Dr Simon Little
PhD MSc(Optom) GradCertOcTher
North Lakes Optometry, QLD
Associate Professor Anthony SL Kwan
MBChB MD(London) FRCOphth FRANZCO
Queensland Eye Institute and University of Queensland
Diabetic eye disease is the leading cause of blindness among the working population (20-60 years old) in Australia.1 According to Diabetes Australia, 280 Australians develop diabetes every day. It is the fastest growing chronic health condition in Australia. An estimated 3.2 million Australians are diabetic or pre-diabetic.1 These statistics are hard to grasp and difficult to ignore.
There is no nationwide screening program to ensure that all diabetic patients have regular eye examinations to detect and appropriately manage their ocular complications, let alone a system robust enough to withstand clinical audit to ensure the most cost-effective delivery of appropriate care and optimal outcomes.
Without a formal comprehensive structure for diabetic eye care, only about 50 per cent of people with diabetes in Australia receive regular eye care.2 Structures designed to detect and appropriately treat cases of diabetic eye disease have been shown to reduce the human and financial costs involved.3,4
Virtually every type 1 diabetic patient and more than 60 per cent of type 2 diabetic patients will have some form of diabetic eye disease within 20 years of diagnosis of their diabetes.2
Classification and management
In major studies, diabetic retinopathy has been classified using the modified Airlie House protocol (Wisconsin system).5 In short, retinopathy is classified as non-proliferative (NPDR) or proliferative (PDR) and within that, maculopathy is classified as ‘monitor’ or ‘treat’. In the most simple of terms, minimal or mild NPDR can be diagnosed and monitored by optometrists, but patients with severe NPDR or PDR should be comanaged with an ophthalmologist, preferably a specialist in medical retina. The Blue Mountains Eye Study found diabetic retinopathy in 32 per cent of known or newly-diagnosed diabetic patients.8 Of those, 1.6 per cent had PDR and 5.5 per cent had macular oedema. Interestingly, 16 per cent of people found to have undiagnosed diabetes had retinopathy as well, so optometrists will often be the first health-care professionals to detect signs of diabetes in these patients as they may present for a routine comprehensive eye examination for other reasons.
If referral to an ophthalmologist is required, it should be graded for urgency, made appropriately, and copied to the other health professionals involved in the care of the patient—for example, general medical practitioner, endocrinologist—to achieve a holistic approach to diabetes, which has numerous potential systemic complications.
All diabetic patients should have visual acuity checked and retinae assessed, at least annually if there is mild NPDR. Retinal photographs should be taken to document any pathology. Optometrists are the obvious choice to provide this service, as practitioners have the skills and expertise to perform a dilated posterior eye examination. Additionally, most optometric practices have retinal cameras to perform baseline photography.
It could be argued that retinal photography should be part of the minimum standard of record-keeping, especially for these at-risk patients.6 At the same visit, patients can be checked for macular oedema, the most common cause of vision loss in diabetic patients.7 Indirect ophthalmoscopy with a 66 D or equivalently high magnification lens can be used. Ideally, macular oedema should also be assessed by imaging with optical coherence tomography (OCT) as this can detect subclinical central macular thickening. Retinal photography and OCT scans are not part of the Medicare-funded comprehensive eye examination, so currently the cost of these services must be covered by the patient.
Given the current circumstances discussed above, we present two case studies to illustrate the present pattern of referral and treatment of diabetic eye disease in Australia. In the first case, the patient, who presented to her optometrist (SL) was yet to be diagnosed as having diabetes mellitus. In the second, the patient was referred by his optometrist to an ophthalmologist sub-specialising in medical and surgical retina (AK).
Undiagnosed diabetic patients may have symptomatic co-existing ocular pathology (Case 1) and established diabetic patients may have asymptomatic eye disease (Case 2). These situations illustrate the need for regular, easily-accessible comprehensive eye care and screening, preferably without the burden and disincentive of prohibitive costs to the individual.
CASE 1. Primary care
KR, a 44-year-old bank teller who lists her spare time activities as netball, swimming, and ‘running around after the kids’, presented to her optometrist (SL) with a three-week history of seeing a small distorted patch in her superior field on down-gaze. When she looked down at the money she was counting, she could see a distorted patch on her customer’s face.
KR, a previous patient of the practice, had always reported good general health, no prescribed medications, and no family history of eye problems. In particular, she believed there were no diabetic sufferers in her family. Her best corrected Snellen visual acuities were 6/6+ in R&L with her -2.00 DS R&L and N4.5 R&L up to 30 cm with a +0.75 Add.
Fundus biomicroscopy revealed an inferior branch vein occlusion (BRVO) in the right eye, with localised exudation and significant haemorrhaging (Figures 1 and 2). The position of this lesion corresponded to her symptoms. The OCT scan revealed no significant macular oedema associated with the BRVO (Figure 3).
|Figure 1. Central retinal image showing inferior branch vein occlusion
||Figure 2. The same eye as in Figure 1, showing the extent of haemorrhaging inferiorly
|Figure 3. OCT EDTRS grid showing near-normal macular thickness
The patient was referred to a local specialist in medical retina, and a report was sent to her GP. Type 2 diabetes, which can be associated with RVO, was discovered by the GP. An ophthalmologist followed the case for two months while the symptoms were settling spontaneously. KR was discharged back to the care of her optometrist once the haemorrhage had largely cleared.
KR still reported minimal distorted vision in the same location in the subsequent visits, with no other signs of complications from the BRVO or any diabetic retinopathy after three months.
As this case illustrates, primary care optometry plays an important role in the management of retinal disease in the context of diabetes. KR was diagnosed and subsequently monitored locally, and did not need expensive specialist care in a private clinic or public hospital. Her GP has instigated a primary care plan to include education on management of type 2 diabetes, and involvement of a dietitian, endocrinologist, podiatrist and optometrist, with the GP serving as gatekeeper and co-ordinator.
CASE 2. Secondary care
TC, a 56-year-old property developer, was referred to a specialist in medical and surgical retina (AK) for management of diabetic retinopathy in 2009 when his optometrist noted diabetic retinopathy in both eyes. He was first diagnosed with late onset diabetes mellitus in 2008 but his diabetic symptoms pre-dated that. His blood sugar control was poor and he was asymptomatic. Visual acuities were 6/6 in each eye.
Fundal examination showed moderate NPDR and diabetic macular oedema without foveal involvement (Figure 4). Macular OCT scans showed some extra-foveal macular thickening (Figure 5). TC underwent focal laser treatment in his right eye to stabilise his vision. He subsequently required bilateral panretinal laser photocoagulation due to the progression to PDR.
|Figure 4. Right eye 2009 pre-treatment
|Figure 5. Right eye OCT 2009 pre-treatment
In 2013, after a few years of poorly-controlled diabetes, TC noted progressive blurring vision in his right eye with a reduction of best corrected visual acuities to 6/15 in that eye (Figures 6 and 7). He developed a recurrence of macular oedema with central macular involvement. Anti-VEGF therapy was recommended and monthly off-label intravitreal Avastin injections were administered. The macular oedema was stabilised in his right eye and visual acuity was maintained at 6/12 (Figures 8 and 9).
|Figure 6. Right eye 2013 pre-Avastin
|Figure 7. Right eye OCT 2013 pre-Avastin
This case highlights the importance of screening for diabetic retinopathy and the importance of good diabetic control to halt the progression of diabetic retinopathy. With better glycaemic control, TC’s diabetic eye disease may not have progressed to the extent that it did.2 This case also demonstrates that focal laser treatment is useful in the management of diabetic maculopathy when the vision is good and the central macula is not involved.9 Regular anti-VEGF injections are the treatment of choice once the central macula is involved and vision is affected.10
|Figure 8. Right eye 2013 post PRP and Avastin
|Figure 9. Right eye OCT 2013 post PRP and Avastin
More must be done to educate the Australian public and general medical practitioners about the risks, signs and symptoms of diabetes and the necessity for regular comprehensive eye care, and a diabetic retinopathy screening program for all Australians, whether symptomatic or not. Public perception still appears to be that eye care is needed only if symptoms are present or when spectacles are needed. Even then, many people buy ready-made reading glasses and do not have their eyes examined.
Primary care optometry has great case-finding potential. The role of the optometrists in the detection and monitoring of diabetic eye disease should be recognised and funded as an important aspect of diabetic health care.
At present, scheduled Medicare benefits for eye examinations by optometrists cover only about 25 per cent of the costs of providing the service and therefore there is significant cross-subsidy from other services optometry provides.
If optometry is to continue as a health-care profession, this funding gap must be addressed. This might be done by increasing benefit levels for consultations where the patient has a specific eye pathology or other conditions requiring ongoing management other than refraction. Introduction of a Medicare item for examination by optometrists of patients with a range of systemic diseases referred by their GP may be useful.
Removing the cap on optometrists’ fees where Medicare benefits apply is a common-sense approach and we welcome it, but it will not assist our most vulnerable patients and groups such as diabetic patients who need more comprehensive services more regularly and can least afford them.
Ophthalmologist specialist care is essential in the moderate to advanced stage of diabetic retinopathy as a delay in appropriate treatment may result in permanent visual loss. The advent of intra-vitreal anti-VEGF injections, adjunct fenofibrate therapy, improved laser equipment and treatment protocols means that the risks of permanent vision loss from diabetic retinopathy are greatly reduced. Of course, this relies on case finding and timely referral for secondary care.9,10
The cases presented here illustrate the benefits of inter-disciplinary co-operation and communication by all health-care professionals concerned, promoting a patient-centred approach to diabetic care in general and diabetic eye care in particular.
We should no longer accept that it is inevitable that blindness is a common consequence of diabetes. With an appropriately-funded national structure in place to find such cases, there would be potential for savings in both financial and human costs.
- Diabetesaustralia.com.au/understanding-diabetes/diabetes-in-australia. Accessed 11/4/14.
- Out of Sight: A Report into Diabetic Eye Disease in Australia. Baker IDI publication 2013.
- Arun CS, Al-Bermani A, Stannard K, Taylor R. Long-term impact of retinal screening on significant diabetes-related visual impairment in the working age population. Diabet Med 2009; 26: 489-492.
- Javitt JC, Aiello LP. Cost-effectiveness of detecting and treating diabetic retinopathy. Annals Internal Medicine 1996; 124 (1 Pt 2): 164-169.
- Lecaire T, Palta M, Zhang H, Allen C, Klein R, D’Alessio D. Lower than expected prevalence and severity of retinopathy in an incident cohort followed during the first 4-14 years of type 1 diabetes: the Wisconsin Diabetes Registry Study. Am J Epidemiol 2006; 164: 143-150.
- Williams GA, Scott IU, Haller JA, Maguire AM, Marcus D, McDonald HR. Single-field fundus photography for diabetic retinopathy screening: a report by the American Academy of Ophthalmology. Ophthalmology 2004; 111: 5: 1055-1062.
- Mitchell P, Wong TY. Management paradigms for macular edema. Am J Ophthalmol 2014; 157: 3: 505-513.
- Mitchell P, Smith W, Wang JJ, Attebo K. Prevalence of diabetic retinopathy in an older community. The Blue Mountains Eye Study. Ophthalmology 1998; 105: 406-411.
- Kwan AS. Laser photocoagulation for diabetic macular oedema in the era of anti-vascular endothelial growth factor therapy: is there a role? Clin Exp Ophthalmol 2012; 40: 6: 535-536.
- Bandello F, Cunha-Vaz J, Chong NV, Lang GE, Massin P, Mitchell P, Porta M, Prünte C, Schlingemann R, Schmidt-Erfurth U. New approaches for the treatment of diabetic macular oedema: recommendations by an expert panel. Eye (Lond) 2012; 26; 4: 485-493.