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Biomedical subjects

M Easterbrook

Publications and source records attributed to M Easterbrook.

At least 19 recordsLinked to original sources
PubMed1999

Rural background and clinical rural rotations during medical training: effect on practice location.

BACKGROUND: Providing health care services in rural communities in Canada remains a challenge. What affects a family medicine resident's decision concerning practice location? Does the resident's background or exposure to rural practice during clinical rotations affect that decision? METHODS: Cross-sectional mail survey of 159 physicians who graduated from the Family Medicine Program at Queen's University, Kingston, Ont., between 1977 and 1991. The outcome variables of interest were the size of community in which the graduate chose to practise on completion of training (rural [population less than 10,000] v. nonrural [population 10,000 or more]) and the size of community of practice when the survey was conducted (1993). The predictor or independent variables were age, sex, number of years in practice, exposure to rural practice during undergraduate and residency training, and size of hometown. RESULTS: Physicians who were raised in rural communities were 2.3 times more likely than those from nonrural communities to choose to practise in a rural community immediately after graduation (95% confidence interval 1.43-3.69, p = 0.001). They were also 2.5 times more likely to still be in rural practice at the time of the survey (95% confidence interval 1.53-4.01, p = 0.001). There was no association between exposure to rural practice during undergraduate or residency training and choosing to practise in a rural community. INTERPRETATION: Physicians who have roots in rural Canada are more likely to practise in rural Canada than those without such a background.

Adult↗
PubMed1999

Detection of color vision defects in chloroquine retinopathy.

OBJECTIVE: The effect of chloroquine toxicity on color vision is unclear. The authors identified the color defects seen in chloroquine retinopathy and determined the sensitivity and specificity of clinical color vision tests for detecting the presence of previously diagnosed chloroquine retinopathy. DESIGN: Case-control study. PARTICIPANTS: Chloroquine retinopathy was defined using previously published criteria. Data from 30 patients with retinopathy and 25 patients using chloroquine but with no evidence of retinal toxicity were collected. METHODS: All patients were tested with the following six clinical color vision tests: Ishihara, Farnsworth D-15, and Adams Desaturated-15 (Dsat-15), City University 2nd Edition (CU), Standard Pseudoisochromatic Plates Part 2 (SPP-2), and American Optical Hardy Rand Rittler (AO HRR). MAIN OUTCOME MEASURES: The number of failures was determined for each test. The types of color vision defects were classified as blue-yellow (BY), red-green (RG), or mixed RG and BY (mixed). RESULTS: Of the 30 patients with retinopathy, 28 (93.3%) of 30 patients failed at least 1 color vision test, demonstrating predominantly mixed defects. Five (25%) of 25 of the control subjects failed at least 1 test, and these defects were predominantly BY. The sensitivity and specificity of the tests are as follows: SPP-2 (93.3%, 88%), AO HRR (76.7%, 88%), Ishihara (43.3%, 96%), Dsat-15 (33.3%, 84%), D-15 (16.7%, 96%), and CU (20%, 92%). CONCLUSIONS: Color vision can be affected by chloroquine and should be tested routinely with a color vision test designed to detect both mild BY and protan RG defects to maximize sensitivity for toxicity. The SPP-2 and AO HRR are two tests that meet these criteria. The Ishihara has a low sensitivity, as do the D-15 tests and CU. All of the tests have similar specificity for chloroquine toxicity. If color vision defects are detected in patients at risk of developing chloroquine retinopathy, additional testing is indicated to rule out toxicity.

Adult↗
PubMed1999

Detection and prevention of maculopathy associated with antimalarial agents.

Rheumatologists use both cholorquine and hydroxychloroquine in the treatment of systemic arthritic and immune disease. Hydroxychloroquine is much more expensive but is better tolerated by patients. My experience in watching patients being switched from one drug to another suggests that chloroquine is more effective in some patients than is hydroxychloroquine. Reynes thought that a review of the literature suggests that chloroquine is more toxic at 250 mg/day as compared to 400 mg of hydroxychloroquine if dose is based on these dosages. This theory may be related, in part, to the observation by Raines and associates that chloroquine crosses the blood-retinal barrier whereas hydroxychloroquine does not. Patients should be assessed 6 months after starting antimalarials. Routine automated perimetry is not indicated. An appropriate examination would include visual acuity testing, color-vision testing, Amsler grid testing, and corneal assessment. Patients should be dosed on the basis of ideal body weight (not actual body weight) to reduce the incidence of macular toxicity. Patients with no risk factors should be examined no more than once a year.

Antimalarials↗
PubMed1997

To wear or not to wear: current contact lens use in the Royal Canadian Mounted Police.

OBJECTIVE: The Canadian Ophthalmological Society was asked by the Royal Canadian Mounted Police (RCMP) and the Canadian Human Rights Commission to render an opinion on the acceptability of contact lenses as a reasonable accommodation to the uncorrected visual acuity standard. DESIGN: Survey by mailed questionnaire. SETTING: Canada. SUBJECTS: All RCMP general duty constables with a visual acuity code of V3, V4, V5 or V6 (n = 348) and a random sample of approximately 25% of the constables with an acuity code of V2 (n = 809). Of the 1040 questionnaires returned, 1037 were usable (final response rate 89.6%). Of the 1037 respondents 316 were in the V3 to V6 group and 721 were in the V2 group. OUTCOME MEASURES: Reported frequency of problems with spectacles or contact lenses, weighted according to sampling fraction. RESULTS: A total of 934 respondents indicated that they used some form of visual acuity correction while on duty; of the 934, 360 reported that they wore contact lenses at least some of the time. Approximately 75% of the spectacle wearers reported having to remove their spectacles because of fogging or rain. Although contact lens dislogement or fogging (21.2%) was less frequent than spectacle dislogement (59.2%), 35.4% of the contact lens wearers reported that they were unable to wear their lenses because of irritation on at least one occasion in the previous 2 years; the median length of time was 3.14 days. When the additional amount of time due to other causes is factored in, it is clear that contact lens users wear spectacles for substantial periods while on duty. CONCLUSIONS: Not only are RCMP general duty constables who usually wear contact lenses likely to have to wear spectacles at some time, but it is also possible that they will have to remove their spectacles and function in an uncorrected state in critical situations. Thus, altering the current standard to allow the use of contact lenses as a reasonable accommodation would not ensure effective and safe job performance.

Canada↗
PubMed1996

Ruptured globes following radial and hexagonal keratotomy surgery.

OBJECTIVE: To ascertain if cases of radial keratotomy wound rupture were occurring and whether the globes ruptured through the corneal incisions. DESIGN: Cases of traumatic ruptured globe after incisional corneal refractive surgery were collected from ophthalmologists and from peer-reviewed and other ophthalmic literature. RESULTS: Twenty-eight human eyes (eight previously unreported) are known to have ruptured through refractive corneal incisions in activities of daily living (n = 12), assault (n = 7), motor vehicle accidents (n = 5), and sports (n = 4). Two patients died of their injuries. Of the remaining 26 ruptured eyes, eight (31%) recovered 20/40 or better visual acuity. Six eyes (23%) were totally blinded, six (23%) were legally blinded, and six (23%) had best corrected visual acuity of 20/40 to 20/100 despite multiple surgical procedures. CONCLUSIONS: As radial keratotomy becomes more popular the pool of patients who may experience traumatic ruptured globe will grow. Every patient who has had radial keratotomy should be aware that the surgery has weakened the eye(s).

Adult↗
PubMed1996

Diagnosis of traumatic cyclodialysis by ultrasound biomicroscopy.

BACKGROUND AND OBJECTIVE: To evaluate the ability of high-frequency ultrasound biomicroscopy to diagnose traumatic cyclodialyses not evident on clinical examination. PATIENTS AND METHODS: Six eyes to six patients with posttraumatic hypotony and/or shallow anterior chamber and suspected cyclodialysis clefts were examined with slit-lamp biomicroscopy, gonioscopy, B-scan ultrasonography, and ultrasound biomicroscopy. Ultrasound biomicroscopy provided high resolution of cross-sectional images of the anterior chamber angle, posterior chamber, and anterior uveal tissue. RESULTS: Ultrasound biomicroscopy confirmed the disinsertion of the ciliary body from the scleral spur and associated ciliary body detachment in all eyes. Gonioscopy failed to demonstrate a cyclodialysis cleft in five eyes because of hyphema (two eyes) and abnormal iris architecture (related to trauma) precluding visualization of the angle recess (three eyes). Using information from ultrasound biomicroscopy imagining, one patient underwent a ciliary body reattachment procedure and repair of the cyclodialysis cleft. CONCLUSION: Ultrasound biomicroscopy is a noninvasive method that can accurately diagnose the presence of traumatic cyclodialyses and can aid in surgical management. It is particularly useful in the presence of hazy media, hypotony, and/or abnormal anterior segment anatomy.

Adolescent↗
PubMed1993

Ultrasound biomicroscopy in the assessment of anterior scleral disease.

High-frequency ultrasound biomicroscopy is a new method of examining subsurface anterior segment structures of the eye at microscopic resolution. The sclera has a high internal reflectivity and can be differentiated from the cornea, and overlying and underlying tissue. Using this modality, we examined 18 patients with various manifestations of scleral disease. Localized anterior staphyloma could be differentiated from other causes of a black spot on the scleral surface. Episcleral thickening could be differentiated from involvement of the sclera itself. Different patterns of scleral involvement could be imaged including diffuse low-reflective mottling, low-reflective nodules extending into the scleral substance, and scleral thinning. Scleral thinning could be assessed and quantified. Underlying changes in the vitreous could be detected. Ultrasound biomicroscopy was a useful adjunct to clinical examination in the assessment of anterior scleral disease.

Adult↗
PubMed1993

An ultrasound biomicroscopic analysis of angle-closure glaucoma secondary to ciliochoroidal effusion in IgA nephropathy.

Immunoglobulin A nephropathy is a common glomerulonephritis of unknown cause. Episcleritis, scleritis, anterior uveitis, and keratoconjunctivitis sicca have been associated with this disease. We diagnosed angle-closure glaucoma secondary to ciliochoroidal effusion in a patient with IgA nephropathy confirmed by biopsy. High-frequency ultrasound biomicroscopy was used to determine internal relationships of angle structures and to follow changes with treatment. Supraciliary effusion undetected by B-scan ultrasound and retinal examination was easily imaged by ultrasound biomicroscopy. Glaucoma mechanisms included forward rotation of the ciliary processes, which caused direct angle closure in a manner similar to plateau iris. Ultrasound biomicroscopy showed that cycloplegia improved this mechanism by retracting the ciliary processes, but angle closure secondary to forward iris bowing from pupil block remained. Iridectomy was performed and immediately opened the angle. Ultrasound biomicroscopy proved a useful method of defining mechanisms and a helpful guide to treatment in this type of glaucoma.

Anterior Eye Segment↗
PubMed1993

The ocular safety of hydroxychloroquine.

The insert currently supplied with hydroxychloroquine states that patients should have an initial ophthalmological assessment and then regular assessments every 3 months. The rheumatologist should expect a report from the ophthalmologist, which includes a corneal assessment of tissue dose, a reference to visual field defects if present on the Amsler grid, and a comment concerning the status of the patient's color vision. Daily dose is more important than duration of dose, regarding maculopathy. The visual prognosis of retinopathy is excellent if the diagnosis is made at an early stage of the disease. This report suggests that ophthalmological review need only occur initially and on a yearly basis if the daily dose of hydroxychloroquine is less than 6.5 mg/kg/d and the duration of therapy is less than 9 years.

Female↗
PubMed1992

Long-term course of antimalarial maculopathy after cessation of treatment.

Since 1980 I have examined some 1650 patients for the presence or absence of antimalarial maculopathy. Bilateral, irreversible visual field defects have been diagnosed is 62 patients, 37 of whom have been followed for at least 4 years. The 22 patients who presented with relative scotomas did not lose central visual acuity; over a median follow-up period of 6.0 years 33 (75%) of the eyes maintained their visual field, 5 (11%) showed some improvement in visual field, 4 (9%) lost some visual field, and 2 (4%) manifested small absolute scotomas. Nine (60%) of the 15 patients who presented with absolute scotomas were symptomatic. Over a median follow-up period of 8.8 years 19 (63%) of the eyes in this group lost one or more lines of visual acuity, including 4 (13%) that became legally blind; 19 (63%) lost field owing to an increase in the size of the absolute scotomas (13 eyes) or the development of new absolute scotomas (6 eyes). The results suggest that the visual prognosis is excellent if antimalarial therapy is stopped at an early stage of the disease.

Chloroquine↗
PubMed1992

Comparison of threshold and standard Amsler grid testing in patients with established antimalarial retinopathy.

To evaluate the sensitivity of threshold Amsler grid testing in the detection of established antimalarial retinopathy, 30 eyes of 15 patients with bilateral, irreversible field defects were examined with the standard Amsler grid and the threshold Amsler grid. Four eyes (13%) showed significant enlargement of large relative scotomas on testing with the threshold Amsler grid. Although only a small proportion of the eyes demonstrated an increase in the size of the scotoma, the patients had established field defects of varying depth, in some cases absolute scotomas. A prospective study in patients with early disease (i.e., with small, shallow scotomas) may be worth while.

Antimalarials↗
PubMed1990

Is corneal deposition of antimalarial any indication of retinal toxicity?

Ninety-five percent of patients on chloroquine demonstrate corneal deposition of the drug with the pupil dilated; less than 10% of patients on hydroxychloroquine show any corneal changes when so examined. I describe one patient on chloroquine and two on hydroxychloroquine who demonstrated large amounts of corneal antimalarial drug, leading to the early diagnosis of definite retinopathy. Examination of the cornea with the pupil dilated may reveal the presence of retinal toxicity in some patients.

Adult↗