Streamline Surgical System
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Background
The field of microinvasive glaucoma surgery (MIGS) has expanded to include a number of different procedures, techniques, and innovative tools. These procedures all have in common the goal of enhancing physiologic aqueous outflow to aid in intraocular pressure (IOP) control and to decrease the risk of progressive glaucoma and associated irreversible vision loss. Some MIGS procedures involve placement of an implant while others involve modification and/or excision of tissue.
The Streamline Surgical System is a novel device intended to target the eye’s natural aqueous outflow pathways, in an implant-free fashion, to achieve IOP-lowering and decrease the risk of progressive glaucomatous disease.
Device
The Streamline Surgical System (New World Medical, Inc; Rancho Cucamonga, CA, USA) is a single-use device composed of a medical-grade stainless steel cannula, which is housed within an outer sleeve. The outer sleeve is contained within a pump system that allows for the delivery of small aliquots of viscoelastic into Schlemm’s canal. A priming port is designed for the luer fitting of an external syringe and loading of the entire device with viscoelastic. An actuator button activates the pump to retract the outer sleeve (exposing the inner cannula) to inject viscoelastic. Three or more punctures of the trabecular meshwork spanning at least three clock hours (90 degrees) to dilate Schlemm's canal can be performed.
Each full depression of the actuator button delivers seven microliters of viscoelastic. A maximum of eight deliveries are possible with the device.
Patient Selection
Indications
The Streamline Surgical System may be used to treat ocular hypertension and open-angle glaucomas. The procedure may be performed in standalone fashion or in combination with other ocular surgeries, including cataract surgery.
The Streamline Surgical System has a 510(k) cleared indication for use during ophthalmic surgery to deliver viscoelastic fluid into the eye. As a separate function, the device also has a second indication with a Class 1 exempt function for use in cutting trabecular meshwork tissue independent of viscoelastic delivery.
Contraindications
Contraindications to the use of the Streamline Surgical System include an inability to view the anterior chamber angle structures, patient cooperation issues, and non-consent to the procedure.
Surgical Technique
The Surgical Streamline System is first primed off of the surgical field and in sterile fashion by affixing the luer of a viscoelastic syringe to the priming port of the device. Viscoleastic is then injected into the device until emergence from the inner cannula tip is noted. Viscoleastic should be injected until air bubbles are no longer present. The procedure may be performed under topical, local, or general anesthesia.
A clear corneal incision of at least 1.8mm width should be performed in usual fashion. Surgical gonioscopy should be performed using standard techniques and an adequate and unimpeded view of the angle structures verified. The device is gripped between the thumb and middle fingers while the forefinger is rested on the actuator button. The outer sleeve is then inserted through the clear corneal incision and, under direct gonioscopic view, into the anterior chamber. While in the anterior chamber and before intended treatment, the actuator button of the device should be pressed to release viscoelastic and clear any microbubbles that may be remnant in the inner cannula. The anterior trabecular meshwork is then approached and applanated with the outer sleeve and the actuator button is firmly depressed for two seconds. The actuator button activates the pump to retract the outer sleeve (exposing the inner cannula) to inject viscoelastic. Afterward, the device is released from the trabecular meshwork and the actuator button is released to restore the inner cannula to the baseline position. Three or more punctures of the trabecular meshwork spanning at least three clock hours (90 degrees) to dilate Schlemm's canal can be performed. The product delivers a maximum of eight boluses of viscoelastic. After completion of the desired number of treatments, the device is withdrawn from the anterior chamber. Reflux bleeding may be noted from the treatment sites. Viscoelastic is then cleared in the usual fashion and the corneal wound is secured.
Outcomes
A prospective non-randomized, open-label trial (ClinicalTrials.gov Identifier: NCT05089474) is currently underway to assess efficacy and safety outcomes with the Streamline Surgical System. Another prospective trial was registered on January 7th, 2021 (www.ClinicalTrials.gov NCT04700189) to evaluate the efficacy and safety of the Streamline Surgical System in patients with mild to severe primary open-angle glaucoma (POAG) undergoing phacoemulsification at two centers in Mexico.[1] The authors reported their results from the first 20 eyes (20 patients) who were followed up for 6 months. One patient did not continue the follow-up. They reported that the mean IOP was significantly reduced from 23.5±2.5 mmHg preoperatively (unmedicated IOP) to 14.7±2.4 mmHg at the 6-month follow-up visit (P<0.001). The mean number of glaucoma medications was significantly reduced from 2.0±0.8 preoperatively to 1.1±1.1 at the 6-month follow-up visit (P<0.001). There were no reported intraocular complications related to the Streamline Surgical System. Postoperatively, steroid-induced ocular hypertension occurred in 3 eyes and resolved on topical medications.[1]
Conclusion
The Streamline Surgical System is an innovative device that is capable of performing localized goniotomies while delivering viscoelastic into Schlemm’s canal. The goal of the procedure is to aid in the re-establishment of physiologic aqueous outflow and to aid in IOP lowering for ocular hypertension and glaucoma.
