GLAUCOMA

MINIMALLY INVASIVE GLAUCOMA SURGERY (MIGS)

What is Minimally Invasive Glaucoma Surgery (MIGS)?

 

A type of glaucoma drainage surgery introduced in 2014, performed in hospital facilities as a day procedure under local anaesthetic using different types of miniature stents.

 

Main features and benefits are:

  • Shorter operating time and quicker recovery.
  • Fewer complications.
  • Delaying major glaucoma drainage surgery (trabeculectomy).
  • Reduction of medication.
  • 24 hour control system, rather than medication reliance.
  • Can be performed either as a stand-alone operation or combined with cataract surgery.

There are three different types of microstents currently available in Australia:

 

iStent (Internal)
Hydrus Stent (Internal)
Xen Stent (External)

 

Who are suitable candidates for MIGS treatment?

 

Mild to moderate open-angle or mixed-mechanism glaucoma patients who:

  • No longer respond to eyedrops or laser treatment.
  • Cannot physically use eye drops, for example those with arthritis.
  • Patients who are allergic to the eyedrops.
  • Those preparing for cataract operations and are also on glaucoma eyedrops.
  • Moderate to severe glaucoma when patients want to delay more invasive surgery.

What is the iStent?

  • Two microscopic non-magnetic titanium stents of less than 0.5mm in length that are surgically implanted into the eye’s drainage canals (trabecular meshwork).
  • They create extra tiny channels that fluid can drain through, lowering eye pressure.
  • Following the procedures, some patients can stop or reduce the number of glaucoma eye drops they used pre-surgery. The glaucoma drop routine is gradually adjusted post-surgery.
  • Requires minimal post-operative care.
  • Safe for anyone needing an MRI.
  • Will NOT trigger metal detectors.

What is the HYDRUS microstent?

  • It’s a highly flexible 8 mm curved device the size of an eyelash.
  • Made up of Nitinol (nickel-titanium alloy), a super-elastic biocompatible alloy, used in many medical implants.
  • It’s implanted along and inside a drainage canal (Schlemm’s canal) to expand its lumen (tube) and enhance the outflow of fluid from the eye and thus reduce eye pressure.
  • Requires minimal post-operative care.
  • The glaucoma drop routine is gradually adjusted post-surgery.
  • Requires minimal post-operative care.
  • Safe for anyone needing an MRI.
  • Avoid if nickel sensitive.

Learn more about the Ivantis Hydrus Microstent here

What is XEN gel stent?

  • A 6mm bio-compatible gelatin-based long stent that’s threaded through the angle between the cornea and the iris into the external sub-conjunctival space.
  • It creates a fluid-filled sac called a “bleb” similar to that used in traditional glaucoma drainage surgery (trabeculectomy).
  • No suturing or major incisions.
  • Lower risk of infection and bleeding (than the tabuculectomy?).
  • Will need more post-operative visits than internal stents (iStent/Hydrus) to check on scarring response.
  • Always need early post op Anti Scarring (5FU) injections and may require Needling Procedure.
  • May also need to perform ocular massage (gentle pushing onto the eyeball) to maintain flow and reduce scarring and failure rate.
What are the possible complications of stent surgeries?
  • Standard local anaesthetic risks eg temporary bruising and droopy eyelids.
  • Bleeding (self-limited) but can prolong visual recovery. Inform your surgeon if you are on blood thinners.
  • Infection (mainly with the XEN stent, but still lower-risk than trabeculectomy).
  • Fluctuation with vision.
  • May require an updated glasses prescription.
  • Initial IOP fluctuation.
    • Very low (XEB) then slowly climbing.
    • Normal or higher (iStent/Hydrus) then slowing declining.
  • Early failure if the openings of the stents are blocked by debris in the iris (iStent/Hydrus) or scar tissue (XEN).
  • May require needling procedures.
  • Cataract formation (if a stand-alone procedure).
  • Removal of the stents if they move or are dislodged. There’s no need to remove them if they fail to function.
  • May require a further operation later, like a trabeculectomy.
Which Type of the Stent Should I have?

 

Depends on

  • Severity and stage of your glaucoma.
  • The target IOP needed to halt your glaucoma’s progression.
  • Physical space available for stent positions.
  • Internal (iStent/Hydrus) stents most suitable for early/milder glaucoma.
  • Xen stents usually used in previously failed internal stents or moderate glaucoma that needs lower IOP.
  • Your surgeon will discuss your individual options.
Will I be able to stop taking my glaucoma eyedrops after having a MIGS?
  • iStent/Hydrus may reduce the numbers of your glaucoma drops by 75% for 3-5 years.
  • Xen stents may achieve similar results but may vary depending on the severity of your glaucoma and individual post-operative scarring response.
What Are the Alternatives to MIGS?

 

Depends on your age, IOP levels and your glaucoma stage or speed of progression.

  • Ocular hypertension.
    • Do nothing.
    • Continue selective laser trabeculoplasty (SLT) with or without medication.
  • Mild/moderate.
    • Do nothing, but risk eventual progression and visual field loss.
    • Additional selective laser trabeculoplasty (SLT) and medication to delay any surgery.
    • Wait until cataracts mature and then perform a combined cataract/glaucoma procedure.
  • Severe to end stage.
    • Do nothing but accept a high risk of significant visual loss.
    • Go directly to a trabeculectomy.
    • Tube implantation (usually for severe refractory glaucoma).

Cyclodiode treatment (strong laser procedure).

 

Trabeculectomy and tube implantation:
  • More invasive procedures.
  • Require longer post-operative care.
  • Have higher infection and bleeding risks.
Cyclodiode laser:
  • A non-reversible high energy laser treatment to destroy the ciliary body (water pump) that produces the eye fluid.
  • Usually reserved for very high IOP and refractory end stage glaucoma.

Your surgeon will explain these options if you require these more invasive surgical treatments.

GLAUCOMA  INFORMATION
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