October 2016

 

REFRACTIVE

 

Using the femtosecond laser to treat a retinal disorder


by Jack Abrams, MD

 
 

“I thought combining [the IMT and the femtosecond laser] would be great as the patient gets the benefits of both technologies.” –Jack Abrams, MD

 
Implantable Miniature Telescope




Postop day 1 of a patient with the Implantable Miniature Telescope





The same patient at her 3-month follow-up appointment Source: Jack Abrams, MD

Why I’ve chosen to use the femtosecond laser for Implantable Miniature Telescope surgery

Femtosecond lasers for cataract surgery are beginning to play a more important role for anterior segment surgeons—and evidence is continuing to emerge that these devices are giving us a more accurate capsulorhexis than can be performed manually. This, in turn, is making our already safe surgeries that much safer. At our practice, we’ve been using the LenSx laser (Alcon, Fort Worth, Texas) with our cataract patients for more than 4 years. But it wasn’t until recently we began to explore the technology’s benefits to help other patients. Take, for example, patients who are referred to us with end-stage age-related macular degeneration. These patients typically have very poor vision—around 20/800—and until recently, had limited options to help provide improved functional vision. They were typically limited to low vision aids to help cope with the tasks of daily living, but these do not provide improved vision. Today, the Implantable Miniature Telescope (IMT, VisionCare, Saratoga, California) is available for these severely visually compromised advanced AMD patients, and I think using the femtosecond laser will be an important component of the surgery. The IMT is just a cataract surgery with a telescope on the lens. Its implantation, however, mandates a bit more finesse as the IMT is not foldable and cannot be implanted through a small incision.

Why use a femtosecond laser

One of the keys to a successful IMT surgery is ensuring the device is properly centered within the capsule. In my opinion, the only way that we can do that with today’s technology reliably and accurately is with the femtosecond laser. The IMT has been designed to return some vision to those with the most severe vision loss, and studies have shown the majority of patients gain at least three lines of best corrected visual acuity.1–3 Using the femto laser removes some of the inaccuracies that we inherently have with a typical handmade capsulorhexis. Because the IMT needs to be centered during our capsulotomy, we can determine the exact capsule size that will work best. The IMT is an advanced technology, and the femtosecond laser is arguably the most advanced technology to create a capsulorhexis on the market today. I thought combining these two technologies would be great as the patient gets the benefits of both technologies.

Adequate dilation is the key

In my opinion, implanting the IMT for surgeons who have never performed an extracap is going to be exponentially more difficult. These devices require an 11- or 12-mm incision, can only be implanted in the capsular bag, and mandate a minimum 7-mm diameter capsulorhexis. Also, the fit of the IMT in the capsular bag means OVD removal is more challenging.

To use the LenSx successfully for this procedure, pupils need to be dilated beyond 7 mm. We can achieve that through the use of phenylephrine 10%, or we can use pledgets to give us the maximum dilation. Unfortunately, some patients do not dilate to the minimum needed for the LenSx; if that occurs I’m comfortable enough with the surgical technique to revert to manual capsulorhexis.

How I perform the surgery

Although we’ve achieved adequate dilation and the laser touches the patient’s eye, occasionally miosis can occur. What has impressed me about the IMT is that a smaller capsulorhexis—6.5 mm or even as small as 6 mm—can still work, although that is not recommended. We have found that a smaller capsulorhexis can accommodate the implant, and the accuracy of the laser allows superior placement of the IMT.

There are a few pearls for IMT implantation with the femtosecond laser. First, ensure you have good wound construction. Before creating the full wound, I recommend using a smaller incision for cataract removal, keeping in mind we need to have an intact capsulorhexis and normal zonular integrity for the device to work properly. After cataract removal, cortical removal is a crucial step. I highly recommend polishing the capsule and then extending the incision, but extreme care is necessary to avoid capsular damage. I think it is essential to do capsular polish after the cataract is out—especially for these patients—because we want to minimize any possibility of posterior capsule opacification. Capsular polish both on the posterior capsule and anterior capsule is important, in my opinion. Next, I prefer to go to at least 11 mm on the limbus; I create the scleral incision and then use a crescent blade to enter the cornea.

Another pearl I have found is to stain the capsule. I use VisionBlue (trypan blue, Dutch Ophthalmic USA, Exeter, New Hampshire) to make visualization of the IMT haptics positioning within the capsular bag easier. This is a longer surgery than most of us are used to—anywhere from 45 minutes to an hour. There are some out-of-pocket costs for the surgeon, but it’s worth it when the patient regains some visual functionality and independence.

I’ve begun using the femtosecond laser for these surgeries and will continue to do so with all of my qualifying patients.

Postop follow-up

I think the most important part postoperatively is to ensure the incision is well healed with no leakage before we move these patients to the low vision specialists for rehabilitation and training. I plan to see these patients on postop day 1, but also 7 to 10 days later before I transfer care. These patients are going to have extensive postop training with the low vision specialist. As cataract surgeons, we need to remember they are not your typical patients—there is no immediate “wow” factor. There will be some necessary training, and there may be some frustration. My patient, however, did very well, going from 20/200 preoperatively to 20/100 postop, with 3 months of follow-up. Two of my colleagues have also implanted the IMT, and all of our patients are seeing substantially better and have regained a significant amount of functional vision. My patient has said she can now see faces and eyes instead of a black mass where heads should be; she can also clearly see colors of clothes. She had to train herself to use both eyes, with the implant eye for central vision and the contralateral eye for peripheral vision. As she told us, “I am reading fantasy novels on my Nook again. I can also watch my favorite PBS programs.” I’m hopeful the Food and Drug Administration will approve the device for pseudophakes as that will considerably broaden our potential patient base.

References

1. Colby KA, et al. Surgical placement of an optical prosthetic device for end-stage macular degeneration: the implantable miniature telescope. Arch Ophthalmol. 2007;125:1118–21.

2. Boyer D, et al. Long-term (60-month) results for the implantable miniature telescope: efficacy and safety outcomes stratified by age in patients with end-stage age-related macular degeneration. Clin Ophthalmol. 2015;9:1099–107.

3. Hudson HL, et al. Implantable miniature telescope for the treatment of visual acuity loss resulting from end-stage age-related macular degeneration: 1-year results. Ophthalmology. 2006;113:1987–2001.

Editors’ note: Dr. Abrams is in private practice in Las Vegas. He has no financial interests related to this article.

Contact information

Abrams: jabrams@abramseye.com

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