Publications by authors named "Nathaniel Tracer"

Purpose: To compare the safety and efficacy of two different techniques for implantation of the XEN Gel Stent, a minimally invasive surgical device for the treatment of refractory glaucoma.

Methods: A retrospective chart review of eyes that received ab interno or ab externo XEN Gel Stent placement from February 2017 to October 2019 was conducted. A single surgeon (NMR) performed all operations. Eyes that received the XEN implant concomitant with a glaucoma drainage device insertion or that were lost to 6-month follow-up were excluded. Intraocular pressure (IOP) change, change in glaucoma medications, frequency of slit lamp revision procedures, and frequency of secondary glaucoma surgeries were the primary outcomes compared between groups.

Results: Fifty eyes that underwent ab interno placement and 30 eyes that underwent ab externo placement were studied. The ab interno cohort demonstrated a mean IOP reduction of 8.4 ± 1.7 mmHg (28.6% decrease) by 12 months, compared to a mean reduction of 12.8 ± 3.0 mmHg (40.1% decrease) in the ab externo group (p = 0.208). Mean reduction in medication use was 1.81 ± 0.29 medications in the ab interno group and 1.86 ± 0.37 in the ab externo group (p = 0.913). By 12 months, 58% of ab interno eyes had required 5-fluorouracil injection compared to 36.7% of ab externos (p = 0.105). Bleb needling was applied to 42% and 26.7% of the eyes, respectively (p = 0.231). A second glaucoma surgery was necessary for 20% of the ab interno cohort and 10% of the ab externo cohort (p = 0.351).

Conclusion: There were no differences in outcomes between ab interno and ab externo placement of the XEN Gel Stent. Both approaches are safe and effective for lowering IOP.

Purpose: To assess whether an association exists between pretreatment corneal hysteresis (CH) and the magnitude of intraocular pressure (IOP) and medication burden reduction following microinvasive glaucoma surgery (MIGS).

Methods: Retrospective chart review of 84 eyes from 57 patients with CH measurements who underwent trabecular meshwork MIGS in a glaucoma practice in New York City with follow-up visits at 3-6 and 9-12 months. MIGS included canaloplasty, goniotomy, microbypass stents, or a combination thereof.

Results: The lowest and middle CH tertiles experienced significantly reduced mean IOP at 3-6-month follow-ups (p = .007, < .001), whereas the highest tertile did not (p = .06). At 9-12-month follow-ups, a significant mean IOP reduction only persisted in the middle tertile (p = .001). For medication burden reduction, only the highest CH tertile experienced significant mean reductions at both 3-6- and 9-12-month follow-ups (p = .015, .028). Notably, 7 patients in the lowest CH tertile failed MIGS and required an additional surgical or laser procedure within 24 months of MIGS, whereas only 3 patients failed in the other tertiles (likelihood ratio < .05). Multivariate analysis excluding MIGS failures demonstrated an inverse association between CH and the magnitude of post-operative IOP reduction at both 3-6- and 9-12-month follow-ups when controlling for baseline IOP and medication changes (p = .002, .026).

Conclusion: There was an inverse association between pretreatment CH and the magnitude of IOP reduction following surgery. There is also evidence of an increased need for repeat surgery or other intervention in patients with lower CH who undergo MIGS.

Purpose: To evaluate reduction in intraocular pressure (IOP) and medications for open-angle glaucoma (OAG) patients 12 months post-ab-interno circumferential viscodilation (VISCO360, Sight Sciences, Menlo Park, CA) in conjunction with cataract surgery.

Setting: Surgical center (New York, United States).

Design: Retrospective study of all OAG patients treated with 360-degree ab-interno viscodilation with cataract surgery by a single surgeon (NR) having 12 months of follow-up. Eyes were stratified by baseline IOP. Group 1: ≥18 mmHg (n=111). Group 2: <18 mmHg (n=69).

Methods: IOP was measured using Goldmann applanation tonometry. Medications, the number of medication-free eyes in each group at 12 months, and adverse events (AE) are reported. Analysis includes descriptive statistics and t-tests evaluating change from baseline.

Results: Groups 1 and 2 had mean baseline IOP of 22 and 14.3 mmHg. Medication use was 0.9 and 1.1 for Groups 1 and 2. At 12 months IOP for Group 1 was reduced 22% to 17.2 mmHg (p<0.0001) on 1.0 medications (p=0.7). IOP for Group 2 was similar to baseline (15.4 mmHg) but with a reduction in medications to 0.6 (p<0.05). The proportion medication free at 12 months was 32% and 47% for Groups 1 and 2 versus 34% and 26% at baseline, respectively. There were few AE (hyphema 1.7%, IOP elevation >10 mmHg >30 days post-op 1.1%, mild inflammation <1%) and no secondary surgical interventions excepting a single paracentesis, one-day postoperative.

Discussion: Treatment goals for the two groups differed. Pressure reduction (Group 1) or medication reduction (Group 2). Viscodilation achieved significant IOP reduction in Group 1 and medication reduction in Group 2 with many patients (both groups) medication free at 12 months. AE were infrequent and transient.

Conclusion: Circumferential ab-interno viscodilation can be combined with cataract surgery and provide an IOP lowering and medication reduction benefit sustained for at least 12 months, for many patients with OAG.

Objective: To determine the relationship between optic disc hemorrhage (DH) and corneal hysteresis (CH).

Methods: Consecutive patients with prior or current photographic evidence of unilateral DH who had undergone CH measurement with the Ocular Response Analyzer (ORA; Reichert, Buffalo, NY) were enrolled. Eyes with a history of corneal disease, refractive surgery, or bilateral DH were excluded. Central corneal thickness (CCT), visual field data, 5 consecutive previous intraocular pressures (IOPs), and maximum documented peak IOP were obtained by chart review. Vertical cup-to-disc ratio (VCDR), the presence of neuroretinal rim notching, number of clock hours of beta zone parapapillary atrophy (ßPPA), and eye with greater ßPPA width were determined from photographs by 2 masked expert examiners.

Results: We identified and analyzed 49 patients with photographically documented unilateral DH. Compared to fellow non-DH eyes, eyes with DH had lower CH (8.7 ± 1.9 vs 9.2 ± 1.7; p = 0.002), higher IOP (15.6 ± 3.6 vs 14.3 ± 4.1; p = 0.017), and greater VCDR (0.79 ± 0.13 vs 0.68 ± 0.23; p < 0.001), but were similar with respect to CCT, ßPPA extent, rim notching, peak IOP, and visual field damage (all p > 0.05). Using multivariate conditional logistic regression analysis, only CH (p = 0.012) and VCDR (p = 0.004) predicted the laterality of the DH.

Conclusions: Lower CH and greater VCDR are independently associated with DH. This suggests that CH may be a structural biomarker for an abnormality of the optic nerve complex that may be associated with progressive glaucoma. Eyes in which DH were detected had lower CH.

CO reduces nickel(2+) cyanides in basic solution to form tetrahedral Ni(0)(CN)(CO)3(-) or Ni(0)(CN)2(CO)2(2-). Both nickel(0) complexes can be oxidized back to nickel(2+) cyanide/hydroxide so that they behave as CO oxidation catalysts in basic solution. A primitive fuel cell was constructed to demonstrate the feasibility of a CO-powered fuel cell.