Visual Impairment

Visual impairment occurs when a person has sight loss that cannot be fully corrected by wearing glasses or contact lenses.  The term covers a number of conditions, including Glaucoma, Macular Degeneration and Cataracts, along with more general problems of low vision, which can be associated with the ageing process.

Definitions for common eye conditions are provided below:

  • Age-Related Macular Degeneration (AMD) – Age-related macular degeneration (AMD) is a painless eye condition that causes you to lose central vision, usually in both eyes. Central vision is what you see when you focus straight ahead. In AMD, this vision becomes increasingly blurred, which means reading becomes difficult, colours appear less vibrant and people’s faces are difficult to recognise. This sight loss usually happens gradually over time, although it can sometimes be rapid. AMD doesn’t affect your peripheral vision (side vision), which means it will not cause complete blindness.
  • Cataracts – Cataracts are cloudy patches that develop in the lens of your eye and can cause blurred or misty vision. They are very common. The lens is the transparent structure that sits just behind your pupil (the black dot in the centre of your eye). It allows light to get to the back of your eye (retina). In some people, cataracts develop in the lens as they get older, stopping some of the light from reaching the back of the eye. Over time, the cataracts become worse and start affecting vision. Many people with cataracts will eventually need surgery to remove and replace the affected lens.
  • Diabetic Retinopathy – Diabetic retinopathy is a common complication of diabetes. It occurs when high blood sugar levels damage the cells at the back of the eye (known as the retina). If it isn’t treated, it can cause blindness. It’s important for people with diabetes to control their blood sugar levels. All people with diabetes are at risk of getting diabetic retinopathy, but good control of blood sugar levels, cholesterol and blood pressure minimises this risk.
  • Glaucoma – Glaucoma is a condition which can affect sight, usually due to a build-up of pressure within the eye. The eyeball contains a fluid called aqueous humour which is constantly produced by the eye, with any excess drained though tubes. Glaucoma develops when the fluid cannot drain properly and pressure builds up, known as the intraocular pressure. This can damage the optic nerve (which connects the eye to the brain) and the nerve fibres from the retina (the light-sensitive nerve tissue that lines the back of the eye).

Figure 10.24 highlights the impact of different eye conditions on vision.

Figure 10.24, Visual impairment patterns expected in different eye conditions

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The likelihood of having eye health conditions increases with age, and the older age profile in Devon contributes to higher prevalence rates locally.  The most common condition is cataracts, which affect around 23,400 people in Devon or just over 3% of the total population.  Around 18,600 people are defined as having impaired vision (poor visual acuity and/or reduced field of vision).  Population ageing and growth have a major impact on the prevalence of these conditions in the population, and their rate of increase, with an increase of around 10 to 12% in visual impairment and associated conditions expected in Devon over the next five years.

Table 10.5, Prevalence of Eye Health Conditions, Devon, 2016 to 2036

Glaucoma9,724 (1.26%)10,693 (1.34%)11,841 (1.44%)13,138 (1.55%)14,040 (1.62%)
Age-Related Macular Degeneration (AMD)9,698 (1.25%)10,785 (1.35%)12,466 (1.51%)14,395 (1.70%)15,677 (1.81%)
Cataracts23,377 (3.02%)26,004 (3.26%)28,959 (3.51%)32,320 (3.81%)34,774 (4.01%)
Low Vision18,628 (2.40%)20,765 (2.60%)24,082 (2.92%)28,099 (3.31%)31,445 (3.62%)

Source: Moorfields Eye Hospital (prevalence) and ONS Sub-National Population Projections (2014-based)

Prevalence rates for visual impairment and associated conditions vary by local authority in Devon, with the lowest percentage prevalence in areas with a younger age profile, such as Exeter and Torridge, and the highest rates seen in East Devon and Teignbridge.  Table 10.6 sets out current estimated prevalence for Glaucoma, Age Related Macular Degeneration, Cataracts and low Vision by local authority district.

Table 10.6, Number and proportion of people with selected eye conditions by Local Authority District, 2016

DistrictGlaucomaAMDCataractsLow Vision
East Devon2,076 (1.50%)2,184 (1.58%)5,077 (3.68%)4,232 (3.06%)
Exeter1,103 (0.87%)1,097 (0.86%)2,574 (2.02%)2,119 (1.67%)
Mid Devon942 (1.18%)906 (1.13%)2,246 (2.81%)1,736 (2.17%)
North Devon1,184 (1.25%)1,170 (1.24%)2,843 (3.01%)2,243 (2.38%)
South Hams1,143 (1.35%)1,110 (1.31%)2,755 (3.26%)2,118 (2.51%)
Teignbridge1,685 (1.31%)1,687 (1.31%)4,052 (3.14%)3,247 (2.52%)
Torridge862 (1.29%)830 (1.25%)2,075 (3.11%)1,570 (2.36%)
West Devon730 (1.33%)714 (1.30%)1,755 (3.20%)1,362 (2.48%)
Devon9,724 (1.26%)9,698 (1.25%)23,377 (3.02%)18,628 (2.40%)

Source: Moorfields Eye Hospital (prevalence) and ONS Sub-National Population Projections (2014-based)

Sight loss certifications per 100,000 population are measured in the Public Health Outcomes Framework, revealing higher levels of sight loss certifications than the national and comparator group rates in Devon.

Figure 10.25, Sight Loss Registrations per 100,000 population, Devon local authority comparator group, 2014-15

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Source: Public Health England Knowledge and Intelligence Team (West Midlands) from data provided by Moorfields Eye Hospital and Office for National Statistics

Three further indicators appear in the Public Health Outcomes Framework relate to the three main eye diseases, which can result in blindness or partial sight if not diagnosed and treated in time. These are age related macular degeneration (AMD), glaucoma and diabetic retinopathy.   These indicators relate to sight loss registrations as a result of these three conditions in particular age groups.  Table 10.7 highlights higher levels of registrations in Devon for these conditions compared with England.  The counts include sight loss due to these conditions as the main cause or if no main cause as a contributory cause, which could result in individuals being counted again under other conditions if more than one contributory cause. Certification is voluntary so true rates may be higher than this analysis shows. As such it is unclear whether differences are due to incidence or data collection levels, so it is not possible to conclude if these differences are due to greater risk in Devon or improved detection and recording.  Incidence may vary due to the risk of sight loss being influenced by health inequalities, including ethnic, deprivation and age profiles of the local population. There are also geographic variations in data collection; in some instances completion of additional examinations required to complete the certification are incentivised. Due to this data collection levels may reflect non-completion of certification rather than just low incidence.  These limitations relate to all four eye health measures in the Public Health Outcomes Framework.

Table 10.7, Sight Loss Registrations per 100,000 population for selected preventable eye conditions and age groups, 2014-15

AMD, aged 65 and over123.2101.0
Glaucoma, aged 40 and over12.211.4
Diabetic Eye Disease, aged 12 and over3.33.4

Source: Public Health England Knowledge and Intelligence Team (West Midlands) from data provided by Moorfields Eye Hospital and Office for National Statistics