Breaking a taboo: treating over the fovea

A MicroPulse laser spares tissue, making it a safe choice for treating chronic ocular conditions.

By Ahad Mahootchi, MD

Two years ago, I began micropulse laser treatments over the fovea for various retinal diseases, including retinal vein occlusion. Since then, I have successfully completed more than 300 procedures, cut my monthly budget for injections down to $13,000 from $42,000, and reduced the number of times patients need to return for more treatment. Overall, my clinic reduced its drug costs by 67%.

Had I attempted using a continuous wave (CW) laser, I could not have reported the same results. With CW, treating the fovea is a disaster. CW laser waves can cause burning in or near the fovea, no matter how low the power. However, with a laser (at 5% duty cycle), a different mechanism seems to be occurring in which there is an increase in production of certain growth factors in the outer retina in response to the laser pulses without the accompanying cellular destruction.

Instead of damaging tissue, this laser treats viable tissue to stimulate a response, which produces more anti-angiogenic inhibitors, such as pigment epithelium derived factor (PEDF) while inhibiting inducers of VEGF.¹ The results often take up to four months to become apparent, primarily because the therapy works at the cytokine level to incite restorative intracellular biological activity.

Figure 1. CW Laser (mETDRS) vs MicroPulse laser before and after treatment with microperimetry, FA, and OCT. CW laser treated areas of spots of decreased retinal sensitivity (second column). MicroPulse treated areas show no damage and even improvement (fourth column). CW treated areas are seen in FAF photos. No FAF is seen in the MicroPulse treated areas.
1. Vujosevic S, Bottega E, Casciano M, Pilotto E, Convento E, Midena E. Retina 2010.

Start of a journey

I used subthreshold CW laser and performed focal CW laser on diabetic retinopathy and vein occlusions for many years, staying away from the foveal avascular zone. The science said treating that area with a laser would be harmful. With a CW laser, no matter how short you keep the pulse or how low you turn the power, you can easily see retinal damage via OCT, fundus autofluorescence (FAF) and microperimetry. When CW laser was all we had, the chance of nonfoveal damage may have been worth the benefits. However, the same didn’t hold true in the fovea.

With the introduction of anti-VEGF therapy, I was able to treat fluid in the fovea that was previously untreatable. Over time, however, I worried about the trends we have all seen: tachyphylaxis and pigmentary atrophy after three to four years of injections.

So, my thoughts turned to treating over the fovea. Our peers in Asia and Mexico have used this laser (at 5% duty cycle — not higher) for over the fovea procedures with success, so I knew it could be done. Having this procedure in the armamentarium, along with anti-VEGF injections, would be an excellent treatment strategy. It would act as a supplement to anti-VEGF injection therapy providing patients with a variety of options in their care and treatment plans. This procedure would offer solutions to several key patient concerns: high cost, frustration associated with receiving repeat injections, tachyphylaxis without alternative agents offered by their insurance plans and atrophy.

And we could treat a variety of conditions including diabetic macular edema (DME), macular edema from vein occlusion, central serous retinopathy, pseudophakic cystoid macular edema and even edema from wet AMD. With fewer injections, we could slow the progression of injection-related macular atrophy, a condition which impairs visual function.¹

Getting ready

The laser I use (Iridex IQ 577) does not burn the retina at a 5% duty cycle. I studied images of low-intensity CW laser burns and compared them to MicroPulse at a 5% duty cycle — I could not see anything in the 5% duty cycle. I reviewed the literature, which did show changes at the 10% duty cycle in some patients. So I avoided that setting. Next, I looked at fluorescein angiography, OCT images and other tests showing 5% duty cycle MicroPulse as well as clinical pictures that showed the resolution of the edema in treated areas. I could not see the treatment per se, but it was obvious something was done because of the resolution of the edema. I then learned how to do test spots to ensure that individual patients got only a safe dose of the laser. I still use that protocol on every patient. Once I understood the safety factor, I began treating closer to the fovea without any negative effects.

I was ready for foveal treatment; I just needed an appropriate patient.

An unexpected result

One such patient came with a branch retinal vein occlusion in an eye that had severe central visual loss already present and wet AMD-related fluid involving another part of the fovea. The patient’s AMD had not responded to intravitreal drug injections. I used the 5% duty cycle laser right over the vein-occlusion affected fovea, and the chronic swelling (caused by wet AMD) in another part of the fovea improved. The patient’s functional visual field dramatically improved. I didn’t think the procedure would harm the patient, like the science predicted, but at most all I expected was a reduction in swelling in the vein-occlusion affected areas.

But an improvement in central field vision? Totally unexpected.

Encore after encore

Following this success, I began treating patients who had received anti-VEGF shots and had 20/80 vision or worse. Not only did their vision improve a line or two, but their injection frequency decreased. I progressed to treating the edema closer to the fovea in patients with better Snellen vision, all without negative effect. Most importantly, my patients did not experience side effects such as visual field loss or microscotomas. In the past two years, I have learned that the laser (at 5% duty cycle) works very well for a variety of macular diseases, such as diabetic macular edema, edema from vein occlusions, central serous retinopathy, pseudophakic cystoid macular edema, and even fluid and edema from wet age-related macular degeneration.

Manage patient expectations

To achieve success in chronic disease treatment (like wet AMD or chronic vein occlusion), make sure patients keep in mind the following:

• The response to subthreshold laser is typically slower than pharmacotherapy and can take four months for noticeable results; however, the results are longer lasting.

• OCT images and vision may stabilize but not necessarily improve.

• Like injections, patients may require more than one treatment. The majority gets only one laser session the first year.

• Anti-VEGF treatments can be continued and potentially reduce in frequency but not always eliminated.

For my patients with edema, I introduce laser treatments early to extend the period of responsiveness of anti-VEGF treatments for as long as possible before atrophy. My typical protocol is to give two injections and then use the laser between the second and third injection. I continue to follow up with patients (without injection) at the same interval I was injecting before using the laser.

Success specifics

• I have seen significant success in treating chronic disease with a micropulse laser.

• Never go higher than 5% duty cycle and always do the test spot protocol.

• Once the therapy “kicks in” after about four months, approximately one-third of my patients do not require further injections for two years.

• Another one-third needs injections two times a year or less.

• The remaining third reduce the frequency of injections by half. For instance, a patient who required 6-week injections can now go three months between injections.

Chronic disease case studies

A 70-year-old female developed wet AMD three years ago after cataract surgery; she had taken a regimen of PreserVision (Bausch & Lomb Inc.), lutein, omega-3 and fish oil. Vision varied from 20/40 to 20/60 on q 6 Avastin (Genentech); however, fluid became increasingly difficult to eliminate. I administered transfoveal yellow MicroPulse laser (Iridex) at 5% duty cycle. The patient’s vision improved to 20/40 without negative side effects; no anti-VEGF injections for 18 months and counting.

A 71-year old male lost vision in one eye to wet AMD 10 years prior and developed wet AMD in functioning eye. Medication regimen included smoking cessation, PreserVision, 20 mg lutein, and fish oil. He received 31 anti-VEGF injections with intervals shortening between the injections. The patient was experiencing atrophy, slowed reading, and vision was 20/40. I performed transfoveal subthreshold laser at a 5% duty cycle. Five months later, fluid remained without dropping vision, so I repeated treatment at 5% duty cycle. Four months later, the patient’s vision was 20/25 without any intravitreal injections for the next 12 months and counting.

A happy fovea

This fovea-friendly laser has proven valuable in my practice. While it is slower to take hold than pharmacotherapy, it is more durable. Tissue remains visibly unchanged during and after treatment. Current literature, substantiated by my own experience, supports its safety and efficacy. Patients report fewer side effects and avoid microscotoma often seen with the CW laser. The ability to delay atrophy can save and extend a patient’s visual life. Finally, my patients, my practice and payers benefit from fewer injections and office visits as well as reduced costs. OM

Dr. Mahootchi is a consultant and speaker for Iridex.

REFERENCE

About the Author
	Ahad Mahootchi, MD, is the medical director of The Eye Clinic of Florida in Zephyrhills, Fla. Voted as one of Florida’s top 10 doctors by PatientsChoice.com, he has a special interest in treating and preventing vision loss for those with diabetes, macular degeneration and glaucoma. Dr. Mahootchi may be reached at am@seebetterflorida.com.