Abstract
Purpose: :
To assess the effect of partial posterior vitreous detachment (pPVD) on Spectralis optical coherence tomography (OCT) measurements of retinal nerve fiber layer thickness.
Methods: :
A retrospective study was conducted using Spectralis OCT retinal nerve fiber layer thickness measurements obtained from patients seen in the Glaucoma Service at the Massachusetts Eye and Ear Infirmary between February 2009 and November 2010. Among the subset of patients with normal eyes, retinal nerve fiber layer thickness measurements were compared in eyes with pPVD to those in eyes without pPVD (controls).
Results: :
Among all imaged patients (n=684), 250 (36.5%) were noted to have pPVD. A total of 134 eyes from 134 normal patients were included (67 in the pPVD group and 67 in the control group). Among patients with pPVD, 42 (62.7%) were bilateral and 25 (37.3%) were unilateral. The mean retinal nerve fiber layer thickness in eyes with pPVD was 96.5 um and that of controls was 89.3 um (p <0.001). Thus, there was a statistically-significant difference in mean retinal nerve fiber layer thickness between eyes with and without pPVD. Mean retinal nerve fiber layer thickness in each quadrant was also analyzed and there was a statistically-significant difference found in the retinal nerve fiber layer thickness of the superior (p <0.001) as well as inferior (p = 0.0001), but not the nasal (p = 0.11) or temporal (p = 0.59) quadrants. The average age of patients with pPVD was younger than that of controls, (51.0 versus 59.5 years, respectively; p = 0.003) as was expected given that complete PVD is more common with increasing age. However, the difference in mean retinal nerve fiber layer thickness measurements between the two groups still achieved statistical significance (p = 0.01) after controlling for age using normative data and thus could not be explained by age alone.
Conclusions: :
Among normal patients examined at a tertiary eye center, a statistically-significant difference was found in Spectralis OCT measurements of retinal nerve fiber layer thickness between eyes with and without pPVD. The presence of pPVD may therefore play a role in the interpretation of Spectralis OCT retinal nerve fiber layer measurements for the diagnosis and assessment of glaucoma.
Keywords: imaging/image analysis: clinical • nerve fiber layer • clinical (human) or epidemiologic studies: systems/equipment/techniques