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Diabetes in primary Care Practice Dr Simon Barnard Life can be too sweet Diabetes in primary care optometric Dr Simon Barnard PhD BSc FCOptom FAAO DCLP DipClinOptom Clarion Hotel Oslo Thursday 24 January 2002 Oslo 1 24 January 2002 Diabetes in primary Care Practice Dr Simon Barnard Table of Contents Table of Contents .............................................................................................. 2 Introduction ....................................................................................................... 3 Epidemiology ..................................................................................................... 3 Prevalence ..................................................................................................... 3 Incidence of blindness ................................................................................... 3 Non-Insulin Diabetes Mellitus (NIDDM) ............................................................. 3 Insulin-Dependent Diabetes Mellituis (IDDM) .................................................... 4 Ocular manifestations of diabetes ..................................................................... 4 Introduction .................................................................................................... 4 Retinal manifestations ................................................................................... 5 Fundoscopy ....................................................................................................... 6 Advantages of indirect versus direct ophthalmoscopy ................................... 6 Indications for referral........................................................................................ 7 Guidelines of the European Working Party for Screening for diabetic retinopathy ..................................................................................................... 7 Informing the GP & Diabetic Physician .......................................................... 8 Useful contact.................................................................................................... 8 Oslo 2 24 January 2002 Diabetes in primary Care Practice Dr Simon Barnard Introduction Diabetic care forms an increasingly important part of general optometric practice with optometrists in some areas of the UK, and indeed across the world in the USA, Canada, Australia and some EC countries such as the Netherlands, examining the majority of diabetics seen for their eye care. In certain Area Health Authorities in the UK there are formal “Shared Care” schemes where the optometrist is paid an additional fee for just carrying out fundoscopy on diabetics. Epidemiology Prevalence 1% of the 60 million population in the UK suffers from Diabetes. The prevalence increases with age to 3 to 4% of the population over the age of 40 years. Norway, with a population of 4.5 million inhabitants has approximately 130,000 people with diabetes. This amounts to some 2.9% of the population. About 0.45% have IDDM and 1.8% suffer from NIDDM. It is estimated that a further 0.65% of the population are undiagnosed. Incidence of blindness In the UK there are 1500 new cases of blindness per year. Non-Insulin Diabetes Mellitus (NIDDM) These patients can survive without exogenous insulin although many eventually require insulin to improve control. The prevalence in the UK is approximately 1% in UK and in Norway 1.8 %. The prevalence in elderly and some groups in the UK, for example Asian communities are higher at around approximately 3 to 5%. The prevalence in Lima Indians of Arizona is reportedly 50%. Migrants to western world seem to be particularly susceptible. Oslo 3 24 January 2002 Diabetes in primary Care Practice Dr Simon Barnard NIDDM is correlated with a combination of relative insulin deficiency and insulin resistance. The latter may be exacerbated by obesity. There is a strong genetic predisposition with twin concordance for NIDDM being 90% compared to only 40% for IDDM. NIDDM accounts for about 75 to 80% of the diabetic population. NIDDM gives high risk of macrovascular complications and usually presents as a syndrome of anomalies including hypertension, hyperlipidaemia, obesity, and insulin resistance. Very often optometrists will hear from their patient that “ I have a just a little sugar” or “I have mild diabetes”. In fact, there is no such thing as “mild diabetes”. Whatever the control required, if not adhered to, the disease will lead to retinal and other damage. Insulin-Dependent Diabetes Mellitus (IDDM) These patients cannot survive without insulin. In the UK the prevalence is about 0.2% with an incidence of 15/100,000/year aged < 21. Most cases present before 30 years and there is a peak incidence at 11-13 years. A possible cause is destruction of the cells of the Islets of Langerhans perhaps through an autoimmune response. Retinopathy is unusual before puberty and usually only presents after at least 10 years. Mortality in < 50 age group is about 5 x higher than non-diabetics. Ocular manifestations of diabetes Introduction Although we often think of retinal changes, it must not be forgotten that other parts of the eye and visual system may be affected including the anterior segment with changes occurring to the iris and lens. Changes in the iris include micro aneurysms and neovascularisation, the latter leading to a secondary glaucoma. The classic “diabetic snowflake cataract” that occurs in acute diabetes is rarely seen. If the patient is swiftly treated, the cataract substantially resolves. Diabetics tend to develop prematurely age related lens changes. Oslo 4 24 January 2002 Diabetes in primary Care Practice Dr Simon Barnard The optometrist is often the first person to suspect diabetes in a patient because of apparent fluctuations in refraction, along with reported symptoms of an unusual thirst and possible a general feeling of malaise or repeated illnesses. The visual pathway may be affected in a variety of ways with, for example, haemorrhages producing visual field defects. Similarly diabetics are more prone to suffering lesions of the ocular motor system with consequent gaze palsies and incomitant strabismus. Retinal manifestations Retinal signs may be categorised into:(1) non-proliferative (a) background (b) pre-proliferative (2) proliferative Let us look at each of these. Background diabetic retinopathy This manifests as: dot and blot haemorrhages. micro aneurysms are also present and are more prevalent temporally. lipid exudates, sometimes call hard exudates may also be present. macular oedema may occur and be focal or diffuse. Pre-proliferative diabetic retinopathy This manifests as more marked background retinopathy but now with the addition of “cotton wool spots” which represent nerve fibre infarction with axonal debris. IntraRetinal Microvascular Anomalies (IRMA) Venous beading and looping Proliferative diabetic retinopathy (PDR) The term proliferation describes the appearance of “new vessels” or “neovascularisation”. These vessels emanate from retinal venules.. Oslo 5 24 January 2002 Diabetes in primary Care Practice Dr Simon Barnard Neovascularisation can occur on the disc (NVD) or as neovascularisation elsewhere (NVE). These vessels are fragile and are prone to bleed into the sub-hylaoid space, giving a flat topped or sub-hylaoid haemorrhage. These can break through into the vitreous to produce a vitreous haemorrhage which will resolve with cicatricisation, and as the fibrous tissue contracts will cause traction leading to retinal detachment Fundoscopy It is necessary to dilate diabetics’ and before doing so the optometrist should check the anterior chamber angle with the slit lamp (Van Herrick technique) and, if the angle appears narrow, with gonioscopy. Drugs of choice to dilate are the anti-muscarinic, Tropicamide 0.5% or 1% and The sympathomimetic, phenylephrine hydrochloride 2.5%. These can be used synergistically to produce maximum dilatation. However, patients with advance diabetic disease, with signs such as peripheral neuropathy, may be “super-sensitive” to sympathomimetics. Phenylephrine should be avoided in these cases because of the risk of adversely affecting the cardiovascular system. As a rule, the optometrist should check the systemic blood pressure of all patients over 40 years of age before using phenylephrine. Advantages of indirect versus direct ophthalmoscopy The best way of examining the diabetic fundus is with a slit lamp lens such as the Volk 66, 70 or 90 D or with contact fundus lens. The direct ophthalmoscope may be used but really is quite inferior. Whilst the direct opthalmoscope gives a field of view of about 10 degrees, this compares with the better field of view around 120 degrees with some slit lamp fundus lenses. Similarly indirect provides stereopsis and better illumination. Retinal photography is also invaluable for screening for and recording changes. Oslo 6 24 January 2002 Diabetes in primary Care Practice Dr Simon Barnard Indications for referral Guidelines of the European Working Party for Screening for diabetic retinopathy Immediate referral Sight threatening retinopathy Proliferative retinopathy NVD NVE Pre-retinal haemorrhage Fibrous tissue Vitreous haemorrhage Fibrous tissue Recent retinal detachment Rubeosis iridis Early referral Lesions likely to be threatening within twelve months Pre-proliferative retinopathy Venous irregularities (beading, loops collaterals) Multiple haemorrhages Multiple cotton wool spots IRMA Non-proliferative retinopathy with macular involvement Reduced VA (? = macular oedema) Lipid of haemorrhage within 1 disc diameter of macular Non-proliferative retinopathy without macular involvement Circinate or plaqued lipid within major temporal arcades Any other finding observer unsure of Lesions not requiring referral to the ophthalmologist Non-proliferative retinopathy Small numbers of cotton wool spots not associated with pre-proliferative changes Occasional haemorrhages/micro aneurysms and lipid not within 1 DD of macular Drusen Oslo 7 24 January 2002 Diabetes in primary Care Practice Dr Simon Barnard Informing the GP & Diabetic Physician In the UK it is mandatory to write a report the patient’s GP following an eye examination. A copy sent to the diabetic physician will be useful/. It should be remembered that although ophthalmological attention may not be necessary, modifications to the general diabetic regime of therapy are sometimes required. Useful contact Norges Diabetesforbund Postboks 6442 Ettersad N-0605 Oslo Tel +47 23 05 18 00 Dr Simon Barnard e-mail [email protected] January 2002 Oslo 8 24 January 2002