Glaucoma and iStent inject Trabecular Micro-Bypassone [Interview] [Transcript]

Dr_Frank_Howes_Glaucoma_and_iStentGuest: Dr Frank Howes
Presenter: Patrick Reyes
Guest Bio: Dr Frank Howes is an ophthalmologist who specialises in laser vision correction, and the treatment of keratoconus and glaucoma. Dr Howes has performed many laser eye surgery procedures including LASIK and ASLA (PRK). He also specialises in cataract surgery and refractive lens exchange (sometimes known as clear lens exchange or lensectomy) as well as refractive procedures.

Segment overview: Glaucoma is a chronic eye disease and a leading cause of irreversible blindness worldwide. In Australia, glaucoma patients are now benefitting from a device called iStent inject Trabecular Micro-Bypassone, one of the world’s smallest FDA-approved medical devices known to be implanted in the human body measuring 1.0 mm long and 0.33 mm wide. It is an entirely new treatment option for glaucoma patients, wherein the device is implanted into the eye’s drainage canal during cataract surgery to restore the natural pathway for fluid outflow and reduce pressure in the eye. Dr Frank Howes, an ophthalmologist who specialises in laser vision correction, talks about glaucoma and how iStent can help patients in their treatment process.

Health Professional Radio – Glaucoma and iStent inject

Patrick Reyes: Hello and welcome to Health Professional Radio, I’m Patrick Reyes and on today’s segment we are joined by Dr. Frank Howes. He is an ophthalmologist from the Eye and Laser Centre Gold Coast who specializes in laser vision correction, cataract surgery, and refractive surgery. Welcome to the show Frank.

Dr. Frank Howes: Hello, nice to meet you.

P: Now go ahead and tell the listeners at home more about yourself and what it is that you do.

H: I’m a glaucoma, cataract, and refractive surgeon with a strong interest in new technologies and means of correcting both short-sightedness, long-sightedness, glaucoma, especially the new variant of so called ‘MIGS’ which stands for Minimally Invasive Glaucoma Surgery. Glaucoma is one of the bigger damages of human vision and we have quite a number of new means now of correcting the problem of … intraocular pressure which is actually the problem which creates the loss of vision in human beings.

P: Before we’ll go ahead and talk about MIGS, what was your motivation or your inspiration into becoming an ophthalmologist?

H: You know it’s one of those things that you wonder what you’re going to do. I knew I was going to be a doctor long ago. One of the interesting features about ophthalmology is the fine motor dexterity of ophthalmic surgery which is one of the fortunate areas of my expertise. I enjoy the microsurgical challenges that ophthalmology offers in that surgical sphere so I guess that’s what drew me into the field and then I have been a very busy micro surgeon since.

P: You are a specialist in laser vision correction and just earlier today, I learned about ASLA because I only knew about LASIK. What is the difference between LASIK and ASLA?

H: ASLA is basically the first generation of laser vision correction that came out where we actually reshape the cornea by working on the corneal surface. It’s a very, very good correction but it takes a little bit longer for the patient to get better. The comparison is LASIK which was the second generation where we actually lift a flap of corneal tissue and do the correction in the stromal bed and then put the flap back down. That’s where around patients are better in 1 to 2 days. Now, we’ve got the third generation of laser correction which is actually called SMILE. And SMILE stands for Small Incision Lenticule Extraction where we actually take the corrective piece of tissue out of the middle of the cornea through a … hole and take that tissue out. It’s another one of this minimally invasive procedures and so I was speaking about MIGS for glaucoma which is Minimally Invasive Glaucoma Surgery. We’ve got Minimally Invasive Refractive Surgery now as well which were SMILE is going and it produces a wonderful correction that’s better the next day.
P: Alright. Let’s go ahead and talk about MIGS or Minimally Invasive Glaucoma Surgery, what exactly are the procedures or treatments for that?

H: Well as I eluded to with respect to the refractive surgery component, where you’ve got this tiny little hole where we take out these bigger pieces of tissue to make the correction and anything that is minimally invasive is good. Now in glaucoma surgery, in the past we’ve used external procedures to make simplistically speaking a hole in the eye, which we cover with the eyes’ own tissue to retire flow and discharge the flow of fluid underneath the … which is the white of the eye. Now the reason that we need to do that is the natural flow pathways inside the eye are blocked. If we access the blocked mechanisms from inside the eye where the fluid of the eyes actually approaching in the normal flow since. If we can fenestrate this area called ‘Trabecular Meshwork’ where the actual obstruction is, we actually facilitate outflow of aqueous humor from the eye in lower pressure. And that is indeed what these little things called ‘Eye Stents’. Now there are a couple of different MIGS procedures and they have different devices but just for the purpose of discussion I’ll restrict our discussion to eye stent. This little device which is the smallest prosthesis use in the human body, it’s about .2mm x .44mm and it is held on the end of a type of injector which we can pass across from one side of the eye to the other to access this trabecular meshwork and it’s called ‘iStent Inject’, so it actually injects the little prosthesis into the trabecular meshwork thereby making a little hole in the blocked trabecular meshwork. As it passes through, it reaches another structure which is called ‘Schlemm’s Canal’ and stands and holds that open, that’s what stenting is. It holds open the structure whether it’s a blood vessel or a canal. This device fenestrates trabecular meshwork and stents Schlemm’s canal, which makes the aqueous humor which is being blocked by the damaged trabecular meshwork with glaucoma flow through the hole into the stented Schlemm’s canal and within access of the so called collected channels where the fluid flows out of the eye into the normal body’s blood circulation again so that’s what an eye stent is.

P: Alright. If anyone wanted to get to use eye stents, are there any precautions that people should know?

H: Well the good news about these eye stents is that they are very, very safe. They basically have no complications and work probably 90% of the time. Unfortunately, that don’t work for everybody because it does little things that are called their … channels of blocked. It’s not by passing that, so we need a different kind of MIGS procedure if we need to bypass the …. channels. But, 90% of the time by bypassing the blocked trabecular meshwork and stenting Schlemm’s canal, we allow the fluid to run out faster, thereby lowering the pressure, thereby lowering the damage at the optic nerve, which causes the damage and glaucoma.

P: Are there any specific misconceptions of glaucoma or MIGS that you would like to clear up?

H: Well it’s certainly what is correct, is the fact that it is minimally invasive and it honestly does have virtually no side effect. The only negative really is that there’s this 10% chance that it might not work for that person. If it is a misconception, that it’s going to work everybody, that’s just not true. But 90% is a pretty good number that someone can hitch their hopes on when they go for this procedure.

P: Alright. Now before we go ahead and end the segment, what’s the message you would like to give our audience as to being part of Health Professional Radio today?

H: If a person has glaucoma or if they have a family member with glaucoma, or if they are very shortsighted, or if they are very longsighted, all those people fit into a glaucoma risk category and should have their eyes check by the local optometrist so that they can be referred through for further care. One of which of those care pathways maybe eye stenting.

P: Alright. Well thank you for joining us today Frank.

H: You’re most welcome. Thank you very much for asking.

P: You’ve been listening to Health Professional Radio. Again, I’m your host Patrick Reyes and we’ve been in conversation with Dr. Frank Howes, as we talked about a bit of laser vision correction and glaucoma, and also MIGS. If you’ve missed our conversation or if you’d like to listen to this interview again, transcripts and audio of this program are available at and also at, and you can subscribe to this podcast on iTunes.

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