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Jessica Moon, Stuart Keith Gardiner, Brad Fortune, Juan Reynaud, Steven L Mansberger; Effect of Trabeculectomy on Optical Coherence Tomography (OCT) Measurements of the optic nerve head Neuroretinal Rim Tissue. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2108.
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© ARVO (1962-2015); The Authors (2016-present)
Researchers and clinicians use OCT measurements of the neuroretinal rim and peripapillary nerve fiber layer to detect progressive glaucoma. Few studies have examined the changes in OCT measurements after IOP lowering with trabeculectomy, and whether OCT parameters remained stable for ongoing assessment.
We identified 19 eyes (15 subjects) with primary open angle glaucoma who had undergone a trabeculectomy. We calculated the change in OCT parameters (minimum rim area (MRA), minimum rim width (MRW), and retinal nerve fiber layer thickness (RFNLT)) as well as parameters thought to be stable in progressive glaucoma (e.g. basement membrane opening (BMO) area) from the visit before the surgery to the visit after the surgery, an interval of approximately 6-months. We also calculated changes in the same eyes over two different 6-month intervals that did not contain trabeculectomy to serve as control. The changes within and between these intervals were compared using a generalized linear model (with compound symmetry correlation structure), accounting for the correlation between time intervals for the same eye.
The Table summarizes the results within the intervals. MRA and MRW both decreased (p<.01) during the intervals that did not contain trabeculectomy, consistent with aging and/or glaucomatous optic disc progression. IOP and RNFLT decreased (p<0.01) during the intervals that included trabeculectomy with nonsignificant increases in MRA and MRW. When comparing the trabeculectomy and control intervals, only RNFL thickness and BMO area remained stable(p>.05), while IOP decreased (p<.001) and all other neuroretinal rim parameters increased significantly (all p<.05). Similarly, trabeculectomy increased the angle above the reference plane for MRA and MRW (P<.05), consistent with a shallowing of the neuroretinal rim to profile.
The ONH neuroretinal rim parameters MRW and MRW increased as IOP decreased following trabeculectomy surgery. This is consistent with previous findings for other ONH parameters such as lamina cribrosa depth or topographic surface height. The RNFL thickness was unaffected and may be a more stable measure of disease progression that can be monitored across time intervals containing glaucoma surgery.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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