Abstract
Purpose :
To determine: preferred imaging modality and technique for locating, and efficacy of trabecular microbypass stent (TMS).
Methods :
9 patients (14 eyes) post combined phacoemulsification, PC IOL, and 1 TMS within last 5 years by single surgeon (JE) examined post-op.Visual acuity (VA), intraocular pressure (IOP), gonioscopy recorded, and an ophthalmic photographer performed all imaging with AS-OCT (Heidelberg Spectralis) and UBM (50 MHz Quantel Aviso).Images parallel and perpendicular to limbus were independently reviewed (JS, SR) assessing if TMS was present, quality of implant image, and areas of lucency adjacent or distal to implant.Pre and post-op IOP and number of glaucoma medications were compared.Data was analyzed using Minitab® for statistical significance, p-value of 0.05.
Results :
Time since operation 866 (±534) days.13/14 TMS were observed with gonioscopy.TMS in all 14 eyes were located by AS-OCT.By UBM in 13/14 eyes (JS) and 14/14 eyes (SR). UBM imaging determined TMS were present, but details of TMS location and surrounding tissues were poorly defined. With AS-OCT TMS were well defined in 12/14 eyes and lucency adjacent to TMS noted in 8 eyes (JS, SR).UBM suggested adjacent lucency in 2 (SR) and 0 patients (JS).IOP and number of meds (mean±SD) were 18.0 (±3.5) and 0.9 (±0.4) preop and 14.4 (±3.8), and 0.8 (±0.7) postop, respectively. Postop IOP was lower (P=0.014) and medication burden unchanged (P=0.738).
Conclusions :
Both UBM and AS-OCT can visualize properly placed TMS implants, in contrast to an in vitro imaging study where TMS were imaged only if dislodged in AC or sulcus.1Greater detail of TMS positioning and surrounding areas is provided by AS-OCT than UBM, in part due to the higher resolution of AS OCT. Imaging both parallel and perpendicular provides more consistent identification of TMS than a single image capture technique.2 UBM can be used to determine if TMS is present, and AS-OCT can provide greater detail. Postoperative reduction in IOP is consistent with previous studies. Number of drops was not reduced. Future studies will investigate if areas of lucency are consistent with greater efficacy.
Ichhpujani P, Katz LJ, Gille R, Affel E. Imaging modalities for localization of an iStent. Ophthal Surg, Lasers & Imaging. 2010;41(6):660-3.
Imaging of Trabecular Microbypass Stent (iStent) Using UBM and AS-OCT. Reich S, Ellant J, Kremer F, Simpson E, Serle J. Poster Presentation. AGS 27th Annual Meeting. CA. 3/2017.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.