Andrew Apel

Risk factors and causative organisms in microbial keratitis.

Purpose: To establish the risk factors, causative organisms, levels of antibiotic resistance, patient demographics, clinical presentations, and clinical outcomes of microbial keratitis at a tertiary hospital in Australia. Methods: Patients who had a corneal scraping for culture over a 5-year period were identified through the local microbiology database, and a retrospective audit of their medical records was carried out. Clinical information was gathered from medical records, and smear, culture, and antibiotic resistance results were from the microbiology database. An index of disease severity was calculated for each patient from scores for the magnitude of the epithelial defect and anterior-chamber reaction and the location of the lesion. Associations between risk factors for keratitis and variables such as patient demographics, causative organism and antibiotic resistance, disease severity, and outcome were analyzed by using analysis of variance and χ2 tests with appropriate correction for multiple comparisons. Results: Two hundred fifty-three cases of microbial keratitis in 231 patients were included. Sixty percent of patients were men, and there was a bimodal distribution in the age of presentation. Common risk factors for keratitis were contact lens wear (53; 22%), ocular surface disease (45; 18%), ocular trauma (41; 16%), and prior ocular surgery (28; 11%). Gram stains were positive in 33%, with a sensitivity of 53% and specificity of 89%. Cultures of corneal scrapings were positive in 65% of cases, and Pseudomonas aeruginosa (44; 17%), coagulase-negative staphylococci (22; 9%), Staphylococcus aureus (19; 8%), and fungi (7; 3%) were commonly recovered. P. aeruginosa was more common than other culture results in contact lens-related cases (55% vs. 0%-23%; P < 0.001), and S. aureus was more common than other culture results in ocular surgery-related cases (29% vs. 0%-21%; P < 0.001). Patients with keratitis related to prior ocular surface disease had more severe keratitis at the time of scraping (P = 0.037). Cultures positive for Fusarium, P. aeruginosa, and other Gram-negative organisms had statistically significantly more severe keratitis at the time of scraping, whereas patients with negative cultures had milder keratitis (P = 0.030). Only 2% of all bacterial isolates were resistant to ciprofloxacin, 20% of Gram-positive isolates were resistant to cephalothin, and no Gram-negative isolates were resistant to gentamicin. Conclusions: In this series, the most common risk factor for keratitis was contact lens wear and the most commonly isolated organism was P. aeruginosa.

Infectious keratitis in orthokeratology

Orthokeratology is a method of changing refraction in myopic patients by using rigid contact lenses to reduce the curvature of the cornea. This treatment was in use in the two cases of corneal ulcer described in this paper and appears to have contributed to the development of their disease. As with extended wear contact lenses, patients undergoing orthokeratology treatment are frequently advised to wear the orthokeratology lenses overnight increasing the risk of corneal ulceration and infection. Patients should be adequately warned of the associated risks and advised that any envisaged benefits of the procedure are temporary.

A longitudinal study of trends in keratitis in Australia.

Purpose: To analyze the changes in risk factors, corneal culture results, antibiotic resistance, treatment, and clinical outcomes of patients with keratitis presenting to a major public hospital in Australia over a 5-year period. Methods: A retrospective audit of all patients who had a corneal scraping between October 1999 and September 2004 at the Princess Alexandra Hospital. Clinical information was gathered from medical records and smear and culture results from the local microbiology database. The trends over time in patient demographics, keratitis risk factors, corneal culture results, antibiotic resistance, treatment, and clinical outcomes were analyzed by using linear regression. By using a moving average, we analyzed differences in the rate of culture of each causative organism for each month of the year with linear regression from the month of highest presentation. The mean of maximum temperatures on the days of presentation between different groups of organisms was compared. Results: The proportion of patients presenting with keratitis related to contact lens wear increased significantly (12%-29%; P = 0.04) and with keratitis related to ocular surgery decreased significantly (18%-8%; P = 0.009) through the study. Antibiotic resistance of cultured bacteria to cephalothin increased significantly (2%-12%; P = 0.02), whereas resistance to ciprofloxacin and gentamicin remained at a low level throughout the study. There was significant variation in the monthly recovery of Pseudomonas aeruginosa (P = 0.04) and fungi (P = 0.02), which were cultured more frequently in summer months, whereas Streptococcus pneumoniae (P = 0.04) was more common in winter months than in other times of the year. Treatment with fluoroquinolones increased significantly (14%-40%; P = 0.002) through the study, and the rate of good outcomes also increased significantly (42%-72%; P = 0.02). Conclusions: In this series, keratitis related to contact lens wear became more frequent, whereas keratitis related to prior ocular surgery became less frequent. Different organism groups showed significant seasonal variations in their presentation, and bacterial resistance to cephalothin increased significantly.

Comparison of the AcrySof SA60 spherical intraocular lens and the AcrySof Toric SN60T3 intraocular lens outcomes in patients with low amounts of corneal astigmatism

Background:  Toric intraocular lenses (IOLs) have been reported to be an effective method of reducing postoperative refractive astigmatism and spectacle dependence following cataract surgery. This study compares a series of patients with low corneal astigmatism implanted with either the AcrySof SA60 spherical IOL or the AcrySof Toric SN60T3 IOL in a quantitative fashion to establish the merit of toric IOLs in these cases.

Clinical outcomes of keratitis

Objection:  To analyse the patient, clinical and microbiological variables associated with poor outcomes from keratitis in patients presenting to a major public hospital in Australia.

Perfluorodecalin Corneal Toxicity: Five Case Reports

Perfluorodecalin is a perfluorocarbon liquid used intraoperatively in retinal detachment repair. It is usually removed at the end of the procedure; however, residual amounts may be retained when poor corneal clarity or intraocular hemorrhage obscures the view. No clinical reports exist on the consequences of retained perfluorodecalin in the anterior segment. We report five cases in which perfluorodecalin was in prolonged contact with the cornea. The period of time for corneal pathology to occur and the role perfluorodecalin played in the etiology of such changes is discussed. A total of 348 patients with retinal detachments in one retinal practice underwent repair using pars plana vitrectomy combined with intraoperative perfluorodecalin between January 1992 and May 1994. Postoperatively, residual perfluorodecalin was observed in the anterior chamber in contact with the corneal endothelium in five patients. The patients were followed clinically for a period of up to 18 months. Four of five patients developed corneal changes from prolonged contact with perfluorodecalin. Corneal edema developed in the area perfluorodecalin-endothelial contact in three of five eyes. The period of perfluorodecalin-endothelial contact before corneal decompensation occurred ranged from 4 to 13 weeks. Two eyes required penetrating keratoplasties for progressive corneal edema. Corneal edema was reversed in one eye after removal of perfluorodecalin from the anterior chamber via multiple paracentesis. One of the remaining eyes developed deep corneal vascularization without edema in the area of perfluorodecalin contact after 12 months. These observations suggest that corneal toxicity may be induced by intraocular perfluorodecalin if it is allowed direct contact with the corneal endothelium for periods as short as 1 month. Some of these changes may be reversible if perfluorodecalin is aspirated from the anterior chamber. Further investigations are required to examine perfluorodecalin-induced corneal toxicity.

Aciclovir‐resistant herpes keratitis

Herpes simplex virus (HSV) keratitis is a common cause of ocular morbidity. Resistance to aciclovir is probably under recognized. We describe three cases of aciclovir‐resistant herpes simplex virus keratitis treated with systemic foscarnet and present a review of the pharmacological options available to manage this condition.

Early Intraocular Pressure After Phacoemulsification Combined With Trabeculectomy

BACKGROUND AND OBJECTIVE To determine the efficacy of combined phacoemulsification--trabeculectomy in preventing early postoperative increases in intraocular pressure (IOP). PATIENTS AND METHODS Eighty patients were enrolled in a prospective cohort study. Thirty-six patients with cataracts and uncontrolled glaucoma underwent combined phacoemulsification--trabeculectomy, and 44 patients with cataracts underwent phacoemulsification alone. The operations were performed in a standardized manner by one surgeon. IOP was measured at 4 hours, 1 day, and 7 days after surgery. The need for intervention (digital massage, medications) and the presence of complications were documented. RESULTS Four hours after surgery, 5.5% of patients undergoing the combined procedure had IOPs greater than 30 mm Hg, compared with 22.7% of phacoemulsification patients (P < .05). No significant difference in IOP was found between the groups at postoperative day 1 or day 7. CONCLUSION These results suggest that combined phacoemulsification-trabeculectomy protects against early postoperative elevations in IOP. This finding may influence the surgical management of cataracts in patients with poorly controlled glaucoma and significant compromise of visual field or optic nerve.

Current status and future prospects for cultured limbal tissue transplants in Australia and New Zealand.

Cultured limbal tissue transplants have become widely used over the last decade as a treatment for limbal stem cell deficiency (LSCD). While the number of patients afflicted with LSCD in Australia and New Zealand is considered to be relatively low, the impact of this disease on quality of life is so severe that the potential efficacy of cultured transplants has necessitated investigation. We presently review the basic biology and experimental strategies associated with the use of cultured limbal tissue transplants in Australia and New Zealand. In doing so, we aim to encourage informed discussion on the issues required to advance the use of cultured limbal transplants in Australia and New Zealand. Moreover, we propose that a collaborative network could be established to maintain access to the technology in conjunction with a number of other existing and emerging treatments for eye diseases.

Outcomes of combined penetrating keratoplasty and cataract extraction compared with penetrating keratoplasty alone.

Purpose:  To compare the rejection rates, graft failure rates, mean visual, keratometric and refractive outcomes of combined penetrating keratoplasty and cataract extraction with penetrating keratoplasty alone.