Anterior segment changes in rabbits after experimental aqueous replacement with various amounts of different perfluorocarbon liquids

Vitreous Substitutes from Bench to the Operating Room in a Translational Approach: Review and Future Endeavors in Vitreoretinal Surgery

Vitreous substitutes are indispensable tools in vitreoretinal surgery. The two crucial functions of these substitutes are their ability to displace intravitreal fluid from the retinal surface and to allow the retina to adhere to the retinal pigment epithelium. Today, vitreoretinal surgeons can choose among a plethora of vitreous tamponades, and the tamponade of choice might be difficult to determine in the ever-expanding range of possibilities for a favorable outcome. The currently available vitreous substitutes have disadvantages that need to be addressed to improve the surgical outcome achievable today. Herein, the fundamental physical and chemical proprieties of all vitreous substitutes are reported, and their use and clinical applications are described alongside some surgical techniques of intra-operative manipulation. The major upcoming developments in vitreous substitutes are extensively discussed, keeping a translational perspective throughout. Conclusions on future perspectives are derived through an in-depth analysis of what is lacking today in terms of desired outcomes and biomaterials technology.

MANAGEMENT OF GIANT RETINAL TEARS USING TRANSSCLERAL DIODE LASER RETINOPEXY AND SHORT-TERM POSTOPERATIVE TAMPONADE WITH PERFLUORO-N-OCTANE

PURPOSE

To determine the results of pars plana vitrectomy for giant retinal tear detachments using transscleral diode laser retinopexy and short-term postoperative tamponade with perfluoro-n-octane (PFnO).

METHODS

Twenty consecutive patients with fresh giant retinal tears were enrolled in a single-arm prospective study. One case was withdrawn for technical reasons. The remainder all underwent pars plana vitrectomy, PFnO injection, transscleral diode laser retinopexy to the edge of the giant retinal tear, and short-term postoperative heavy liquid tamponade. None of the cases had scleral buckling or lensectomy.

RESULTS

Nineteen cases (18 male and 1 female) with a mean age of 41 years (range 10-69 years) were followed up for a period of 6 months. Postoperative tamponade with PFnO was maintained for a mean of 7.6 days (range 4-21 days), after which it was exchanged for sulfur hexafluoride (SF6), perfluoropropane (C3F8) gas, or balanced salt solution. Final reattachment rate was 100%, with 3 (15.7%) patients requiring additional surgery. Best-corrected visual acuity at final follow-up was 20/40 or better in 11 eyes (58%), between 20/60 and 20/200 in 7 (37%), and 20/400 in 1 (5%).

CONCLUSION

In this series of acute giant retinal tears, transscleral diode laser retinopexy together with the use of PFnO for short-term postoperative tamponade achieved excellent anatomical and visual results.

Inflammation induced by perfluorocarbon liquid: intra- and postoperative use

Perfluorocarbon liquids (PFCLs) are useful and safe surgical tools in vitreoretinal surgery. The use of PFCL as a tamponade has been controversial due to the corneal toxicity, retinal infiltration, and inflammatory reaction in experimental studies. Several authors have studied in humans the anatomical and functional outcome and adverse effects of perfluorocarbon liquids used as short-, medium-, and long-term tamponade. PFCLs develop dispersion a few days after injection and droplets may move into the anterior chamber and cause corneal endothelial damage. When PFCLs are used as postoperative tamponades for more than one week, a foreign-body inflammatory reaction is observed in up to 30% of cases but such a reaction does not induce PVR, and it resolves after removal of PFCLs. Although most clinical studies have found no signs of retinal toxicity such as progressive visual acuity deterioration or macular anatomical changes, few performed ERG or retinal histological analysis.

[Perfluorocarbon liquids and vitreoretinal surgery in 2011]

Perfluorocarbon liquids (PFCLs) are one of the most innovative recent tools for vitreoretinal surgery. PFCLs are characterized by their number of carbon atoms, which has an impact on the density, viscosity, surface tension, vapor pressure, the boiling point, and the refraction index. PFCLs are routinely used because of their high gravity (double that of water) and their low viscosity. Furthermore, they are immiscible in water, optically clear with refraction indices similar to that of water, allowing visualization of an interface between the PFCL and saline. The use of intravitreally injected liquid PFCLs as adjunctive agents to vitreoretinal surgery plays an important role in facilitating retinal reattachment, especially in cases of giant retinal tear, trauma, and/or proliferative vitreoretinopathy. PFCLs are also used as intraoperative instruments to re-establish intraocular volume, assist in separating membranes adherent to the retina (in proliferative diabetic retinopathy, for example), and manage the dislocated crystalline lens and intraocular lens.

Perfluorodecaline residue in the anterior chamber of a patient with an intact crystalline lens: a case report

Background

Perfluorocarbon liquids are frequently used as intraoperative tools in vitreoretinal surgery and may occasionally be retained in the vitreous cavity. We report a patient who underwent pars plana vitrectomy for a giant tear after receiving blunt trauma to his right eye and sustained postoperative perfluorocarbon liquid residue in the anterior chamber in spite of an intact crystalline lens.

Case presentation

Perfluorodecaline was used as a temporary retinal tamponade. Three weeks after the surgery, a residue of heavy liquid was observed in the anterior chamber, even though the patient had an intact crystalline lens without any tilt or dislocation. The remnant of the heavy liquid was taken out of the anterior chamber immediately to avoid secondary complications.

Conclusion

Presence of heavy liquids in the anterior chamber may be associated with zonular defects even though the patient has an intact crystalline lens.

Heavy silicone oil versus standard silicone oil as vitreous tamponade in inferior PVR (HSO Study): design issues and implications

PURPOSE

Proliferative vitreoretinopathy (PVR) is the most important reason for blindness following retinal detachment. Presently, vitreous tamponades such as gas or silicone oil cannot contact the lower part of the retina. A heavier-than-water tamponade displaces the inflammatory and PVR-stimulating environment from the inferior area of the retina. The Heavy Silicone Oil versus Standard Silicone Oil Study (HSO Study) is designed to answer the question of whether a heavier-than-water tamponade improves the prognosis of eyes with PVR of the lower retina.

METHODS

The HSO Study is a multicentre, randomized, prospective controlled clinical trial comparing two endotamponades within a two-arm parallel group design. Patients with inferiorly and posteriorly located PVR are randomized to either heavy silicone oil or standard silicone oil as a tamponading agent. Three hundred and fifty consecutive patients are recruited per group. After intraoperative re-attachment, patients are randomized to either standard silicone oil (1000 cSt or 5000 cSt) or Densiron((R)) as a tamponading agent. The main endpoint criteria are complete retinal attachment at 12 months and change of visual acuity (VA) 12 months postoperatively compared with the preoperative VA. Secondary endpoints include complete retinal attachment before endotamponade removal, quality of life analysis and the number of retina affecting re-operation within 1 year of follow-up.

RESULTS

The design and early recruitment phase of the study are described.

CONCLUSIONS

The results of this study will uncover whether or not heavy silicone oil improves the prognosis of eyes with PVR.

Antifungal Activity of Intraocularly Used Liquids against Aspergillus

The antifungal effectiveness of liquids used as intraocular tamponading agents in vitrectomy was tested against a strain of Aspergillus niger. This microorganism is a frequent causative factor of endophthalmitis. The strain belonged to the ATCC collection (A. niger ATCC 16404). The samples tested were: (a) perfluorocarbons: perfluorodecalin and perfluoroctane, (b) silicone oils: Siloil 1,000 and Siloil 5,000, and (c) balanced salt solutions: BSS and BSS Plus. The experiment consisted in inoculating the samples with the microorganism, in preserving the samples in 25 degrees C in the dark, and in taking small amounts of each product for counting surviving microorganisms at t = 0 and then after 1 day, and 1, 2, 3 and 4 weeks. Among the samples tested, perfluorocarbons and silicone oils conform to the standards. No increase, and in some samples decrease, in the number of microorganisms is observed during the second week, while the number drops to zero at the end of the experiment. Therefore, the use of these liquids is safe.

Use of perfluorohexyloctane as a long-term internal tamponade agent in complicated retinal detachment surgery

PURPOSE

To report the use of perfluorohexyloctane, a liquid semifluorinated alkane that is heavier than water, as an internal tamponade agent in surgery for complicated retinal detachments.

DESIGN

A consecutive interventional case series from three study centers.

METHODS

In 23 consecutive eyes (23 patients, 19 men and four women, mean +/- standard deviation (SD) age of 58.5 years +/- 16.1) perfluorohexyloctane was used for long-term internal tamponade. Included were eyes with complicated retinal detachment involving the lower two quadrants of the fundus. Excluded were patients with diseases in the fellow eye or severe systemic disease. A pars plana vitrectomy was performed, including membrane peeling and retinotomy where necessary.

RESULTS

The mean duration for perfluorohexyloctane being left in situ was 76 days (SD 37.64) (range, 35-202 days). Four weeks following the removal of perfluorohexyloctane 19 of the 23 patients had total reattachment of the retina; three eyes had a recurrence of retinal detachment. One patient was lost to follow-up. The mean follow-up after perfluorohexyloctane removal was 97 days (range, 48 to 169 days). Cataract formation or progression was noted in nine of the 10 eyes. There were two cases with high intraocular pressures. Dispersion into small droplets was observed as early as 3 days postoperatively in three of the 23 patients. At least 12 of the 23 patients had an obvious dispersion by the time of perfluorohexyloctane removal. There was no sign of optic atrophy, retinal necrosis, or retinal vascular occlusion.

CONCLUSION

Perfluorohexyloctane was tolerated as a long-term internal tamponade agent without obvious signs of damage to the retina or optic disk. Of all the complications noted, the most common was that of dispersion of the perfluorohexyloctane bubble into droplets.