Can ocriplasmin replace vitrectomy?

ocriplasmin-for-vitreomacular-tractionFor many years, vitrectomy has been a solution for vitreomacular adhesions including macular pucker, macular hole, and macular vitreomacular traction. However, surgery has a high risk of complications such as infection, retinal detachment, haemorrhage and cataract. Therefore, for the past two decades, researchers have been developing molecular (enzymatic), rather than surgical treatments for these conditions, eventually creating ocriplasmin.

RANZCO Fellow Clinical Associate Professor Andrew Chang from Sydney Retina Clinic and Day Surgery said:

“The vitreous body is adherent to the internal limiting membrane of the retina through a biochemical glue composed of proteoglycans including fibronectin and laminin. As the vitreous liquefies with aging, these vitreoretinal adhesions weaken and a posterior vitreous detachment (PVD) occurs. Partial PVD can give rise to vitreoretinal interface disorders. This spectrum of pathology includes vitreomacular adhesion (VMA), vitreomacular traction (VMT) and macular hole (MH). These pathologies can give rise to impaired vision, metamorphopsia and visual field defects. Vitrectomy surgery has been shown to reliably treat these conditions, though it carries with it associated surgical risks.

Ocriplasmin is a protease with activity against fibronectin and laminin. Injected intravitreally, this drug cleaves the vitreoretinal interface and can induce posterior vitreous detachment. Phase III clinical trials have demonstrated the safety and efficacy of this drug, with resolution of VMA between 27 and 58%. With appropriate patient selection, rate of successful VMT release and MH closure can be optimised. This includes patients who are younger than 65 years of age, phakic, without epiretinal membrane, with full thickness MH < 250um and vitreomacular adhesion < 1500um.

Adverse events encountered with ocriplasmin are mostly related to self-limited visual disturbances such as photopsia. There have been observations of ERG abnormalities and ellipsoid layer alterations noted on OCT. These largely do not correlate with visual acuity, and the long-term ramifications of these changes are not clear.

Ocriplasmin serves as an important pharmacological tool in the management of vitreoretinal interface disorders. Though the success rate is not as high as vitrectomy surgery, in certain situations it may be a suitable first-line treatment. Further phase IV clinical trial data will refine the safety and efficacy profile of this drug.

In Australia, there are new MBS Item codes for OCT diagnosis and subsequent follow-up at day 28. Imminent PBS listing is expected in December 2016. Access to the OCT reading centre is available for ophthalmologists to obtain a second opinion regarding the type of VMT.

A review on who is the best candidate for ocriplasmin pointed out the benefits of ocriplasmin based on the MIVI – TRUST study and other studies are as follows:

  • Ocriplasmin 125 μg was overall more effective than placebo in the treatment of the symptomatic VMT syndrome
  • Patients treated with ocriplasmin had more resolution of macular hole when compared to placebo
  • Foveal thickness decreased after ocriplasmin injection
  • The best outcome from start through 6 months was found in patients younger than 65 years of age and with absence of ERM, occurrence of phakic eyes, VMT <1,500 μm in diameter, and presence of FTMH of <250 μm diameter.

The Australian Prescriber listed the contraindications for the use of ocriplasmin as follows:

  • Administration of ocriplasmin in both eyes at the same time or repeat administration in the same eye is not recommended.
  • Ocriplasmin is not recommended in conditions: proliferative diabetic retinopathy, neovascular age-related macular degeneration, retinal vascular occlusion, aphakia, high myopia, uncontrolled glaucoma, a macular hole over 400 micrometres in diameter, a history of retinal detachment or vitreous haemorrhage, recent eye surgery or eye injection
  • Pediatric use is not recommended since the benefit was not found in a study of ocriplasmin in children scheduled for vitrectomy

 

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Photo credit: escritorio47 via Visual Hunt / CC BY-ND

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