Prevalence of diabetic retinopathy in Type 2 diabetes in developing and developed countries.

BACKGROUND: As the global prevalence of diabetes increases, so will the numbers of people with diabetic retinopathy. Our review aimed to provide a comprehensive picture of available studies of diabetic retinopathy and how prevalence varies around the developed and developing world. METHODS: A detailed literature search using PubMed was undertaken. The following search term was used: 'diabetic retinopathy AND prevalence'. The titles and abstracts of all publications identified by the search were reviewed and 492 studies were retrieved. Inclusion and exclusion criteria were applied. RESULTS: A total of 72 articles from 33 countries were included. There were only 26 population-based studies using fundus photography (12 in developing countries), of which only 16 (eight in developing countries) were published since 2000. Prevalence estimates varied from as low as 10% to as high as 61% in persons with known diabetes and from 1.5 to 31% in newly diagnosed diabetes. Across all the studies, the median (interquartile range) prevalence of any diabetic retinopathy in known diabetes was 27.9% (22-37%) and 10.5% (6-16%) in newly diagnosed diabetes. Prevalence of diabetic retinopathy was higher in developing countries. CONCLUSION: Significant gaps exist in that reliable population-based data from developing nations and indigenous populations in particular are lacking. Major differences in study characteristics and methodologies make comparisons very difficult. More research is required and study methodologies must be better standardized. This will provide important information for prevention and treatment strategies.

Impact of mass treatment of onchocerciasis with ivermectin on the transmission of infection.

Onchocerciasis is a major blinding disease that, until recently, has been essentially untreatable. Ivermectin is a safe and effective drug for the mass treatment of onchocerciasis and when used on an individual basis, it reduces the ability of the treated person to transmit Onchocerca volvulus infection. In the present study, the effect of community-based ivermectin treatment on the degree of transmission within the community was assessed by determining the incidence of new infection in children. Ivermectin was distributed annually on three occasions to the eligible members of a population of approximately 14,000 people living on a rubber plantation in a forest area endemic for onchocerciasis. After 2 years, the prevalence of infection in 5-year-old children decreased by 21%. The annual incidence in an uninfected cohort of children decreased by 35% and, after age-specific adjustment, the reduction in incidence in 7- to 12-year-old children was 45%. Thus, community-based distribution of ivermectin led to a significant reduction in incidence of new infection. These findings suggest that ivermectin can be important in reducing the transmission of onchocerciasis.

An immunogenic Onchocerca volvulus antigen: a specific and early marker of infection.

Onchocerciasis (river blindness) is a serious health problem and a severe obstacle to social and economic development, especially in Africa. A complementary DNA fragment coding for an Onchocerca volvulus antigen (OV-16) was cloned and expressed in the plasmid vector pCG808fx. Immune responses to this O. volvulus-specific recombinant antigen were detectable in patients with documented onchocerciasis; the antibody response was also detectable at 3 months and at more than 1 year before infection could otherwise be detected in humans and in chimpanzees experimentally infected with O. volvulus third-stage larvae.

The effects of ivermectin on transmission of Onchocerca volvulus.

Ivermectin, given to onchocerciasis patients as a single oral dose of 200 micrograms per kilogram of body weight, substantially reduced the uptake of Onchocerca volvulus microfilariae by Simulium yahense, an efficient black fly vector of the parasite in the tropical rain forests of West Africa. Three months after treatment, patients given ivermectin infected flies at a significantly lower rate than those who had received diethylcarbamazine or placebo, thereby reducing the number of developing larvae in the vector population. This diminished rate of infectiousness was also evident 6 months after treatment. These results strongly suggest that ivermectin could be effective in interrupting transmission of Onchocerca volvulus for epidemiologically important periods of time.

Prevalence and associations of presenting near-vision impairment in the Australian National Eye Health Survey.

PurposeTo describe the prevalence and associations of presenting near vision impairment (NVI) in Indigenous and non-Indigenous Australians.MethodsA sample of 3098 non-Indigenous Australians (aged 50-98 years) and 1738 Indigenous Australians (aged 40-92 years) living in 30 randomly selected Australian sites were examined as part of the population-based National Eye Health Survey (NEHS). Binocular presenting NVI was defined as near vision worse than N8 (20/50).ResultsIn total, 4817 participants (99.6% of the total sample, comprising 3084 non-Indigenous Australians and 1733 Indigenous Australians) had complete data on near visual acuity. The overall weighted prevalence of presenting NVI was 21.6% (95% CI: 19.6, 23.8) in non-Indigenous Australians and 34.7% (95% CI: 29.2, 40.8) among Indigenous Australians. In the non-Indigenous population, higher odds of presenting NVI were associated with older age (OR=1.68 per 10 years, P<0.001), fewer years of education (OR=0.95 per year, P<0.001) and residing in Remote geographical areas (OR=1.71, P=0.003) after multivariate adjustments. Among Indigenous Australians, older age (OR=1.69 per 10 years, P<0.001), fewer years of education (OR=0.91 per year, P=0.003) and residing in Inner Regional (OR=2.01, P=0.008), Outer Regional (OR=2.17, P=<0.001) and Remote geographical areas (OR=1.72, P=0.03) were associated with greater odds of presenting NVI.ConclusionsNVI represents a notable public health concern in Australia, affecting approximately 20% of non-Indigenous Australian and one-third of Indigenous Australian adults.

The economic impact and cost of visual impairment in Australia.

AIMS: To quantify the total economic costs of vision loss in Australia. METHODS: Prevalence data of visual impairment, unpublished data on indirect costs, and national healthcare cost databases were used. RESULTS: Vision disorders cost Australia an estimated A$9.85 billion in 2004. A$4.8 billion is the loss of wellbeing (years of life lost as a result of disability and premature mortality). Vision disorders rank seventh and account for 2.7% of the national loss of wellbeing. Direct health system costs total A$1.8 billion. They have increased by A$1 billion over the last 10 years and will increase a further A$1-2 billion in the next 10 years. Cataract, the largest direct cost, takes 18% of expenditure. The health system costs place vision disorders seventh, ahead of coronary heart disease, diabetes, depression, and stroke. Indirect costs, A$3.2 billion, include carers' costs, low vision aids, lost earnings, and other welfare payments and taxes. CONCLUSIONS: Even a developed economy such as Australia's cannot afford avoidable vision loss. Priority needs to be given to prevent preventable vision loss; to treat treatable eye diseases; and to increase research into vision loss that can be neither prevented nor treated.

Moraxella keratitis: predisposing factors and clinical review of 95 cases.

AIM: To analyse the clinical presentation, identify predisposing risk factors and evaluate the outcome of treatment of Moraxella keratitis. METHODS: A retrospective analysis was carried out of culture-proved cases of Moraxella keratitis from hospital records during a 10-year period (from December 1995 to November 2005) at the Corneal Unit of the Royal Victorian Eye and Ear Hospital, Melbourne, Australia. RESULTS: 95 episodes of Moraxella keratitis were identified in 92 patients. 3 (3.2%) patients had recurrent keratitis. The mean age of the patients was 70 (range 17-93) years. Multiple predisposing factors were identified in 23 (24%) eyes, including corneal graft (n = 15), previous herpes keratitis (n = 15) and eye lid diseases (n = 15). Adjunctive procedures were carried out in 42 eyes. These included botulinum toxin injection (n = 17), tarsorraphy (n = 12), penetrating keratoplasty (n = 8), enucleation (n = 3), tissue adhesive and bandage contact lens (n = 4), and conjunctival flap (n = 5). Polymicrobial infection was present in 17 eyes. Final visual acuity was counting finger or less in 25 (26%) eyes. CONCLUSIONS: Local ocular predisposing factors play a major role in Moraxella keratitis. This infection has a poor visual outcome attributable to both the nature of the infection and the predisposing factors.

Randomised controlled trial of topical ciclosporin A in steroid dependent allergic conjunctivitis.

AIM: To evaluate the efficacy, safety, and therapeutic effect of topical ciclosporin A 0.05% as a steroid sparing agent in steroid dependent allergic conjunctivitis. METHODS: Prospective, randomised, double masked, placebo controlled trial comparing signs, symptoms, and the ability to reduce or stop concurrent steroid in steroid dependent atopic keratoconjunctivitis and vernal keratoconjunctivitis using 0.05% topical ciclosporin A compared to placebo. Steroid drop usage per week (drug score), symptoms, and clinical signs scores were the main outcome measures. RESULTS: The study included an enrolment of 40 patients, 18 with atopic keratoconjunctivitis and 22 with vernal keratoconjunctivitis. There was no statistical significant difference in drug score, symptoms, or clinical signs scores between the placebo and ciclosporin group at the end of the treatment period. No adverse reactions to any of the study formulations were encountered. CONCLUSIONS: Topical ciclosporin A 0.05% was not shown to be of any benefit over placebo as a steroid sparing agent in steroid dependent allergic eye disease.

Diagnostic thresholds for diabetes: the association of retinopathy and albuminuria with glycaemia.

AIM: We examined the association of fasting plasma glucose (FPG), 2-h plasma glucose (2hPG) and HbA1c with retinopathy and microalbuminuria using both deciles of glycaemia and change point models, to validate current diagnostic criteria for diabetes and to identify therapeutic thresholds for glycaemic control. METHODS: The Australian Diabetes Obesity and Lifestyle study (AusDiab), conducted in 1999-2000, included adults aged > or =25 years from 42 randomly selected areas of Australia. Retinopathy and albuminuria were assessed in participants identified as having diabetes (based on self report and oral glucose tolerance test), impaired fasting glucose, impaired glucose tolerance and in a random sample with normal glucose tolerance. Data were available for 2,182 participants with retinal photographs and 2,389 with urinary albumin/creatinine results. RESULTS: The prevalence of retinopathy in the first 8 deciles of FPG and HbA1c and the first 9 deciles of 2hPG were 7.2, 6.6, and 6.3%, respectively and showed no variation with increasing glucose or HbA1c. Above these levels, the prevalence rose markedly to 18.6% in the top 2 deciles of FPG, 21.3% in the top 2 deciles of HbA1c and 10.9% in the top decile of 2hPG. The thresholds for increasing prevalence of retinopathy were 7.1 mmol/l for FPG, 6.1% for HbA1c and 13.1 mmol/l for 2hPG. The prevalence of microalbuminuria rose gradually across deciles of each glycaemic measure. Thresholds were less clear than for retinopathy, but were seen at a FPG of 7.2 mmol/l and HbA1c of 6.1%, with no evidence of a threshold effect for 2hPG. CONCLUSIONS: The prevalence of retinopathy rose dramatically in the highest deciles of each glycaemic measure, while for microalbuminuria the increase of prevalence was more gradual. The FPG values corresponded well with the WHO diagnostic cut-point for diabetes, however the 2hPG value did not. HbA1c thresholds were similar for both retinopathy and microalbuminuria and compared well to values shown in other studies. These results support current targets for FPG and HbA1c in preventing microvascular complications.

Quantitative carcinogenesis in man: solar ultraviolet B dose dependence of skin cancer in Maryland watermen.

Skin cancer is the most common form of cancer in humans and occurs primarily on sun-exposed areas of the body. In a study of 808 Caucasian Maryland watermen, we examined the prevalence of nonmelanoma skin cancer in relation to age and exposure to solar ultraviolet B (UVB) radiation. For each study subject, the exposure to solar UVB radiation for each year of life after the age of 16 years was calculated. We obtained the data for this analysis by combining a detailed occupational history with laboratory and field measurements. Prevalence of the three major types of nonmelanoma skin neoplasms was analyzed: squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and actinic keratosis (AK). Average annual exposure to UVB radiation was strongly correlated with the prevalence of SCC, but not with the prevalence of BCC or AK. This finding is consistent with dose saturation (plateau in dose-response relationship) for the induction of BCC and AK in humans with high annual exposure to UVB radiation. In addition, two small groups of apparently hypersusceptible individuals were present in the population. One group had SCC despite low annual exposure to UVB radiation, and the other group had multiple skin cancers despite average exposure to UVB radiation.

Impact of unilateral and bilateral vision loss on quality of life.

AIM: To investigate whether unilateral vision loss reduced any aspects of quality of life in comparison with normal vision and to compare its impact with that of bilateral vision loss. METHODS: This study used cluster stratified random sample of 3271 urban participants recruited between 1992 and 1994 for the Melbourne Visual Impairment Project. All predictors and outcomes were from the 5 year follow up examinations conducted in 1997-9. RESULTS: There were 2530 participants who attended the follow up survey and had measurement of presenting visual acuity. Both unilateral and bilateral vision loss were significantly associated with increased odds of having problems in visual functions including reading the telephone book, newspaper, watching television, and seeing faces. Non-correctable by refraction unilateral vision loss increased the odds of falling when away from home (OR = 2.86, 95% CI 1.16 to 7.08), getting help with chores (OR = 3.09, 95% CI 1.40 to 6.83), and becoming dependent (getting help with meals and chores) (OR = 7.50, 95% CI 1.97 to 28.6). Non-correctable bilateral visual loss was associated with many activities of daily living except falling. CONCLUSIONS: Non-correctable unilateral vision loss was associated with issues of safety and independent living while non-correctable bilateral vision loss was associated with nursing home placement, emotional wellbeing, use of community services, and activities of daily living. Correctable or treatable vision loss should be detected and attended to.

High prevalence of diabetic retinopathy and nephropathy in Polynesians of Western Samoa.

OBJECTIVE: To determine the prevalence of diabetic retinopathy and nephropathy retinopathy and nephropathy and to define associated risk factors in Polynesian Western Samoans with non-insulin-dependent diabetes mellitus (NIDDM) or impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS: A 1991 population-based study in Samoan adults (ages 25-74 years) included a 75-g oral glucose tolerance test, anthropometric measurements, and blood pressure recordings. Subjects with NIDDM or IGT had 45-degree stereo photographs taken (n = 263) (three standard fields of the right eye), and retinopathy was graded in comparison with Airlie House photographs. First-morning urine samples (n = 304) were also collected from these subjects and from a subsample with normal glucose tolerance. Urinary albumin concentration (UAC) was measured by radioimmunoassay: microalbuminuria was defined as UAC of 30-299 micrograms/ml; and macroalbuminuria among subjects with Proliferative diabetic retinopathy was found in 4.5% of known diabetic subjects. The prevalence of elevated UAC was 15.0% in subjects with IGT, 26.0% in newly diagnosed diabetes subjects, and 23.4% in known diabetes subjects. For all diabetic subjects (n = 162), the factors independently associated with diabetic retinopathy (logistic regression) were duration of diabetes, fasting plasma glucose, and body mass index (inversely). Duration of diabetes, serum triglyceride concentrations, and systolic blood pressure were independently associated with elevated UAC in all diabetic subjects (n = 138), and fasting plasma glucose had borderline significance. CONCLUSIONS: Diabetic retinopathy and albuminuria are common in Polynesian Western Samoans. Duration of diabetes and level of glycemia were the most important associated factors. These data underline the need for cost-effective programs for the detection and early treatment of diabetes in Western Samoa and other developing populations with high susceptibility to NIDDM.

Improvement in severe onchocercal skin disease after a single dose of ivermectin.

PURPOSE: Skin disease is the most common clinically important manifestation of onchocerciasis. Ivermectin, a newly available drug, is well tolerated and effective in Onchocerca volvulus infection. However, little information is available regarding its effect on onchocercal skin disease. The purpose of this study was to examine, in patients with well-characterized onchodermatitis, the effect of a single dose of ivermectin. SUBJECTS AND METHODS: Twenty-one persons with severe onchodermatitis were followed over a 6-month period. In order to evaluate the effect of ivermectin on their skin lesions, photographic transparencies were made before treatment and at 3 and 6 months after treatment. These were then evaluated in a blinded fashion. RESULTS: Following a single dose of 150 micrograms/kg, there was a significant improvement in dermatitis in the first 3 months after treatment. All 14 persons with the worst skin disease showed improvement. The drug had no demonstrable effect on depigmented lesions over the period of observation. Treatment was well tolerated. CONCLUSION: Single-dose ivermectin shows promise as the first acceptable treatment for severe onchocercal dermatitis.

Corneal epithelial basement membrane changes in diabetes.

The corneas of 12 eye donors with maturity-onset diabetes were obtained, and the corneal epithelial basement membranes were studied by transmission electron microscopy. Similar tissue was obtained from 12 nondiabetic eye donors who were matched for age (within 2 years) and race. The mean thickness of the corneal epithelial basement membrane in nondiabetic patients was 0.33 micrometer (+/- 0.11 S.D.), which gives a normal range of 0.11 to 0.55 micrometer. None of the nondiabetic basement membranes lay outside this range. The basement membranes of four of the 12 diabetics exceeded this thickness. No race or sex difference was seen in basement membrane thickness, nor was a clear trend seen with age. Multilaminated basement membranes were seen in eight diabetic patients and six nondiabetic patients. Multilamination was more clearly related to basement membrane thickness than to the presence or absence of diabetes.

Clearance of chlamydial elementary bodies from the conjunctival sac.

The rate of disappearance of inactivated Chlamydia trachomatis elementary body (EB) preparations from the conjunctival sac was studied in monkeys. Direct fluorescent antibody (DFA) cytology showed that the majority of EB had been cleared from the eye within 24 hr of the inoculation of 1 X 10(6) inactivated EB, although small numbers of EB could be detected for up to 144 hr. The rate of clearance in normal and ocular immune animals did not differ, and formalin-killed and UV-inactivated EBs disappeared at a comparable rate. These studies suggest that chlamydial EB are cleared relatively quickly from the eye and support the notion that EBs detected by DFA cytology indicate the presence of current infection.

Evaluation of photographic methods for documentation of lens opacities.

Several systems have been developed to document lens opacities photographically. In general, the settings for these photographs have been standardized, but there has been no scientific basis for the selection of these settings. We investigated several of these variables. We examined the effect of degree of angulation of the slit beam in slit photography of the nucleus and found no difference in the grading of nuclear opacities in paired photographs taken with illumination angles of 30 or 40 degrees. Similarly, we found no difference between black-and-white and color film in the detection or grading of either cortical or posterior subcapsular opacities in retroillumination photographs and no difference if a Neitz or an Oxford cataract camera was used. In view of the equivalence of these methods, we would advocate, for reasons of ease of application and cost, the use of a single-color slit-lamp photograph with a 30 degree slit angle for documenting nuclear opacities, and the use of black-and-white retroillumination photography with either the Neitz or Oxford cataract cameras for cortical and posterior subcapsular opacities.

Attempted oral immunization with chlamydial lipopolysaccharide subunit vaccine.

The effects of oral immunization with a recombinant vaccine expressing chlamydial lipopolysaccharide (LPS) on subsequent ocular challenge with Chlamydia trachomatis were studied in cynomolgus monkeys. Groups of four or five monkeys were given an oral vaccine containing 5 X 10(8) parent or recombinant Escherichia coli on days 0, 14, and 35 and were challenged with either 2 X 10(3) or 5 X 10(3) inclusion forming units of viable purified elementary bodies on day 42. On clinical and microbiologic grounds, oral immunization failed to protect monkeys against subsequent ocular challenge. Antichlamydial IgG or IgA antibodies were not induced by oral vaccination, and the antibody response following ocular challenge was similar in vaccinated and nonvaccinated animals. Paradoxically, however, while nonvaccinated control animals developed antibodies against chlamydial LPS detectable by immunoblotting after chlamydial challenge, the LPS vaccinated animals did not. This study demonstrates that the oral recombinant vaccine expressing chlamydial LPS was ineffective in protecting against chlamydial eye infection and strongly suggests that chlamydial LPS may not be an important antigen for protective immunity against chlamydia.

Immune mechanisms in chlamydial eye infection. Development of T suppressor cells.

In vitro proliferation assays of whole peripheral blood mononuclear leukocytes (PBML) and PBML depleted of suppressor T cells were performed in cynomolgus monkeys after they had received one, two, or repeated ocular inoculations with Chlamydia trachomatis. Whole PBML responded only weakly to chlamydial antigen, and responses to concanavalin A were depressed for 12 wk following ocular infection. Depletion of the suppressor T cell population did not result in increased chlamydia-specific proliferation until 14-20 wk after initial antigen contact, suggesting that circulating suppressor T cells are not responsible for the initiation of the chronic state.

Use of photographic techniques to grade nuclear cataracts.

Methods for objectively documenting and grading different varieties of lens opacities are needed in order to conduct research on risk factors for cataracts. This study tested the feasibility and reliability of using two different photographic methods to grade nuclear opacities. Photographs were taken of 41 eyes using a regular Topcon SL-5D photo slit lamp, and using a Topcon SL-45 (Scheimpflug) camera. The photographs were graded against a set of four standard photographs of increasing nuclear opacification. Densitometric analyses were also performed on both sets of photographs. The clinical grade, on examination, of the nucleus was compared to the examiner's grade of each photograph. Agreement was fair between the examination results and the grading of the photographs. Inter-observer reliability was high (kappa = 0.71) with photographs taken using the photo slit lamp. Moreover, the severity grading of the photographs showed a good correlation with the severity of opacity as determined by densitometric analyses. On the basis of these data, and on the field experience, the use of photographs of the nucleus obtained by photo slit lamp may be used in epidemiological surveys.