Safety of 3 Tesla Magnetic Resonance Imaging on iStent Implants: An Ex-Vivo Study.

PRCIS: Our study shows that iStent implant does not cause significant image artifacts, heating, or displacement during magnetic resonance imaging (MRI) scan. This device can be safely used in patients undergoing MRI scans using 3 Tesla (3T) machines. PURPOSE: The iStent is a medical grade titanium implant commonly implanted in the anterior chamber angle of glaucomatous eyes in order to reduce intraocular pressure and medication burden. As many people now have these devices implanted in their eyes, the issue of their compatibility with MRI in terms of safety and interference with interpretation of these studies commonly arises. The purpose of this study is to evaluate the safety of 3T MRI scans in eyes that have undergone iStent implantation and to assess the interference of the implant to the scan interpretation. MATERIALS AND METHODS: An ex vivo model of sheep eye with an iStent and proximately placed heat detector probe was used to study changes in the temperature during MRI 3T scan. The study included 2 fresh eyes with preserved extraocular muscles and orbital fat tissue placed in the orbital cavity of a human skull. Each eye with orbital content was scanned with a 3T MRI machine. RESULTS: No displacement of the implant was observed during MRI scanning. The heat detector showed mild temperature elevation during the first minutes of the scan from 14.6 to 16.5°C. The iStent was best visualized in T2 turbo spin echo sequences and showed no significant artifacts. CONCLUSION: iStent implants did not move during the MRI scan, showed minimal interaction with the magnetic field in terms of heating and image distortion. These interactions were not strong enough to present a substantial risk to patients with this implant undergoing an MRI scan.

The effect of hemodialysis on individual retinal layer thickness.

PURPOSE: The aim of this study was to employ newly developed advanced image analysis software to evaluate changes in retinal layer thickness following hemodialysis. METHODS: A non-randomized prospective study of patients with end-stage renal disease assessed on the same day before and after hemodialysis. Intraocular pressure and central corneal thickness were analyzed, and spectral domain optical coherence tomography results were automatically segmented using the Orion software and then compared. All patients had normal retinal optical coherence tomography findings before hemodialysis. RESULTS: Of the 31 suitable end-stage renal disease patients treated with hemodialysis who provided consent to participate, seven were unable to complete all evaluations, leaving 24 patients for analysis in the final study group. Their mean age was 66.67±14.3 years (range: 35-88), and 62.5% were males. Mean central corneal thickness did not change following hemodialysis (563.4±30.2 µm to 553.1±47.2 µm, p=.247), while mean intraocular pressure decreased (14.48±2.5 mmHg to 13.16±2.28 mmHg, p=.028). Individual mean retinal layer thickness showed no significant change, including the retinal nerve fiber layer (40.9±6.8 µm to 40.1±5.2 µm, p=.412), the ganglion cell and the inner plexiform layer (68.66±8 µm to 69.03±7.6 µm, p=.639), and the photoreceptor layer (50.26±2.8 µm to 50.32±3.1 µm, p=.869). Total retinal thickness similarly remained constant, with a mean of 303.7±17.3 µm before and 304.33±18.4 µm after hemodialysis (p=.571). CONCLUSIONS: Thickness of retinal layers, as assessed by individual segmentation, and central corneal thickness were not affected by hemodialysis treatment, while intraocular pressure was significantly reduced among patients with end-stage renal disease without pre-existing ocular pathology who were undergoing hemodialysis. These results support the view that hemodialysis does not have a negative impact on the retinal morphology of end-stage renal disease patients, who comprise a population with high rates of diabetic and/or hypertensive retinopathy as well as vision-threatening complications.

Effect of Rho-associated kinase inhibitor on human corneal endothelial cell apoptosis.

PURPOSE: To evaluate whether exposure to Rho-associated protein kinase (ROCK) inhibitor will promote human-cultured corneal endothelial cells (CECs) survival in a commercial storage medium. SETTING: Edith Wolfson Medical Center, Holon, and Sheba Medical Center, Tel Hashomer, Israel. DESIGN: Experimental study. METHODS: Fragments of human donor corneolimbal rings were stored in commercial storage media for 1 week, half with the addition of 10 µM ROCK inhibitor (Y-27632). Evaluation of CECs for early and late apoptosis\necrosis rates was performed using anti-human CD166 antibody and flow cytometric double staining analysis of propidium iodide and Annexin V. RESULTS: CECs of 6 corneolimbal rings demonstrated a reduced early apoptosis rate (4.35% ± 1.07% vs 12.18% ± 5.5%, P = .026) and a reduced late apoptosis\necrosis rate (5.5% ± 2.39% vs 9.43% ± 2.61%, P = .004) compared with control. Subsequently, the rate of apoptotic CECs expressing ROCK was significantly lower in cells exposed to ROCK inhibitor compared with cells that were not (19.01% ± 4.17 vs 30.42% ± 4.27, P < .001). CONCLUSIONS: ROCK inhibitor reduced endothelial cell loss in vitro and might be used to limit or slow CEC loss in donor corneal tissue during eye banking. This might be a promising new method for promoting future graft survival.

Prophylactic exposure of human corneal endothelial cells to Rho-associated kinase inhibitor reduced apoptosis rate after phacoemulsification: Ex vivo study.

PURPOSE: To evaluate whether prophylactic exposure of corneal endothelial cells (CECs) to a selective Rho-associated kinase (ROCK) inhibitor will inhibit CEC apoptosis after phacoemulsification. SETTING: Laboratory evaluations at the Edith Wolfson Medical Center, Holon, Israel and the Chaim Sheba Medical Center, Tel-Hashomer, Ramat-Gan, Israel and the Chaim Sheba Medical Center, Tel-Hashomer, Ramat-Gan, Israel. DESIGN: Experimental study. METHOD: Human donor corneolimbal rings were divided into fragments that were stored in commercial storage media with or without the addition of 10 mM ROCK inhibitor for 1 week and were then exposed to phacoemulsification energy. Samples were dissociated into single cells by trypsin digestion and CECs were targeted using the antihuman CD166 antibody, a new biomarker. The CEC survival was evaluated for early and late apoptosis rate with flow cytometric analysis of annexin-V and propidium iodide (PI) double staining. RESULTS: Six corneoscleral rings from 4 donors were studied. After phacoemulsification, CEC exposed to ROCK inhibitor demonstrated a 37.06% reduction in early apoptosis rate (29.36% ± 4.33% [SD] versus 46.65% ± 1.51%, P = .006) and 45.27% reduction in late apoptosis rate (17.6% ± 16.81% versus 32.16% ± 26.30%, P = .007), compared with controls. Subsequently, ROCK levels in apoptotic CECs were significantly lower in cells incubated with ROCK inhibitor than the control medium. CONCLUSIONS: In this ex vivo study, ROCK inhibitor reduced endothelial loss and thus, could be used to limit or slow down CEC loss. Rho-associated kinase inhibitor might be used before cataract surgery, especially in high risk patients. This might be a promising new method for preventing pseudophakic bullous keratopathy.

Photoreceptor Integrity Predicts Response to Anti-VEGF Treatment.

PURPOSE: Assessing changes in foveal photoreceptor microstructure (FPM) following intravitreal anti-VEGF treatment may serve as a prognostic marker in patients with macular edema (ME). METHODS: Sixteen eyes belonging to newly diagnosed patients with ME were included in this prospective longitudinal study. FPM integrity was evaluated at baseline and at the end of a series of anti-VEGF injections. RESULTS: Treatment led to a significant improvement in mean visual acuity (VA) and central macular thickness. A larger FPM defect was associated with lower VA, both before and after treatment. Patients with larger FPM defects at baseline had smaller VA improvements, and the improvement in FPM integrity was associated with VA improvement (every 100-µm FPM recovery contributed to a gain of 0.04 logMAR). CONCLUSIONS: Recovery of FPM after anti-VEGF treatment was significantly associated with a VA improvement. Direct measurement of photoreceptor integrity might provide an additional tool for the assessment of retinal function and treatment response in patients newly diagnosed with ME.

Comparison of the Tolerability of Diclofenac and Nepafenac.

PURPOSE: Topical nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used for the prevention and treatment of inflammation and pain following cataract surgery. Preservative-free diclofenac and nepafenac drops are commonly used ophthalmic NSAIDs. The purpose of this study was to compare the tolerability of diclofenac to that of nepafenac. METHODS: In this prospective patient-blinded study, consecutive patients undergoing cataract surgery were included. One drop of nepafenac 0.1% and diclofenac sodium 0.1% were instilled in the right and left eyes, respectively, one immediately after the other, 1 day before surgery. Visual analog scale (scale 0-10) was used to measure patient discomfort, itching, burning, and pain at 1 second (s), 15 s, 1 minute (min), and 5 min postadministration. RESULTS: Overall, 44 eyes of 22 patients were included in this study. Diclofenac and nepafenac had high and similar tolerability at all time points with no significant difference regarding all aspects of tolerability. A vast majority of patients (72%) did not prefer 1 drop over the other in terms of overall comfort. CONCLUSIONS: Both diclofenac and nepafenac seem to have similar high tolerability. Diclofenac may be an affordable alternative to nepafenac and therefore should be considered by prescribing physicians, specifically in preoperative cataract patients.

Quantification of metamorphopsia using the MacuFlow test before and after vitreoretinal surgery.

BACKGROUND AND OBJECTIVE: This pilot study evaluated the clinical utility of the MacuFlow software in measuring metamorphopsia prior to and following surgery in patients with vitreoretinal diseases. PATIENTS AND METHODS: Four patients with vitreoretinal disorders causing metamorphopsia were included in this pilot study. Visual acuity (VA), optical coherence tomography and MacuFlow scores were recorded prior to and following surgical intervention. RESULTS: The mean preoperative VA was 0.59 ± 0.09 logMAR, central macular thickness 491.2 ± 41.3 µm and calculated macular volume 8.99 ±1.47 mm(3). These parameters improved postoperatively to a mean VA of 0.30 ± 0.22 logMAR, central macular thickness of 372.8 ± 85.4 µm and macular volume of 7.94 ± 1.34 mm(3) but did not reach statistical significance. The mean preoperative MacuFlow score was 14.02 ± 8.21, which significantly improved postoperatively to 5.4 ± 3.13 (p = 0.045). CONCLUSIONS: This is the first study to demonstrate the clinical utility of MacuFlow for the quantification of metamorphopsia and its improvement or resolution following surgery. This simple method may be a valuable addition for the clinical assessment and monitoring of patients with retinal diseases causing metamorphopsia.

Minimal astigmatism after sutureless planned extracapsular cataract extraction.

PURPOSE: To evaluate astigmatism after mini-nuc extracapsular cataract extraction (ECCE) in which a chevron incision is enlarged to 6.0 to 7.0 mm for easier nucleus removal and to compare the results with those using a 5.0 mm incision. SETTING: Department of Ophthalmology, The Edith Wolfson Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Holon, Israel. METHODS: Thirty eyes of 29 patients were enrolled in this study. Keratometry was performed preoperatively and 3 to 9 months postoperatively. The incision length was 6.0 mm in 6 eyes, 6.5 mm in 10 eyes, and 7.0 mm in 14 eyes that had mature cataract. RESULTS: The mean induced astigmatism calculated by simple subtraction was 0.12 diopter (D) +/- 0.51 (SD), 0.16 +/- 0.98 D, and 0.67 +/- 0.91 D for the 6.0 mm, 6.5 mm, and 7.0 mm incision, respectively. By vector analysis, the mean induced astigmatism was 0.60 +/- 0.30 D, 0.75 +/- 0.67 D, and 1.36 +/- 0.77 D, respectively. Results by both methods showed no significant difference between the previously reported 5.0 mm incision and the 6.0 mm and 6.5 mm incisions. The 7.0 mm group had statistically significantly greater induced astigmatism than the 5.0 mm group (P =.01, simple subtraction; P =.002, vector analysis). CONCLUSIONS: Enlarging the size of the chevron incision up to 7.0 mm resulted in a small increase in induced astigmatism. The enlarged incision simplified the operative technique.