Management of retained intravitreal lens fragments after cataract surgery.

With the rise of popularity of phacoemulsification as the preferred surgical method for cataract extraction, there has been an increased incidence of posterior dislocation of lens fragments. The appropriate management of this complication both during and after cataract extraction is discussed in this review. It is suggested that vigorous attempts by the cataract surgeon to retrieve intravitreal lens fragments should be avoided. Timely referral to a posterior segment surgeon for pars plana vitrectomy and removal of lens fragments can result in good visual outcome. Complications, such as glaucoma and retinal detachment, may develop in some cases. The importance of careful clinical follow-up is emphasized.

Treatment of experimental Staphylococcus epidermidis endophthalmitis with oral trovafloxacin.

PURPOSE: To investigate the ocular pharmacokinetics and efficacy of oral trovafloxacin, a novel fluoroquinolone antibiotic, in Staphylococcus epidermidis endophthalmitis. METHODS: Albino rabbits (n = 20) were infected with an intravitreal inoculum of S epidermidis (1.0 x 10(8) colony-forming units [CFU/0.1 ml) and 24 hours later received a single oral dose of trovafloxacin (250 mg/kg). Serum and intraocular samples from infected and control (noninfected) eyes were obtained up to 24 hours after antibiotic administration for measurement of trovafloxacin levels. A second group of rabbits (n = 72) was infected intraocularly and randomized 24 hours later to oral trovafloxacin (250 mg/kg twice a day) for 6 days or no treatment (control). Treatment efficacy was assessed by vitreous culture, clinical examination, and histopathology. RESULTS: Following a single dose of trovafloxacin, maximal vitreous levels were achieved at 8 hours in infected eyes, with a penetration ratio of 36%. Vitreous levels were greater than 15 times the minimum inhibitory concentration of the strain employed. In animals with established endophthalmitis, treated eyes were sterilized after 5 days (P = .0495) compared with control eyes, which autosterilized at 14 days. Clinical and histologic examination revealed significant amelioration of anterior segment inflammation in treated eyes, although severe destruction of posterior segment structures occurred in both groups after 6 days of therapy. CONCLUSIONS: These data support trovafloxacin as a potential oral agent for treatment or prophylaxis of S epidermidis endophthalmitis, although retinal alterations that occur over the period required for vitreous sterilization suggest that it will not replace intravitreal therapy in established endophthalmitis.

Optic nerve avulsion.

OBJECTIVE: To characterize the presentation, role of diagnostic imaging, and course in patients with optic nerve avulsion. METHODS: A retrospective review of medical records of all 6 patients with optic nerve avulsion who were seen at the Massachusetts Eye and Ear Infirmary, Boston, from January 1, 1991, to July 31, 1995. RESULTS: The initial visual acuity ranged from 20/100 to no light perception. All 6 patients underwent neuroimaging, including computed tomography, magnetic resonance imaging, or both. B-scan ultrasonography was performed on 4 patients, and the condition of 1 patient was evaluated with color Doppler ultrasonography to assess the optic nerve vasculature. In 1 patient, a computed tomographic scan was suggestive of an optic nerve avulsion. Neuroimaging in the other 5 patients, including 2 patients who underwent magnetic resonance imaging, failed to demonstrate an avulsion. During a follow-up period of up to 25 months, 4 patients showed no improvement in visual acuity, 1 patient improved from no light perception to bare light perception, and 1 patient improved from 20/100 to 20/25. CONCLUSIONS: These data suggest that final visual outcome was dependent on initial postinjury visual acuity. Neuroimaging, B-scans, and Doppler ultrasonography were usually not helpful in establishing the presence of optic nerve avulsion, although they may be useful in evaluating comorbid conditions.

Implication of pneumolysin as a virulence factor in Streptococcus pneumoniae endophthalmitis.

PURPOSE: To determine if pneumolysin, a multifunctional cytotoxin produced by Streptococcus pneumoniae, may be a virulence determinant in the pathogenesis of pneumococcal endophthalmitis. METHODS: Lewis rats (n = 20) were injected intravitreally with purified recombinant pneumolysin at the following doses; 3.9 hemolytic units (HU), 39 HU, 390 HU, 3.9 x 10(3) HU, and 3.9 x 10(4) HU. After 24 hours, eyes were examined clinically and enucleated for histopathologic examination to elucidate the dose-response relationship. To determine the temporal progression of the disease model, a second group of rats (n = 8) were injected intravitreally with 390 HU of pneumolysin. At 6 and 48 hours, eyes were examined clinically and enucleated for histopathology. RESULTS: Eyes injected with pneumolysin demonstrated increasing anterior and posterior segment inflammation in response to increasing doses of administered toxin. The onset of inflammation and tissue damage occurred rapidly, and was maximal at 24 to 48 hours. The clinical and histopathologic changes observed mimicked those of S. pneumoniae endophthalmitis. Histopathologic analysis demonstrated rapid onset of iridocyclitis and vitritis with polymorphonuclear leukocyte influx, inner retinal necrosis, and retinal detachment. Retinal pigment epithelial necrosis and choroiditis were noted at the highest doses administered. Inflamed eyes were shown to be sterile. CONCLUSIONS: Pneumolysin injected intravitreally induces many of the clinical and histopathologic features of pneumococcal endophthalmitis, and may play an important role in the inflammation and tissue damage that occurs in pneumococcal endophthalmitis.

Inhaled steroids: effect on intraocular pressure in patients without glaucoma.

OBJECTIVE: To evaluate the risk of intraocular pressure (IOP) elevation in patients receiving inhaled steroid therapy. DESIGN: Prospective study. SETTING: Four private practices in New Jersey. PATIENTS: A total of 187 patients (99 men and 88 women) with no documented history of glaucoma about to begin inhaled steroid therapy for various pulmonary conditions were enrolled. Of the 187, 183 were followed at 12 weeks. INTERVENTIONS: Measurement of the IOP with the Tono-Pen before therapy was started and 12 weeks after therapy was started. OUTCOME MEASURE: IOP. RESULTS: No significant rise in IOP was observed. No patient had a rise in IOP greater than 4 mm Hg. CONCLUSIONS: Although isolated case reports indicate a definite risk of glaucoma in the presence of inhaled steroid therapy, the risk appears to be small.

Endogenous fungal endophthalmitis.

Endogenous fungal endophthalmitis has increased in the past half-century because of the advent of antibiotics and indwelling catheters. The disease process can produce highly suggestive, though nonpathognomonic, ocular signs that assist the clinician in reaching a diagnosis. Intraocular inflammation, especially if it is granulomatous in nature in a patient with one or more of the risk factors already discussed, should raise the suspicion of fungal endophthalmitis. If a diagnosis remains elusive, vitreous biopsy is indicated for proper identification of a fungal organism. Although a particular therapeutic regimen has not yet been prospectively established, compelling arguments can be made to treat nearly all patients with endogenous fungal endophthalmitis with a systemic antifungal such as amphotericin B or fluconazole. A possible exception includes an IVDA-related endophthalmitis in a patient with negative blood cultures and without other evidence of fungemia. Vitrectomy and intravitreal amphotericin B (with or without intravitreal corticosteroid) should be considered in cases of endogenous fungal endophthalmitis in which there is substantial vitreous involvement, and also in cases in which there is clear progression of disease despite initial therapy with an appropriate systemic antifungal agent. Prompt therapy following early diagnosis will help reduce significant visual loss in all forms of fungal endophthalmitis.

Effect of intravitreal dexamethasone in treatment of pneumococcal endophthalmitis in rabbits.

PURPOSE: To investigate whether corticosteroid therapy would decrease the inflammation and tissue damage associated with pneumococcal endophthalmitis. METHODS: Albino rabbits were injected intravitreally with 1000 live organisms of Streptococcus pneumoniae and randomized after 24 hours to treatment with intravitreal vancomycin hydrochloride alone (n = 10), combination intravitreal vancomycin and intravitreal dexamethasone (n = 10), or no treatment (n = 10). After 2 weeks, the eyes were examined clinically and enucleated for histopathologic examination. RESULTS: Eyes treated with vancomycin and dexamethasone had significantly less intraocular inflammation and more preservation of retinal tissue than untreated eyes or eyes treated with vancomycin alone (P < .05, Fisher's exact test). Untreated and vancomycin-treated eyes were indistinguishable on clinical and histologic examination. Marked anterior and posterior segment inflammation with total retinal necrosis was noted in eyes from both groups. CONCLUSION: Intravitreal corticosteroid therapy may play an important role in minimizing the inflammation and tissue damage associated with pneumococcal endophthalmitis.

Differential activation of yeast adenylate cyclase by wild-type and mutant RAS proteins.

In these experiments we demonstrate that purified RAS proteins, whether derived from the yeast RAS1 or RAS2 or the human H-ras genes, activate yeast adenylate cyclase in the presence of guanine nucleotides. These results confirm the prediction of earlier genetic and biochemical data and for the first time provide a complete biochemical assay for RAS protein function. Furthermore, we observe a biochemical difference between the RAS2 and RAS2val19 proteins in their ability to activate adenylate cyclase after preincubation with GTP.