What is the iStent Implant?
The iStent is a tiny titanium implant device measuring about 1 mm in length that is inserted into the eye from an injector system during a minimally invasive glaucoma surgery to treat mild to moderate open-angle glaucoma. The iStent is the tiniest implantable device in the world that has been approved for use in the human body. A study conducted in the US concluded that about 68% of people who underwent iStent implantation were able to manage their glaucoma successfully without medication for about a year.
Glaucoma is an eye condition characterized by damage of the optic nerve, which transfers the pictures we see from the eye to the brain, due to increased intraocular pressure (IOP) or internal eye pressure. The increase in eye pressure is a result of accumulation of eye fluid (aqueous humour). This may be due to the production of too much fluid in the eye or the inability of fluid to drain out properly from the eye. If left untreated, glaucoma can lead to progressive vision loss and ultimately blindness.
How Does the iStent Work?
The iStent device functions similar to stents used to treat narrowed or blocked arteries (blood vessels) to prevent strokes and heart attacks. When arteries get blocked or clogged, a stent provides access for the free flow of blood. The iStent device works in the same way. When you have glaucoma, your eye’s natural drainage system gets clogged over time. The iStent works by creating a permanent opening to facilitate the outflow of accumulated fluid, thereby reducing intraocular pressure to maintain optimum pressure within the eye.
Indications and Contraindications of iStent Procedure
The iStent procedure is mostly indicated for use in conjunction with cataract surgery to reduce intraocular pressure in individuals with cataract and mild to moderate open-angle glaucoma.
However, the iStent is contraindicated for use in individuals with:
- Primary or secondary angle closure glaucoma, including neovascular glaucoma
- Retrobulbar tumour
- Thyroid eye disease
- Sturge-Weber Syndrome
- Any other conditions causing elevated episcleral venous pressure
Preparation for iStent Procedure
Preoperative preparation for iStent procedure will involve the following steps:
- A thorough eye examination is performed by your doctor to check for any medical issues that need to be addressed prior to surgery.
- Depending on your medical history, social history, and age, you may need to undergo tests such as blood work and imaging to help detect any abnormalities that could threaten the safety of the procedure.
- You should refrain from using makeup or lotion around the eyes a few days prior to the surgery.
- You will be asked if you have allergies to medications, anesthesia, or latex.
- You should inform your doctor of any medications, vitamins, or supplements that you are taking.
- You should refrain from medications or supplements such as blood thinners, aspirin, or anti-inflammatory medicines for 1 to 2 weeks prior to surgery.
- Refrain from smoking pre- and post-procedure for a specific period of time, as this may hamper proper healing.
- You should not consume any solids or liquids at least 8 hours prior to surgery.
- Arrange for someone to drive you home as you will not be able to drive yourself after surgery.
- A written consent will be obtained from you after the surgical procedure has been explained in detail.
Procedure for iStent Implantation
The iStent implantation is mostly performed under local anaesthesia, where your doctor inserts the iStent device into the eye through a surgical procedure. The surgery involves the following steps:
- Your surgeon will first numb your eye with anaesthetic eye drops.
- An eyelid holder will be placed on your eye to prevent the eye from blinking.
- A small incision is made into the cornea to properly place the device.
- Utmost care is taken to place the stent into the eye through the trabecular meshwork, a filter-like tissue located in the anterior chamber of the eye, where the eye fluids normally drain.
- Once the stent is in place, it facilitates an exit between the anterior chamber of the eye and Schlemm’s canal.
- This enables the eye fluid to bypass the clogged and damaged drainage system of the eye and exit into the deeper tissues of the eye, thereby lowering intraocular pressure.
- The incision is then closed, and a protective shield is placed over the eye to complete the operation.
Postoperative Care and Recovery
In general, postoperative care and recovery after iStent implantation involves the following:
- Arrange for someone to drive you home.
- You should wear a protective eye shield for at least a week at night or while napping to protect the eye from rubbing in your sleep.
- Keep both eyes closed and rest as much as possible during recovery.
- You may experience sensitivity to light, blurred vision, or tearing.
- You may notice some eye pain or discomfort for the first few days for which your doctor will prescribe medications as needed.
- Steroid and antibiotic drops as well as artificial tears are prescribed to minimize the risk of infection, dry eye, and inflammation.
- Limit reading and watching TV for the first few days.
- Do not swim or use a hot tub, spa, or whirlpool for at least 2 weeks to reduce the risk of eye irritation and infection.
- Do not apply eye makeup, cologne, lotions, or aftershave for one week.
- Avoid strenuous activities and heavy lifting for a week so that there is no stress on the eye as it heals.
- Wear sunglasses while outdoors to prevent discomfort from sun exposure and dusty environment.
- You may need to take off from work for at least a week or two to facilitate recovery.
- A periodic follow-up appointment will be scheduled to monitor your progress.
Advantages of iStent Procedure
Some of the advantages of the iStent procedure over other traditional glaucoma surgeries include:
- Easy to perform
- Faster recovery
- High safety profile
- Speedy recovery
- Less expensive
- Minimal damage to eye tissue
- Reduces the side effects or inconvenience of using eye drops
- Avoids or delays the need of more risky surgical interventions
Risks and Complications of iStent Procedure
The iStent implantation is a relatively safe procedure; however, as with any eye surgery, there are potential risks and complications that may occur, such as:
- Retinal tears
- Retinal detachment
- Corneal oedema
- Corneal abrasion
- Stent obstruction
- Stent dislocation
- Failure to improve eye pressure