Microbial keratitis in Thailand: a survey of common practice patterns.

OBJECTIVE: To describe the current practice patterns and prescription preferences in treating microbial keratitis in Thailand. MATERIAL AND METHOD: A questionnaire was designed and sent to ophthalmologists to describe their practice in patients with microbial keratitis. The questionnaire also presented two case scenarios with microbial keratitis; the less severe in the first patient and the more severe in the second. The recipients were asked about their diagnostic and therapeutic approaches. The surveys were mailed to 300 ophthalmologists around the country. RESULTS: One hundred and forty-three surveys (48.6%) were used in the analysis. Over half the respondents (56%) would do corneal scraping for some patients with suspected microbial keratitis. Smears and cultures of corneal specimens are the most common diagnostic tools (92%) to identify the causative organisms. Of the respondents, 60% would treat Case 1 as an outpatient, compared with 90% would admit Case 2. About half the respondents (47%) would initiate treatment in Case 1 without obtaining scrapings, whereas 79% would prefer microbial work up in Case 2. Monotherapy with topical fluoroquinolone was the most common initial antibiotic prescribed for Case 1 (36%), whereas in Case 2, combined fortified antibiotics (23%) and combined topical antibiotic and topical antifungal (22%) were preferred. For fungal keratitis, topical natamycin and amphotericin B were the most common choices (20% each). CONCLUSIONS: Most Thai ophthalmologists appear to treat patients with suspected microbial keratitis differently, depending on etiology and severity. However, there are some variations in management. The validity of this approach should be established to specify patterns that are most safe and effective.

Assessment of the anterior structures of eyes in a normal Northern Thai group using the Orbscan II.

OBJECTIVES: To evaluate the anterior structures of the eyes in normal Northern Thais include the corneal topography and thickness, as well as the anterior chamber depth (ACD) and the white-to-white (WTW) using the Orbscan II system. MATERIAL AND METHOD: One hundred and six eyes of 56 normal subjects were investigated using the Orbscan II. The simulated keratometry (SimK), astigmatism, corneal thickness, ACD and WTW were collected. The axial power maps as well as anterior and posterior elevation maps were read and categorized. Corneal thickness was measured in different regions and the pachymetry patterns were classified. RESULTS: The mean SimK was 44.18 (1.41)/43.30 (1.46) diopters (D) and the mean astigmatism was 0.93 (0.58) D. Symmetric bow tie was the most common axial power pattern in the anterior cornea (57.6%), followed by asymmetric bow tie (19.8%), irregular patterns (12.3%), round (9.4%), and oval (0.9%). Incomplete ridge (40.6%) and island (34%) were common elevation patterns observed in the anterior corneal surface, and island (92.5%) was the most common topographic pattern in the posterior. The thinnest point on the cornea had an average thickness of 512.49 (35) micron and was located at an average of 0.43 (0.24) mm from visual axis. In the pachymetry maps, round (47.2%) and oval (45.3%) were common patterns. The mean ACD and WTW was 2.79 (0.35) and 11.61 (0.36) mm, respectively. CONCLUSION: The present study demonstrated the normal variations of anterior segment structures of the eyes in normal Northern Thais using the Orbscan II topography system. This information may be useful for comparison with further quantitative studies of various abnormal states.

Vision screening in schoolchildren: two years results.

OBJECTIVE: To assess the prevalence of visual impairment and ocular abnormalities among schoolchildren in Chiang Mai. DESIGN: A community-based survey. SUBJECTS AND METHOD: The vision screening project was conducted from June 2000 to March 2002. Students in grade I in the Chiang Mai municipal area were examined for visual acuity (VA), color vision, ocular alignment, anterior segment and fundus. Subjective refraction was done in students with subnormal vision (VA 20/30 or less). Referral to the hospital for further evaluation and treatment was made for students with strabismus, amblyopia and other ocular abnormalities. RESULTS: A total of 3,431 and 3,467 students were enrolled in 2000 and 2001, respectively. The prevalence of normal vision (VA 20/20), VA 20/30 or better in at least one eye and 20/40 or less in at least one eye were similar in both years (87%, 5.7%, 7.3% and 85%, 6.4%, 8.7%, respectively). There was no statistically significant difference in visual acuity among boys and girls in either year (p = 0.6 and p = 0.2). Prevalence of abnormal color vision was 4.2%. Other causes of visual impairment in both years included strabismus (1.5% and 6.2%), amblyopia (1.1% and 1.4%) and some congenital abnormalities. Most cases of amblyopia were due to uncorrected refractive errors. CONCLUSION: The authors found that over 10% of school-aged children had subnormal vision. The important causes of visual deterioration came from refractive errors, strabismus and amblyopia. The authors concluded that vision screening is a cost-effective way of reducing visual morbidity from preventable visual impairment, which is a tragedy that cannot be ignored.