Purchase this article with an account.
Julia Teister, Oliver Gramlich, Theresa Lueckner, Maren Kriechbaum, Norbert Pfeiffer, Franz Grus; Investigation of the retinal thickness using Spectralis OCT® reveals a significant decrease after short time elevation of IOP. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1458.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
An important, yet not exclusive aspect for glaucoma is the occurrence of elevated intraocular pressure (IOP). The purpose of the present study was to identify minimal pathomorphological changes of the retina using conventional optical coherence tomography (OCT) after a short term elevation of IOP. Additionally, morphological changes of the retina during loop manipulation were investigated.
The IOP of the right eye (OD) of male Long Evans rats (n=12) was elevated for 60 minutes, five days a week over a duration of 6 weeks. Left eye (OS) served as control. Animals were sedated by DorbeneVet®. The IOP was manipulated to an average of 35 mmHg, using a vascular loop tightened around the globe. Before, during and after manipulation, ten values of IOP were measured using TonoLab. Retinal thickness (RT) was measured at about 700, 800 and 900 µm distance to the optic nerve head (ONH) in each superior, inferior, nasal and temporal retinal area. For OCT the following setup was chosen: picture size 20”x 15”, high resolution, 15.25 diopter, 1024 A-scans and ART 30 frames. The reference arm was adjusted manually. All evaluations were done simultaneously for OD and OS. In addition, OCT investigation during IOP elevation with the loop was performed.
For the short term elevation of IOP, a mean elevation level of 35.4±2.7 µm was achieved, while contralateral IOP values ranged at 10.6±0.8 µm. OCT examination revealed a significant decrease of 2.3% of the mean RT between IOP-elevated (191.1±11.6 µm) and the untreated eye (195.5±10.8 µm, p<0.005) after six weeks. Significant differences were found in the nasal retina (OD: 190.1±7.9 µm, OS: 197.7±9.8 µm, p< 0.003) and superior retina (OD: 183.1±9.1 µm, OS: 190.0±12.2 µm, p<0,02). Additionally, OCT investigation during loop manipulation revealed morphological changes such as retinal distortion and deformation of the ONH towards the eye background.
The results of this study demonstrate that a short term elevation of the intraocular pressure is sufficient to induce structural damage upon the retina. A conventional OCT was sufficient to detect even slight, but significant changes of the RT. The deformation of the ONH might be comparable to cupping phenomena occurring in glaucoma patients. Therefore, this model and OCT techniques might be suitable to investigate mechanisms of optic nerve cupping.
This PDF is available to Subscribers Only