Evidence-based Canadian guidelines for tele-retina screening for diabetic retinopathy: recommendations from the Canadian Retina Research Network (CR2N) Tele-Retina Steering Committee.

OBJECTIVE: The purpose of this report is to develop a consensus for Canadian national guidelines specific to a tele-medicine approach to screening for diabetic retinopathy (DR) using evidence-based and clinical data. METHODS: Canadian Tele-Screening Grading Scales for DR and diabetic macular edema (DME) were created primarily based on severity grading scales outlined by the International Clinical Diabetic Retinopathy Disease Severity Scale (ICDR) and the Scottish DR Grading Scheme 2007. Other grading scales used in international screening programs and the clinical expertise of the Canadian Retina Research Network members and retina specialists nationwide were also used in the creation of the guidelines. RESULTS: National Tele-Screening Guidelines for DR and DME with and without optical coherence tomography (OCT) images are proposed. These outline a diagnosis and management algorithm for patients presenting with different stages of DR and/or DME. General guidelines detailing the requirements for imaged retina fields, image quality, quality control, and follow-up care and the role of visual acuity, pupil dilation, OCT, ultra-wide-field imaging, and artificial intelligence are discussed. CONCLUSIONS: Tele-retina screening can help to address the need for timely and effective screening for DR, whose prevalence continues to rise. A standardized and evidence-based national approach to DR tele-screening has been proposed, based on DR/DME grading using two 45° image fields or a single widefield or ultra-wide-field image, preferable use of OCT imaging, and a focus on local quality control measures.

Systematic review of Purtscher's and Purtscher-like retinopathies.

PURPOSE: (1) To describe the clinical characteristics of Purtscher and Purtscher-like retinopathies, including etiologies, fundoscopic signs, results of complementary investigation, treatments, and outcomes. (2) To compare visual acuity (VA) of patients receiving corticosteroids for PuR compared with observation. METHODS: Systematic review of several databases (1980-2010): Medline, EMBASE, ISI, EBSCO, Science Direct and Google Scholar. Study selection criteria included: (A) Studies of PuR with ophthalmology assessments; (B) ≥3 of 5 diagnostic criteria of PuR; (C) Quantified VA at presentation. For quantitative assessment (purpose 2), we selected only studies that reported whether corticosteroids were administered, and with vision assessments after at least 1 month. RESULTS: (1) From 670 studies initially found, 40 were included (68 cases, 110 eyes): 1 prospective, 5 case series, and 34 case reports. Mean VA at presentation was 1.3 logMAR (logarithm of the minimum angle of resolution) (<20/200; range: 20/20-light perception). Purtscher flecken were underreported. Trauma and acute pancreatitis were the most frequent etiologies. There were six deaths, all with systemic associations. (2) There was no statistically significant difference between VA improvement for patients treated with corticosteroids compared with observation. Visual prognostic factors identified included etiology (pancreatitis and trauma were associated with higher probability of visual improvement) and male gender. CONCLUSION: Due to limitations of case reports and series, the presented data are only useful as broad characterizations of the clinical course of PuR. Further studies, possibly including trials to assess the effectiveness of corticosteroids use, and larger prospective cohort studies, are necessary, but may not be feasible to conduct.

Comparison of the potential acuity meter and the visometer in cataract patients.

PURPOSE: To compare the Guyton-Minkowski Potential Acuity Meter (PAM) and the Haag-Streit Lotmar Visometer (Visometer) in their ability to predict postoperative best corrected visual acuity (BCVA) in cataract surgery. SETTING: University of British Columbia/Vancouver General Hospital Eye Care Center, Vancouver, British Columbia, Canada. METHODS: In total, 292 eyes (223 patients) of subjects with cataracts and no known macular or optic nerve pathology were recruited over 6 months. Preoperative predictions of postoperative BCVA were compared with actual postoperative BCVA. The usefulness of these instruments as a 'diagnostic test' for predicting true surgical success (defined as postoperative BCVA of 20/40 or better) from predicted surgical success (PAM or Visometer predicted acuity 20/40 or better) was analysed. RESULTS: Neither the PAM nor the Visometer predictions were statistically significant predictors of postoperative BCVA. The sensitivities of PAM and Visometer for predicting surgical success were 84.7% and 96.1%, respectively. The specificity of the PAM and Visometer for predicting surgical success was 27.3% and 9.1%, respectively. Overall, 92.7% of patients had 'successful surgery'. Given a predicted success from the PAM or Visometer the post-test probability of success was 93.5% and 93.1%, respectively. Given a predicted failure from the PAM or Visometer there was a post-test probability of surgical success of 87.5% and 84.6%, respectively. CONCLUSION: We found no clinical benefit to support using the PAM or Visometer in the preoperative assessment of cataract patients with no known retinal or optic nerve pathology.

Stage specificity of novel growth factor expression during development of proliferative vitreoretinopathy.

OBJECTIVE: To compare the relative levels of connective tissue growth factor (CTGF), platelet-derived growth factor alpha (PDGF-AA), and hepatocyte growth factor (HGF) in glial and retinal pigment epithelial (RPE) cells of epiretinal membranes from proliferative vitreoretinopathy (PVR). METHODS: A total of 37 PVR membranes, of various stages, underwent fluorescent immunohistochemisty and confocal laser scanning microscopy to localize CTGF, HGF, and PDGF-AA in RPE and glial cells. RESULTS: Numerous RPE, and relatively fewer glial cells, were found in all stages of PVR. CTGF immunoreactivity increased from early to late stage PVR and was principally expressed by RPE cells in early stage, and by glial cells in late stage PVR. HGF, expressed by both RPE and glial cells, was principally expressed in mid-stage PVR. PDGF-AA, expressed by both cell types, demonstrated a uniform level of staining throughout all stages of PVR. CONCLUSIONS: RPE and glial cells contribute to the expression of CTGF, HGF, and PDGF-AA during PVR, but with specific developmental patterns. PDGF-AA is expressed uniformly throughout all stages of PVR, while HGF expression peaks during mid stage, and CTGF expression is highest during late stage PVR. These results allow for the development of stage-specific therapeutics for PVR that may allow targeting of the early proliferative and/or the late tractional stages of PVR.

The prevalence of low vision and blindness in a Canadian inner city.

PURPOSE: To ascertain the prevalence and primary causes of visual impairment in a sample of patients from Vancouver's downtown eastside (VDES). MATERIALS AND METHODS: A total of 200 patients seeking nonophthalmic medical care at the Vancouver Native Health Society (VNHS) clinic in Vancouver's inner city (downtown eastside) participated in this observational case-series study. For each participant, we obtained demographic information, a medical and ocular history, and performed a complete eye exam. The prevalence of visual disability using standard North American criteria was reported. Causes of visual loss were also reported based on Canadian National Institute for the Blind (CNIB) guidelines. RESULTS: A total of 200 patients participated in our study. The median age of our sample was 46 years, 69% were male. There were very high rates of comorbid medical conditions including HIV, Hepatitis B/C, IV drug use, and diabetes. The raw prevalence of visual disability based on best-corrected visual acuity (BCVA) was 500 per 10,000; this was over nine times greater than in the general Canadian population. The raw prevalence rate of 'presenting visual disability' based on presenting visual acuity (PVA) was 2400 per 10,000. Major causes of visual disability were cataract and retinal disease. Although age-related macular degeneration and diabetic retinopathy represent major causes of vision loss in North America, no cases were noted in our sample. CONCLUSION: The overall prevalence of visual disability was alarmingly high in this disadvantaged community. These results identify both ophthalmic disease and access to refraction and prescription spectacles as a significant health concern among people living in the VDES.

Vitreous leptin levels in retinal disease.

BACKGROUND/AIMS: The purpose of this study was to investigate the relationship between vitreous leptin levels and retinal diseases. METHODS: Levels of vitreous leptin were evaluated in proliferative diabetic retinopathy (PDR) and a variety of other retinopathies including: macular disease, neovascular maculopathies, primary retinal detachments, and vascular occlusive disease. RESULTS: In patients with PDR (N=7), the average vitreous level of leptin (37.4 ng/ml) was significantly higher than that in patients with PVR (<1.0 ng/ml, P<0.05). Vitreous leptin level in patients with PVR or macular disease (N=18), with or without diabetes, was not significantly different from the control subjects who had retinal detachment only (N=7). CONCLUSION: The results show that the leptin level in vitreous taps is elevated in PDR. We suggest that leptin plays an active role in PDR.

The prevalence of low vision and blindness in Canada.

PURPOSE: The purpose of this study was to ascertain the prevalence and primary causes of visual impairment in a representative Canadian population. METHODS: We reviewed a representative sample of patients who attended ophthalmologists' offices in a medium-sized Canadian city between 1996 and 2001 in order to estimate the prevalence of visual impairment. Demographic data, visual diagnoses, best-corrected visual acuities (BCVA), and visual field information were recorded. Visual status was categorized based on accepted World Health Organization (WHO) and North American criteria. Population data were obtained from the Canadian census. RESULTS: The prevalence of low vision and blindness in our population was 35.6 and 3.8 per 10 000 individuals, according to the WHO classification, and 71.2 and 23.6 per 10 000 individuals, using the North American definition. Among individuals with some vision loss (vision worse than 20/40), cataract and visual pathway disease were the most common causes, together accounting for 40% of visual impairment. Age-related macular degeneration and other retinal diseases were the next most common causes of vision loss. Diabetic retinopathy and glaucoma were less frequently encountered as causes of visual impairment. CONCLUSION: The overall prevalence of low vision and blindness in Canada are in keeping with data from large population-based studies from other developed nations. Cataract, visual pathway disease, and macular degeneration are the leading causes of visual impairment. These results are important for enhancing our understanding of the scope of vision health in Canada and may direct future health planning and cost-utilization research.

An evaluation of photographic screening for neovascular age-related macular degeneration.

BACKGROUND: Photographic screening for neovascular age-related macular degeneration (AMD) is not commonly employed because the prevalence of treatable disease is low and fluorescein angiography is considered necessary for the diagnosis of this form of AMD. However, there may be a role for colour retinal imaging in assisting with the diagnosis and triage of subjects with neovascular AMD. The purpose of this study was to evaluate the utility of colour fundus photographs for identifying subjects with potentially treatable neovascular AMD. METHODS: A total of 74 stereo pairs of Kodachrome colour slides of subjects with AMD were evaluated (i) nonstereoscopically, (ii) stereoscopically, and (iii) stereoscopically with visual acuity and visual symptom data. Two retina specialists read the images to identify active exudative lesions. RESULTS: The kappa statistic comparing the retinal specialists diagnosis of treatable neovascular AMD from color slides was excellent. The sensitivity and specificity of nonstereo images for the appropriate categorization of lesions was 0.95 and 0.90 respectively. The evaluation of stereo pairs was more sensitive, but less specific, 0.98, 0.83, as was the evaluation of stereo-pairs with clinical histories and visual acuities, 1.00, 0.77. CONCLUSIONS: The evaluation of colour images for subjects with suspected exudative macular degeneration can be diagnostic for neovascular AMD and may expedite the appropriate referral of patients for more timely angiography and treatment. Incorporating more clinical information for the image evaluators ((i) stereo image pairs and/or (ii) presenting symptomatology and visual acuity data) led to a decrease in the false-negative rate, but also decreased the screening specificity.

Pegaptanib for neovascular age-related macular degeneration.

(1) Neovascular (wet) age-related macular degeneration (AMD) results from the growth of abnormal blood vessels under the retina (choroidal neovascularization). Sudden and permanent vision loss occurs as these vessels grow, leak, bleed, and scar. (2) A human protein, vascular endothelial growth factor (VEGF), is implicated in the development of wet AMD. Pegaptanib attaches to VEGF and blocks its action. (3) In two concurrent, high quality studies using identical research methods, pegaptanib demonstrated a therapeutic advantage over placebo for the prevention of vision loss due to neovascular AMD. (4) Pegaptanib is injected into the eye every six weeks. This carries the risk of endophthalmitis (intraocular infection), lens damage (if accidentally penetrated), and retinal detachment. Systemic side-effects have not been associated with pegaptanib.

The prevalence of diabetes in the Cree of western James Bay.

Diabetes prevalence and general demographic data for individuals with diabetes were evaluated in the Cree of Moose Factory, Ontario. Individuals with diabetes were identified through a retrospective review of the diabetes registry as well as of outpatient and inpatient records. The crude prevalence of diabetes was 62 (95% confidence interval: 54 72) per 1,000. The direct age-standardized prevalence of diabetes was 103 per 1,000 for the entire population (95% confidence interval: 89 118 per 1,000, standardized to the 1991 Canadian population). The estimated rate of diabetes in the Canadian population is approximately 5%. The average age of individuals with diabetes in the community was 53 years; the average duration of diabetes was 8.2 years. Most of the population with diabetes were female (64 %) and were using anti-hypertensive medications (64%). This study presents diabetes prevalence data for the population of Moose Factory, Ontario, that indicate a higher prevalence than in both the Canadian population and other Cree populations in the region.

Polypoidal choroidal vasculopathy masquerading as central serous chorioretinopathy.

OBJECTIVE: To differentiate polypoidal choroidal vasculopathy (PCV) from central serous chorioretinopathy (CSC). DESIGN: A retrospective, observational case series. PARTICIPANTS: Thirteen patients originally diagnosed with CSC proved to have PCV after more extensive evaluation and follow-up. METHODS: A clinical and angiographic review of patients with manifestations of CSC, including macular detachment. MAIN OUTCOME MEASURES: Demographic data, funduscopic examination, and fluorescein and indocyanine green (ICG) angiographic findings. RESULTS: Thirteen patients initially suspected of having CSC were ultimately diagnosed as having PCV. These eyes had exudative macular detachments secondary to a small caliber, polypoidal choroidal vascular abnormality or so-called polypoidal choroidal neovascularization. The clinical manifestations in the fundus varied. They included multiple, variably sized serous pigment epithelial detachments, neurosensory retinal detachment, lipid deposition, patchy atrophy of the pigment epithelium and indistinct staining from decompensation of the posterior blood-retinal barrier on fluorescein angiography. In reality, the suspected PEDs proved to be polypoidal lesions of PCV when imaged with ICG angiography. CONCLUSIONS: The clinical diagnosis of CSC or PCV generally poses little challenge to the experienced retinal specialist. However, in CSC with persistent and/or recurrent exudation, a myriad of retinal pigment epithelial changes may evolve that make it difficult to differentiate these two entities. In such patients, ICG angiography is useful in differentiating CSC from PCV. An accurate clinical diagnosis is important since each of these entities, CSC and PCV, may differ in terms of their risk factors, natural course, and visual prognosis.

Radiation exposure: a new risk factor for idiopathic perifoveal telangiectasis.

OBJECTIVE: To examine the association between previous radiation exposure and idiopathic perifoveal telangiectasis (IPT). DESIGN: A multicentered, individually matched, case-control study design was used. PARTICIPANTS/CONTROLS: Sixty-five case subjects were matched with 175 control subjects. Individuals with unequivocal evidence of angiographically confirmed IPT were included as cases. Control subjects were matched for center, age, and gender. MAIN OUTCOME MEASURE: The main exposures of interest were a history of therapeutic head or neck irradiation and environmental radiation exposure. METHODS: A standardized questionnaire was administered to case and control subjects. Data were collected for the main exposures of interest as well as pertinent covariates. Conditional logistic regression was used to evaluate therapeutic and environmental radiation as risks for IPT. RESULTS: On univariate analysis, head or neck irradiation was associated with IPT (odds ratios [OR] = 4.15, 95% confidence interval [CI] = 1.30-13.24). While controlling for diabetes and family history of diabetes, IPT was found to be associated with both head or neck irradiation (OR = 4.06, 95% CI = 1.20-13.76) and with environmental irradiation (OR = 6.73, 95% CI = 1.06-42.74). CONCLUSIONS: This study presents a previously unreported association between prior radiation exposure and IPT.

Polypoidal choroidal vasculopathy and neovascularized age-related macular degeneration.

OBJECTIVE: To determine the nature and frequency of polypoidal choroidal vasculopathy (PCV) in a series of patients suspected of having neovascularized age-related macular degeneration (AMD). METHODS: A prospective analysis of 167 consecutive, newly diagnosed patients aged 55 years or older with presumed neovascularized AMD was performed. All patients were examined with fundus biomicroscopy as well as fluorescein and indocyanine green angiography. RESULTS: Choroidal neovascularization secondary to AMD was diagnosed in 154 (92.2%) of 167 patients; 13 (7.8%) patients had PCV. The patients affected by PCV were younger than those with AMD (P = .01). Peripapillary choroidal neovascularization was seen in 3 (1.9%) of 154 patients with AMD and 3 (23.1%) of 13 patients with PCV (P = .006). Significant drusen were present in 63 (70%) of 90 fellow eyes with unilateral AMD compared with only 1 (16.7%) of 6 eyes with PCV (P = .02). Only 5 patients with AMD (3.2%) were nonwhite compared with 3 patients with PCV (23.1%) (P = .02). CONCLUSIONS: A measurable number of elderly patients with findings suggestive of neovascularized AMD and serosanguineous macular manifestations will instead have PCV. Polypoidal choroidal vasculopathy can occur in any sex or race, but is more commonly seen in the peripapillary area, without associated drusen, and in nonwhite patients. It is important to differentiate AMD from PCV because there are significant differences in the demographic risk profile, natural course, visual prognosis, and management of these patients.

Indocyanine green angiography: an evaluation of image enhancement for the identification of occult choroidal neovascular membranes.

PURPOSE: To determine the diagnostic yield of occult choroidal neovascularization from examination of nonenhanced digital indocyanine green (ICG) angiograms versus examination of both nonenhanced and contrast-enhanced angiograms. METHODS: Fifty consecutive occult choroidal neovascular membranes were examined using ICG angiography at the Queen's University Eye Department. These studies were retrospectively reviewed in a masked fashion using the nonenhanced images. A subsequent examination of the same images was then performed using both the nonenhanced and contrast-enhanced images. Each study was graded as focal hyperfluorescence, plaque hyperfluorescence, isofluorescence, or hypofluorescence. RESULTS: Of the cases reviewed, only 36% (18/50) of the membranes were well-defined on nonenhanced ICG angiography, compared with 58% (28/50) using image enhancement in addition to the nonenhanced images. This was a statistically significant difference in image definition between the two groups (chi-square test; P < 0.005). CONCLUSION: Contrast-enhanced angiograms, when used in conjunction with nonenhanced ICG images, allowed for a significantly higher diagnostic yield when compared with the study of nonenhanced images alone.

A microendoscopic test card for ophthalmic endoscopes.

Ophthalmic endoscopes allow examination of intraocular structures when traditional surgical microscopic visualization is limited or impossible. Periodic evaluation of the optical precision of these instruments is essential to ensure optimal intraoperative performance. A test card has been developed to aid in the calibration of ophthalmic endoscopes. Its 5 test targets assess white balance and fiberoptic bundle integrity, focus and resolution, orientation, color fidelity, and angle of view.

Releasable "U" suture for trabeculectomy surgery.

Overfiltration after glaucoma surgery can lead to significant complications. Tight suturing of the trabeculectomy flap reduces this problem but can lead to higher pressure and poor drainage of aqueous. Releasable sutures often leave irritating exposed suture ends. We describe a simple two-arm releasable suture technique that leaves no exposed suture ends until one arm of the suture is removed. Good control of postoperative pressure with few complications was achieved in 28 cases using this technique, which allows manipulation at the slit lamp of the trabeculectomy flap, obviating laser lysis of the sutures.

House dust mite hyposensitization.

A double-blind controlled trial of house dust mite hyposensitization was carried out in 14 patients with asthma, who were hypersensitive on skin testing to the house dust mite alone. Measurements were made, using a Wright's peak flowmeter, during the 15-month trial period. Precautions were taken in the home to reduce the mite population. At the end of the trial, no clinical improvement was noted subjectively or objectively, despite a reduced bronchial sensitivity to allergen in the treated group. The role of the house dust mite as a cause of asthma is discussed.