Vitrectomy in the management of peripheral uveitis

The natural history of peripheral uveitis may eventually lead to indications for vitreous surgery. Over a 7-year period, a consecutive series of 12 eyes in nine patients with peripheral uveitis underwent vitreous surgery. Indications for surgery included persistent dense vitreous inflammation, vitreous hemorrhage, traction retinal detachment (RD), and epiretinal membrane formation. Patients were followed for an average of 22 months. Six eyes (50%) required further surgery after the development of RD, recurrent vitreous hemorrhage, or cataract formation. The preoperative finding most frequently associated with postoperative complications was the presence of active neovascularization of the vitreous base. Final visual acuity ranged from 20/30 to 20/100 showing an average improvement of 5 Snellen lines. Persistent cystoid macular edema significantly limited visual improvement in five patients. Patients undergoing vitreous surgery for management of peripheral uveitis may show a significant degree of visual improvement though multiple operations may be required. Control of active neovascularization is an important factor in limiting postoperative complications and the need for further surgery.     

Photocoagulation to prevent retinal detachment in acute retinal necrosis

Retinal detachment (RD) occurs in more than 50% of eyes with acute retinal necrosis (ARN) and is the leading cause of visual loss in this syndrome. In order to decrease the incidence of RD in ARN, the authors treated 12 eyes of 10 patients with prophylactic laser photocoagulation. Retinal detachment occurred in two eyes (17%). Over the same time period, seven eyes with ARN did not receive prophylactic laser treatment, most often because of dense vitreous debris, with a 67% rate of RD. Prophylactic photocoagulation treatment should be considered in the management of patients with ARN.     

Mechanisms of intraocular pressure elevation after pars plana vitrectomy

A prospective study of 222 consecutive patients undergoing pars plana vitrectomy was done to determine the incidence and mechanisms of postoperative intraocular pressure (IOP) elevation. Within 48 hours of surgery, postoperative IOP increased by at least 5 to 22 mmHg in 136 eyes (61.3%) and to 30 mmHg or more in 79 eyes (35.6%). Presumed mechanisms of open-angle glaucoma included intraocular gas expansion (28.4%), inflammatory trabecular meshwork obstruction (4.5%), silicone oil-related glaucoma (3.6%), and erythroclastic glaucoma (2.2%). Closed-angle mechanisms included pupillary block glaucoma (6.8%) and ciliary body edema (3.6%). Factors which were associated with postvitrectomy pressure elevation included placement of a scleral buckle, either intraoperatively (P = 0.003) or before vitrectomy (P = 0.001), intraoperative scatter endophotocoagulation (P = 0.041), intra-operative lensectomy (P = 0.024), and development of postoperative fibrin membranes (P = 0.038). Surgery was required to lower IOP or relieve pupillary block in 25 eyes (11.3%).     

Decrease in the risk of bilateral acute retinal necrosis by acyclovir therapy

We reviewed the course of 54 patients who had unilateral acute retinal necrosis at initial examination. Thirty-one patients were treated with acyclovir, whereas 23 were not. Of the 31 patients treated with acyclovir, 27 (87.1%) had fellow eyes that remained disease-free throughout a median follow-up of 12 months. Of the 23 patients not treated with acyclovir, seven (30.4%) had fellow eyes that remained disease-free throughout a median follow-up of 11 months. Survival analysis indicated that the fellow eyes of the group of patients treated with acyclovir were more likely to remain disease-free than the fellow eyes of the group not treated with acyclovir (P = .0013). Two years after initial onset, the proportion of fellow eyes that remained disease-free was 75.3% for the group treated with acyclovir and 35.1% for the group not treated with acyclovir. These results suggest that acyclovir treatment reduces the risk of involvement of the fellow eye in patients with acute retinal necrosis.     

Resolution of an apparent choroidal melanoma

A 67-year-old white woman had a lesion that clinically, echographically, and angiographically appeared to be consistent with choroidal melanoma. At follow-up examination 2 months later, the lesion had clinically completely resolved. A limited choroidal hemorrhage simulating a choroidal melanoma is postulated.     

A computerized method for rapid quantification of gallbladder volume from real-time sonograms

A computerized method that requires only 1-2 minutes to quantify gallbladder volume from real-time sonograms is described. This time is considerably shorter than that required using the hand-calculation method. There was a highly significant correlation between gallbladder volumes calculated by computer and hand (r = 0.97; P less than .001).     

Three-compartment wrist arthrography: use of a low-iodine-concentration contrast agent to decrease study time

To decrease examination time, the authors used a contrast agent with a low iodine concentration for three-compartment (radiocarpal joint, distal radioulnar joint, midcarpal compartment) wrist arthrography. The material was used in 24 patients. Many patients demonstrated dissipation of contrast material in the radiocarpal joint by 30 minutes after injection. By 45 minutes, all patients demonstrated sufficient dissipation to permit the second injection. The technique produces diagnostic images and reduces the time required for the study.     

Extended ocular drug delivery systems for the anterior and posterior segments: biomaterial options and applications

Introduction: The development of new therapies for treating various eye conditions has led to a demand for extended release delivery systems, which would lessen the need for frequent application while still achieving therapeutic drug levels in the target tissues.

Areas covered: Following an overview of the different ocular drug delivery modalities, this article surveys the biomaterials used to develop sustained release drug delivery systems. Microspheres, nanospheres, liposomes, hydrogels, and composite systems are discussed in terms of their primary materials. The advantages and disadvantages of each drug delivery system are discussed for various applications. Recommendations for modifications and strategies for improvements to these basic systems are also discussed.

Expert opinion: An ideal sustained release drug delivery system should be able to encapsulate and deliver the necessary drug to the target tissues at a therapeutic level without any detriment to the drug. Drug encapsulation should be as high as possible to minimize loss and unless it is specifically desired, the initial burst of drug release should be kept to a minimum. By modifying various biomaterials, it is possible to achieve sustained drug delivery to both the anterior and posterior segments of the eye.