Use of ophthalmologic services by diabetic patients in Nova Scotia.

To evaluate the possible public health consequences of diabetic retinopathy in Nova Scotia, we investigated the number and frequency of ophthalmologic examinations in patients with diabetes mellitus. A total of 36,683 people (4.2%) were identified from the administrative database of the provincial health department as having a diagnostic code of diabetes during the period March 1987 to February 1990. All billings by ophthalmologists for these patients during the same period were then identified. Of the 36,129 patients aged 10 years or more, 17,518 (48.5%) had seen an ophthalmologist at least once during the study period, and 5218 (14.4%) had seen an ophthalmologist approximately annually. Increased age and being female were associated in univariate logistic regression analysis with higher use of ophthalmologic services. The medical insurance system is free of direct costs to patients, and there are enough ophthalmologists to meet patient needs (4.35 per 100,000 population). The findings indicate that most diabetic patients in Nova Scotia are not seen at least once a year, as recommended by the Expert Committee of the Canadian Diabetes Advisory Board, despite ready availability of ophthalmologic care.

Negative predictive value of a population-based preschool vision screening program.

BACKGROUND: The Enhanced Vision Screening Program is a population-based vision screening program that has, at present, examined 59,782 children. Its main goal is to detect amblyopia, strabismus, and high refractive errors. An average of 11,910 4 1/2- to 5 1/2-year-old children are screened yearly. The current study determines the negative predictive value of the screening program: For a subject having passed the vision screening test, what is the probability of not having amblyopia, strabismus, or high refractive errors? METHODS: Of the 11,734 subjects who passed the vision screening, 200 were randomly chosen to undergo a strictly defined gold standard examination by an orthoptist and an ophthalmologist. RESULTS: Of the 200 randomly chosen subjects, 157 underwent the gold standard evaluation. The negative predictive value of the Enhanced Vision Screening Program was 97.6% for any potentially vision-threatening ocular condition. It was 98.7% if we considered only the visually significant ocular problems that the test was designed to detect. CONCLUSION: Because the negative predictive value of the Enhanced Vision Screening Program is not 100%, some children with amblyopia, strabismus, or refractive errors are missed. Occasionally, a rare, potentially vision-threatening condition may go undetected. Parents should be made aware of this when they receive the results of the vision screening.

Giardiasis outbreak from a chlorinated community water supply.

A giardiasis outbreak from a chlorinated, unfiltered surface water supply in Penticton, British Columbia (pop. 25,000) from June to August 1986 resulted in 362 laboratory-confirmed cases. A telephone survey estimated an attack rate of over 12%. A reservoir pond containing Giardia-infected beaver was implicated as the source. A case-control study with 65 cases did not find any significant associations. A retrospective case-finding survey of records from eight (out of 35) general physicians estimated that 1,500 physician visits occurred and produced an epidemic curve in close parallel with that from laboratory-confirmed and reported cases. Despite improvements on the reservoir, another outbreak occurred when this water source was reinstituted in October for several weeks, confirming our conclusion that it was the source of the first outbreak. Various options for reducing the risk of future outbreaks are being explored including full water treatment.

Epidemiologic approach to open-angle glaucoma: 2. Survival analysis of adverse drug reactions. Report of the Canadian Ocular Adverse Drug Reaction Registry Program. The Collaborative Glaucoma Study Group.

Medical treatment, intraocular pressure (IOP) and adverse drug reactions were recorded in a prospective multicentre study of 71 unselected, newly diagnosed cases of open-angle glaucoma. Eight ophthalmologists recorded standard information at five visits over a mean interval of 12.1 months. No limitations were imposed on the choice of drugs or interval between visits. The IOP was satisfactorily controlled throughout the follow-up period with the first drug prescribed in 36% of eyes. In an additional 10% to 13% the IOP was stabilized with alternative therapy, prescribed for approximately one-third of eyes per visit. A total of 27 patients reported 18 severe and 31 mild suspected adverse reactions during the follow-up period. Survival analysis showed that there was no significant difference between the proportions of patients continuing treatment with the first, second and third drug prescribed (half-life of treatment approximately 210 days in all three cases). However, when only changes for unsatisfactory pressure were considered, the half-life of treatment was significantly longer, 350 days (p = 0.02).

Epidemiologic approach to open-angle glaucoma: 1. Control of intraocular pressure. Report of the Canadian Ocular Adverse Drug Reaction Registry Program.

In a multicentre study eight glaucoma consultants prospectively followed 71 unselected cases (130 eyes) of newly diagnosed open-angle glaucoma at five visits over a mean interval of 12.1 months. A standard flow chart was used to record the medical treatment, intraocular pressure (IOP) and indications for any changes in therapy. No limitations were imposed on the choice of drugs. The mean IOP before treatment was 28 mm Hg. There was a significant reduction in mean IOP of 7.64 mm Hg in response to the first drug prescribed (p less than 0.0001) but none thereafter, despite changes in treatment in 25% to 32% of eyes at each visit. The mean standard deviation of IOP for all eyes was 2.62 mm Hg. Of 99 changes in therapy in 67 eyes, 40% were made when the IOP was within 3 mm Hg of the mean satisfactory pressure for a particular case. The findings indicate the need to make corrections for variation and fluctuation in IOP when evaluating pressure response. The pharmacologic effect of the drugs appeared less important than the patient's ability to tolerate the drugs without severe adverse reactions.