Purchase this article with an account.
Nishanth Uli, Ashraf Mahmoud, Gloria Fleming, Cynthia J Roberts; Preliminary study shows lamina cribrosa intensity on Optical Coherence Tomography is related to translaminar pressure gradient in subjects without glaucomatous nerve damage. Invest. Ophthalmol. Vis. Sci. 2020;61(7):3923.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The lamina cribrosa (LC) is considered the primary site of glaucomatous damage, and the translaminar pressure gradient (TLPG) is proposed to play a role in this damage. LC intensity (LCI) on optical coherence tomography (OCT) has been studied as a parameter to assess glaucomatous damage, but its relationship with TLPG remains unknown. In this cross-sectional study, we test the hypothesis that LCI on OCT is related to TLPG in normal (NML), ocular hypertension (OHT), normal tension glaucoma (NTG) and primary open angle glaucoma (POAG) patients.
60 patients underwent OCT and lumbar puncture to assess cerebrospinal fluid pressure as a proxy for intracranial pressure (ICP). Intraocular pressure (IOP) of each eye was measured concurrently using a pneumotonometer and TLPG calculated as IOP minus ICP. We assessed image quality of each image and excluded images with quality score less than 30. After quality assessment, images of 34 eyes were analyzed (NRM N=18, OHT N=4, NTG N=5, POAG N=7) using the program ImageJ. A rectangular section around the LC was chosen and the section’s maximum brightness obtained (brightness levels ranged from 0 to 255). Thresholding was performed by selecting pixels in the section with brightness above 60% of the maximum. Finally, LCI was calculated as the mean brightness level of these pixels. Linear regression was performed between LCI and TLPG by group with significance threshold p < 0.05.
There was a statistically significant relationship between LCI and TLPG in the NRM (p=0.004, Rsqr=0.147, mean TLPG=7.23+/-2.55mmHg, mean LCI=125.91+/-25.34) and OHT (p=0.029, Rsqr=0.364, mean TLPG=8.79+/-2.51mmHg, mean LCI=119.06+/-26.11) groups, where higher LCI corresponded to lower TLPG. However, this relationship was not significant for the NTG (p=0.860, mean TLPG=5.42+/-2.56mmHg, mean LCI=141.70+/-31.78) and POAG (p=0.396, mean TLPG=7.76+/-5.52mmHg, mean LCI=127.33+/-27.92) groups.
The lamina cribrosa intensity on OCT is influenced by the translaminar pressure gradient only in the absence of glaucomatous nerve damage in this preliminary study. It is possible that nerve damage alters the optical properties of the LC and thus its sensitivity to pressure. Of note, our quality threshold of 30 may be too high as the majority of initial subjects did not meet this standard.
This is a 2020 ARVO Annual Meeting abstract.
This PDF is available to Subscribers Only