Does direct ophthalmoscopy improve retinal screening for diabetic eye disease by retinal photography?

Nonmydriatic fundus camera for diabetic retinopathy screening in a safety net hospital: effectiveness, prevalence, and risk factors

PURPOSE

To evaluate diabetic retinopathy (DR) prevalence and risk factors, and the effectiveness of nonmydriatic fundus camera as a screening tool for the detection of DR, in a safety net hospital.

METHODS

This was a retrospective, population-based, cross-sectional study. Diabetic patients, referred by their primary care physicians to a DR community screening program, were included. A Topcon TRC NW-6S camera was used to obtain 45-degree digital color fundus images. Images were interpreted by retina specialists using a quality rating system. Patients with retinal findings or unreadable photographs were referred for a complete examination. Outcome measures were attendance rates, photograph quality, DR prevalence, and associated risk factors.

RESULTS

A total of 948 diabetic patients were sent for camera screening, with an attendance rate of 65.6%, which increased during the study period. The mean age was 55.8 ± 11.6 years, the majority (56.9%) were Hispanic, and 43.5% were uninsured. Overall photograph quality rating was relatively high, with 81.7% graded as good or fair. Thirty photographs (2.9%) were unreadable. The prevalence of newly diagnosed DR was 11.1%. Independent DR-associated risk factors included Hispanic race (odds ratio [OR] = 2.29), lack of health insurance (OR = 2.49), longer duration of diabetes (OR = 1.07), higher HbA1c levels (OR = 1.19), presence of diabetic complications (OR = 2.93), and lack of previous eye examination (OR = 13.22).

CONCLUSIONS

Nonmydriatic fundus camera is an effective and feasible screening tool for the early detection of DR in a safety net institution. It should be considered in areas with limited access to health care to improve quality of care and potentially reduce vision loss rates.

Rates of referable eye disease in the Scottish National Diabetic Retinopathy Screening Programme

AIMS

Diabetic retinopathy screening aims to detect people at risk of visual loss due to proliferative diabetic retinopathy, but also refers cases of suspected macular oedema (maculopathy). At the introduction of screening, ophthalmology was concerned that referral rates would be unmanageable. We report yield of referable disease by referral reason for the first 5 years of the programme.

METHODS

We extracted screening results from a nationwide clinical diabetes database to calculate annual referral rates to ophthalmic clinics. We used logistic regression to examine associations between clinical measures and referable disease.

RESULTS

182 397 people underwent ≥ 1successful retinal screening between 2006 and 2010. The yield of referable eye disease was highest in the first 2 years of screening (7.0% and 6.0%) before stabilising at ∼4.3%. The majority of referrals are due to maculopathy with 73% of referrals in 2010 based on a finding of maculopathy.

CONCLUSIONS

The commonest cause for referral is for suspected macular oedema (maculopathy). Referral rates for retinopathy have stabilised, as predicted, at relatively low rates. However, ophthalmology workload continues to rise as new treatment options (ie, monthly intraocular injections) have unexpectedly increased the impact on ophthalmology. A review of the screening referral path for maculopathy may be timely.

[Diagnosis, therapy and follow up of diabetic eye disease]

Diabetes mellitus causes diabetic retinopathy, diabetic macular edema, optic neuropathy, cataract or dysfunction of the eye muscles. The incidence of these defects correlates with disease duration and quality of the metabolic control. The recommendations of the Austrian Diabetes Association for the diagnosis, the therapeutic procedures and requirements for adequate follow up depending on the stages of the different forms of diabetic eye disease are summarized.

Diabetic retinopathy at diagnosis of type 2 diabetes in Scotland

AIMS/HYPOTHESIS

The aim of this study was to examine the prevalence of and risk factors for diabetic retinopathy in people with newly diagnosed type 2 diabetes mellitus, using Scottish national data.

METHODS

We identified individuals diagnosed with type 2 diabetes mellitus in Scotland between January 2005 and May 2008 using data from the national diabetes database. We calculated the prevalence of retinopathy and ORs for risk factors associated with retinopathy at first screening.

RESULTS

Of the 51,526 people with newly diagnosed type 2 diabetes mellitus identified, 91.4% had been screened by 31 December 2010. The median time to first screening was 315 days (interquartile range [IQR] 111-607 days), but by 2008 the median was 83 days (IQR 51-135 days). The prevalence at first screening of any retinopathy was 19.3%, and for referable retinopathy it was 1.9%. For individuals screened after a year the prevalence of any retinopathy was 20.5% and referable retinopathy was 2.3%. Any retinopathy at screening was associated with male sex (OR 1.19, 95% CI 1.14, 1.25), HbA(1c) (OR 1.07, 95% CI 1.06, 1.08 per 1% [11 mmol/mol] increase), systolic BP (OR 1.06, 95% CI 1.05, 1.08 per 10 mmHg increase), time to screening (OR for screening >1 year post diagnosis = 1.12, 95% CI 1.07, 1.17) and obesity (OR 0.87, 95% CI 0.82, 0.93) in multivariate analysis.

CONCLUSIONS/INTERPRETATION

The prevalence of retinopathy at first screening is lower than in previous UK studies, consistent with earlier diagnosis of diabetes. Most newly diagnosed type 2 diabetic patients in Scotland are screened within an acceptable interval and the prevalence of referable disease is low, even in those with delayed screening.

Hypoglycemia in Type 1 Diabetes Mellitus

Spontaneous hypoglycemia is uncommon in the general (nondiabetic) population, but iatrogenic hypoglycemia is rife in patients with type 1 diabetes mellitus, among whom hypoglycemia constitutes a barrier to optimal glycemic control. The obligate dependence on exogenous insulin, together with the current imperfection in insulin therapies, generates degrees of blood glucose fluctuations that often exceed physiological boundaries in these patients. Downward swings in blood glucose levels, if sustained, result in hypoglycemia and significant morbidity and mortality. Hypoglycemia in type 1 diabetes indicates an imbalance between caloric supply and glucose use in response to insulin or exercise. Counterregulatory mechanisms that auto-correct iatrogenic hypoglycemia often become progressively impaired in these patients. This defective counterregulation, together with the imperfections in insulin delivery, set the stage for significant morbidity from iatrogenic hypoglycemia. Recurrent episodes of iatrogenic hypoglycemia induce a state of hypoglycemia unawareness and defective counterregulation, which defines the syndrome of hypoglycemia-associated autonomic failure (HAAF). The reduced awareness of, and counterregulatory responses to, hypoglycemia in patients with HAAF lead to worsening episodes of severe hypoglycemia. Approaches to the prevention of hypoglycemia include glucose monitoring, patient education, meal planning, and medication adjustment. In patients with HAAF, scrupulous avoidance of iatrogenic hypoglycemia may restore the symptomatic and counterregulatory responses to hypoglycemia. Behavioral training focusing on recognition of the more subtle symptoms and signs of evolving hypoglycemia may be beneficial to some patients with HAAF. A methodical search for the pattern and etiology of iatrogenic hypoglycemia is a prerequisite for the identification of the best preventive approach. With proper education, patients with type 1 diabetes and their physicians can learn to prevent or minimize the risk of hypoglycemia while pursuing excellence in glycemic control.

A national retinal screening programme for diabetes in Scotland

The Health Technology Board Scotland (HTBS) have issued recommendations for eye screening in patients with diabetes. These are based on evidence-based clinical studies. Evidence-based studies do not answer all the practical issues, and some conclusions have thus been extrapolated from the known evidence base. Other factors such as patient issues, organizational issues and cost effectiveness have also been incorporated into the recommendations. HTBS recommend single-field digital retinal photography. Retinal photography best addresses the issues of adequate sensitivity and accountable quality assurance. Non-mydriatic photography is recommended, followed by immediate use of dilating eye drops if it is unsuccessful, followed by slit-lamp examination if both of these approaches fail. An independent grading scheme has been established, which is similar to the 'Global', and compatible with the National Screening Committee (NSC) grading scheme. The rationale for these recommendations, and debate behind some of the decisions, is laid out in this article.

Algorithmic evaluation of metabolic control and risk of severe hypoglycemia in type 1 and type 2 diabetes using self-monitoring blood glucose data

The optimization of metabolic control in Type 1 and Type 2 diabetes mellitus (T1DM and T2DM, respectively) [i.e., the maintenance of near-normal hemoglobin A(1c) (HbA(1c)) without increasing the risk of hypoglycemia] could be enhanced by analysis of self-monitoring blood glucose (SMBG) data assessing complementary processes: exposure to hyperglycemia and hypoglycemia. We present algorithms that simultaneously estimate HbA(1)c and risk for significant hypoglycemia using 45-60 days of SMBG. The algorithms were developed using a primary data for 96 subjects with T1DM (n = 48) and T2DM, and were validated in an external data for 520 subjects with T1DM (n = 231) and T2DM. All subjects were on insulin. In the primary (external) data the estimation of HbA(1c) had absolute error of 0.5 (0.7) units of HbA(1c) and percent error of 6.8% (8.1%); 96% (96%) of all estimates were within 20% from reference HbA(1c). The SMBG-estimated value of HbA(1c) was closer to current reference HbA(1c) than a reference HbA(1c) value taken only 2-3 months ago. The results in T1DM and T2DM were similar. Linear model predicted future significant hypoglycemia (R(2) = 62%, p < 0.0001). The leading predictor was a previously introduced Low Blood Glucose Index, which alone had R(2) = 55%. Probability model assessed accurately the odds for future moderate/severe hypoglycemia (coefficients of determination 92%/94%). Four risk categories were identified; within moderate- and high-risk category, there was no difference between T1DM and T2DM in the occurrence of prospective significant hypoglycemia. SMBG data allow for accurate estimation of the two most important markers of metabolic control in T1DM and T2DM - HbA(1c) and risk for hypoglycemia.