Newsletter Summer 2012

Dear patients and friends,

This is the first in what I would hope will be a series of quarterly newsletters, the purpose of which is to give you a flavour of new developments in Ophthalmology, and in particular areas that relate to my practice, namely retinal conditions including surgical and non-surgical conditions of the retina, macular degeneration and diabetic eye disease (as both are important causes of visual loss) as well as cataract surgery. I would like to include conditions that are of particular interest to you because some may be reasonably common and others may be visually disabling, however please do not hesitate to let me know if there are any particular topics that you may be interested in for inclusion in future letters. In this first letter, I thought of 2 topics of particular interest, the first being the role of laser in cataract surgery since so many patients ask me if I will do their cataract by laser or not, and the second is wet age-related macular degeneration treatments, as this is such a devastating condition if left untreated and yet potentially a treatable condition for a significant number of patients who present early enough. I hope you enjoy the newsletters and I look forwards to hearing from you.

Hadi Zambarakji MB ChB, FRCOphth, D.M
info@retinacare.org.uk
Spire Roding Hospital, Roding Lane South, Ilford. IG4 5PZ.

Femtosecond Laser Cataract Surgery

There is a growing body of evidence around a new approach to cataract surgery, which may be more efficient than today’s standard procedure. The new approach, using a special laser called the femtosecond laser, is FDA-approved, but not yet widely available.

Femtosecond lasers first became available for refractive surgery in 2001, when they were introduced for the purpose of creating the corneal flap in LASIK (laser in-situ keratomileusis). The flaps created by femtosecond lasers were more reproducible, uniform, closer to their intended thickness and centration, and had improved safety profiles compared with those made by manual technique (using a keratome). Since then, the use of femtosecond lasers has been expanded to other corneal surgeries and most recently has been applied to cataract surgery.

What are the benefits of using the Femtosecond Laser in cataract surgery?

The world of ophthalmology had witnessed a number of innovations in cataract surgery since the advent of phacoemulsification, including the use of smaller incisions, new development in lens materials and the use of special lens designs that can correct for astigmatism as well as multifocal lenses . Many surgeons believe that there are aspects of the phaco operation that can be improved, and for this reason the femtosecond laser is capturing the imagination of cataract surgeons. The femtosecond laser does all the things that ophthalmologists currently do in cataract surgery; however, it does them more accurately and more reproducibly. Most surgeons would agree that it is very challenging to make the capsulotomy (the initial opening in the lens capsule before the lend of removed by phaco) perfectly round, perfectly centered, and of the exact diameter that they wish every single time. The Femtosecond Laser can help achieve a perfectly round capsulotomy, perfectly centered, and of the exact diameter that they wish every single time.

It also minimizes and, in some cases, eliminates the need for phaco by breaking up the nucleus into tiny cubes, which can then be aspirated from the eye. It can also be especially useful for harder lenses. In addition, the femtosecond laser incisions will reliably release less energy than other lasers, preventing excessive rise in temperature.  This will protect the endothelial cells of the cornea within the eye, therefore ensuring corneal clarity.

How does the Femtosecond Laser work?

The Femtosecond Laser system uses an optical coherence tomography (OCT) system to provide real-time images of the anterior segment (the front of the eye). To perform a cataract procedure, the surgeon first programs the laser for the corneal incisions and the capsulotomy, and then the lens fragmentation pattern.

Next, the eye is docked to the laser and the integrated OCT captures three-dimensional images of all ocular structures within the anterior segment. These images are projected onto the video microscope screen along with overlays of the preprogrammed laser treatment. The surgeon then makes any adjustments via touch screen and begins the treatment.

Because femtosecond lasers work from the inside out, the cataract procedure is carried out in reverse compared to a standard surgery. First, the cataract is fragmented. This is followed by the creation of the anterior capsulotomy. Then, the corneal incisions are performed. Once the corneal incisions are complete, the surgeon removes the fragmented cataract, performs cortical clean-up, and then implants the lens implant. This is of course an oversimplification of the laser procedure, as I do not wish in any way to imply that that this is a simple procedure that is totally risk-free. Complications do occur and those who are currently using Femtosecond laser for cataract surgery have reported and presented their early experience with the laser and risks and complications.

Is it really worth it?

Today, there are six companies that manufacture and sell femtosecond lasers in the United States. Currently, both Alcon and LensAR are pioneering the new use for femtosecond lasers in cataract surgery. Other femtosecond lasers are under development around the world, including in Germany, France and Lithuania.

However, many surgeons would argue that there is no real need to unanimously adopt this new technology when the current method is so effective. The main advantage of Femtosecond laser-assisted cataract surgery is that it causes less corneal swelling in the early postoperative period and may cause less trauma to corneal endothelial cells than the standard procedure, but that does not indicate that it is safer or more effective than manual (standard) phacoemulsification. The lasers are elegantly designed, ergonomically excellent, have brilliant software and hardware, but companies manufacturing these lasers currently sell the Femtosecond for several hundred thousand pounds and insurance companies may not be wiling to pay the additional cost of the surgery performed by the laser which could mount to 2-3 thousand pounds per eye.  Despite the fact that the laser makes cataract surgery more precise and reproducible, set-up costs are still too high to make the laser widely available based on the current price. Standard phacoemulsification cataract surgery is still an exceedingly effective and safe procedure.

Current treatments for wet age-related macular degeneration (AMD)

AMD is the most common cause of blindness in the Western world and the leading cause of blindness in patients older than 65 years of age. AMD is a progressive degenerative disease of the retina that is classified into two types:

1. nonexudative or dry AMD (90%) characterized by drusen, pigment changes, and retinal pigment epithelial atrophy.
2. exudative or wet AMD characterised by choroidal neovascularization (CNV) and scarring (10%).

Risk factors include age, heredity, gender (female), race (Caucasian), smoking, nutrition, photic exposure, hypertension, light iris color, hyperopia. Symptoms are decreased vision, central blurred vision (scotoma), and visual distortion (metamorphopsia) with a range of severity from minimal in mild cases of dry AMD to severe in advanced cases of dry AMD and in wet AMD.

Treatments:

1. Medical Treatment for dry AMD:

Carefully monitoring of vision and the use of oral vitamin supplements (vitamins C, E, A, zinc, and copper), Lutein/Zeaxanthin and omega 3 supplements and low vision aids. New agents are in development that may slow the progression of geographic atrophy (a form of dry AMD) and reduce the risk of developing CNV.

2. Treatments for wet AMD:

1. Laser: This was evaluated in the Macular Photocoagulation Study (MPS), which showed a treatment benefit for patients with well-demarcated extrafoveal or juxtafoveal CNV. However, many patients do not qualify for laser treatment because the lesion is location too close to the centre of the macula (the retina) and treatment would result in severe visual loss.
2. Photodynamic therapy (PDT) with verteporfin: This treatment is able to prevent vision loss in some eyes with subfoveal lesions, predominantly classic and occult, with no classic CNV. This has largely been superseded by the use of anti-VEGF agents.
3. Anti-VEGF agents: Intravitreal injections (injections in the vitreous cavity of the eye) of various drugs have proven to be an effective treatment and have revolutionized the treatment and prognosis of wet AMD.
   1. Pegaptanib (Macugen; EyeTech Inc.) was the first FDA-approved drug. This is not used any longer for the treatment of wet AMD.
   2. Ranibizumab (Lucentis; Genentech) was the next FDA-approved agent and is the most effective for all forms of CNV.
   3. Bevacizumab (Avastin; Genentech) is similar to Lucentis but FDA-approved for colorectal cancer (used off-label for treating wet AMD). Avastin is not licensed for use in the eye. However, the second year data from the Comparison of AMD Treatment Trial (CATT) is a landmark trial that showed the two drugs have equivalent effects on visual acuity. Patients receiving as needed injections had slightly less visual gain than those receiving monthly injections. Rates of cardiovascular complications (myocardial infarction, stroke and death) were similar with both drugs. Data from the IVAN studies (UK) were released in May this year and also show that Avastin and Lucentis are equally effective at preventing visual loss secondary to wet AMD.
   4. Aflibercept (VEGF Trap Eye; Eylea) is injected into the vitreous every 2 months after a loading dose and is being evaluated in clinical trials. Data from the VIEW studies showed that VEGF Trap Eye has similar efficacy, safety and tolerability to Bevacizumab (Lucentis) injected monthly. Aflibercept (Eylea; Regeneron pharmaceuticals) was approved by the US Food and Drug Adminstration (FDA) in November 2011 for the treatment of wet AMD. Bayer has submitted an application for marketing authorization in Europe, Japan and other countries.

   Although these anti-VEGF agents have improved our ability to treat wet AMD, there are safety concerns about their use because all of them can get into the systemic circulation thereby placing patients at risk for arteriothrombotic events such as hypertension, myocardial infarction, and stroke.

4. Combination therapy: This strategy has its supporters, and has been more popular in some parts of Europe. Combining PDT and anti-VEGF agents has been shown to be safe with similar visual results and reduced numbers of injections.
5. Radiation therapy: Previous trials looking at external radiation (including proton beam radiation) showed no benefit, but there are no large-scale trials that have compared external radiation to anti-VEGF agents. Internal radiation (delivered through a probe after performing a vitrectomy operation) is being investigated in combination with anti-VEGF agents.In my next newsletter, I would like to summarise in a bit more detail the current data relating to the head to head avastin/lucentis trials for wet AMD as well the data available relating to Aflibercept (VEGF Trap Eye; Eylea) for wet AMD
6. Surgery: Surgery may also play a role in very few select cases. Submacular surgery should be considered to remove CNV or displace hemorrhage in cases with large submacular hemorrhage. Macular translocation is another surgical technique that has been used but has largely been superseded by anti-VEGF treatments.

In my next newsletter, I would like to summarise in a bit more detail the current data relating to the head to head avastin/lucentis trials for wet AMD as well the data available relating to Aflibercept (VEGF Trap Eye; Eylea) for wet AMD.

Hadi Zambarakji

No comments yet

Leave a comment