Suprachoroidal Drainage—Centenarian Progress: An Inventor’s Perspective

11 Suprachoroidal Drainage—Centenarian Progress: An Inventor’s Perspective

Minas Theodore Coroneo

At the start of my ophthalmology training in the early 1980s, two of the three formative events occurred that contributed to my invention of a modern suprachoroidal stent.

As a junior trainee in Australia, I often served weekend, night-shift, and on-call duty, and thus saw many trauma cases. At the time, the sport of indoor cricket had become popular in Sydney, and it led to so many eye trauma cases that I accumulated enough cases to write my first ophthalmologic publication.1 A case of traumatic cyclodialysis made an impression; the low pressure was difficult to manage at a time when treatment options for glaucoma were relatively limited. I noted that cyclodialysis and the suprachoroidal space are a low-resistance pathway—if only it could be controlled. One of the cases in the cricket eye injury literature had been described by Arthur D’Ombrain,² an Australian ophthalmologist, the first to recognize traumatic glaucoma.³ I also attended a basic science course in New Zealand where I met Professor A.C. Molteno, the inventor of the Molteno glaucoma drainage devices and subsequently learned to implant these devices.

Recognizing that the trabecular meshwork was likely to be the most sophisticated biological valve that had ever evolved, I went on to complete my doctorate on the electrophysiology of trabecular meshwork cells,⁴ confirming that there was more than one cell type in the angle, and that a population of trabecular meshwork cells was excitable and likely contractile.

I saw glaucoma as a “dismal” subspecialty; despite technically perfect surgery, operations failed, patients’ vision often deteriorated, and the well-known treatment limitations and paradoxes led me to realize that I did not wish to be a glaucoma subspecialist. I continued research on central issues in glaucoma and developed an in vitro model for pressure-induced apoptotic cell death and means by which it could be blocked via TRAAK channels, which are pressure-sensitive cell membrane channels.^5,6

Carrying out challenging cataract surgery in the Australian outback provided the stimulus for my first invention in ophthalmology—the use of trypan blue as a capsular and ocular dye. The first United States patents for VisionBlue were issued in 2002,^7,8 and the product entered the market.⁹ This invention steered me toward cataract and refractive surgery and I became interested in how surgical techniques like phacoemulsification had revolutionized anterior segment surgery and how it even provided a safe intervention for narrow-angle glaucoma.¹⁰ It dawned on me that glaucoma needed an equivalent to “phaco” to create a similar revolution for glaucoma management. The case of traumatic hypotony resurfaced just at the time when the first intraocular lens that could be rolled into a cylinder less than 1 mm in diameter, the ThinOptX (Abingdon, VA) intraocular lens (IOL), was developed in 2002.¹¹

My interest in ultraviolet light and the focusing of peripheral light by the anterior eye¹² resulted in the development of a dysphotopsia-free intraocular lens^13,14 and so I had a keen interest in intraocular lens technology. Whereas most people saw an IOL, all I could think of was that the optic could be “repurposed, that is, connected to a tube and inserted atraumatically through a small side-port incision, transcamerally, into the suprachoroidal space. I obtained ThinOptX lenses, glued fine tubing to them (Fig. 11.1), and performed a series of experiments in perfused porcine eyes. A U.S patent was issued¹⁵ in 2007.

In reviewing this area of research, it was apparent that following Leopold Heine’s¹⁶ landmark paper in 1905, describing cyclodialysis as a new operation for treating elevated intraocular pressure in uncontrolled glaucoma, many attempts have been made to take advantage of the suprachoroidal pathway to treat glaucoma. The combination of improved biomaterials and surgical implant techniques, which largely evolved from advances in cataract surgery, has resulted in relatively minimally invasive, atraumatic implantation of micro-stents into both the angle and the suprachoroidal space. The technology was licensed to Transcend Medical (Menlo Park, CA) in September 2006, and the Cypass (“ciliary bypass”) micro-stent was developed. I was employed by this company as a consultant and contributed to both the design evolution and the development of the surgical technique. Recently, it has been reported that the implantation of this micro-stent effectively lowers intraocular pressure in > 80% of patients at 1 year.¹⁷ In cases of suprachoroidal implantation, it appears that finally, a century after Heine’s work, a controlled cyclodialysis had been achieved. In a small way, with my contribution to the potential “phaco-like” transformation of glaucoma surgery, it is hoped the outlook and practice in this area will be less dismal.