Magnetic resonance imaging reveals possible cause of diplopia after Baerveldt glaucoma implantation

Abstract

Purpose To assess if ocular motility impairment, and the ensuing diplopia, after Baerveldt Glaucoma device (BGI) implantation, is related to the presence of a large fluid reservoir (bleb), using Magnetic Resonance Imaging (MRI). Methods In a masked observational study (CCMO-registry number: NL65633.058.18), the eyes of 30 glaucoma patients with (n = 12) or without diplopia (n = 18) who had previously undergone BGI implantation were scanned with a 7 Tesla MRI-scanner. The substructures of the BGI-complex, including both blebs and plate, were segmented in 3D. Primary outcomes were a comparison of volume and height of the BGI-complex between patients with and without diplopia. Comparisons were performed by using an unpaired t-test, Fisher’s Exact or Mann-Whitney test. Correlations were determined by using Spearman correlation. Results The median volume and height of the BGI-complex was significantly higher in patients with compared to patients without diplopia (p = 0.007 and p = 0.025, respectively). Six patients had an excessively large total bleb volume (median of 1736.5mm3, interquartile range 1486.3–1933.9mm3), four of whom experienced diplopia (33% of the diplopia patients). Fibrotic strands through the BGI plate, intended to limit the height of the bleb, could be visualized but were not related to diplopia (75% versus 88%; p = 0.28). Conclusions With MRI, we show that in a significant number of diplopia cases a large bleb is present in the orbit. Given the large volume of these blebs, they are a likely explanation of the development of diplopia in at least some of the patients with diplopia after BGI implantation. Additionally, the MR-images confirm the presence of fibrotic strands. As these strands are also visible in patients with a large bleb, they are apparently not sufficient to restrict the bleb height.

Bleb morphology of glaucoma drainage devices on magnetic resonance imaging

“…We also report that larger volume blebs in the 75th-100th quartile were significantly associated with scleral flattening underneath the bleb (p = 0.0049). This is likely associated with the volume effect and has been reported previously with large BGI blebs (Islamaj et al, 2022).…”

“…Detorakis et al (2009) and Sano et al (2015) reported an inverse correlation between IOP and bleb volume. Conversely, Ferreira et al (2015) reported an positive correlation between bleb dimensions (height and volume) and pre‐ and post‐operative IOP, while other studies reported no correlations (Islamaj et al, 2022; Iwasaki et al, 2017).…”

“…Indeed, Iwasaki et al (2017) found about only half of BGI imaged showed a double‐layered bleb but his sample was imaged significantly later (average 15.2 ± 10.1 months), which may indicate that the distribution of aqueous between the upper and lower ‘compartments’ may vary over time. Also, Islamaj et al (2022) published a series of 7‐Tesla MRI scans on BGI patients, which showed double‐layered blebs with large inferior blebs (492.3 mm 3 on average) with visible connective tissue strands within the endplate fenestrations, which suggests these strands may have a limited function regarding bleb volume restriction.…”

Magnetic Resonance Imaging in the Clinical Care for Uveal Melanoma Patients—A Systematic Review from an Ophthalmic Perspective

“…In addition to these anatomical scans, functional MRI-scans provide different quantitative imaging biomarkers which can aid in the differential diagnosis, staging and assessment of therapy response [26,28,34,[37][38][39]. It has been shown that these MRI scans can be performed safely and reliably at field strengths up to 7 tesla, in patients with modern intraocular lenses (IOL) or a Baerveldt glaucoma implant, after silicon oil tamponade and with tantalum markers sutured to the sclera [33,[49][50][51][52][53][54][55].…”