San Jose Eye Institute

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What is the iStent inject?

iStent inject

The iStent inject Trabecular Micro-Bypass System is used at the time of cataract surgery to lower pressures in patients with glaucoma. It is made by Glaukos, the company that also makes the original iStent Micro-Bypass Stent. The main difference between the iStent inject and the original iStent is that with the iStent inject, two stents are utilized, whereas the original iStent only uses one stent. The iStent inject is also significantly smaller, with the largest dimension only measuring 360 μm (or 0.360 mm) long.

Glaucoma is a medical condition where the pressure inside the eye is too high, leading to progressive optic nerve damage. Open angle glaucoma, the most common form of glaucoma, is essentially a backing-up of fluid due to a drain that has become increasingly clogged. The main drain in the eye is called the trabecular meshwork.

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What is the CyPass Micro-Stent?

CyPass Micro-Stent

The CyPass Micro-Stent is a small medical device used at the time of cataract surgery to lower pressures in patients with glaucoma.

Glaucoma is a medical condition where the pressure inside the eye is too high, leading to progressive optic nerve damage. Open angle glaucoma, the most common form of glaucoma, is essentially a backing-up of fluid due to insufficient outflow through the natural drainage system.

In the eye, there are two distinct drainage systems: the traditional trabecular meshwork, and the uveoscleral pathway. Many of the more potent glaucoma eye drops work to decrease eye pressure by increasing the flow through the uveoscleral pathway.

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What is the iStent?

The Glaukos iStent

The iStent Trabecular Micro-Bypass Stent is a tiny medical device used at the time of cataract surgery to lower pressures in patients with glaucoma. It is so small, that at its largest dimension, it is only 1 mm long.

Glaucoma is a medical condition where the pressure inside the eye is too high, leading to progressive optic nerve damage. Open angle glaucoma, the most common form of glaucoma, is essentially a backing-up of fluid due to a drain that has become increasingly clogged. The main drain in the eye is called the trabecular meshwork.

The iStent is placed within the trabecular meshwork, creating an open passage though this clogged drain. The Retention Arches (see above image) keep the iStent buried in position within the trabecular meshwork, and only the Snorkel is exposed. The Lumen of the Snorkel allows the fluid in the eye to easily bypass the trabecular meshwork, and in turn, results in a lower intraocular pressure.

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Can my cataract come back after cataract surgery?

No. Once a cataract is completely removed, it does not come back. However, a secondary cataract, also known as a posterior capsular opacity, can develop. A posterior capsular opacity is essentially a scar tissue that forms behind an implanted lens following cataract surgery. Sometimes, this scar tissue can be seen immediately after cataract surgery, but more often, it develops over time, from months to years afterwards. As it grows, it can adversely affect vision, just as a cataract does, and will need to be treated.

A posterior capsular opacity can be treated by a laser procedure called a YAG capsulotomy.  It is a painless procedure that takes about 5-10 minutes and is usually covered by medical insurance. The laser literally makes an opening in the scar tissue, centered on the visual axis. Patients can then see clearly through the opening. This solution is typically good for life and should not need to be repeated.

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What is the Tecnis Symfony Toric Lens?

Symfony Toric Lens

The Tecnis Symfony Toric lens is an intraocular lens that is implanted during cataract surgery after the cataract has been removed. Briefly, the Symfony lens allows patients to see a continuous range of clear vision, usually from far away distances to intermediate range distances (such as computer screens), without the need for bifocals or progressive glasses. Read more details about the Symfony lens here.

However, to achieve this range of clear vision, the patient cannot have significant astigmatism, or warping on the surface of the eye. For those patients who do have astigmatism, the Symfony Toric lens can be used to address this problem.

Astigmatism can be thought of as an asymmetric warping on the surface of the eye, like a football instead of a basketball. This “football” has a certain orientation, or axis, on the eye. The toric component of the Symfony Toric lens also has a “football” shape, which is marked by two sets of linear dots on the lens surface. If the two “footballs” are placed opposite of each other (90 degrees apart), they can cancel each other out and lead to an overall “basketball” appearance, essentially reducing the astigmatism of the eye.

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