Purchase this article with an account.
Rouzbeh Amini, Jonathan L Grimm, Ning-Jiun Jan, Donald J Brown, Ian A Sigal; Lamina cribrosa pore size increases when human eyes are subjected to acute intraocular pressure elevation. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4249.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To quantify eye-specific areal, circumferential, and radial stretches induced within the lamina cribrosa (LC) and pia matter of human eyes subjected to acute intraocular pressure (IOP) elevation.
Five human eyes from three donors aged 23-82 were scanned using second harmonic generated (SHG) imaging (Zeiss 510 Meta LSM). The optic nerves were cut to allow imaging of the LC from the posterior direction. Images up to a depth of 300 µm (2 µm depth resolution) were acquired at IOPs ranging from 10 to 50 mmHg, after allowing equilibration for 30 min. Mosaic lateral resolution varied from1.76 to 4.97 µm/pixel. Digital image correlation techniques were used to calculate the deformation mapping between maximum intensity projection images at low and at elevated IOP (Sigal IA, et al. IOVS 2013; In-Press). The LC beams, LC pores, and pia matter were segmented manually. Stretches were calculated for each segmented section separately.
In all samples the LC pores areal stretch increased significantly when IOP was elevated (P’s< 0.0001, single-tailed t-test for each sample, Figure). In the pia region, in all but one case, the circumferential stretch was significantly higher than the radial stretch (P’s < 0.0001, single-tailed paired t-test). Further, in all but one case, the value of both circumferential and radial stretches was significantly higher than one (P’s< 0.0001, single-tailed t-test for each sample). Although the standard deviations of the measured values were relatively small, there were regional differences in the stretch values of the LC pores, LC beams, and pia matters of the eyes (Figure).
We measured eye-specific IOP-induced directional deformations of the pores and beams of the LC as well as those of pia matter in uncut and unfixed human eyes. The most interesting outcome was the increase in the average area of the LC pores during exposure to high IOP. Thus, for the majority of the retinal ganglion cell axons, the passage through the LC expanded. Only for a small minority of the axons did the physical space for passing the LC narrowed. In the pia region, as expected, the direction of higher stretch (i.e. circumferential direction) matched the gross ECM structure. Such matching further exemplifies how in numerous regions of the ocular globe (e.g. pia, corneal limbus, etc.), the tissue structure anisotropy is closely related to its mechanical function.
This PDF is available to Subscribers Only