Abstract
Purpose: :
To examine whether structural differences exist in lamina cribrosa pore geometry in vivo between fellow eyes in normal non-human primates.
Methods: :
En face reflectance images (840 nm) of the anterior lamina cribrosa were acquired in vivo in left and right eyes of 5 normal rhesus monkeys and 1 monkey with unilateral laser-induced experimental glaucoma using a dual deformable mirror, confocal adaptive optics scanning laser ophthalmoscope (AOSLO). AOSLO videos were analyzed off-line using MATLAB, ImageJ, and Adobe Photoshop to produce registered images and identify individual pores. Laminar pore parameters (pore area, nearest neighbor distance, and elongation [ratio of major to minor axis lengths of best-fitting ellipse]) were calculated globally, within 45° sectors, and centrally vs. peripherally in each eye and compared between fellow eyes.
Results: :
Mean laminar pore area, nearest neighbor distance, and elongation were 1047 ± 183 µm2 (± st. dev.), 42.5 ± 6.12 µm, and 1.70 ± 0.04, respectively, across all normal eyes. On average, pore area and elongation were smaller centrally than peripherally in 10 of 10 and 9 of 10 eyes, respectively. Globally, there were no statistical differences in laminar pore parameters between left and right eyes in 4 of 5 normal monkeys (t-test, P>.05). When comparing sectors, pore area and elongation were statistically different between fellow eyes in only the superior-temporal sector for all normal monkeys (P<.05). In 1 monkey with early unilateral experimental glaucoma, all laminar pore parameters were significantly greater (P<.05) in the glaucomatous eye versus the contralateral control eye (and aforementioned normal eyes). Mean pore areas, nearest neighbor distances, and elongations in this animal’s glaucomatous vs. control eyes were 1642 µm2 vs. 1243 µm2, 62.2 µm vs. 48.3 µm, and 2.25 vs. 1.68, respectively.
Conclusions: :
Anterior laminar pore geometry tended to be similar between fellow eyes of normal monkeys. The values collected from these normal eyes will serve as normative data for future studies that examine changes in pore geometry in vivo during experimental glaucoma.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • lamina cribrosa • imaging/image analysis: non-clinical