diabetic eye disease and low vision

7/29/2019 Diabetic Eye Disease and Low Vision

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Diabetic Eye Disease and Low Vision

Niamh Stone; Barbara Ryan; Anne Sinclair

Posted: 01/17/2012; British Journal of Diabetes and Vascular Disease. 2011;11(6):282-287. 2011 Sage Publications, Inc.

Abstract and Introduction

Abstract

Diabetic retinopathy is the most common cause of registrable blindness among the working

age population of the UK. Primary prevention associated with improved medical

management and the introduction of national screening programmes aim to reduce the

incidence of eye disease. Should retinopathy develop, there are several treatments that can

help to preserve vision. While these interventions can prevent or delay visual loss, many

patients with diabetes still experience significant functional and practical difficulties as a

result of impaired vision. Recognising visual problems at an early stage is important as this

ensures improved support from the multidisciplinary team with appropriate education, timely

visual impairment registration and access to support services.

Introduction

Despite improved detection and increasing availability of effective treatment, the prevalence

of DR is increasing.[1] Better medical management of diabetes, early detection and timely

treatment of DR reduce the risk of blindness. However, patients at any stage of their diseasemay be struggling to cope with the practical difficulties related to impaired vision. This

presents a challenge to the ophthalmologist and the diabetes team, who must balance the need

to motivate patients to persevere with treatment, with the promotion of early contact with

rehabilitation services. This overview highlights the current issues associated with visual

impairment and diabetes and includes practical advice for those working with patients in

community and hospital-based practice.

Defining Low Vision

A person with low vision is one who has an impairment of visual function which causes

restriction in that person's everyday life, for whom full remediation is not possible byconventional spectacles, contact lenses or medical intervention. This definition includes, but

is not limited to, those who are registered as blind and partially sighted. [2]

Epidemiology of Sight Loss in Diabetes and the Cost to Society

Analysis of UK registration data has identified DR as the most common cause of registrable

blindness in the working age population. In 19992000, 17.7% of blind registrations in the

1664 age group were for DR (figure 1), compared with 11.9% in 19901991. A doubling in

both blind and partial sight registrations for DR in the over 65s was also noted over the same

period, probably reflecting the rising numbers and increasing longevity of people with

diabetes.[1]


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Figure 1. Causes of blindness in England and Wales ages 1664 based on certifications from

April 1999March 20001

Reprinted by permission from Macmillan Publishers Ltd: Eye,1 copyright 2008.

A study commissioned by the RNIB estimated that in 2009, 40,982 persons were partiallysighted and 24,976 blind as a result of DR. By 2020, numbers are predicted to rise to 46,473

partially sighted and 29,957 blind. This study also calculated the potential cost to society.

Loss of earning potential and costs for care give a predicted financial deficit of nearly 700

million for 2010 in the UK. The total cost for the current decade in the UK is estimated to be

6.5 billion.[3]

How Does Visual Loss Occur in Diabetes?

Diabetes can affect ocular health in a number of ways which impact differently on visual

function, causing partial or total loss of vision that is transient or permanent. (Table 1).

[4]

[ CLOSE WINDOW ]

Table 1. Range of ocular complications associated with diabetes4

Ocular tissue Conditions more common in diabetes

Lids Xanthelasma

Blepharitis

Orbital cellulitus (including mucormycosis)


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Conjunctiva Infectious conjunctivitis

Cornea Reduced sensitivity leading to punctate keratitis and erosions

Iris Poor dilation

Rubeosis

Lens Transient refractive changes

Cataract

Possible increase risk of endophthalmitis post surgery

Vitreous Traction detachments associated withneovascularisation

Retina Retinopathy

Maculopathy

Retinal vein occlusions

Retinal artery occlusions

Ocular ischaemic syndrome

Optic nerve Papillopathy

Anterior ischaemic neuropathy

Glaucoma

Cranial nerves 3rd/4th/5th/7th nerve palsies

Intracranial Stroke-induced visual loss

Charles Bonnet syndrome

PDR may give rise to floaters due to early vitreous haemorrhage, progressing to total

'blackout' with a dense haemorrhage. Advanced or untreated PDR with tractional detachment

can lead to 'no perception of light', although this is becoming increasingly rare.

DMO is initially associated with blurring of central vision that predominantly affects reading.

In advanced stages distance acuity is also poor, but the peripheral function is unaffected

allowing the person to maintain navigational vision.

Laser photocoagulation is a well-established treatment for PDR and DMO. [5] It can reduce the

visual field, however, which may affect fitness to drive. [6] Laser to the peripheral retina can

also affect night vision or lightdark adaptation.[7] It is likely that anti-VEGF therapy in

combination with laser will have a significant impact on the future management of both PDR

and DMO.[8,9]

Other causes of sight threatening disease in diabetes include vascular occlusions,[10,11] non-

arteritic ischaemic optic neuropathy and diabetic papillopathy. [1214] Cataracts reduce visual

acuity and contrast sensitivity. The Framingham Eye Study reported as much as a fourfold

increase in the prevalence of cataracts in patients younger than 65 years of age with diabetes.[15] It is also well accepted that people with diabetes experience transient changes in refractive


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status in association with hyperglycaemia or hypoglycaemia.[16,17] While this causes only

temporary visual impairment it may impact on ability to work or drive.

A hemianopia or quadrantanopia secondary to stroke has a major impact on functional ability,

often compounded by lack of awareness of the reason for the visual difficulty. This is often

neglected by professionals who do not recognise the need for referral to rehabilitationservices.[18]

Finally, visual hallucinations are common in people with poor vision and up to one third of

patients referred for vision rehabilitation have complex and often frightening visual

hallucinations consistent with the Charles Bonnet syndrome.[19]

Practical Advice for Professionals Caring for Visually Impaired Patients

For people with diabetes and sight loss, attending multiple hospital clinics can be frustrating.

From the initial inability to read clinic appointment letters with inadequate font size, through

to poor hospital signage and overcrowded, badly lit waiting rooms, clinic visits can become

stressful to the point where attendance may be affected.

Clinicians have a responsibility to make the patient experience easier. For instance, being

able to guide a visually impaired person into the clinic room can enhance the doctorpatient

relationship and get the consultation off to a better start. More details are available on the

RNIB website (figure 2).[20]


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Figure 2. Guiding a patient into your room can be helpful

History taking should include an assessment of the impact of sight loss on safety and coping

skills. Difficulty with simple tasks such as reading pharmacy labels or a BGM or setting an

insulin delivery device at the correct number of units may interfere with diabetic control

(figures 3 and 4). Rehabilitation workers can liaise with community or diabetes nurses to

provide appropriate devices and training to help a person manage their blood sugar controlindependently.


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Figure 3. Using a magnifier to read medicine bottle labels


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Figure 4. An insulin pen viewed under a stand magnifier

It is worthwhile enquiring about falls, especially in the elderly. Although there is currently

little direct evidence relating the effects of DR to falls, any patient with lower limb

neuropathy may have problems with walking and gait thus increasing their fall risk,

particularly if they already have visual problems.[2123] In these cases, referral to a

rehabilitation worker may be beneficial to exclude trip hazards and improve lighting in thehome (figure 5). For some, mobility training will aid falls prevention.

Exercise levels may be affected by sight difficulties and previously active people lose fitness

when they cannot go out independently. Local services should have information on sport and

fitness programmes for people with a visual impairment.

Loss of employment and driving ability are particularly distressing and are associated with

depression.[24,25] Empathetic listening and an awareness of the patient's concerns are an

essential part of care and in keeping with the 'Duties of adoctor'. [26] In some cases referral for

treatment of depression may be required.


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Registration

Although people with sight loss can access certain social services without certification and

registration, the process automatically triggers a referral to the patient's local support services

and facilitates the process. Depending on the person's circumstances, registration, particularly

as severely sight impaired/blind, may entitle them to financial and other benefits (Table 2). [27]Unfortunately, many eligible patients are not offered certification, especially those having

ongoing treatment and outpatient follow-up.[28,29]

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Table 2. Summary of benefits and concessions

Benefit orconcessionPartial-sighted/sight

impaired

Blind/severely sight

impaired

Disability Living Allowance (DLA) or

Attendance AllowanceYes Yes

Blind person's personal income tax

allowanceN/A Yes

Additional income support or pension

creditYes Yes

Council tax reduction Yes Yes

Incapacity benefit Yes Yes

NHS sight test Yes Yes

Television licence reduction N/A Yes

Car parking concessions Possible Yes

Access to work equipment and travel costs Yes Yes

Articles for the blind postage Yes Yes

Railcard Yes Yes

Local travel schemes Possible Possible

Free directory enquiries Yes Yes

Free telephone installation charge and line

rental (not Scotland)Possible Yes

Consultant ophthalmologists are the only professionals who may complete a certification

form, with the patient's informed consent. Certification designates the patient as either being

severely sight impaired (blind) or sight impaired (partially sighted). The person is then

registered with their local authority, which contacts specialist social services for an

individualised needs assessment. This help is provided by rehabilitation workers who give

advice and support with activities of daily living and mobility training, and specialist socialworkers who assist with financial and emotional support.


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The criteria for registration include visual acuity and visual field measures (Table 3). In

England, Wales and Northern Ireland, the new CVI form replaces the terms 'blind' with

'severe sight impairment' and 'partially sighted' with 'sight impairment'. In Scotland,

certification is through the BP1 form, which uses the older blind and partially sighted

terminology. This system is, however, under review.

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Table 3. Categories of certification

Severely sight impaired(Blind) Sight impaired(Partially sighted)

Visual acuity < 3/60 Visual acuity of 3/60 to 6/60

Visual acuity > 3/60 but < 6/60 with a very contracted

visual field (unless longstanding)

Visual acuity of up to 6/24 with

moderate restriction of visual field

Visual acuity better then 6/60 with a very constricted

visual field (especially inferior defects but excluding

hemianopia with visual acuity better than 6/18)

6/18 or better with a gross field

defect (hemianopia or gross

constriction)

Low Vision Aids

There are a variety of distance and near aids, both optical and electronic, available to help

with daily living tasks. For example, a magnifier can help a person to read small print on

packets, which can be important to maintaining a healthy diet. These can be obtained through

hospital low vision services or through some local optometry practices. A full description of

the types of appliances available is outside the scope of this article but are fully described instandard texts.[30,31] More examples are shown in figures 57.


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Figure 5. A distance aid for television viewing


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Figure 6. Various models of CCTV are available. The material tobe viewed is placed on an

XY table.


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Figure 7. Dimly lit stairs can be dangerous

Aids for Blood Glucose Monitoring and Insulin Delivery

The choice of BGM is important for people with a visual impairment. Since the introduction

of monitors with integrated speech (i.e. where display data is spoken), BGMs have become

more accessible. Monitoring may be facilitated by high contrast large font displays and tactileor coloured control buttons. Operating manuals in large print or in electronic format (which

are read using a computer or with magnifying software) also assist patient motivation,

providing a sense of control over their disease.

Insulin delivery devices vary in their accessibility for people with sight loss. Those with

large, round, egg-timer-like displays, or with audible clicks as the dial passes each number,

are usually easier to use than those with small LCD displays and no auditory or tactile cues. It

is important to inform patients that different devices exist and that it may be necessary to

experiment in order to find the most appropriate device for their needs. [32,33] A study by Uslan

et al.[34] showed no significant correlation between accuracy of insulin dosing and visual

status.


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Conclusion

Diabetes is a common cause of sight impairment and many patients experience significant

functional and practical difficultiesas a result of poor vision. It is important to recognise

visual problems as early as possible so that the multidisciplinary team can understand, assess

and treat their patients' needs fully, ensuring appropriate information-giving, timelyregistration and access to relevant support services.

Sidebar

Key Messages

DR is the most common cause of registrable blindness among the UK working age

population

Causes of low vision in diabetes are multifactorial

Early recognition of visual problems allows access to appropriate support

Certification as visually impaired acts as a gateway to benefits, but is not essential for

certain services

[ CLOSE WINDOW ]

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Abbreviations and acronyms

RNIB, Royal National Institute of Blind People; DR, diabetic retinopathy; DMO, diabetic

macular oedema; PDR, proliferative diabetic retinopathy; VEGF, vascular endothelial growth

factor; CVI, Certificate of Visual Impairment; BGM, blood glucose monitor

Funding

This research received no specific grant from any funding agency in the public, commercial,or not-for- profit sectors.

Conflict of interest

The authors declare that they have no conflicts of interest.

British Journal of Diabetes and Vascular Disease. 2011;11(6):282-287. 2011 Sage

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