Stanley Chang

Intraoperative Perfluorocarbon Liquids in the Management of Proliferative Vitreoretinopathy

Three low-viscosity perfluorocarbon liquids were used intraoperatively for hydrokinetic manipulation of the retina during vitreous surgery for retinal detachment with advanced proliferative vitreoretinopathy. All 23 patients had massive proliferative vitreoretinopathy (Grade D, Retina Society classification), and 16 (69.6%) had Grade D-3 with a closed-funnel configuration. In 21 eyes the retina could be flattened intraoperatively by perfluorocarbon liquids without requiring posterior retinotomy for internal drainage of subretinal fluid. The temporary mechanical fixation of the retina provided by this tool facilitated the removal of epiretinal membranes and release of traction. Fifteen eyes (65.2%) maintained long-term retinal reattachment with follow-up of six months or more. These liquids are useful adjuncts in the management of retinal detachment with severe proliferative vitreoretinopathy.

Therapeutic Ultrasound in the Treatment of Glaucoma: II. Clinical Applications

Focused, high-intensity therapeutic ultrasound was used to treat 69 selected patients with uncontrollably elevated intraocular pressure (IOP). This new technique selectively thins scleral collagen, and produces focal damage to the ciliary epithelium. These tissue modifications provide a reduction in IOP pressure to 25 mmHg or less in 83% of patients with a minimum three-month follow-up period.

Perfluorocarbon Gases in Vitreous Surgery

Fifty-six patients with complicated retinal detachments were managed with vitreous surgery and one of two perfluorocarbon gases. These gases are capable of greater expansion and greater longevity compared to sulfur hexafluoride. Forty-five patients received perfluoropropane (C3F8), eleven received perfluoroethane (C2F6). The retinas of 31 patients (55.4%) were attached at six months after the disappearance of the gas. In many instances, operations performed with air-sulfur hexafluoride mixtures had failed and the retina was subsequently reattached with the use of the perfluorocarbon gases. The major complications were increased intraocular pressure, which was usually transient, and gas-induced lens opacities.

Therapeutic Ultrasound in the Treatment of Glaucoma: I. Experimental Model

Controlled ultrasonic energy was used to treat a series of laboratory animals in which glaucoma had been induced experimentally. Insonification successfully reduced elevated intraocular pressure in the majority (86%) of test animals. Histopathologic review of globes examined at varying time intervals following treatment showed localized thinning of the sclera with intact conjunctiva, allowing filtration and focal disruption of ciliary epithelium. This technique of treating elevated intraocular pressure in a noninvasive manner offers potential for clinical application in humans.

Perfluorocarbon Liquids in the Management of Traumatic Retinal Detachments

Low viscosity perfluorocarbon liquids were used as an intraoperative tool during vitrectomy for retinal detachment (RD) after penetrating ocular trauma. These liquids are immiscible with water and have specific gravities from 1.8 to 1.9. Intraoperatively, the perfluorocarbon liquids flattened the retina in 14 eyes by displacing the subretinal fluid through peripheral breaks. Posterior retinotomy was not required for internal drainage of subretinal fluid. Pooled subretinal fluid was displaced from the macular area in five patients. The perfluorocarbon bubble mechanically stabilized the retina during epiretinal membrane dissection. The perfluorocarbon liquid was removed and replaced perfluorocarbon gas or silicone oil. In 11 patients followed for more than 6 months after the final surgery, eight (73%) eyes were anatomically successful, with six (54.5%) gaining visual acuity of 20/400 or better.

Management of Intraocular Foreign Bodies

Thirty-five consecutive cases of perforating ocular injuries with retained intraocular foreign body (IOFB) are examined in this retrospective study. Of the 35 cases with injuries, 30 (86%) were due to metallic foreign bodies. Of these, 25 (83%) involved foreign bodies of ferromagnetic origin. Magnetic extraction in combination with pars plana vitrectomy (or when possible, magnetic extraction alone) was successfully used to remove these foreign bodies. Even in cases where posterior vitrectomy is indicated, magnetic extraction allows good control of the foreign body during removal minimizing surgical trauma and the subsequent postoperative inflammatory response.

Perfluorocarbon liquid in the management of retinal detachment with proliferative vitreoretinopathy.

PURPOSE To describe the techniques and results of perfluoro-N-octane used during vitrectomy for managing retinal detachment with severe proliferative vitreoretinopathy (PVR). METHODS The authors retrospectively studied 223 consecutive patients who underwent vitreoretinal surgery for severe PVR (93% D1-D3). Patients underwent an average of 1.72 prior vitreoretinal surgeries. Perfluoro-N-octane was used intraoperatively to flatten the retina, avoiding posterior drainage retinotomy, to identify areas of residual retinal traction and periretinal membranes, to stabilize the peripheral retina during dissection of anterior PVR, and to help determine the extent and location of relaxing retinotomies. Extended-term gas tamponade was used in 91% of eyes. All patients were followed for a minimum of 6 months. RESULTS Seventy-eight percent of the retinas were reattached posterior to the scleral buckle after a single vitreoretinal surgery and 96% were reattached after multiple surgeries. An average of 1.24 vitrectomy surgeries were required. The final visual acuity was 20/400 or better in 74% of eyes and 20/80 or better in 30% (P = 0.004). Preoperative hypotony (intraocular pressure < or = 5 mmHg) and multiple prior vitreoretinal surgeries were associated with a poor final visual acuity (P = 0.01 and 0.02, respectively). Preoperative hypotony (intraocular pressure < or = 5 mmHg) was associated with a greater frequency of relaxing retinotomies (P = 0.02). Retained perfluoro-N-octane was observed postoperatively in the vitreous cavity in 1.3% and subretinal perfluoro-N-octane in 0.9%. CONCLUSION Experience with perfluoro-N-octane has demonstrated its usefulness both diagnostically and therapeutically as an intraoperative tool and improved the anatomic and visual outcome for retinal detachment complicated by severe PVR.

Does the presence of heparin and dexamethasone in the vitrectomy infusate reduce reproliferation in proliferative vitreoretinopathy

Abstract• Background: Reproliferation following vitrectomy for proliferative vitreoretinopathy (PVR) causes redetachment in up to 55% of cases. Heparin and corticosteroids have each been shown to inhibit the development of proliferative vitreoretinopathy (PVR) in experimental models. However, little information is available on the use of these agents in humans. • Methods: In this pilot study, 62 eyes of 62 patients with severe PVR requiring vitrectomy were prospectively randomized to receive either BSS Plus (control) or BSS Plus with heparin and dexamethasone (HD) in the infusate. • Results: After one operation, the retina was reattached in 42 (71%) of 59 eyes: 22 (65%) of 34 eyes in the control group and 20 (80%) of 25 eyes in the HD group (P = 0.16). Reproliferation developed in 26.5% of the control group (9 of 34 eyes) and 16% of the HD group (4 of 25 eyes; P = 0.26). Postoperative hemorrhage was significantly more frequent in the HD group (P = 0.02) but did not influence final visual or anatomic outcome. Hypotony was less frequent in the HD group but the difference was not significant (P = 0.063). • Conclusion: The trend from this randomized pilot study suggests that HD supplementation of the vitrectomy infusate may reduce the reproliferation rate in PVR and possibly reduce the rate of hypotony. Postoperative hemorrhage was more frequent with HD but did not cause redetachment or alter visual outcome. A multicenter trial involving more patients would be required to better evaluate the efficacy of HD as a pharmacologic adjunct to PVR surgery.

Iris Neovascularizadon in Proliferative Vitreoretinopathy

Purpose: The purpose of this study is to report on the prevalence, incidence, and associated risk factors of iris neovascularization in nondiabetic patients undergoing vitrectomy for retinal detachment complicated by proliferative vitreoretinopathy (PVR). Methods: The authors conducted a retrospective review of 141 consecutive nondiabetic patients undergoing vitrectomy for recurrent retinal detachment resulting from PVR. Univariate and multivariate analyses were performed on all patients to determine which preoperative, intraoperative, and postoperative factors were associated with the development of postoperative iris neovascularization. Results: Twenty-seven of the 141 (19%) patients were noted with preoperative and/or postoperative iris neovascularization. Four of eight patients presenting with preoperative iris neovascularization had complete regression after successful reattachment of the retina. Results of analysis of the remaining 133 patients without iris neovascularization preoperatively showed residual retinal detachment as the most significant risk factor for postoperative iris neovascularization. In the absence of panretinal photocoagulation, none of the 27 patients developed neovascular glaucoma. Conclusions: The development of iris neovascularization preoperatively or postoperatively is not necessarily a predictor of a poor anatomic and/or visual result. Iris neovascularization in PVR rarely if ever progresses to neovascular glaucoma. Panretinal photocoagulation is not indicated in these patients. Retinal reattachment is the most important factor in the prevention and/or resolution of postoperative iris neovascularization. The development of iris neovascularization in PVR appears to be a multifactorial process requiring multiple variables acting in concert.

Perfluorocarbon Effects on Rabbit Blood-Retinal Barrier Permeability

Studies have been made of the effects of intravitreal perfluoro-n-octane on the permeability to fluorescein of the blood-retinal barrier in rabbits. At day 1 after injection, there is increased aqueous humor fluorescence that reflects the physical disturbance to the eye following injection. From that time through 7 weeks, there is no evidence of any overt toxicity to the blood-retinal barrier. The retention in the vitreous of a small volume of perfluoro-n-octane following its intraoperative use would not be expected to induce a toxic response. Some effect on an already compromised retina cannot, however, be excluded.