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Background: Patients often ask whether the relief they experience with botulinum A toxin will diminish with time, resulting in the need for an increased dosage and more frequent administration. We performed a retrospective study to examine these questions., Methods: We reviewed the charts of 28 patients (17 with benign essential blepharospasm and 11 with hemifacial spasm) seen between 1989 and 1994 by one ophthalmologist at the botulinum clinic at a university-affiliated hospital in Edmonton. All patients had had at least 6 botulinum A toxin treatments; 17 had had 12 or more treatments, and 7 had had 20 or more treatments. A follow-up data collection form was used to record duration of effect, dosage and side effects. We analysed the data on duration of effect and dosage versus treatment number for individual patients and for the overall group using linear regression analysis., Results: There was no clinically or statistically significant change in duration of effect over time (mean slope 0.024 [95% confidence interval (CI) -0.218 to 0.266]). A positive mean slope of 0.677 (95% CI 0.252 to 1.102) was observed for the change in dosage over time. This trend was most likely related to the practitioner's habit of using half the normal maintenance dosage for the initial injection. When we eliminated the data for the first injection and recalculated the dosage requirement over time, the mean slope for the change in dosage was 0.321 (95% CI -0.084 to 0.726), confirming stable dosage requirements over time., Interpretation: The results suggest that patients can be reassured that duration of benefit and dosage requirements will likely remain stable over time for at least their first 20 treatments.

Background: Diabetic retinopathy is a leading cause of vision loss in North America. We compared mydriatic seven-field stereoscopic digital imaging to 100 ASA slide film photography for the identification of diabetic retinopathy via teleophthalmology., Methods: Patients from a northern Alberta community with diabetes mellitus diagnosed by a physician were asked to participate in a teleophthalmology pilot project. Patients were enrolled at four different times between October 1999 and June 2000. Seven 30 degree fields of the retina were photographed with both slide film and digital imaging (resolution 2008 x 3040 pixels) through a dilated pupil. Slide film was developed and reviewed in a masked fashion by a retinal specialist. Digital images for each patient were transmitted by satellite to Edmonton and analysed a minimum of 2 months after the original slide film. Retinal abnormalities were graded with the use of the Early Treatment Diabetic Retinopathy Study extension of the modified Airlie House classification. We calculated the sensitivity and specificity of digital imaging for the identification of features of diabetic retinopathy as seen on slide film. Pearson's correlation coefficient was also calculated., Results: A total of 121 patients (241 eyes), of whom 114 (94.2%) had non-insulin-dependent diabetes, participated in the study. The average duration of diabetes was 8.5 years. Of the 121 patients 57 (47.1%) had diabetic retinopathy, 12 (9.9%) had clinically significant macular edema and 2 (1.6%) had neovascularization. Pearson's correlation coefficient for the presence of retinopathy between slide film and stereoscopic digital imaging was 0.92 for microaneurysms, 0.80 for hemorrhages, 0.45 for intraretinal microvascular abnormalities, 0.32 for venous beading, 1.00 for neovascularization of the disc, 1.00 for neovascularization elsewhere in the retina and 0.97 for clinically significant macular edema (p < 0.001). The correlation between the two techniques for severe nonproliferative diabetic retinopathy (NPDR) was 0.86 and for high-risk proliferative diabetic retinopathy 1.00 (p < 0.001)., Interpretation: Stereoscopic digital imaging has a high level of correlation with slide film for the identification of most features of diabetic retinopathy, including microaneurysms, hemorrhage, severe NPDR, high-risk proliferative diabetic retinopathy and clinically significant macular edema.

Diabetic eye disease is present in remote communities across Canada. A pilot study was designed to assess the feasibility of stereoscopic digital imaging to identify levels of diabetic retinopathy via teleophthalmology. Diabetic patients were assessed for diabetic retinopathy by seven field stereoscopic digital imaging through a dilated pupil. Images were transferred by satellite to a tertiary eye center for review by a retinal specialist. Images were viewed stereoscopically on a video monitor, with grading of all images using a modified Early Treatment Diabetic Retinopathy Study (ETDRS) classification. Patients found to have treatable diabetic retinopathy were transferred to a tertiary eye center for assessment and treatment by a retinal specialist. One hundred patients (199 eyes) had stereoscopic digital imaging of the retina. Microaneurysms were identified in 70 eyes, hard exudates in 31 eyes. Two eyes were identified with neovascularization of the disc (NVD) and 15 eyes with clinically significant macular edema (CSME). All eyes identified by stereoscopic digital imaging with treatable disease were confirmed by clinical examination with contact lens biomicroscopy. Stereoscopic digital imaging of the retina enables the identification of diabetic retinopathy. Further research is needed to delineate the sensitivity and specificity of stereoscopic digital imaging when compared to slide film and clinical examination.

We describe the use of long-term dilation and patching therapy in the management of three cases of pediatric monocular cataract. The cataracts were felt to be visually significant in the undilated state but consistent with good formed vision in the dilated state. One patient had a congenital cataract managed from 4 weeks of life, and two patients had late diagnosed cataracts of indeterminate onset presenting with dense deprivation amblyopia. The congenital cataract patient ultimately demonstrated recognition acuity of 20/40, and both the older children ultimately demonstrated an acuity of 20/30. We recommend considering long-term dilation and conventional amblyopia therapy rather than lensectomy in such cases if the cataract is felt to be consistent with development of good formed vision in the dilated state.