Denis M. O'Day

National Outcomes of Cataract Extraction: Increased Risk of Retinal Complications Associated with Nd.-YAG Laser Capsulotomy

PURPOSE The authors studied 57,103 randomly selected Medicare beneficiaries who underwent extracapsular cataract extraction in 1986 or 1987 to determine the possible association between performance of neodymium (Nd):YAG laser capsulotomy and the risk of subsequent retinal break or detachment. METHODS Cases of cataract surgery were identified from Medicare claims submitted in 1986 and 1987 and were followed through the end of 1988. Episodes of cataract surgery, posterior capsulotomy, and retinal complications were ascertained based on procedure and diagnosis codes listed in physician bills and hospital discharge records. Lifetable and Coxs proportional hazards models were used to analyze the risk of retinal detachment or break in patients undergoing and not undergoing capsulotomy during the period of observation. RESULTS Of the 57,103 persons identified as having undergone extracapsular cataract extraction in 1986 or 1987, 13,709 subsequently underwent Nd:YAG laser capsulotomy between 1986 and 1988. A total of 337 persons had aphakic or pseudophakic retinal detachments between 1986 and 1988 and an additional 194 underwent repair of a retinal break. Proportional hazards modeling shows a 3.9-fold increase in the risk of retinal break or detachment among those who underwent capsulotomy (95% confidence interval: 2.89 to 5.25). Younger patient age, male sex, and white race also were associated with increased risk of retinal complications after extracapsular cataract extraction. CONCLUSION The authors conclude that there is a statistically significant increase in the risk of retinal detachment or break in those patients who undergo capsulotomy after cataract extraction. Therefore, capsulotomy should be deferred until the patients impairment caused by capsular opacification warrants the increased risk of retinal complications associated with performance of capsulotomy.

Acanthamoeba Keratitis: A Growing Problem in Soft and Hard Contact Lens Wearers

Eleven contact lens-wearing patients presented with Acanthamoeba keratitis. Eight cases were culture- and/or stain-positive for Acanthamoeba and three were presumed to have Acanthamoeba keratitis based on history and clinical findings. Six wore daily wear soft contact lenses, two wore extended-wear soft contact lenses, one wore a polymethylmethacrylate hard contact lens, one wore a gas-permeable hard contact lens, and one wore a Saturn lens (combined hard and soft lens). Four patients used distilled water and salt tablet saline, three used tap water and salt tablet saline, two used tap water rinse, two used well water rinse or storage, and one used intravenous (IV) saline. It is apparent that all contact lens wearers are at some risk for Acanthamoeba keratitis developing if proper contact lens care is not maintained. Of great concern is the inability of most current chemical sterilization methods to kill the organism if the lens becomes contaminated. Heat disinfection will kill Acanthamoeba trophozoites and cysts but the lens must not be placed into contaminated solutions afterward. Prevention is very important because medical and surgical treatment failures are frequent. Eye care practitioners who fit contact lenses are advised to use heat disinfection for low-water content stock soft contact lenses, and to use hydrogen peroxide without a catalyst for a minimum of 6 hours for all other stock lens fitting sets, to specifically inquire about contact lens care habits used by their patients, and to discourage the use of homemade saline solutions.

Corneal penetration of topical amphotericin B and natamycin

The corneal uptake and penetration of 14C-labelled 0.15% amphotericin B and 5% natamycin were studied in Dutch-belted rabbits. Corneal levels of natamycin were substantially higher than amphotericin B. For both drugs, these levels were influenced by corneal contact time. In corneas debrided of epithelium, both agents entered the corneal stroma and levels were detected in aqueous in the therapeutic range. However, in corneas with intact epithelium, penetration was negligible for amphotericin B (0.23 microgram/gm at 2 mins). By contrast, although penetration of natamycin was greatly reduced, 7.0 micrograms/gm were present at 2 mins.

The Problem of Bacillus Species Infection with Special Emphasis on the Virulence of Bacillus cereus

Although Bacillus cereus is an uncommon ocular pathogen, infection with it usually results in loss of the eye. Although previous reports have emphasized endogenous infection, our recent experience indicates the importance of B cereus infection following trauma. Management is hampered by ineffectiveness of current empirical antibiotic regimens. This microorganism is resistant to both the penicillins and the cephalosporins. Although B cereus is susceptible to gentamicin, our studies indicate that gentamicin by itself is inadequate to eradicate the infection. B cereus, however, is susceptible to clindamycin and combined therapy with gentamicin and clindamycin appears to offer the best approach. Early diagnosis is the key to successful treatment. We believe the clinical circumstances likely to lead to B cereus infection, as well as the manifestations of the disease itself, are sufficiently distinctive to alert the ophthalmologist to the possibility of this infection. Prompt recognition of the infection should allow institution of appropriate therapy before permanent structural changes occur.

Epidemic Postsurgical Candida Parapsilosis Endophthalmitis: Clinical Findings and Management of 15 Consecutive Cases

Fifteen cases of postoperative Candida parapsilosis endophthalmitis occurring secondary to a contaminated lot of an irrigating solution were studied. All patients underwent a vitreous tap or diagnostic and therapeutic vitrectomy. Eleven of the 15 specimens were positive for the organism. Fourteen patients were treated with pars plana vitrectomy surgery. All patients were treated with intravitreal amphotericin B and systemic amphotericin B and 5-fluorocytosine. Two clinical recurrences were successfully treated with intravitreal amphotericin B, removal of the pseudophakos, and oral ketoconazole. The intraocular lens was retained in 11 of the 14 pseudophakic patients. Final visual acuities ranged from 20/25 to no light perception with eight of 15 patients having 20/60 or better visual acuities. Measurable levels of intraocular amphotericin B were found after systemic amphotericin B administration. Two patients with totals of 20 and 30 micrograms of intravitreal amphotericin B over 48 and 96 hours, respectively, had near normal ERGs one year later. Posterior capsulotomy and vitrectomy appear to decrease amphotericin B toxicity and allow sequential intraocular injection of this drug within a short time period.

Improving Diabetic Retinopathy Screening Ratios Using Telemedicine-Based Digital Retinal Imaging Technology The Vine Hill Study

OBJECTIVE—To evaluate the impact of a telemedicine, digital retinal imaging strategy on diabetic retinopathy screening rates in an inner-city primary care clinic. RESEARCH DESIGN AND METHODS—This retrospective cohort study included all diabetic patients aged ≥18 years (n = 495) seen at Vine Hill Community Clinic between 1 September 2003 and 31 August 2004. Patients were offered ophthalmology referral or digital screening. Patients choosing referral received the next available (within 3 months) appointment at the Vanderbilt Eye Clinic; patients choosing digital screening were screened during the visit. RESULTS—Retinal screening was documented for 293 (59.2%) patients, a significant improvement compared with the 23% baseline rate. Of 293 patients screened, 92 (31.4%) were screened in ophthalmology, and 201 (68.6%) were digitally screened. Among the 201 digitally screened patients, 104 (51.7%) screened negative and were advised to rescreen in 1 year, 75 (37.3%) screened positive and were nonurgently referred to ophthalmology, and 22 (11.0%) screened positive for sight-threatening eye disease and were urgently referred for ophthalmological follow-up. Digital imaging technical failure rate was 0.5%. Referral status was associated with race/ethnicity (χ2 = 7.9, P < 0.02) with whites more likely to screen negative than non-whites (62.4 vs. 47.8%, respectively). Sight-threatening disease among non-whites (14.7%) was more than double that observed for whites (5.9%). CONCLUSIONS—Digital imaging technology in the primary care visit can significantly improve screening rates over conventional methods, increase access to recommended diabetic eye care, and focus specialty care on medically indigent patients with greatest need.

Pharmacologic management of keratomycoses

Fungal corneal infections can be very difficult to treat. An evolving understanding of the pharmacology of the currently available antifungal agents has led to improved medical treatment of the keratomycoses. The pharmacology, pharmacokinetics, spectrum of activity and toxicity of these agents is reviewed and promising new antifungal compounds and modes of treatment are discussed.

Intraocular penetration of systemically administered antifungal agents.

Amphotericin B, 5-flucytosine (5-FC), and ketoconazole levels were estimated in vitreous and aqueous samples taken from four patients undergoing therapeutic vitrectomy for fungal endophthalmitis. The levels of amphotericin B in the vitreous of three patients were low (.04 - .17 microgram/ml). However, 5-FC was present in a concentration of 22.2 micrograms/ml in one patient. In another case the aqueous level of ketoconazole was 0.35 microgram/ml. The vitreous in the same patient contained 0.71 microgram/ml of the drug.

Statistical analysis for experimental models of ocular disease: Continuous response measures

Experimental designs in ophthalmologic research frequently treat both eyes of a subject in the same fashion: e.g., therapy with a specific drug or control. In these two-eye designs, observations from the same subject are often positively correlated. Failure to account for this correlation is a serious error which overstates the precision of studies, resulting in falsely significant results. This paper reviews the statistical methods appropriate for studies where endpoints are quantitative. We present: (1) the use of analysis of variance (t-test when there are 2 treatment conditions) to estimate differences between all experimental treatments, (2) the use of contrasts to estimate differences between specific treatments, and (3) methods for analysis of data from multiple experiments. Because of the ubiquity of incorrect analysis of data from two-eye designs in the ophthalmologic research literature and the serious consequences of this error, we propose a limited statistical review of manuscripts to ascertain if the statistical analysis matched the experimental design.

Hla Antigens in Recurrent Stromal Herpes Simplex Virus Keratitis

HLA-A, HLA-B, and HLA-C antigens were typed on 48 patients with recurrent herpes stromal keratitis. The HLA-Aw30 antigen occurred three times more frequently in patients with herpes stromal keratitis than in those who lack the Aw30 antigen. When the data for the probability of the HLA-Aw30 were corrected for the number of variables studied, the corrected P value was not significant. A previous report of an increased frequency of HLA-B5 with recurrent herpes keratitis was not confirmed by our study. No significant associations with the HLA-C antigens were noted. HLA-DR antigen typing of 25 herpes stromal keratitis patients indicated that the HLA-DRw3 antigen appeared to have an increased frequency in herpes stromal keratitis. However, the small sample size studied precluded interpretation of the increased phenotypic frequency and the possible association of HLA-DRw3 and herpes stromal keratitis needs further study.