Treatment and Technology

Treatment and Technology

Reduction of intraocular pressure (IOP) is the only proven treatment to delay glaucoma progression.9-10 The IOP needed to stop vision loss depends on how the optic nerve of each individual responds to increases in pressure.11-17The American Academy of Ophthalmology (AAO) proposes that IOP should be reduced by 20-30% from the level where damage is first measured.18 A target IOP of 12 mmHg may stop glaucoma from progressing in most patients;16,19 but some patients may need to lower their IOP even further to keep their glaucoma from getting worse.16,17

The most common treatments for glaucoma are topical, IOP-lowering eye drops and laser treatments. However, increased understanding of the eye and IOP have led to a new technology that offers a potential solution for patients whose needs are not being met by current glaucoma treatment options.

Pharmacotherapy

There are several classes of topical IOP treatments, some of which have been available for centuries (Pilocarpine drops were introduced in 1875).20 Most topical eye drops aim to decrease IOP by decreasing aqueous humor production and/or by increasing drainage of  aqueous humor through one or both of the outflow pathways. 20 Studies show these drops can reduce IOP by 15-39% for some patients; however, dosing regimens can be complex and some patients experience substantial local and systemic side effects. 20

Laser treatments

Laser treatments may be offered in addition to, or instead of pharmacotherapies. Laser treatment is applied either to the ciliary body (where aqueous humor is produced) or to the trabecular meshwork (one of the places through which aqueous humor drains from the eyes). 20

Advanced glaucoma surgeries

When pharmacological and laser treatments are ineffective, patients may require glaucoma surgery. There are two main kinds of conventional glaucoma surgeries: trabeculectomies and implantation of glaucoma drainage devices (GDDs).

Trabeculectomy

Studies have shown that these surgeries may not be effective in the long term. The Tube Verses Trabeculectomy (TVT) Study reported trabeculectomy failures of 40-60% within 3 years after the surgery, and 50-70% failed within 5 years after the surgery. In this study, failure was defined either as 1) having an IOP that was not reduced by 20% below baseline or 2) having IOP > 14 mmHg.21

Unsustainable and unpredictable IOP lowering is mainly due to the fact that these devices drain aqueous humor in between tissues where scarring can occur. Specifically, trabeculectomies aim to create a little reservoir for drainage called a bleb. This bleb is created in the space below the conjunctiva. Bleb scarring is a major issue and requires close management. Even with the addition of anti-scarring agents like mitomyocin C, trabeculectomies lead to increased incidence of several other complications.

Glaucoma Drainage Devices (GDDs)

GDDs, like the Ahmed and Baerveldt Implants, have been used as an alternative surgical means to reduce IOP by creating a passageway for aqueous humor to leave the eye through a tube attached to a large plate. This passageway, or shunt guides aqueous humor from the anterior chamber, under the conjunctiva. Similar to trabeculectomies, anti-scarring agents are used to avoid additional complications like strabismus (squinting or misalignment of the eyes). However, GDDs may lead to erosion of the conjunctiva or may even be extruded, or forced out of place. Efforts to reposition or remove a GDD could cause additional complications 22,23; therefore, they are commonly not removed when they fail and a new GDD may need to be placed. Because of the size of the drainage plate, there is a limit to the total number that can be placed during the course of the patient’s life.

When trabeculectomies and GDDs fail, patients are left with few options. A last resort for patients may include procedures called trans-scleral laser cyclophotocoagulation (TS-CPC) and endocyclophotocoagulation (ECP). These are highly invasive procedures that destroy parts of the ciliary body to stop if from producing so much aqueous humor.24,25 Patients who undergo these procedures are at risk for a condition called hypotony, or low IOP. Hypotony can lead to severe complications, including accumulation of fluid, bleeding, detachment of the retina, and loss of vision.

Sollevio

Alievio is developing a next generation treatment option that will target IOP below 14 mmHg and adjust it noninvasively based on the needs of the patient. This noninvasive adjustability is made possible by Sollevio’s mechanism of resistance which is located within a soft outlet tube that lies externally underneath the eyelid. Physicians can set a new IOP for a patient during an office-visit by simply adjusting the resistance of the device under local anesthesia.

Smaller reservoir:

Unlike other GDDs, Sollevio does not require a large plate to maximize drainage because it drains aqueous humor externally. Its smaller size also allows for easier revision surgery and removal, if necessary.

Comfort:

Sollevio’s outlet tube is as soft as a contact lens and lies underneath the eyelid, which is the least sensitive area on the surface.

How does Sollevio differ from existing Glaucoma Drainage Devices (GDDs)?

Sollevio differs from existing GDDs such as Ahmeds and Baerveldts because of its improved design and novel drainage site. Key features of Sollevio offer the possibility of improved patient outcomes and include the following:

  • No bleb:

    A bleb is a blister or fibrous capsule used in conventional glaucoma surgeries to store AH. Blebs are a major source of post-operative complications and interventions. Sollevio avoids the use of blebs since it drains externally.

  • Noninvasive postoperative adjustment:

    Sollevio’s outlet tube has a resistance mechanism that can be adjusted to reach its target IOP based on the needs of the patient. The physician can easily access the outlet tube by simply lifting the eyelid.

  • A barrier against infection:

    Sollevio includes a micropore filter to minimize the risk of infection.

Sollevio meets a significant unmet need among patients who want effective, IOP-reducing treatment without the risks and complications associated with conventional glaucoma surgeries. The innovative technology behind Sollevio’s design offers physicians the flexibility to adjust IOP to each patient’s individual needs. These adjustments take place noninvasively, within the comfort of the physician’s office, and require only local anesthesia. The glaucoma community anxiously awaits a treatment option like Sollevio.

References
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  13. Gedde SJ, Schiffman JC, Feuer WJ, et al. Treatment outcomes in the Tube Versus Trabeculectomy (TVT) study after five years of follow-up. Am J Ophthalmol. 2012;153(5):789-803.
  14. Lim KS, Allan BD, Lloyd AW, et al. Glaucoma drainage devices; past, present, and future. Br J Ophthalmol. 1998;82(9):1083-9.
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  17. Jennings BJ, Mathews DE. Complications of neodymium: YAG cyclophotocoagulation in the treatment of open-angle glaucoma. Optom Vis Sci. 1999;76(10):686-91.