Recent Noteworthy Studies to Stimulate Discussion and Debate
Andrew E. Mathis, PhD, Medical Editor
■ Vitrectomy vs scleral buckle. A pair of articles in the September 2010 issue of Archives of Ophthalmology lays out the debate between scleral buckling and vitrectomy as surgical techniques.
Arguing in favor of scleral buckling are Edward Hurlbut Ryan, Jr., MD, and Robert Ajit Mittra, MD, of Vitreo-Retinal Surgery, PA, in Edina, MN, and the Department of Ophthalmology at the University of Minnesota. They make the case that scleral buckling is superior in cases of limited retinal detachment (RD) without vitreous detachment, posterior vitreous detachment with retinal tears and subtotal acute RD, and RD due to inferotemporal dialysis. They also state that scleral buckling has great value as an adjunct to vitrectomy.
Conversely, Deborah Y. Chong, MD, and Dwain G. Fuller, MD, JD, of Texas Retina Associates, argue for pars plana vitrectomy alone. They challenge the conventional wisdom that rhegmatous RD requires scleral buckling along with PPV, and they cite small-gauge vitrectomy and improved wide-angle viewing systems among the reasons.
For more information on this ongoing controversy, please turn to Subspecialty News of this issue.
■ PDT for PCV. A team of retinal physicians from the University of Coimbra in Portugal have shown that photodynamic therapy with verteporfin (Visudyne, Novartis) is effective in treating polypoidal choroidal vasculopathy. Their three-year data appear in the September 2010 issue of Retina.
The study authors undertook a study of 42 eyes in 38 patients with PCV who were treated exclusively with PDT. Patients were examined every three months and retreated whenever fluid appeared on fluorescein angiography. While recurrence and retreatment were frequent (in 59.3% of eyes), they were not associated with additional loss of visual acuity. At three years, three-fourths of the patients had no significant loss of vision, and 14.8% actually improved.
The authors argue that the best data available now support the notion that PDT is a superior treatment for PCV than ranibizumab (Lucentis, Genentech). This finding is significant given ongoing trials comparing ranibizumab to PDT for PCV, as well as other advanced forms of AMD.
■ Avastin and systemic VEGF. With results from the head-to-head ranibizumab vs bevacizumab (Avastin, Genentech) CATT trial yet to appear, safety concerns about bevacizumab continue. The question of whether intravitreal injections of bevacizumab can alter systemic VEGF levels is addressed by an article in the September 2010 issue of the British Journal of Ophthalmology.
The authors, who serve in the Department of Ophthalmology at Kansai Medical University in Osaka, Japan, injected 11 eyes of 11 patients with type 2 diabetes with a single 1.25 mg injection of bevacizumab. Thirty nondiabetic patients served as controls. Blood samples collected at one day, seven days, and one month were measured for concentrations of VEGF and pigment epithelium�derived factor (PEDF).
At one day, the mean VEGF concentration dropped from 114.0 pg/mL to 9.7 pg/mL — a statistically significant decline that persisted out to one month. PEDF levels also dropped out to one month, although the mean decline was much smaller.
The authors decisively conclude that bevacizumab does enter the bloodstream. They recommend, therefore, that any patient treated with bevacizumab have systemic VEGF levels monitored and be screened for potential adverse effects.
■ OSA and ocular disorders. While obstructive sleep apnea (OSA) has been linked to several medical disorders, including serious cardiac effects, what are its effects on the eyes? Deepak P. Grover, MD, who is on the faculty of the Department of Neuro-ophthalmology at the Thomas Jefferson University in Philadelphia, addresses this question in an article posted online in September and to appear in Current Opinions in Ophthalmology.
Among the ocular disorders believed to be associated with OSA are central serous chorioretinopathy (CSCR), retinal vein occlusion, and nonarteritic ischemic optic neuropathy (NAION). While the studies on NAION and RVO are limited, there is a greater amount of data to suggest that OSA's effect on neurotransmitters may have a direct relationship with CSCR. Since the natural history of CSCR is generally favorable, controlling OSA may be a particular help in treating this disorder.
Since other disorders, such as glaucoma, papilledema and floppy iris syndrome, have been linked to OSA in the literature, Dr. Grover urges all ophthalmologists to ask their patients about sleep quality when taking medical histories and to refer them when appropriate to a sleep medicine specialist. RP