The Dragonflies and Damselflies (Insecta: Odonata) of Canada: species list, geographical distribution, status, and conservation ranks.

As of August 2023, 220 species in 57 genera and 10 families of damselflies and dragonflies (Insecta: Odonata) are recorded for Canada. Since the publication of the first edition in 2005, 14 species have been added to the list; one,Neurocordulia obsoleta (Say) has been removed because of a misidentification and another, Sympetrum occidentale, has been to synonymy. Conservation ranks are given for species in all 13 provinces and territories. English and French names for all listed species are included. Literature sources are discussed and presented, as is information on species status and the addition and exclusion of species. Sections on taxonomy and variation, subspecies, presumed hybrids, the introduction of exotic species, notable range extensions and observations, and conservation and protection are also provided.

Is diabetic retinopathy screening worthwhile among people first diagnosed with diabetes at older ages? A cohort study of Norfolk diabetic retinopathy screening programme.

AIMS: England's Diabetic Eye Disease Screening Programme offers screening to every resident over age 12 with diabetes, starting as soon as possible after diagnosis and repeated annually. People first diagnosed with diabetes at older ages have shorter life expectancy and therefore may be less likely to benefit from screening and treatment. To inform decisions about whether diabetic eye screening policy should be stratified by age, we investigated the probability of receiving treatment according to age at first screening episode. METHODS: This was a cohort study of participants in the Norfolk Diabetic Retinopathy Screening Programme from 2006 to 2017, with individuals' programme data linked to hospital treatment and death data recorded up to 2021. We estimated and compared the probability, annual incidence and screening costs of receiving retinal laser photocoagulation or intravitreal injection and of death, in age groups defined by age at first screening episode. RESULTS: The probability of death increased with increasing age at diagnosis, while the probability of receiving either treatment decreased with increasing age. The estimated cost of screening per person who received either or both treatments was £18,608 among all participants, increasing with age up to £21,721 in those aged 70-79 and £26,214 in those aged 80-89. CONCLUSIONS: Diabetic retinopathy screening is less effective and less cost-effective with increasing age at diagnosis of diabetes, because of the increasing probability of death before participants develop sight-threatening diabetic retinopathy and can benefit from treatment. Upper age limits on entry into screening programmes or risk stratification in older age groups may, therefore, be justifiable.

Frequency of visual involvement in a 10-year interdisciplinary cohort of patients with giant cell arteritis.

BACKGROUND: We present the largest study of the frequency and nature of visual complications in a cohort of 350 patients consecutively diagnosed with giant cell arteritis (GCA). METHODS: All individuals were assessed using structured forms and diagnosed using imaging or biopsy. A binary logistic regression model was used to analyse data for predicting visual loss. RESULTS: Visual symptoms occurred in 101 (28.9%) patients, with visual loss in one or both eyes in 48 (13.7%) patients. Four patients had binocular visual loss. Anterior ischaemic optic neuropathy (N=31), retinal artery obstruction (N=8) and occipital stroke (N=2) were the main causes of visual loss. Of the 47 individuals who had repeat visual acuity testing at 7 days, three individuals had improvement to 6/9 or better. After introducing the fast-track pathway, the frequency of visual loss decreased from 18.7% to 11.5%. Age at diagnosis (odds ratio (OR) 1.12) and headache (OR 0.22) were significant determinants of visual loss in a multivariate model. Jaw claudication trended to significance (OR 1.96, p=0.054). CONCLUSIONS: We recorded a visual loss frequency of 13.7% in the largest cohort of patients with GCA examined from a single centre. Although improvement in vision was rare, a dedicated fast-track pathway reduced visual loss. Headache could result in earlier diagnosis and protect against visual loss.

Incidence and progression of diabetic retinopathy during 17 years of a population-based screening program in England.

OBJECTIVE: To estimate the incidence of diabetic retinopathy in relation to retinopathy grade at first examination and other prognostic characteristics. RESEARCH DESIGN AND METHODS: This was a dynamic cohort study of 20,686 people with type 2 diabetes who had annual retinal photography up to 14 times between 1990 and 2006. Cumulative and annual incidence rates were estimated using life tables, and risk factors for progression were identified using Cox regression analysis. RESULTS: Of 20,686 patients without proliferative diabetic retinopathy (PDR) or sight-threatening maculopathy at their first retinal examination (baseline), 16,444 (79%) did not have retinopathy, 3,632 (18%) had nonproliferative retinopathy, and 610 (2.9%) had preproliferative retinopathy. After 5 years, few patients without retinopathy at baseline developed preproliferative retinopathy (cumulative incidence 4.0%), sight-threatening maculopathy (0.59%), or PDR (0.68%); after 10 years, the respective cumulative incidences were 16.4, 1.2, and 1.5%. Among those with nonproliferative (background) retinopathy at baseline, after 5 years [corrected] 23% developed preproliferative retinopathy, 5.2% developed maculopathy, and 6.1% developed PDR; after 10 years, the respective cumulative incidences were 53%, 9.6%, and 11%. Patients with nonproliferative retinopathy at baseline were five times more likely to develop preproliferative, PDR, or maculopathy than those without retinopathy at baseline (adjusted hazard ratio 5.0 [95% CI 4.4-5.6]). CONCLUSIONS: Few patients without diabetic retinopathy at the initial screening examination developed preproliferative retinopathy, PDR, or sight-threatening maculopathy after 5-10 years of follow-up. Screening intervals longer than a year may be appropriate for such patients.

Use of PCR to diagnose Toxoplasma gondii chorioretinitis in eyes with severe vitritis.

Two cases are reported of intraocular inflammation in which severe vitritis hampered the fundal view, making an accurate clinical diagnosis impossible, and vitreous analysis using conventional techniques was unhelpful. PCR for Toxoplasma gondii was positive in both cases and provided the only way of confirming the diagnosis. Other ocular samples also underwent PCR for Toxoplasma DNA and the specificity of this approach is demonstrated.