Dennis P. Han

Spectrum and Susceptibilities of Microbiologic Isolates in the Endophthalmitis Vitrectomy Study

PURPOSE To determine the microbiologic spectrum and antibiotic susceptibilities of infecting organisms in postoperative endophthalmitis and to evaluate the effects of operative factors on the microbiologic spectrum. METHODS Patients with bacterial endophthalmitis presenting within six weeks of cataract extraction or secondary intraocular lens implantation (IOL) were evaluated. Cultures and Gram stains were performed on intraocular specimens and susceptibility tests on the isolates. RESULTS Confirmed microbiologic growth was demonstrated from intraocular specimens from 291 of 420 patients (69.3%). Gram-positive bacteria were isolated from 274 patients (94.2%) with confirmed growth and gram-negative bacteria from 19 (6.5%). Two hundred twenty-six of the 323 isolates obtained (70.0%) were gram-positive, coagulase-negative micrococci, 32 (9.9%) Staphylococcus aureus, 29 (9.0%) Streptococcus species, seven (2.2%) Enterococcus species, ten (3.1%) miscellaneous gram-positive species, and 19 (5.9%) gram-negative species. All gram-positive isolates tested were susceptible to vancomycin. Seventeen gram-negative isolates (89%) were susceptible to both amikacin and ceftazidime and two (11%) were resistant to both. Anterior chamber or secondary IOL implantations were associated with higher rates of infection with gram-positives other than coagulase-negative micrococci than were posterior chamber IOL implantations (P = .022) or primary cataract extractions (P = .024). CONCLUSIONS Gram-positive, coagulase-negative micrococci predominated in this series. Vancomycin was active against all gram-positive isolates tested. Amikacin and ceftazidime showed equivalent activity against gram-negative isolates. Secondary or anterior chamber lens implantations were associated with a possible spectrum shift toward gram-positive organisms other than the coagulase-negative micrococci.

Endophthalmitis: A Review of Current Evaluation and Management

Purpose: To review the current state of evaluation and management of various forms of endophthalmitis. Methods: A review of the literature is included, encompassing endophthalmitis occurring after ocular surgeries, intravitreal injection, trauma, and systemic infection. Based on this review, current principles and techniques for evaluating and treating these forms of endophthalmitis are discussed. Results: Postoperative endophthalmitis after cataract surgery is the most common presentation. Conclusions from the Endophthalmitis Vitrectomy Study (EVS) remain a foundation for management of postcataract surgery endophthalmitis, notably prompt intravitreal antibiotic administration after vitreous sampling, with consideration for pars plana vitrectomy in severe cases. The potential impact of advances since the EVS, such as oral fourth generation fluoroquinolones and new vitrectomy techniques, are also discussed. The management of postcataract endophthalmitis is compared and contrasted to endophthalmitis occurring after other ocular surgeries, intravitreal injection, trauma, and systemic infection. Although some principles remain common, treatment rationales differ with other forms of endophthalmitis based on differing clinical circumstances, such as the virulence of organisms that are frequently encountered. Conclusions: Endophthalmitis is a serious, potentially vision threatening condition which can present in various settings. Prompt recognition and treatment are key in maximizing outcomes.

Vision-threatening Complications of Surgery for Full-thickness Macular Holes

OBJECTIVE To study complications of vitrectomy surgery for full-thickness macular holes. DESIGN A multicentered, randomized, controlled clinical trial. PARTICIPANTS Community and university-based ophthalmology clinics. INTERVENTION Standardized macular hole surgery versus observation. MAIN OUTCOME MEASURES Assessment of anatomic and visual outcomes and determination of postoperative complications at 12 months after randomization. RESULTS Posterior segment complications were noted in 39 eyes (41%). The incidence of retinal pigment epithelium (RPE) alteration and retinal detachment (RD) were 33% and 11%, respectively. One RD due to a giant retinal tear resulted in a visual acuity of light perception. Other complications included a reopening of the macular hole in 2 eyes (2%), cystoid macular edema in 1 eye (1%), a choroidal neovascular membrane in 1 eye (1%) and endophthalmitis in 1 eye (1%). Eyes with complications had significantly worse visual acuity outcomes as determined by the Early Treatment Diabetic Retinopathy Study, Word Reading, and Potential Acuity Meter charts (P < 0.01 for all comparisons). Eyes with macular holes greater than 475 microns were more than twice as likely to have complications than eyes with holes less than 475 microns (odds ratio [OR] = 2.2, P = 0.07). Before surgery, the stage of the hole was related to postoperative RPE changes (P < 0.0001) and the occurrence of postoperative RD (P = 0.0002). Intraoperative trauma was related to the occurrence of these complications (P < 0.0001 for RPE changes, P = 0.02 for RDs). Epiretinal membrane removal was related to RPE changes (P = 0.02) but not RDs. CONCLUSIONS The RPE alterations and RDs are common after macular hole surgery and result in significantly reduced postoperative visual acuity. The RPE changes may be related to surgical trauma or light toxicity. Further efforts to reduce complications associated with macular hole surgery are indicated.

Mechanisms of Intraocuular Pressure Elevation after Pars Plana Vitrectomy

Abstract 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 openangle 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), intraoperative 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%).

Endophthalmitis after Pars Plana Vitrectomy

Purpose: To describe the clinical course and incidence of culture-proven Postvitrectomy endophthalmitis in 18 patients from five academic centers and three private practices. Methods: Patients undergoing pars plana vitrectomy for recent trauma or endophthalmitis were excluded. The average age was 58 years (range, 21–85 year). Sixty-one percent of the patients (11/18) had diabetes mellitus. The indication for initial vitrectomy was vitreous hemorrhage (n = 10), macular epiretinal membrane (n = 3), recurrent retinal detachment with proliferative vitreoretinopathy (n = 2), retinal detachment with retinoschisis (n =1), proliferative diabetic retinopathy with tractional retinal detachment (n =1), and dislocated intraocular lens (n =1). None of these eyes received prophylactic intraocular antibiotics during the vitrectomy. Results: All eyes were treated with intraocular antibiotics after the diagnosis of Postvitrectomy endophthalmitis was made. Final visual acuity ranged from 20/20 to no light perception and included five eyes with 20/50 or better visual acuity and 11 eyes with less than 5/200 visual acuity. Nine eyes had a final visual acuity of no light perception. Of the 16 eyes infected with a single organism, 71 % (5J7) of eyes infected with coagulasenegative staphylococci retained 20/50 or better final visual acuity compared with no eyes (0/9) infected with other organisms ( P = 0.005). Two eyes infected with both coagulase-negative Staphylococcus and Streptococcus had a final visual acuity of 20/ 400. Three eyes with a total hypopyon later had enucleation or evisceration. Based on the data from four medical centers, the incidence of endophthalmitis after pars plana vitrectomy performed over the last 10 years was 9/12,216 (0.07%). Conclusion: Endophthalmitis after vitrectomy is rare. Postvitrectomy bacterial endophthalmitis caused by organisms other than coagulase-negative staphylococci has a poor visual prognosis.

Diabetic macular edema associated with glitazone use.

Purpose: To describe diabetic macular edema (DME) in patients who developed fluid retention as a consequence of glitazone use. Methods: A chart review identified 30 patients who used pioglitazone or rosiglitazone and had both lower extremity edema and macular edema. Clinical reports, photographs, and fluorescein angiograms were reviewed. Patients followed for >3 months were analyzed separately. Results: Seventeen patients took oral pioglitazone, 11 took rosiglitazone, and 2 took both drugs at different times. Eleven patients were observed for >3 months after cessation of glitazones. Mean weight gain during drug administration in this group was 30 lb, and mean weight loss after drug discontinuation was 19 lb. Rapid reduction in macular edema off drug occurred in only 4 of 11 patients, but 8 of 11 had reduced edema over 2 years. Mean visual acuity in this group at the initial visit was 20/60, and at the final visit, it was 20/85. Four eyes of three patients had resolution of diffuse macular edema with improved vision after cessation of glitazones without laser treatment. Conclusions: Fluid retention occurs in 5% to 15% of patients taking glitazones. In some of these patients, glitazone use appears to be a cause of macular edema, and drug cessation appears to result in rapid resolution of both peripheral and macular edema. Fluid retention associated with glitazone use should be considered when assessing treatment options for patients with DME, especially those with concomitant peripheral edema.

Tissue Plasminogen Activator for Postvitrectomy Fibrin Formation

The authors injected 25 micrograms of recombinant tissue plasminogen activator (tPA) into the anterior chamber or vitreous cavity of 23 eyes of 22 patients with severe intraocular fibrin formation that developed after vitrectomy surgery for complicated cases of proliferative vitreoretinopathy (PVR) (13 eyes), diabetic traction retinal detachment (TRD) (7 eyes), or endophthalmitis (3 eyes). Tissue plasminogen activator injected an average (+/- standard deviation) of 73 +/- 63 hours after vitrectomy surgery resulted in complete fibrinolysis in 21 of 23 eyes and partial fibrinolysis in one eye. The mean time to fibrin resolution was 3.0 +/- 1.0 hours. Four eyes required repeat tPA injection for recurrent fibrin formation; repeat injection resulted in complete fibrinolysis in each case. The mean follow-up duration after tPA administration was 6 months. At the final follow-up examination, the retina was totally attached in 18 of 23 eyes and was partially attached in 2. Visual acuity improved in 12 eyes (52%); it was at least 20/400 in 8. Complications of tPA injection included hyphema (2 patients) and corneal stromal thickening (2 patients). Mild, transient, periocular pain that was easily managed with non-narcotic analgesia developed in three patients.

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.

Macular Phototoxicity Caused by Fiberoptic Endoillumination During Pars Plana Vitrectomy

Three cases of retinal phototoxicity were caused by light from the endoilluminator used in vitrectomy. Preoperative clinical examination, color photography, and fluorescein angiography in all three cases failed to disclose retinal pigment epithelial changes. Postoperative clinical findings, photographs, and fluorescein angiograms are highly suggestive of the presence of retinal phototoxicity. The characteristics of these lesions and surgical conditions implicate the endoilluminator as the source of photic injury. The macular lesions were noted within one week of the surgical procedure, measured between 2 and 5 disk diameters in size, involved the fovea in two eyes, and resulted in marked decrease in visual acuity in two of three eyes, with persistence in one eye. Initially, whitening of the outer retina was present, but was replaced by pigmentary mottling at the level of the retinal pigment epithelium within a few weeks. Preventive measures to avoid macular phototoxicity associated with vitrectomy are discussed.

The association of HLA-DR15 and intermediate uveitis.

PURPOSE To evaluate the association between human leukocyte antigen (HLA-DR15) specificity and intermediate uveitis. METHODS Eighteen patients diagnosed with intermediate uveitis underwent HLA-DR15 serotyping. Additionally, DNA-based phenotyping for a specific HLA-DR15 allele was performed in four patients. The clinical features of HLA-DR15-positive intermediate uveitis were compared with those of HLA-DR15-negative intermediate uveitis. RESULTS Thirteen of 18 patients (72%) were positive for HLA-DR15. The frequency of the HLA-DR15 specificity in intermediate uveitis patients was significantly higher than in the control subjects (relative risk, 6.36; P < .001). Each of four patients tested carried the specific allele, DR beta 1*1501, which has been associated with multiple sclerosis. In the HLA-DR15-positive group were four patients (31%) with coexisting multiple sclerosis or optic neuritis, one patient with coexisting narcolepsy, and three patients (23%) with a family history of multiple sclerosis. Retinal periphlebitis, especially if bilateral, was a frequent ophthalmoscopic finding in HLA-DR15-positive intermediate uveitis. CONCLUSIONS This study identifies a significant association between intermediate uveitis and the HLA-DR15 specificity. Patients who are HLA-DR15-positive and have intermediate uveitis may have systemic findings of another HLA-DR15-related disorder. Intermediate uveitis may belong to a constellation of HLA-DR15-related disorders, which includes multiple sclerosis, optic neuritis, and narcolepsy.