原文如下:
Are intravitreal injections safe and effective in previously vitrectomized eyes? It may depend on the type of drug, according to Damien C. Rodger, MD, PhD, during the Retina Subspecialty Day on Friday.
More frequent injections with triamcinolone? In a literature review, Dr. Rodger noted that studies conducted with rabbit eyes do not support changing frequency or dosage in vitrectomized versus nonvitrectomized eyes for ranibizumab or dexamethasone. However, studies on triamcinolone acetonide show that the vitreous half-life was less than that in controls (1.6 vs. 2.9 days), and the steroid was detected in only 1 of 42 eyes in the vitrectomized group versus 4 of 6 control eyes at 1 month postinjection. Thus, these data suggest that more frequent injections of triamcinolone acetonide may be necessary in vitrectomized eyes.
Vitreous status influences implant localization. Additionally, Dr. Rodger's retrospective study on dexamethasone implants showed that implants may behave differently in vitrectomized eyes. The implant was found to localize to the retinal surface, settling inferiorly in 100% of the vitrectomized eyes compared with 6.8% of the native eyes. Of concern, more vitrectomized eyes also experienced a vitreous hemorrhage (20% vs. 1.5%, respectively).
Possibility of a retinal strike. Finally, Dr. Rodger discussed his prospective ex vivo study in enucleated porcine eyes. This showed that a dummy dexamethasone implant injected 4 mm inferotemporally to the limbus struck the retina in 11 of 12 vitrectomized eyes, compared with just 1 of 12 control eyes. To reduce the possibility of a retinal strike, Dr. Rodger suggests aiming away from macula or optic nerve in vitrectomized eyes.—Keng Jin Lee
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