F4H5: A novel substance for the removal of silicone oil from intraocular lenses

Aim: Adherent silicone oil on intraocular lenses (IOLs) following retinal detachment surgery induces large and irregular refractive errors and multiple images, and gives rise to glare, distorted and often poor vision. Its removal remains challenging, often requiring mechanical wiping or explantation. F 4H5 is a new semifluorinated alkane into which silicone oil is readily soluble. The aim is to establish the effectiveness of F4H5 in removing silicone oil from three different types of IOL in vitro. Method: Silicone lenses (Tecnis ZM900, Advanced Medical Optics, Inc.), hydrophobic acrylic lenses (MA60, Alcon Laboratories, Inc.) and PMMA lenses (Ocular Vision, Inc) were first immersed in phosphate-buffered saline, second in silicone oil, then in F4H5 (Fluoron GmbH) for 10 min and lastly vigorously agitated in F4H5 for 1 min. They were weighed at each stage using scales accurate to 0.0001 g to measure the weight of the adherent oil. Dynamic contact angle (DCA) analysis was used to assess their surface properties. Results: Immersion in F4H5 alone removed 96.1% (±1.23) by weight of silicone oil from the hydrophobic acrylic lenses, 91.4% (±1.58) from the silicone and 95.6% (±1.44) from the PMMA IOLs. Immersion combined with 1 min of agitation increased the removal to 98.8% (±0.46) from the acrylic IOLs, to 93.7% (±0.48) from the silicone IOLs and to 100% (within ±0.0001 g) from every PMMA IOL. After treatment with F4H5, all IOL were optically clear. DCA hysteresis curves remained permanently altered. All measurements were highly reproducible. Conclusion: F4H5 was highly effective at removing the bulk of the silicone oil from all three groups of IOL. The DCA measurements suggested that their surface properties were permanently modified.published_or_final_versio

A guide to the removal of heavy silicone oil

Aim: Heavy silicone oil removal can be challenging and differs considerably from conventional oil. Traditionally, strong active aspiration had to be applied through a long 18G needle just above the optic disc. We present a novel technique using a much shorter (7.5 mm) and smaller (20G) needle allowing its removal "from a distance." Method: Active aspiration on a vacuum of 600 mm Hg of the "viscous fluid injector" was applied using the 20G cannula in a polymethylmethacrylate model eye chamber that was surface-modified to mimic the surface properties of the retina. Measurements were taken using still photographs. Results: Under injection the maximum diameter of a silicone oil bubble supported by interfacial tension alone was 5 mm for a steel and 7 mm for a polyurethane cannula. Under suction, the silicone bubble changed shape and became conical, thus further increasing the cannula's reach. This conical shape illustrated "tubeless siphoning," which is a physical property of non-Newtonian fluids. Discussion: The use of shorter and smaller gauge cannula for removal of Densiron obviates the need to enlarge the sclerotomy beyond 20G or to apply suction in close proximity to disc and fovea. This potentially reduces the risk of iatrogenic damage such as entry site tears or postoperative hypotony.published_or_final_versio

Peel and peel again

Aim: To determine if the internal limiting membrane (ILM) was present in the epiretinal membrane (ERM) when we deliberately tried to perform a "double peel" for macular pucker. Methods: Pars-plana vitrectomy and a "double peel" were carried out. The ERM and ILM were stained with Trypan Blue and peeled separately over the same area. The amount of ERM present in ILM specimens and the amount of ILM present in ERM specimens were evaluated by histological examination. Results: Seventeen eyes in 17 patients were included. It was possible to double peel in all cases. Five of 17 ERM specimens (29%) contained ILM fragments. When ILM was present on the ERM, it represented less than 50% of the sample. One ILM specimen was lost as result of an administrative error; of the remaining 16 specimens, residual ERM was found in six, and cellular remnants were observed on the vitreous surface in a further six of the ILMs. Clinically, no recurrence of ERM was found. Conclusion: ILM was present in some ERM specimens seemingly over the same area that an intact ILM was subsequently peel. We speculate that the ILM in the ERM represent a secondary basement membrane and that the surgical plane of dissection for most ERM peel is between the ERM and the native ILM, making it feasible to double peel routinely.published_or_final_versio

What pressure is exerted on the retina by heavy tamponade agents?

Background: Histological changes in the retina during the use of heavy tamponade agents have been linked with the pressure on the retina caused by the increased specific gravity of the agent. This paper calculates the possible increases in pressure due to these agents and questions the validity of this argument. Methods: A model eye chamber was used to make measurements of the shape of F6H8 bubbles, with incrementally increasing volumes, and thus calculate the maximum possible increase in pressure under the tamponade agent. Results: The maximum increase in pressure under an F6H8 tamponade which completely fills an eye with a diameter of 2.2 cm would be 0.52 mmHg. Conclusions: This increase in pressure is within normal diurnal pressure changes in the eye; therefore, it would seem unlikely that such an increase could cause the histological changes observed. With increasing volumes of a heavy tamponade agent, aqueous is excluded from a greater area of retina. This could account for the pathological changes reported. © Springer-Verlag 2004.link_to_subscribed_fulltex

Outcomes of delayed vitrectomy in open-globe injuries in young patients

PURPOSE: The timing of vitrectomy for severe penetrating eye injury to the posterior segment remains controversial; this is particularly pertinent if patients are children and young adults. We present our results of the surgical procedure in young patients after penetrating eye injury using a delayed approach. METHODS: Noncomparative interventional study of patients up to 29 years of age who had vitreoretinal surgery for penetrating eye injury. Surgical procedure was performed in seven eyes of six patients. Posterior vitrectomy was performed because of hemophthalmos after waiting for a mean of 49 days (range, 17-90 days) after posterior vitreous detachment was confirmed on ultrasound examination. RESULTS: The mean postoperative follow-up period was 22 months (range, 9-35 months). Of the 7 patients, 6 (85.7%) achieved visual acuity (Snellen acuity) of 6/12 or better and 4 eyes (57.1%) reached 6/6. At the last follow-up, all patients were pseudophakic, 2 required secondary lens implants, and retinal detachment developed in 1 patient. CONCLUSION: This consecutive case series underlines the fact that a delayed approach is compatible with good visual prognosis in relatively young patients.link_to_subscribed_fulltex

Bulbusberstung: Vorgehen und Ergebnisse = Rupture of the Globe: What to Do, What not to Do.

Due to their complexity, globe ruptures are highly compromising traumas for the patient. This is due on the one hand to the eye injury itself with the accompanying loss of vision and on the other hand due to the need for extended treatment with uncertain prognosis and the resulting psychological stress. Globe ruptures are among the prognostically most unfavorable injuries due to the force and peak pressure impacting the eye. Furthermore, contusional retinal necrosis may be of significance prognostically. In the present review, we discuss treatment of globe ruptures involving retinal surgery. We discuss the primary sugery, its chronological planning and extent as well as the necessity for follow-up interventions. We also discuss the origin of traumatic retinal detachment with differential diagnosis of giant retinal tear versus oradialysis as well as secondary sequelae of traumas such as formation of macular holes and their treatment. On this basis, the use of buckling surgery versus pars-plana vitrectomy is discussed. Further focus is set on the role of the iris lens diaphragm in surgery of globe ruptures