Retinal Tolerance of DFPE, a Novel Perfluoro-Chemical

Abstract

Purpose:: The development of perfluorocarbon liquid as an intraoperative tool during vitreoretinal surgery has been a valuable addition to the surgical management of complicated retinal detachment. Nevertheless, there remains a need for substances that can be left in the eye postsurgically. High-density perfluorocarbon liquids in current use are not appropriate because of rapid dispersion into small droplets and potential toxicity. We have tested retinal tolerance to a novel medium density liquid - DFPE - a partially fluorinated 10-carbon material.

Methods:: Thirteen (13) rabbits underwent two-port 25 gauge mechanical vitrectomy. In 9 rabbits, DFPE (0.8-1.2 ml) was placed in the vitreous cavity of one eye; 4 rabbits with balanced salt solution, served as control.Eyes were followed ophthalmoscopically and electroretinographic recordings were obtained pre-operatively (baseline) and at 1, 3 and 6 months postoperatively. Enucleation was carried out at 6 months and histological evaluation completed on 2 eyes.

Results:: On examination, it was determined that vitreous fills with DFPE reached 50% in 4 eyes and 20-50% in 4 eyes. DFPE appeared to be well tolerated with just mild vitreous inflammation in 2 eyes and greater inflammation in 2 eyes. Dispersion of the fluid appeared 2 weeks postoperatively and for the remainder of follow-up globule size remained stable. Posterior subcapsular cataracts were noted in eyes with large fills of DFPE. Cellular debris was observed at the interface between DFPE and physiological fluid in 6 of 9 eyes and this remained unchanged for 6 months.With ERG recording at 1, 3 and 6 months postoperatively, there was no effect on the latency and amplitude of the A-wave as compared to saline-injected eyes or fellow non-operated control eyes. B wave amplitudes, however, were increased at 1, 3 and 6 months. Histological evaluation of 2 DFPE filled eyes after 6 months showed the presence of some giant cells on the surface of the retina. Thickening of the inner retina was observed inferiorly due to Muller cell hypertrophy. There was no loss of outer nuclear layer thickness but occasional photoreceptor nuclei dropout was observed.

Conclusions:: DFPE is relatively well tolerated but is prone to dispersion, mild intraocular inflammation and retinal changes over a prolonged period of time. Long-term studies will determine if these changes are reversible following removal of DFPE.

Keywords: vitreous substitutes • retinal detachment • proliferative vitreoretinopathy