The vital role of optometry in disease detection: ophthalmic public health Part 3 C18446 O/D.
The eyes, having a rich blood supply, are intricately associated with the cardiovascular system. The fundus, as seen by ophthalmoscopy, is the only site in the body where blood vessels can be observed directly and non-invasively, giving vital clues to the systemic status. A number of systemic, cardiovascular factors affect the large blood vessels around the body, but additionally impact on microvasculature in the eye too.
Retinopathy can be caused by a number of systemic factors, such as diabetes, hypertension, hypercholesterolemia, anaemia and human immunodeficiency virus (HIV) positive status. Additionally, a number of lifestyle factors such as smoking, nutrition and obesity, can impact on the health of other structures in the eye, such as the lens, eg, diabetic cataract. Equally, the impact of visual loss due to ocular or systemic pathology can have serious effects on an individual's day-to-day function, such as their ability to attend appointments for clinical care, adherence with medication, and general lifestyle. For instance, those people with advanced age-related macular degeneration (AMD) may find it increasingly difficult to view their medication and/or dosages, and thereby have difficulty managing their systemic health conditions. The role of the specialist low vision optometrist as a public health practitioner is pivotal here, as they can provide essential support with optical and non-optical aids, to raise morale and confidence and reduce the impact of the ocular disease.
The broader determinants of health, such as socio-economic factors, can also have a significant impact on the rate of diagnosis of eye disease. With some ocular conditions presenting with a pre-disposition for certain ethnic groups, late presentation can result in permanent visual loss. Areas such as inequalities in health provision and poor awareness of the importance of regular eye examinations, and the uptake of referrals and treatment, are certainly in need of address.
Cardiovascular disease (CVD)
Cardiovascular disease, encompassing conditions such as myocardial infarction (MI) and cardiovascular accidents (CVAs), is the most common cause of death in the western world. (1)
In addition, cardiovascular disease accounts for up to 80% of premature excess mortality in patients with diabetes. (1) Its causes are multi-factorial and include common risk factors such as smoking, hyperglycaemia, hypertension, diabetes and obesity. The following conditions outline the ocular manifestations of cardiovascular disease, and highlight the important role an optometrist may have in the prevention of sight loss due to such eye disease, but more importantly, the vital role in referral for essential cardiovascular assessment and treatment.
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Whilst it is commonly known that chronic hypertension is an important risk factor for CVD, including stroke, heart failure and arterial aneurysms, it is, in addition, an important risk factor for a number of eye conditions. The retina is one of the "target organs" that are damaged by sustained hypertension. Subjected to excessively high blood pressure over prolonged periods of time, the microvasculature of the eye is damaged due to arteriosclerosis and ischaemia, resulting in thickening, bulging and leaking blood vessels, the formation of aneurysms, haemorrhages, and oedema, and ultimately resulting in neovascularisation and fibrosis.
These changes need to be monitored closely, as they can result in reduced VA and even papilloedema; swelling of the optic nerve head can be seen in cases of malignant hypertension. However, most patients with hypertensive retinopathy present without visual symptoms, although they may report decreased vision or headaches. Examination of the fundus and vasculature can reveal minute atherosclerotic changes (eg, "nipping" of veins by overlying arteries--Figure 1), and the patient can be referred for further investigation and treatment of the systemic cause. In addition, the practitioner can offer advice on general lifestyle changes to help reduce the future impact of hypertension on the patient's health, eg, regular exercise and eating healthily.
Retinal vein occlusion
Retinal vein occlusion (RVO) is a common vasculopathy affecting adults, which may lead to a painless loss of vision in one or both eyes, and is associated with other common systemic co-morbid conditions. It occurs when the central retinal vein, the blood vessel that drains the retina, or one of its branches, becomes blocked. Branch retinal vein occlusions (BRVO) occur more frequently than central retinal vein occlusions (CRVO). (2) A systematic review (3) about atherosclerotic risk factors for RVO, which included 21 studies on 2,916 cases, revealed that hypertension and hyperlipidaemia (cholesterol > 6.5 mmol/l) were significantly associated with any form of RVO. The percentage of people with any form of RVO attributed to hypertension was 47.9%, whilst those attributed to diabetes mellitus was 4.9%, and to hyperlipidaemia 20%. (3) Hyperlipidaemia was especially common in those suffering RVO under the age of 50 years, whilst this was true in 50% of those aged over 50 years. Disorders in lipoprotein metabolism may contribute to the aetiology of RVO. The Beaver Dam Study (4) found that chronic renal failure and other secondary causes of hypertension and diabetes, such as acromegaly and Cushing's syndrome, were also causes of both BRVO and CRVO.
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In patients over the age of 50 years and with RVO, up to 64% have hypertension. A new diagnosis of uncontrolled hypertension is a common finding. Inadequately controlled hypertension is associated with recurrence of RVO in the same eye or fellow eye involvement. (5) Other significant risk factors for RVO include atrial fibrillation, age, smoking and obesity.
Optometrists examining patients who present with risk factors for RVO should offer patients advice about the need for regular eye examinations, maintaining control of associated systemic conditions and general lifestyle choices to reduce the risk of RVO occurring in the future.
Central retinal artery occlusion (CRAO)
Painless loss of monocular vision is the usual presenting symptom of retinal artery occlusion (RAO). "Ocular stroke", as this eye condition is often known, is commonly caused by embolism of the central retinal artery. Patients with CRAO have significant systemic illness, namely hypertension, atherosclerosis or diabetes. These patients are at extreme risk of cardiovascular disease and MI. Patients presenting with CRAO often have a previously undiagnosed vascular risk factor that may be amenable to medical or surgical treatment. (6) For this reason, rather than a prompt referral to ophthalmology, these patients need an urgent referral to a cardiologist for complete evaluation, particularly if the CRAO has been present for more than 24 hours. If CRAO has been present for less than 24 hours, A&E referral is always advised in order to reduce the risk of permanent vision loss. Carotid artery atherosclerosis is observed in 45% of CRAO cases, with 60% or more stenosis occurring in 20% of cases. Atherosclerotic disease is the leading cause of CRAO in patients aged 40-60 years.
The damage that stroke does in the brain impacts the visual pathways too, resulting in visual field loss, blurred vision, double vision and "moving images". When stroke affects the visual areas of the brain, it can cause 'visual neglect' (lack of awareness to one half of the body or space), as well as difficulties with judging depth and movement.
Many stroke survivors will have a functional disability following their stroke, of which visual disability is just one aspect. Visual field loss is reported to occur in 20-67% of cases, although some visual field impairment is due toaprevious stroke or pre-existing ocular pathology. (7)
Visual assessment for stroke survivors is acknowledged briefly in the National Stroke Strategy, where it is stated that vision and visual perceptual difficulties are components requiring multi-faceted stroke-specific rehabilitation and support. National clinical guidelines produced for acute stroke and transient ischaemic attack (TIA) by the National Institute for Health and Clinical Excellence (NICE) and the Royal College of Physicians state that stroke can present with sudden loss of any neurological disturbance, which can include visual loss. Every patient should therefore receive a practical assessment of VA, an examination of visual field and provision of information on driving requirements. Any patient whose visual field defect causes practical problems (eg, the impact of hemianopia on the ability to read--Figure 2) should be taught compensatory techniques. For patients with significant visual field loss or reduction in VA, further specialist assessment should be sought, eg, for those wishing to return to driving.
In a survey carried out in 2010,8 45% of stroke services provided no formal vision assessment for patients. Of those providing a vision assessment, 15% were basic qualitative assessments. It is therefore of vital importance that any vision loss or visual disturbances detected during a routine eye examination are referred by optometrists to appropriate medical care, as well as therapeutic care to both physiotherapy and occupational therapy, as required. Such interactive close working between optometry and allied healthcare professionals will result in meeting the healthcare needs of both patients who have experienced a minor CVA, unknown to themselves or to the medical care teams, and those who have been under medical care but have had no visual assessment.
Diabetes and diabetic retinopathy
The prevalence of diabetes mellitus for all age groups worldwide was estimated to be 2.8% in 2000 and is expected to increase to 4.4% in 2030. (9) The total number of people with diabetes mellitus worldwide is projected to rise from 171 million in 2000 to 366 million in 2030. (9) The most important demographic change to the prevalence of diabetes mellitus across the world, however, appears to be the increase in the over 65 years age group.
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According to a UK health survey, by the year 2020, the cases of type 2 diabetes mellitus could soar by as much as 98%;10 whilst approximately half of this increase is due to the changing age and ethnicity of the population, the other half is due to the projected increase in obesity. (10)
The early detection of diabetes mellitus is, therefore, an enormous public health challenge. Up to 21% of patients with type 2 diabetes mellitus have retinopathy at the time of first diagnosis and therefore optometrists have a key role to play in the early detection and diagnosis of this disease.
Diabetic retinopathy is the most common cause of blindness in working age people in the UK. Modifiable risk factors include glycaemic control, hypertension, hypercholesterolemia and smoking. As found in the Diabetes Control and Complications Trial, (11) intensive blood glucose control reduces the risk of new onset diabetic retinopathy, and slows the progression of existing retinopathy for patients with type 1 diabetes mellitus. This was also confirmed for type 2 diabetes mellitus by the UK Prospective Diabetes Study (UKPDS).12 As such, the tight management of blood sugars has a significant impact on the prevention and progression of diabetic retinopathy and should be an important consideration for patients, who need to be educated by GPs, diabetologists and ophthalmologists. In addition to glycaemic control, there is also evidence to suggest that control of systemic hypertension reduces the risk of new onset diabetic retinopathy, and slows the progression of existing diabetic retinopathy too. (13)
An eye examination is likely to detect fluctuating or blurred vision, unstable refractive status due to glycaemic shifts and retinopathy (Figure 3), and as such the optometrist has a key role to play in the early detection and diagnosis of diabetes mellitus. Eye care practitioners will also have an immense role to play for those patients who experience vision loss from diabetic retinopathy in the long-term, for example the provision of low visual aids and rehabilitation from visual field loss (eg, due to pan-retinal laser photocoagulation treatment) (Figure 4).
Age-related macular degeneration (AMD)
AMD is the leading cause of blindness in the western world and is a chronic degenerative disease of the macula. This leads to loss of central vision, which may be profound, obscuring all details apart from in the periphery. The disease affects mainly those aged 50 years or over. AMD and vascular disease share similar risk factors. Recent data suggest that AMD may independently predict stroke or coronary heart disease. (7) Indeed, this study (7) found that AMD predicted stroke and cardiovascular events over the long-term in persons aged 49-75 years. Patients with wet AMD were over four times more likely to have moderate to severe hypertension than those without AMD. (7) As such, patients with cardiovascular disease also need to be educated on the possible impact of their systemic condition on the eyes, not just in terms of vascular or hypertensive changes, but also about the risks of associated disease such as AMD.
As public health professionals, eye care practitioners are well-placed to combat vision loss from AMD by offering patients with strong risk factors, family history, and/or early signs of this disease appropriate advice about risk reduction. This should include the need for regular eye examinations, advice about ocular protection from ultraviolet (UV) light, and dietary supplementation with antioxidants and vitamins (this will be discussed in more detail in the next article of this series).
Optometrists have an integral role to play in providing optimal care for their patients. With changes to the health care landscape and the shift towards greater investment in public health, the role of optometrists can expand to raise the profile of eye health and proactively seek to reach the needs of people at greater risk of developing sight loss. Understanding the local population demographics and eye health needs should inform the design of health services, as well as, pivotally, informing public health agendas to ensure that no individual is prevented from accessing services and treatment they need to maintain good health, independence and well-being.
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Optometrists have a key role as part of a larger multi-disciplinary team of healthcare and public health professionals. The close association between ocular and systemic health requires all medical specialties to consider the impact on an individual. An optometrist's skill and expertise in detecting potentially serious disease for early diagnosis and management makes them an essential part of a healthcare team across primary and secondary care.
Module questions Course code: C-18446 O/D
PLEASE NOTE There is only one correct answer. All CET is now FREE. Enter online. Please complete online by midnight on April 6, 2012--You will be unable to submit exams after this date. Answers to the module will be published on www.optometry.co.uk/cet/exam-archive. CET points for these exams will be uploaded to Vantage on April 16, 2012. Find out when CET points will be uploaded to Vantage at www.optometry.co.uk/cet/vantage-dates
1. Patients with wet AMD were:
a) more than four times more likely to have moderate to severe hypertension than those without AMD
b) more than six times more likely to have moderate to severe hypertension than those without AMD
c) more than four times more likely to have mild to moderate hypertension than those without AMD
d) more than four times more likely to have mild to moderate hypertension than patients with diabetic retinopathy
2. Patients with retinal arterial occlusion (RAO) are at extreme risk of experiencing:
b) malignant hypertension
c) myocardial infarction
3. The most common systemic association with retinal vein occlusion is:
4. At the time of first diagnosis with diabetes mellitus:
a) Up to 21% of patients with type 2 diabetes will have some retinopathy
b) Up to 21% of patients with type 1 diabetes will have some retinopathy
c) Up to 21% of patients will experience blurred vision, or vision disturbances
d) Up to 21% of patients will require management with insulin
5. Stroke can be associated with all of the following visual symptoms EXCEPT:
a) visual field loss
c) ocular pain
d) blurred vision
6. In an individual aged between 49-75 years, AMD may independently predict:
d) cardiovascular disease
See http://www.optometry.co.uk clinical. Click on the article title and then on 'references' to download.
Sonal Rughani, BSc (Hons), MCOptom
Sonal Rughani is an optometrist working as eye health adviser to the RNIB's Prevention of Sight Loss Programme. Clinical areas of interest are low vision, learning disability and diabetic retinopathy. She is studying for a Masters in Public Health. She is also a councillor for the College of Optometrists.
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|Title Annotation:||CONTINUING EDUCATION & TRAINING|
|Date:||Mar 9, 2012|
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