Retinal research replete with innovative studies

Our Spotlight on Vitreoretinal Surgery sorts through the latest in vit/ret research.

The latest therapies and surgical techniques for vitreoretinal disorders display a level of innovation that could justify cautious optimism among retinal subspecialists.

Diverse research is taking a fresh look at age-related macular degeneration (AMD), choroidal neovascularization (CNV), retinal detachment and other disorders.

Investigators are looking at vitrectomy in a new light, for example, with emerging techniques aimed to stabilize or improve visual acuity and improve macular edema. Transpupillary thermotherapy (TTT) is another topic that has generated interest as new evidence surfaces demonstrating its safety and its positive effect on visual acuity.

In this Spotlight on Vitreoretinal Surgery, Ocular Surgery News provides a summary of what is happening now — and what is on the horizon — for retinal research.

ILM peeling

Vitreoretinal research is always a key element of the scientific program at the Association for Research in Vision and Ophthalmology (ARVO) meeting. This year’s meeting was no exception.

One study was presented by Shunji Kusaka, MD, director of the Osaka Prefectural General Hospital’s department of ophthalmology in Osaka, Japan.

Dr. Kusaka looked at the long-term results of pars plana vitrectomy with and without the removal of the internal limiting membrane (ILM) on diffuse diabetic macular edema (DME).

He concluded that ILM removal can improve foveal thickness and visual acuity in these eyes, though he was unable to establish a clear reason.

One explanation could be that ILM removal may eliminate vascular endothelial growth factor and VEGF-producing glial cells that exist there, and therefore facilitate clearance of cytokines in the retina to the vitreous cavity, Dr. Kusaka said.

Patients who underwent posterior vitreous detachment without ILM removal appeared to also experience a decrease in foveal thickness, but with no improvement in visual acuity, the study concluded.

Off-label use of Visudyne

Also at ARVO, a group of researchers showcased a phase 2 trial studying the safety and efficacy of Visudyne therapy in minimally classic CNV in wet AMD.

Neil M. Bressler, MD, one of the principal investigators, said the study concluded that patients with minimally classic choroidal lesions could benefit from off-label use of this therapy, which is recommended for predominantly classic lesions.

The Visudyne in Minimally Classic Trial showed a reduction in vision loss in patients with smaller, minimally classic CNV when treated with Visudyne and photodynamic therapy (PDT). The results show a safe potential extension of verteporfin (Visudyne, Novartis Ophthalmics) injections with PDT.

Visudyne has been shown to slow growth of abnormal blood vessels beneath the retina, stopping leakage associated with wet AMD. While the Food and Drug Administration has not approved use of the drug on patients with minimally classic lesions, Dr. Bressler said many medical associations support the off-label use.

This trial included 117 patients, followed for 12 months, from 19 clinical centers in Europe and the United States.

Besides proving Visudyne’s benefits to a new group of patients, other objectives were to compare two light fluence rates, to observe reduction of visual acuity loss in patients with Visudyne therapy versus a placebo group and to determine a safe treatment profile for patients.

Vitrectomy vs. scleral buckling

Another presenter at ARVO explained how vitrectomy can be used for selected complex forms of primary retinal detachment as surgical techniques become more sophisticated.

Stanley Chang, MD, of New York, described how vitrectomy, with or without scleral buckling, appears to present some advantages to better provide control of retinal detachment.

He emphasized that vitrectomy is indicated for conditions including media opacity, giant retinal tears, posterior retinal breaks, moderate to advanced proliferative vitreoretinopathy and the inability to find a retinal break.

In cases for which vitrectomy is indicated, Dr. Chang recommended the use of surgical adjuncts to help prevent complications. He mentioned panoramic viewing systems, intraoperative perfluorocarbon liquids and high-speed cutting as a few highly effective tools.

Dr. Chang did not, however, recommend vitrectomy if the retinal breaks are located at the margin of the vitreous base insertion. In those instances, he said scleral buckling is the sensible choice.

He also cautioned that certain complications tied to vitrectomy have to be resolved. Namely, nuclear cataracts virtually always form postoperatively, so he called for more research into the reasons behind this development.

TTT on wet AMD

Two recent journal studies examined the effect of TTT on wet AMD, and both concluded that this unorthodox procedure could help prevent extensive visual loss.

One study, conducted by Allen B. Thach, MD, and associates from Phoenix, determined that large-spot TTT is effective in stabilizing the visual acuity in patients with occult CNV due to AMD. Dr. Thach explained that the diode laser is theoretically safer than the thermal laser in that there is less damage incurred by the nerve fiber layer.

Most patients (71%) in this study were found to have stable or improved visual acuity at the 6-, 9- and 12-month follow-up visits. In contrast, 29% lost two lines or more of visual acuity on the Snellen letter chart.

In the other study, conducted by Peep V. Algvere, MD, Dr. Algvere and associates found that TTT has the capacity to prevent moderate to severe visual loss in predominantly occult CNV related to AMD. At 1-year follow-up, most patients in this study avoided moderate and severe vision loss, defined as a loss of 15 letters or three lines and 30 letters or six lines, respectively.

Neither study was able to conclusively state how TTT produced the results it did. Dr. Algvere suggested that the mode of TTT produces a transient occlusion of the choriocapillaris, causing a reduction in blood flow, which in turn inhibits angiogenic growth.

Surgical ablation for AMD-related condition

Alternative treatments for AMD-related conditions are also under investigation.

Researchers at Will Eye Hospital in Philadelphia have presented their findings pertaining to a newly described manifestation of AMD known as retinal angiomatous proliferation (RAP).

In a study published recently in Archives of Ophthalmology, Arunan Sivalingam, MD, and associates said they were able to improve visual acuity in a small number of patients with this condition by using surgical lysis of the feeding arteriole and draining venule of an RAP lesion.

The researchers included patients with RAP stage 2, opting to exclude patients with stage 1 and 3 because those with stage 1 may be asymptomatic and those with stage 3 often have advanced, irreversible damage.

Among those who underwent surgical ablation of an RAP lesion, improvement in clinical, angiographic and tomographic appearance was noted in all cases.

Once the lysis was completed on the feeding and draining vessels, the pigment epithelial detachment that has been associated with RAP appeared to be completely resolved after about a week.

The small-scale study included four eyes of three consecutive patients who had been identified from Dr. Sivalingam’s clinical practice.

Vitreous tap for safer phaco

Another recent study looks at a technique to make phacoemulsification maneuvers safer and easier in eyes with shallow anterior chambers.

Riccardo Acciarri, MD, and colleagues from Cesena, Italy, performed a vitreous tap followed by cataract surgery in 10 eyes. They found that the aspiration of part of the vitreous creates the space to perform phaco maneuvers in eyes where they would otherwise be impossible because of the insufficient space between the lens and the endothelium.

The surgical technique involves peribulbar anesthesia, followed by the performance of a conjunctival peritomy, a paracentesis and a sclerectomy 4 mm from the limbus. The anterior chamber is filled with a dispersive viscoelastic from a side port, followed by pars plana vitrectomy using an automated posterior vitrectomer, Dr. Acciarri explained.

The study found that this technique produced good visual results, with uncorrected visual acuity improving from preoperative 20/200 to postoperative 20/40.

Dr. Acciarri further explained that he believes vitreous tap is a superior alternative to drugs in these eyes because drugs have been found to have either little efficacy or negative side effects on circulation.

While recognizing that the vitreous tap technique is not without risk, Dr. Acciarri said he believes they are “calculated risks.”

Skillful surgery, he said, is the key to reducing vitreous complications during phacoemulsification. Vitreous tap requires skill and experience to be performed safely. However, when done correctly, it can reduce the risk of endothelial damage, as well as prevent intraoperative iris prolapse and suprachoroidal hemorrhage in hyperopic eyes, according to Dr. Acciarri.

New foldable IOL for vit/ret surgery

Finally, Giuseppe Migliorati, MD, from Udine, Italy, spoke recently in Paris about a new foldable IOL that presents an effective response to the requirements of eyes undergoing vitreoretinal surgery.

Dr. Migliorati explained how the Ultima IOL from Corneal is to be used as a last choice, when regular IOLs are not appropriate.

He said it is the first scleral-fixation lens that is foldable and can therefore be implanted through a 4-mm incision, thereby reducing the risk of astigmatism.

Dr. Migliorati said he has implanted about 15 Ultima IOLs, mostly in cases of complicated ocular trauma or vitreoretinal surgery.

He described one patient who had retinal detachment and subluxated crystalline lens. Dr. Migliorati performed cataract surgery, implanted the lens in the sulcus without sutures and then carried out a vitrectomy with the use of gas and silicone oil tamponade.

Because of the lens’ large, 6.5-mm optic, it allows for excellent visualization of the ocular fundus and stays very stable during surgery, Dr. Migliorati explained.