After a delay in getting TGA approval, the Xen Gel Sten has finally been approved for use in Australia.
The stent will get prosthesis listing in mid March and should then be available for all to use.
What is the Xen Sten?
In one of my previous postings, I wrote about the Cypass shunt, which became available in Australia late last year. The Cypass shunt is one of a number of MIGS devices of which the Xen stent also belongs.
The main differences are where the stent is placed, the main indication for its use and most importantly, the fact that the Xen stent does not require concomitant cataract surgery. This means that anyone, cataract or not can have this stent.
The Xen stent is used ab interno and unlike the Cypass which drains into the suprachoroidal space, drains subconjunctivally. In this regard, it is in essence, a filtration procedure but without the need to create a scleral flap or a conjunctival dissection.
In some regards it is also like tube surgery as there is a gel stent which drains subconjunctivally.
How is the Xen Stent implanted?
The procedure can be performed with or without cataract surgery. Through a 1.5mm clear corneal incision, the stent is introduced into the anterior chamber, across to the opposite side and inserted through scleral wall to lie externally, subconjunctivally.
Before this is done, Mitomycin C is injected at the exit site to raised the conjunctiva and create space for the stent to drain into. That is essentially all there is to it.
There have been reports of a high rate of Tenon cyst formation however this is not a great problem and can to a large extent be mitigated by needling at the time of the procedure.
Who is this for?
The ideal patient is one who is on maximally tolerated topical therapy and who has exhausted all other pressure lowering means such as SLT
A typical example would be a patient with poorly controlled pressure and possible evidence of worsening visual fields and or progressive rim loss
What is involved?
The procedure is performed as a day case under local anaesthetic. Surgical time is expected to be around 15 minutes
What is the expected outcome?
Most likely better pressure control with a likely reduction in the need for medication and even possibly, a complete cessation of all medications. Like all procedures and treatments however there will always be a spread of outcomes.
What is the cost?
This procedure is covered by Medicare and the health funds. For uninsured patients, the cost is not yet known until the actual cost of the stent is announced
Today I implanted three patients with the new Cypass shunt. All had poorly controlled glaucoma, one on four lots of medication with still a high pressure.
I will be seeing them on their first day tomorrow and it is my expectation that they will all be able to at the very least reduce their medications and at best, come off them altogether .
If this shunt works out well it may well be a replacement for a trabeculectomy in those patients who have coexisting cataract
Dr Joseph San Laureano from Melbourne Eye Centre is very excited to announce that we are now implanting the new Cypass microstent in patients who have glaucoma and are having cataract surgery.
What is the Cypass?
The Cypass microstent is a small shunt which is implanted into the supraciliary space at the time of cataract surgery which lowers the intraocular pressure by allowing drainage of aqueous. It inserted with an introducer into the area just below the scleral spur and into the supraciliary space
Who is the Cypass for?
The Cypass is currently TGA approved in Australia for patients who have glaucoma and are undergoing cataract surgery. It is also approved as a stand alone procedure but at present there is no Medicare item that will allow this.
The shunt is implanted at the end of the cataract procedure.
What will the Cypass accomplish?
The Cypass will lower the intraocular pressure to the point that medications (eye drops) may no longer be necessary. At the very least, a reduction in the number of eye drops or a better control of pressure
Is Cypass safe?
Cypass is classified as minimally invasive glaucoma surgery (MIGS) and to date there have not been any reported adverse events
What does Cypass cost?
Dr San Laureano is currently NOT charging for the Cypass. It is been implanted as part of the cataract procedure. The only requirement is that patients have private health insurance. If a non insured patient wishes to have the Cypass, it can be done at the patients cost
ASLA stands for Advanced Surface Laser. It is really no different to PRK.
PRK was the original term used to mean a laser vision correction on the surface of the cornea without first creating a LASIK flap. PRK was largely superseded by LASIK due to quicker recovery time and no discomfort.
Over time however, PRK has had a resurgence owing to the fact that it is a better procedure in some people and the procedure of choice if the cornea is thin. It has become more sophisticated, with better software algorithms that use modern ablation profiles. This has led to better visual outcomes. As the algorithms have progressed, it was decided to re-name PRK to ASLA.
Some clever marketing has tried to create the impression that it is a new procedure but it it is still really PRK, although on steroids.
ASLA vs LASIK
Long term, there is no difference in results between ASLA and LASIK. ASLA is not an inferior procedure and patients having it are not disadvantaged in any way. It is simply as stated, more uncomfortable and visual recovery takes longer.
In some respects, ASLA is safer as there is no corneal flap to worry about and all its attendant risks such as epithelial ingrowth, striae or dislodgement of the flap.
There is no difference in cost.
How is ASLA performed?
There are numerous ways to perform ASLA. Most commonly, the epithelial surface is removed using a blade, motorised burr or alcohol. Alcohol removal is quicker but there is some suggestion that this may lead to recurrent erosions long term.
The new Schwind Laser that we are using performs transepithelial ASLA, meaning that the epithelium is automatically removed by the laser. This results in a cleaner and more precise result.
Once the epithelial surface is removed, the laser then continuous on to re-shape the surface of the cornea. In the case of someone with myopia (shortsightedness) the laser tends to flatten the central portion of the cornea. In the case of hyperopia (long sightedness), the laser steepens the central cornea instead. The process is similar to a lathe, altering the shape of a piece of wood.
This of course is all done under anaesthetic, which is administered with eyedrops only. That is, there are no injections or needles involved.
At the end of the procedure, a contact lens is placed into the eyes and left there for three days until the new epithelium has grown back.
What happens after the ASLA procedure?
After the procedure, you can go home with antibiotic and anti-inflammatory eye drops.
Review is on the third day after the procedure for removal of the contact lenses. This can be either in our clinic or with your optometrist.
Vision is quite good after a few days but improves over the next few weeks and months.
Eye drops are used for two weeks and lubricants for 6-12 months
How long does ASLA last?
Generally, this correction is permanent. However as we age, our bodies (and eyes) change. This may lead to a change in your need for glasses long term. This can be corrected at a future date with an enhancement using the laser, or if the change is only small, glasses or contact lenses.
Some people do experience regression, which is where some of the original myopia or hyperopia returns. If this occurs, an enhancement can be performed once the regression stabilises.
How do I decide wether to have LASIK or ASLA?
This decision is not one that you need to make yourself, rather your particular set of circumstances will govern which approach is best for you
Long term safety of ASLA
ASLA is generally safer than LASIK although both are safe.This is because less corneal surface is removed with ASLA. With LASIK, the flap is usually around 120 microns in thickness which does not contribute to the structural integrity of the cornea. Hence, corneas that have had ASLA have a thicker residual base with consequent less long term risk of complications