Deformation of the early glaucomatous monkey optic nerve head connective tissue after acute IOP elevation in 3-D histomorphometric reconstructions.
OBJECTIVE
To retest the hypothesis that monkey ONH connective tissues become hypercompliant in early experimental glaucoma (EEG), by using 3-D histomorphometric reconstructions, and to expand the characterization of EEG connective tissue deformation to nine EEG eyes.


METHODS
Trephinated ONH and peripapillary sclera from both eyes of nine monkeys that were perfusion fixed, with one normal eye at IOP 10 mm Hg and the other EEG eye at 10 (n=3), 30 (n=3), or 45 (n=3) mm Hg were serial sectioned, 3-D reconstructed, 3-D delineated, and quantified with 3-D reconstruction techniques developed in prior studies by the authors. Overall, and for each monkey, intereye differences (EEG eye minus normal eye) for each parameter were calculated and compared by ANOVA. Hypercompliance in the EEG 30 and 45 eyes was assessed by ANOVA, and deformations in all nine EEG eyes were separately compared by region without regard for fixation IOP.


RESULTS
Hypercompliant deformation was not significant in the overall ANOVA, but was suggested in a subset of EEG 30/45 eyes. EEG eye deformations included posterior laminar deformation, neural canal expansion, lamina cribrosa thickening, and posterior (outward) bowing of the peripapillary sclera. Maximum posterior laminar deformation and scleral canal expansion co-localized to either the inferior nasal or superior temporal quadrants in the eyes with the least deformation and involved both quadrants in the eyes achieving the greatest deformation.


CONCLUSIONS
The data suggest that, in monkey EEG, ONH connective tissue hypercompliance may occur only in a subset of eyes and that early ONH connective tissue deformation is maximized in the superior temporal and/or inferior nasal quadrants.
Yang
Hongli
H
Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Health System, Portland, OR 97208-3950, USA.
Thompson
Hilary
H
Roberts
Michael D
MD
Sigal
Ian A
IA
Downs
J Crawford
JC
Burgoyne
Claude F
CF
D000208:Acute Disease; D000818:Animals; D003238:Connective Tissue / Q000473:pathology*; D004195:Disease Models, Animal; D005901:Glaucoma / Q000209:etiology* / Q000473:pathology; D021621:Imaging, Three-Dimensional; D007429:Intraocular Pressure; D008252:Macaca fascicularis; D008253:Macaca mulatta; D008297:Male; D009798:Ocular Hypertension / Q000150:complications*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000209:etiology* / Q000473:pathology