerve Head (ONH) Structural Change in Young vs. Old Monkey Early Experimental Glaucoma (EEG). Invest. Ophthalmol. Vis. Sci. 2010;51(13):4805.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To test the hypothesis that ONH structural change is greater in young versus old monkey EEG eyes even when most of the young EEG eyes experience lower cumulative IOP insults.
SD-OCT and Confocal Scanning Laser Tomography (CSLT) (Spectralis and HRT, Heidelberg Engineering) were performed 30 minutes after manometric IOP lowering to 10 mm Hg on both eyes of 4 young (1.5 to 2.6 years) and 4 old (18.6 to 21.9 years) monkeys every 1-2 weeks pre and post-unilateral laser-induced, chronic IOP elevation until the onset of CSLT-determined EEG. Within the 40 radial B-scans of the pre-sacrifice,15º SD-OCT volumes, four masked operators delineated the retinal and ONH landmarks necessary to quantify: retinal nerve fiber layer thickness (RNFLT), RNFL volume, rim width, rim volume, rim area, Neural Canal Opening (NCO) depth relative to peripheral Bruch’s Membrane/RPE, Anterior Lamina Cribrosa Surface (ALCS) position (relative to the NCO reference plane), pre-laminar tissue thickness (PLT) and NCO area for each eye. Effects of treatment (EEG vs control) and age (young vs old) were assessed by ANOVA for each SD-OCT parameter as well as for mean, peak and cumulative IOP.
The cumulative inter-eye IOP differences were 474, 574, 583 and 680 mmHg*days in the young and 352, 752, 1241 and 1243 mmHg*days in the old EEG eyes. Highest detected IOP ranged from 28-37 mm Hg in the young EEG eyes and 38-42 mm Hg in the old EEG eyes. Treatment effects were significant for all SD-OCT parameters except NCO area and PLT, RNFLT and RNFL volume. While the only significant age-treatment interaction detected was for mean IOP (old>young; p=0.0495), there were clear trends observed for all ONH parameters changing more in young than old EEG eyes. Statistically significant inter-eye differences for ONH parameters were also more frequent in young EEG eyes (43%) compared to old EEG eyes (23%). Two young EEG eyes exhibited the largest ALCS position changes (43.8 and 53.2%) while two old EEG eyes displayed the smallest ALCS position changes (9.0 and 9.1%).
Our study is the first to use SD-OCT imaging to detect EEG ONH structural change in young and old eyes. While the number of eyes is small, our data suggest that on average old eyes require higher IOPs of longer duration to manifest CSLT-detected ONH structural change and that, at its onset, the magnitude of this change will be less in old (compared to young) eyes. The relationship of these findings to optic nerve axon loss is currently under study.
This PDF is available to Subscribers Only