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Diabetes and Diabetic Eye Disease (L2016)

4T CPD in Australia | 1CD in New Zealand | 24 October 2015

 

EXCLUSIVE TO LUXOTTICA

This module explores diabetes mellitus and diabetic retinopathy both in the context of the global community and current situation in Australia. A review of diabetes and diabetic retinopathy is covered. Diagnosis, management and treatment of diabetic retinopathy are examined from an evidence-based perspective to understand the best practices.

Learning Outcomes

At the completion of this module you will:

  • Understand the epidemiology of diabetes mellitus and diabetic retinopathy, including magnitude and risk factors
  • Refresh your knowledge of ocular complications of diabetes mellitus
  • Understand the clinical presentation of diabetic retinopathy and most current classifications of diabetic retinopathy
  • Appreciate the advantages of new imaging technology in detecting and monitoring diabetic retinopathy
  • Understand the evidence for management and treatment of diabetic retinopathy
  • Understand the current diabetic eye disease screening programs globally and in Australia
  • Understand the role of optometry in diabetic eye care
  • Understand the importance of a multidisciplinary approach to care in diabetes mellitus

Assessment

You will be required to complete a multiple choice exam at the end of the module based on evaluating scans from a number of clinical cases. Your responses will be automatically marked by the E-Learning system and a mark instantly returned.

Introduction

Diabetes mellitus is the most common non-communicable disease in the world that results in significant morbidity and mortality due to cardiovascular complications, eye and kidney disease and limb amputation. This makes diabetes mellitus the most challenging public health issue of the 21st century as throughout the world it is now reaching epidemic levels.

Diabetes mellitus is a major cause or avoidable blindness in both developing and the developed world.

In Australia, diabetes mellitus is the:

  • Most common reason for commencing renal dialysis
  • The most common cause of blindness in people under the age of 60 years
  • The most common cause of non-traumatic lower-limb amputation
  • A major cause of cardiovascular disease
  • One of the most common chronic diseases in children

Due to its rising prevalence, optometrists will be seeing more patients with this condition. It is important for optometrists to have a comprehensive understanding of diabetes mellitus, and its ocular complication diabetic retinopathy, so as to provide the very best of care to the patients seen.

Epidemiology of Diabetes and Diabetic Retinopathy

Diabetes

Definition of Diabetes

Diabetes mellitus is a chronic metabolic disorder, which is characterised by hyperglycaemia resulting from defects in insulin secretion, insulin action or both. The chronic hyperglycaemia of diabetes leads to long-term dysfunction, damage and eventual failure of nearly all bodily organs, in particular, the heart, blood vessels, eyes, kidneys and nerves.

Type 1 diabetes occurs due to autoimmune destruction of the pancreatic beta cells, which produce insulin. In Australia, approximately 10% of all persons with diabetes have Type 1.1 Type 2 diabetes is due to insulin resistance and/or abnormal insulin secretion. In Australia, approximately 85 per cent of persons with diabetes have Type 2.1

The World Health Organisations diagnostic criteria for diabetes is the results from the impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) that tests the level of venous plasma glucose concentration at fasting and two-hour intervals.2

Magnitude of Diabetes

The global prevalence of diabetes was estimated to be 8.3% of adults (382 million people) in 2013, with 175 million currently undiagnosed.3 The number of people with diabetes is expected to rise beyond 592 million in 25 years.3


 
FIG 1 - Fig. 1 Increasing global prevalence of diabetes.3

The AusDiab study found the prevalence of diabetes in adult Australian men to be 8.0% and 6.8% in adult Australian women.4 In addition to this, another 16% of adults had impaired glucose tolerance or impaired fasting glucose.4 Every day in Australia approximately 275 adults are developing diabetes.1 Each year 0.8% of Australian adults develop diabetes.1

This equates to approximately 1.1 million Australians with diagnosed diabetes, of which 120, 000 people have Type 1, 956, 000 people with Type 2, and 23, 600 women with gestational diabetes.5 The estimated total number of Australians with diabetes and pre-diabetes is 3.2million.5 The number of people with diabetes is projected to reach 2 million in 2025,6 and 3.3 million by 2031.7

Diabetes in more common in males (4.9%) than in females (3.8%), and the prevalence of Type 2 diabetes increases with age, such that only 0.3% of Australians aged <35 years have been diagnosed rising to around 14-16% of those aged >65 years.8 (Figure 2)

Fig. 2 Australians diagnosed with diabetes by age group in 2007-8.8

Classification of Diabetes

Type 1 Diabetes

Develops due to autoimmune destruction of the pancreatic beta cells (insulin-producing cells) with typical onset in childhood or early adulthood, although it can develop at any age. Treatment is either insulin injections or continuous infusion of insulin through an insulin pump.

Type 1 diabetes often develops suddenly and can produce symptoms such as:

  • Abnormal thirst and a dry mouth
  • Frequent urination
  • Lack of energy, extreme tiredness
  • Constant hunger
  • Sudden weight loss
  • Slow-healing wounds
  • Recurrent infections
  • Blurred vision

People with Type 1 diabetes can lead a healthy life through daily insulin therapy, close monitoring, a healthy diet and regular physical exercise.

Type 2 Diabetes

Characterised by an insulin resistance and/or abnormal insulin secretion, either of which may predominate. There is a strong genetic propensity, which is unmasked by lifestyle factors such as obesity or lack of exercise. Age of onset is typically after 40 years of age, but can occur in younger adults and even adolescents. Treatment includes lifestyle changes, diabetic medications or insulin injections.

Type 2 diabetes is the most common type of diabetes, occurring usually in adults, but is now being seen in children and adolescents. Most people with Type 2 diabetes can be unaware of their illness for many years resulting in damage occurring to the body due to excessive glucose.

The prevalence of Type 2 diabetes is growing rapidly worldwide due to economic development, aging populations, increasing urbanisation, dietary changes, reduced physical activity and changes in other lifestyle patterns.9

Pre-diabetes

A condition where blood glucose levels are elevated, but not high enough to be classified as diabetes. Two million Australians have pre-diabetes which if left untreated, may develop into Type 2 diabetes within 5 to 10 years.10 As well, people with pre-diabetes are more likely to have a heart attack or stroke.

Impaired Fasting Glucose (IFG): This condition is diagnosed when fasting blood glucose level is found to be higher than normal but not high enough to be called diabetes.

Impaired Glucose Tolerance (IGT): This condition is diagnosed when blood glucose levels are higher than normal but still not high enough to be called diabetes.

Being diagnosed with pre-diabetes does not mean the person will go on to develop Type 2 diabetes. If the person makes the appropriate lifestyle changes, such as losing weight, eating healthily, exercising regularly and ceasing smoking there will be a decreased risk of developing diabetes.

Gestational Diabetes

Diabetes that is first identified during pregnancy. Occurs when women develop a resistance to insulin and subsequent high blood glucose during pregnancy. Gestational diabetes usually occurs around the 24th week of pregnancy. The diabetes disappears after the child is born, but the mother has a high risk of developing Type 2 diabetes within 10-15 years.

Known Diabetes

Diabetes that has been diagnosed by a health care professional.

Undiagnosed Diabetes

Diabetes that is identified as part of a health survey, through blood testing, in a person not previously known to have diabetes.

Risk Factors of Diabetes

The AusDiab study found the risks factors for diabetes to be obesity, physical inactivity, hypertension, dyslipidaemia and metabolic syndrome.1

Ethnicity is also a risk factor for diabetes, with people of southern European, Asian, Aboriginal, Torres Strait Islander, and Pacific Islander descent being at higher risk.11

AUSDRISK

The data collected from the AusDiab Study was used to develop and validate a simple risk score to predict incident diabetes based on demographic, lifestyle and simple anthropometric information. The diabetes risk assessment tool provides a simple, non-invasive method to predict 5-year risk of developing Type 2 diabetes. The tool utilises nine risk factors that are either known or easily self-assessed. The nine risk factors are:11

  • Age
  • Gender
  • Ethnicity
  • Parental history of diabetes
  • History of high blood glucose level
  • Use of antihypertensive medications
  • Smoking
  • Physical inactivity
  • Waist circumference

Different answers to the questionnaire are attributed different points that add up to give an overall score. A score of 5 or less indicates low risk, 6-11 is intermediate risk and 12 or more has high risk.

FIG – 3 Aboriginals, Pacific Islanders and Asians are at higher risk of developing diabetes.


Diabetic Retinopathy

Definition of Diabetic Retinopathy

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus. There are four main processes at play with diabetic retinopathy: the appearance of microaneurysms, increased vascular permeability, capillary occlusion, and fibrous and neovascular proliferation.12 These processes can be categorised into either non-proliferative or proliferative DR that are outlined in Table 1. Diabetic Retinopathy (DR) evolves slowly with no symptoms, until vision loss develops usually 15 years after onset of diabetes.13

Table 1. Stages of Diabetic Retinopathy

Magnitude of Diabetic Retinopathy

Diabetic retinopathy accounts for approximately 5% of the 37 million blind persons in the world.14 The global prevalence of DR is 34.6%, with the prevalence of PDR being 6.96%, DME being 6.81% and sight-threatening DR being 10.2%.  It is estimated that 93 million people globally have DR.15 Of these, 17 million people have PDR, 21 million have DME and 28 million people with sight-threatening diabetic retinopathy (STDR).15

The AusDiab Study found that 15.3% of Australians with known and unknown diabetes had DR.4 In the population of known diabetics (both type I and II) prevalence was 24.5% and in type II only it was 21.9%.4 The prevalence of DR in newly diagnosed cases was 6.2%.4 In Australians with known diabetes, 19.8% had NPDR and 2.1% had PDR.4 In Australians with newly diagnosed diabetes, there were no cases of PDR.4
Prevalence of DR in other population-base studies were as follows:

Melbourne VIP study: 21.9% in those with self-reported diabetes.16

Blue Mountains Eye Study (BMES) was 35.5% based on self-reported diabetes and FPG values.17

The impact of visual impairment goes beyond the individual. Both communities and economies lose earning capacity and productivity. Thus, the social and financial costs of visual impairment and blindness are affect families, communities and the entire country.

Risks Factors of Diabetic Retinopathy

The risk factors for Diabetic Retinopathy found by the AusDiab study4 were:

  • Duration of diabetes
  • HbA1c
  • Systolic blood pressure (SBP)
  • Urinary albumin
  • Creatinine ratio
  • Fasting plasma glucose (FPG)
  • C-peptide
  • Insulin/hypoglycemic tablet use.

Ocular Complications of Diabetes

A loss of fine detail in central vision is typically one of the first and most common symptoms of DR. Night vision problems, flashes and floaters are other less common symptoms of DR.18

Common ocular symptoms of undiagnosed diabetes include:18

  • Blurred or fluctuating vision
  • Diplopia
  • Ocular dryness

Table 2 is a listing of all the known ocular complications of diabetes.

Table 2. Ocular complications of diabetes.18

 

Clinical Presentation and Classification of Diabetic Retinopathy


Clinical Presentation of Diabetic Retinopathy

Non-Proliferative Diabetic Retinopathy

Non-proliferative diabetic retinopathy (NPDR) is characterised by the presence of:

  • Microaneurysms: clinically detectable lesion located in the inner nuclear layer of the retina
  • Dot and Blot Haemorrhages: located in the middle retina
  • Hard exudates: located between the inner plexiform and inner nuclear layers
  • Vascular changes: beading, looping and sausage like segmentation of the veins
  • Cotton wool spots: soft exudates or nerve fibre infarcts, resulting from capillary occlusion of the retinal nerve fibre layer
  • Intraretinal microvascular abnormalities (IRMA): which are dilated capillaries that seem to function as collateral channels, and frequently seen adjacent to the areas of capillary closure
  • Retinal edema: characterised by accumulation of fluid between the outer plexiform layer and inner nuclear layer, that may later involve the entire layers of the retina.

Fig. 4 NPDR showing dot/blot haemorrhages, hard exudate and venous beading

Proliferative Diabetic Retinopathy

The Early Treatment of Diabetic Retinopathy Study (ETDRS) found that approximately 50% of patients with very severe NPDR progress to proliferative diabetic retinopathy (PDR) within 1 year.19 PDR is characterised by the presence of neovascularisation. There are two classifications of neovascularisation:

  • New vessels at disc (NVD): new vessels may proliferate at the optic nerve head
  • New vessels elsewhere (NVE): new vessels may proliferate along the course of the major vascular arcades.

The new vessels mostly grow along the posterior hyaloid and sudden vitreous contraction may result in rupture of these fragile vessels.

Fig. 5 PDR showing NVE and NVD

Classification of Diabetic Retinopathy

ETDRS19 has classified NPDR into mild, moderate severe and very severe and PDR into early PDR and high-risk PDR. The ETDRS classification is outline in Table 3.


Table 3. ETDRS Classification.19

As this classification is quite complex, the International Clinical Diabetic Retinopathy Disease Severity scale was developed as an easily understandable scale to classify NPDR. This scale is outlined in Table 4. Optometry Australia has adopted the International Clinical Diabetic Retinopathy Disease Severity Scales in 2014 as part of their guidelines on DR.

Table 4. International Clinical Diabetic Retinopathy Severity Scales and recommended referral patterns.20

Diabetic Macular Edema

Macular edema is the most common cause of moderate visual loss. The intraretinal fluid originates from leaking microaneurysms, or diffuses from capillary incompetence areas. Sometimes the pockets of fluid are so large that can be seen as cystoid macular edema (CME).

Diabetic macular edema (DME) is retinal thickening within two disc diameters of the centre of macula. The ETDRS categorise DME into clinically significant macular edema (CSME) or non-CSME.

CSME includes any one of the following lesion:

  1. Retinal thickening at or within 500 microns from the centre of macula
  2. Hard exudates at or within 500 microns from the centre of macula associated with thickening of the adjacent retina
  3. An area or areas of retinal thickening at least one disc area in size, at least a part of which is within one disc diameter of the centre of macula.

 

The International clinical diabetic macular edema severity scale has devised a simpler classification of DME.20 The International clinical diabetic macular edema severity scale has been adopted by the Optometry Australia in 2014 as part of their Clinical Guidelines for diabetes. 

Table 5. International Clinical Diabetic Macula Edema Scales and recommended referral patterns.20

Fig. 6 OCT HD Raster showing retinal thickening at macula

Fig. 7 OCT HD Raster showing retinal thickening and cystic changes at macula

 

Imaging Techniques That Assist in Diagnosis

ETDRS 7-Standard Fields

Dilated retinal examination and photography are integral to the diagnosis and management of DR. The gold standard for detection of DR is the ETDRS 7- standard field 35mm colour 30 degree stereoscopic fundus photography.21 ETDRS photography requires skilled photographers, pupil dilation and the use of 35mm slide film, which can be problematic for screening all the patients that need to be imaged. The positioning of the 7 standard fields is depicted in Fig. 8.

Fig. 8 ETDRS 7-standard fields.21

Optos Daytona - Ultrawide Digital Retinal Scan

The Optos Daytona scanning laser ophthalmoscope, allows the imaging of up to 200 degrees (82%) of the retina in a single image, compared to 30% with ETDRS photography.22,23

In a recent study comparing the agreement between Ultrawide imaging and ETDRS photography in determining the severity level of DR, it was found that UW imaging demonstrated high agreement and substantial or better correlation compared with both lesion level and clinical level grading of ETDRS photographs.22 In the same study, DME grading of ultrawide field images demonstrated high agreement and substantial correlations with ETDRS photographs at the clinical level. Silva et al 201222 found that the sensitivity and specificity of ultrawide imaging for detecting different stages of DR is given in Table 6.

 
Table 6. Sensitivity and Specificity of Optos UWDRS for identifying DR diagnosed on ETDRS photography.22

 
Fig. 9 Optos image compared to ETDRS 7-standard fields.22

Research has also shown that whilst 60% of all DR lesions are predominantly evident in the retinal area imaged by ETDRS defined fields, approximately 30% of haemorrhages, IRMA, and NVE are located predominantly outside the ETDRS defined 7-standard fields.23 Silva et al 201323 found the presence of these lesions outside the ETDRS 7-standard fields suggested a more severe classification of DR in 10% of eyes studied.

Lesions identified by UWDRS in peripheral areas not captured by ETDRS photography, might aid in determining more accurate rates of disease progression for patients with DR,23 as research has suggested that some of the earliest clinical changes in DR may occur in the mid-peripheral fundus.24,25 Figure 10 shows diabetic lesion located outside the ETDRS field, in peripheral fields 3 and 4. Incorporating an Optos UWDRS into your diabetic eye screening protocol is likely to enhance detection of diabetic retinopathy and provide more information on progression of the disease. Thus it is important to highlight to our diabetic patients the importance of a UWDRS in their screening for diabetic retinopathy.

It should be noted as well, that the Optos green laser separation results in high-contrast imagery that highlights retinal structures including retinal haemorrhages and exudate. Thus the green separation is helpful in assessment of vascular diseases such as DR.

 Fig. 10 UWDRS with overlay of ETDRS fields and ultrawide periphery fields us in the study.23

OCT

Traditional methods for assessing DME included contact and non-contact slit-lamp biomicroscopy, indirect ophthalmoscopy, fluorescein angiography (FA) and fundus stereo-photography. The introduction of OCT allows for an objective assessment of DME with effectiveness in both qualitative and quantitative description. OCT allows enhanced diagnosis, classification and follow-up.

In a recent study, OCT was found to detect a higher frequency of DME compared to slit-lamp biomicroscopy and FA, with frequency levels being 94.5%, 82.1% and 88.8% respectively.26 The sensitivity of the OCT to detect DME was very high at 98.6%.26

Several authors have propose an classification of DME based on OCT findings:26,27,28,29,30,31,32

  • Type 1 focal macular thickening: sponge-like swelling of the retina with a generalised, heterogeneous, mild hyporeflectivity compared to normal retina.
  • Type 2 diffuse macular edema without cysts
  • Type 3 cystoid macular edema: presence of intraretinal, round or oval cystoid areas of low reflectivity, which are typically separated by highly reflective septae.
  • Type 4 tractional macular edema: presence of epiretinal membranes, vitreomacular traction or both.
  • Type 5 serous retinal detachments: focal, arch-like elevations of neurosensory retina overlying a hyporeflective, dome-shaped space.
 Fig. 11 Macular Cube showing retinal thickening at the macula.

 

Management

Control of Condition

It has been clearly demonstrated in several multi-centred randomised clinical trials that DR can be effectively prevented or treated. The key studies are summarised below.

Diabetes Control and Complications Trial (DCCT)33,34

Tight control of blood glucose levels lead to:

  • reduced the risk of progression of DR by 54%
  • reduced development of severe NPDR or PDR by 47%
  • 56% risk reduction in need for laser treatment
  • 23% risk reduction in developing diabetic macular oedema

UK Prospective Diabetes Study (UKPDS)35,36,37

Tight control of blood glucose levels lead to:

  • 37% risk reduction in microvascular changes
  • 34% risk reduction in need for laser treatment
  • 47% risk reduction in decreased vision

Early Treatment of Diabetic Retinopathy Study38,39,40

  • Found that PRP can reduce risk of severe vision loss to <2% if administered at appropriate stage
  • Focal laser treatment reduced moderate vision loss by 50%

Early diagnosis of DR and prompt treatment can prevent 98% of vision impairment.41,42,43 The key strategies for prevention of DR are early detection through effective screening and optimal control of risk factors, such as glycaemia and blood pressure.12,44

Treatment of Diabetic Retinopathy

The primary treatment method for patients with DR who are at high risk of vision loss is laser photocoagulation. Unfortunately laser photocoagulation is not highly effective treatment as about 50% of patients with DR progress despite multiple treatments.12 Laser photocoagulation destroys retinal tissue resulting in scars which can lead to poor night vision, altered colour vision, constricted peripheral vision and reduction in visual acuity.12

Researchers have recently turned their attention to pharmacological interventions for treatment of DR. The pharmacological agents that are now being used in treatment of DR are corticosteroids and anti-VEGF (vascular endothelia growth factor), however their exact role and guidelines will become clearer as results of prospective randomised clinical trials are released.12

 
Fig. 12 Composite image showing extensive pan-retinal photocoagulation scarring.

 
Fig. 12 Fundus Autofluorescence image showing extensive pan-retinal photocoagulation scarring. Hypofluorescence represents destroyed RPE and neurosensory layer. This patient would have a very constricted field of view.

 

Diabetic Eye Screening Programs

Most Diabetic eye screening programs rely on retinal photography, which is cost effective compared with no screening or opportunistic screening.45,46

Current screening for diabetic retinopathy in western countries is unsatisfactory. For example, in the United States only approximately 40-60% of people with diabetes are seen annually by an ophthalmologist.47

Diabetic Eye Screening Programs Globally

France: OPHDIAT Telemedicine

The ophtalmologie-diabete-telemedecine (Ophdiat) a telemedicine program was implemented in France in 2004. The program meets the French National Health Authority’s recommendation of annual fundal examinations for diabetic patients with no documented or mild retinopathy.48 The Ophdiat program has several local screening centres that are linked through a central server to the Ophdiat Reading Centre. At the local screening centres, orthoptists or nurses take retinal photographs with non-mydriatic retinal cameras. Images are transmitted to the central server, where they are read and graded by ophthalmologists.49 The grading Ophthalmologists must be certified by the Ophdiat Reading Centre.

The Ophdiat telemedicine program is a fast non-invasive technique that frees up time that is better spent on diabetic education. The program can also be used in a variety of locations such as outpatient clinics and hospitals. However, the main detractor to this program is poor compliance to attending screenings. A five year review of the Ophdiat showed that 26.55% of screening resulted in referral for advanced DR.48 Compliance of patients to the annual telemedicine retinal photography was poor with 77.23% screened only once in 5 years, 15% screened twice and 5% three times.48

New Zealand: National Diabetes Retinal Screening

The NZ National Diabetes Retinal Screening program was introduced in 2001 and is administered by the District Health Boards (DHBs) who out-source the program to providers in 26 locations.50 The providers are either Diabetes Centres, local hospital Eye Departments, Ophthalmologists or Optometrists. Diabetic patients are referred into the retinal screening service by their general practitioner (GP). In 2006 the National Diabetes Retinal Screening Grading System and Referral guidelines were published.

A multi-centred audit conducted in 2008 found a number of issues with the program.50 Despite the introduction of the screening system and referral guidelines in 2006, it was found that grading processes varied between audit locations and practitioner groups and there was no quality assurance of the gradings.50 Referral pathways for screen-detected cases were not monitored, causing patients to drop out of the system.50 Both of these issues are a direct consequence of the program lacking national standards, training and accreditation for the graders.

UK:NHS Diabetic Eye Screening Program

The UK NHS Diabetic Eye Screening Program (DESP) invites all individuals (12 year/>) registered in a NHS primary care centre with diabetes are to attend a screening location for an annual screening by digital retinal photography. The program is delivered by more than 80 local programs across England by a range of providers.51 Three models of screening exists, which are:51

  1. Static clinics using retinal cameras in hospitals or diabetic centres
  2. Mobile clinics using retinal cameras in GP surgeries or screening vans
  3. Optometry-based services by accredited optometrist.

 

All screeners must undergo a training and accreditation program that awards a Level 3 Qualification in Diabetic Retinopathy Screening. Retinal images are acquired and then graded by the certified graders according to the NHS DESP specification. The results are forwarded to the patient’s GP within six weeks.51 Depending on the results the patient will either be recalled annually, invited back for more frequent screening or referred on to Ophthalmology.

The main strength of this program is there is evidence that it actually effective for those who attend screening. The frequency of STDR among the diabetic eye screening population decreased from full implementation of the program in 2008 compared to 2011.52 The frequency of STDR at subsequent screenings in 2008 was 21.6% for those who had mild NPDR detected at the initial screen, and 9.2% for those with no DR at initial screen.52 In 2011, the frequency of STDR was only 8.4% for those with mild NPDR at initial screen and 3.2% for those with no DR at initial screen.52 What this tells us is that the program is effectively detecting STDR in newly diagnosed diabetes at initial screen and moving them out of screening into ophthalmological care. The effectiveness of the program lies in its strong emphasis on quality assurance, with standardised grading criteria, formalised monitoring pathway and accredited screeners.52

Weaknesses of all programs

Although retinal image screening programs improve access to care and identifying patients who require further evaluation, they are not a substitute for a comprehensive eye examination. Full examinations are required if images are unreadable and for follow-up of any abnormalities   detected by screening. Another downside of retinal image screening programs that are conducted by technicians or non-eye care professionals is that cataracts, glaucoma and other ocular conditions are not detected.

Diabetic Eye Care Programs Australia

Currently, there is no universal screening program in Australia for DR. Many pilot programs run by different organisations have been proposed or trialled with varied success. Population-based studies show that between 30-50% of diabetic Australians are not adequately screened for diabetic retinopathy.53,54,55

NHMRC Guidelines

The National Health and Medical Research Council (NHMRC) introduced guidelines for diagnosis and treatment of Diabetic Retinopathy in 1997 and then updated these in 2008.56 The purpose of guidelines is to help practitioners made appropriate decision around managing diabetic patients.56 The NHMRC screening guidelines for DR are outlined below.

Screening for Diabetic Retinopathy56

  • Dilated ophthalmoscopy or slit lamp biomicroscopy with a suitable lens (e.g. 78D), should be performed by ophthalmologist, optometrist and other trained medical examiners to detect presence and severity of DR and DME.
  • Use on non-mydriatic retinal photography by trained examiner if dilated fundus examination not possible.
  • All people with diabetes should have DFE and VA assessment at diagnosis of diabetes and at least every 2 years.
  • Screen children with pre-pubertal diabetes for DR at puberty.
  • High risk patients (longer duration of diabetes, poor glycaemic control, poor lipid control and poorly controlled hypertension) without DR should be screened at least annually.
  • Examine patients with any sign of NPDR annually or 3-6 month intervals, depending on DR level.
  • Refer urgently to ophthalmologist (within 4 weeks) if there is any unexplained fall in VA, suspicion of DME or PDR.

Proposed and Piloted Screening Programs

There have been two proposed programs in recent years and neither has come to fruition. The first program proposes that GP undertake the diabetic eye screening through acquisition of retinal images. A recent survey of Australian GPs found that they lack interest in screening for DR, with only 41% interested in conducting DR screening.41 As well GPs lack confidence in detecting the clinical signs of DR and were ill-equipped to do the screening. All of these factors would need to be address with appropriate training and the investment in retinal cameras before GPs could undertake DR on their own.

The second program that was piloted between September 2009 and March 2010, proposed that DR screening should be conducted at pathology collection services. In this program technicians acquired non-mydriatic photographs, which were sent to the Centre for Eye Research Australia for assessment. A report outlining the results and follow-up recommendations was sent electronically to the patient’s GP within 2 weeks of screening.57 In general this program was shown to be feasible, however the main concern was that 22% of images acquired were un-interpretable due to poor image quality.57

Role of Optometry in Diabetic Eye Care

Optometrists are ideally positioned to screen for DR for a number of reasons such as having the appropriate skills, access to necessary diagnostic equipment and being accessible to the public. As well, as essential health care providers for patients with diabetes, optometrists have both the capacity and responsibility to increase patient awareness about the condition.

Optometric Diabetic Eye Examination

  • Medicare provides an item code (10915) that should be used for comprehensive eye examinations where mydriatic eye drops have been instilled and a dilate fundus examination performed in a known diabetic patient.
  • Whilst a comprehensive eye examination should be conducted on all diabetic patients, as ocular complications of diabetes can affect many different ocular structures, there are four key parts to a diabetic consultation.
  • Case History: A diabetic case history should include the type and duration of diabetes, past glycaemic control, medications systemic history, frequency and results of self-monitored blood glucose and recent laboratory tests for HbA1C, serum lipids and proteinuria.58
  • Visual Acuity Assessment: Assessing VA is important in establishing a base line and using this to determine if visual function is being impaired. Visual acuity should be assessed at every appointment.56
  • Fundus Examination: As per NHMRC guidelines a dilated fundus examination should be conducted on every diabetic patient using suitable lenses. It is also good practice to acquire a digital image of the retina to document absence or presence of DR and allow comparisons at each and every follow up visit.58 It is expected that Luxottica Optometrists comply with these recommendations.
  • Patient Education: provide clear and concise patient education on importance of regular eye examination in diabetes, as well the importance of controlling systemic risk factors for the development and progression of DR and vision loss.58

Optometry Australia's Recommended Examination Procedures for patients with Diabetes

Optometry Australia has provided a detail guideline of all the tests that should be included when assessing a patient with diabetes.59 These are summarised below.

  • Visual Acuity (with correction): Distance and near, monocularly, including  pinhole acuity is indicated.
  • Pupil reactions: Direct/consensual and near pupillary responses.
  • Ocular motility: Extent, fluency and symmetry of ocular movements in all directions of gaze, ruling out eye movement anomalies. Relevant history taking regarding the onset and direction of diplopia is necessary. If diplopia is manifest, cover test and prism neutralisation is also indicated.
  • Visual field screening: Confrontation and/or visual field assessment as per Medicare guidelines for perimetry.
  • Refraction: On indication where patient reports a change in vision or visual function or where a change in habitual visual acuity is measured.
  • Slit lamp biomicroscopy: Recommended at every visit to check for neovascularisation, diabetic cataract and corneal integrity.
  • Tonometry: As indicated, recommended pre and post pupil dilation.
  • Stereoscopic fundus examination with dilation: NHMRC guidelines describe pupil dilation using 0.5 to 1.0% tropicamide as safe. Dilated fundus examination increases the sensitivity of DR screening so is considered mandatory in performing ophthalmoscopy or slit lamp biomicroscopy unless contraindicated by the presence of a potentially occludable anterior chamber angle. 2.5% phenylephrine hydrochloride, unless contraindicated, may help achieve maximum pupillary dilation, especially for people of Aboriginal and Torres Strait Islander descent and patients with heavy iris pigmentation.

Frequency of Examination

Optometry Australia, in line with American Optometric Association (AOA), American Academy of Ophthalmology (AAO), and the Joslin Diabetes Centre (JDC), recommends that all people with diabetes undergo annual eye examinations unless a practitioner recommends more frequent reviews based on observed changes.

Current State of the Nation

A recent survey of 568 Australian optometrists found that the current level of care provided by Australian optometrists may have some opportunities.60

It was found that the most commonly used ophthalmic equipment by Optometrist for diagnosing DR was the direct ophthalmoscope (72%), slit-lamp biomicroscopy (65%), BIO (56%) and retinal photography (51%).60 About 90% of optometrists reported performing dilated fundus examinations on most patients with known diabetes.60 Interesting, it was found that optometrist who ‘often’ or ‘always’ used a retinal camera were more confident in detecting diabetic changes, such as microaneurysms, new vessels elsewhere, and macular edema.60 The study found that reading the NHMRC guidelines at least once were associated with increased confidence in detecting macular edema.60

The opportunities for Optometrist are to:

  • Read and follow the NHRMC and OA guidelines
  • Routinely perform dilated examinations on persons with diabetes
  • Utilise retinal imaging, such as DRS, UWDRS and OCT to enhance detection of DR and DME
  • Actively seek continuing professional development on diabetes and DR.

Multidisciplinary Approach To Diabetic Care

Multidisciplinary Approach in Australia

Diabetes cannot be optimally managed in isolation and a multidisciplinary team approach is essential for success. The benefits of integrated, multidisciplinary approach for management of chronic illness are well documented. The Diabetes Control and Complication Trial (DCCT) provided evidenced that a multidisciplinary approach to care results in improved metabolic control and better overall outcomes. An Australian study showed that patients in multidisciplinary care had improved metabolic control and decreased cardiovascular risk factors.61

An effective multidisciplinary team for diabetes should have a coordinator to oversee the entire team.18 This is usually a GP. For a multidisciplinary approach to work there must be mutual respect and trust among the team members where information can flow freely. The GP needs to know what is happening with their patient’s eyes. Unfortunately, too often eye care providers fail to complete the communication link back to the GP.18 Likewise, specific information from the GP about the patient’s diabetes history and current level of glycaemic control is important to the eye care provider. It is recommended that each member of the team should communicate their results and recommendations to other members of the team clearly and in a timely manner.18

Structure care of diabetic patients, offered by multidisciplinary teams, is associated with improved health outcomes.62,63 In 1999, the Australian Government introduced GP rebates for enhanced primary care (EPC) multidisciplinary care planning.64 The guidelines stated that care planning required collaboration between GPs, health practitioners and patients with chronic illnesses.65 In 2005, GP management plans (GPMPs) and team care arrangement (TCAs) replaced EPC care plans. GPMPs are indicated for any patients with a chronic illness who would benefit from structured care. TCAs are intended for patients with complex care needs, who require collaboration between health providers, and allow patients to claim rebates for allied health and dental care. Research shows that care planning plays an important role both in prompting and in facilitating referrals by GPs to AHPs.64

In Australia the primary members of a multidisciplinary team are: person with diabetes, their family/carer, GP, Endocrinologist/Paediatrician, Credentialed Diabetes Educator (CDE), Dietician, and Podiatrist. Other health care professionals that frequently participate in care are: Practice Nurse, Specialist medical practitioners (e.g. Ophthalmologist/Obstetrician), Exercise Physiologist, Optometrist and Psychologist and/or social worker.66

 
Fig. 14 It takes a multidisciplinary team to care for a person with diabetes

Self-Management

There is strong evidence base, both internationally as well as in Australia, for self-management. People with diabetes who were engaged by their multidisciplinary team to self-manage their diabetes had improved health outcomes, better quality of life and a reduce need for health services.67

Self-management occurs when the persons with diabetes (and their family/carers) work in partnership with their multidisciplinary team to achieve the best health outcomes. The seven principles of self-management that health professionals should use with patients to promote self-management, as defined by the Flinders Model, are:68

  • Know your condition
  • Be actively involved with GP and health professionals
  • Follow the Care Plan that is agreed upon
  • Monitor symptoms and respond to them
  • Manage the physical, emotional and social impact of the condition
  • Live a healthy lifestyle
  • Readily access support services

Practice Incentive Program

The Practice Incentives Program (PIP) is aimed at supporting general activities that encourage continuing improvements, quality care, enhanced capacity and improved access and health outcomes for patients. The PIP Diabetes Incentive aims to encourage GPs to provide earlier diagnosis and effective management of people with known diabetes. Often optometrist might be sent a copy of the patient’s diabetes care plan which may be developed by a GP as part of the PIP.

Effective Communication in a Multidisciplinary Approach

Effective communication and collaboration with the multidisciplinary team results in optimal care and can increase your referral base. Establishing solid relationships and utilising available channels of communication is essential for effective communication. The best way to establish a good working relationship is through personal contact.

How do you do this? Start by sending a letter of introduction requesting a face-to-face meeting to local health care professionals (HCP). Next phone the HCP or drop by their practice to make an appointment to see them. At the appointment, explain to the HCP how you can help them care for their patients by providing information about the patient’s ocular health. During the meeting ask how the HCP how they would prefer to receive this information on their patients and what information they are actually seeking. Do they prefer paper reports or electronic reports? For detailed information on how to network with GPs and health professionals, refer to Institute of Learning module, “Influential Communication: Networking for Growth”.

The most important tool for effective communication in multidisciplinary care in diabetes is the patient report. It is important that optometrists report to the GP, endocrinologist and the CDE the results following every visit, whether there are signs of DR or not.69 As GP and endocrinologists are aiming to achieve optimal levels of glycaemic control for their patients, knowledge regarding absence or presence of DR, can play an important role in determining correct treatment and management options.69 As well, GPs, endocrinologist and CDE should receive a copy of any referral letter made for that patient to ophthalmology.

Be sure to communicate actively with everyone on the multidisciplinary team. This includes the patient as well. It is important to communicate openly and effectively with your patient. The manner in which information is delivered is essential to it being received in a positive and constructive manner. You must encourage and support self-management through effective communication with the diabetic patient. Using a traditional “top-down” approach to medical communication leaves the patient with unsavoury feelings of condescension. Commanding someone with a chronic condition will not work. We should aim to employ an influential communication style when working with diabetic patients. Communication based on motivational interviewing techniques has been shown to help patients with chronic diseases, such as diabetes, modify lifestyle behaviours to maintain optimum health.

When communicating with a diabetic patient is sure to consider the following:70

  • Establish rapport by trying to understand patient’s perspective.
  • Do not be judgemental, especially if the patient shows resistance to change. If a patient feels they are being judged the will erect barriers, which will make establishing rapport and engaging in effective communication, very difficult.
  • Help the patient appreciate the value of healthy change. Show them what is possible and how embracing the healthy lifestyle will result in better quality of life.
  • Help the patient identify necessary areas of change, and elicit a commitment to a change in their behaviour. We know from the principles of influence, that people feel strong pressure to be consistent with their own words and actions. So if a patient verbalises to you that they will change their behaviour, they will more likely be successful in making that change.
  • Motivate patients by acknowledging and complimenting them when they have changed their behaviour. The principles of influence tell us that people are more likely to comply with requests if they have been praised for previous success. So if your patient has been compliant to an action, praise them, and they will be more likely to continue that behaviour.

Fig. 15 Optometrists need to communicate effectively with diabetic patients.

 

Conclusion and References

Conclusion

Diabetes mellitus is the most challenging public health issue of the 21st century with its prevalence now reaching epidemic levels. The number of Australians diagnosed with diabetes is expected to rise from the current 1.1 million to 3.3 million in 2031. With the increasing prevalence of diabetes, an increase in prevalence of diabetic retinopathy will be seen as well. As the evidence shows that tight control of diabetes reduces risks of diabetic retinopathy, and that there is effective treatment available to prevent loss of sight for diabetic retinopathy, screening for diabetic eye disease is an important public health initiative. Optometrists can and will play a key role in screening for diabetic retinopathy. Optometrists are ideally positioned due to having the knowledge, skills and necessary diagnostic equipment to undertake diabetic eye disease examinations. The introduction of the Optos Daytona with ultrawide field imaging capability allows Luxottica optometrists a fast non-invasive superior technique to screen for diabetic retinopathy. Guidelines, such as the Optometry Australia Clinical Guidelines for Diabetes and the NHMRC Guidelines for Diagnosis and Management of Diabetic Retinopathy will assist optometrists in decision making and thus care of their patients. It is important that optometrist adopt a multidisciplinary approach, encouraging self-management by the patient and collaborating with general practitioners, diabetic educators and other allied health professionals. To achieve a multidisciplinary approach, optometrists need to embrace influential communication and actively participate in networking with general   practitioners and health professionals.

 

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' ...Diabetes mellitus is the most challenging public health issue of the 21st century with its prevalence now reaching epidemic levels... '