If age-related changes in visual function occur in combination with eye conditions then this can result in significant visual impairments. The most prevalent eye conditions in older people include cataract, glaucoma, age related macular degeneration (AMD) and diabetic retinopathy. Tideiksaar (2002/3) referred to these as the “Big Four” noting that these conditions caused “a multitude of symptoms that increased fall risk”.
Specific eye conditions including visual problems that could increase the risk of falling are discussed below.
Cataracts are the most common cause of treatable vision loss in the UK and are caused by cloudiness of the lens which prevents light reaching the retina resulting in poor vision, increased sensitivity to glare and difficulties seeing under low light levels. Because the reduction in sight is gradual or just accepted as a consequence of old age, cataracts may not be reported. Evans et al (2004) estimated that 26 per cent of cases of sight loss in people aged over 75 years were due to cataracts which could be successfully treated in almost 90 per cent of all cases.
Cataract surgery has a high level of efficacy and has minimal complications. A randomised control trial undertaken by Harwood et al (2005) supported this and confirmed the benefits of first eye cataract surgery in reducing the risk of falls. A Canadian study suggested that patients who waited more than 6 months for cataract surgery may experience a reduced quality of life and increased rate of falls during that time (Hodge et al: 2007). Friedman et al (2005) noted that nursing home residents faced significant obstacles to obtaining cataract surgery but that this intervention can improve the quality of life of frail nursing home residents. These barriers included lack of willingness by family members, guardians or residents themselves in consenting to surgery; difficulties with transportation and lack of advocates to arrange appointments.
Glaucoma is caused by a build-up of aqueous humour as a result of drainage problems and this produces a build-up of pressure within the eye. The condition can be treated with daily eye drops or an artificial drainage hole created in the eye. However, it is vital that this disease is detected early to prevent damage to the cells of the retina and optic nerve fibres causing peripheral visual field loss. The resulting ‘tunnel’ vision effect can cause difficulties with mobility and identification of hazards.
A diagnosis of glaucoma and self-identified worsening of vision has been identified as predictors of falling (Dolins and Harrison: 1997). The Salisbury Eye Evaluation found that visual field loss was a primary vision component in increasing the risk of falling (Freeman et al: 2007). Likewise a prospective Los Angeles Latino Eye study confirmed an independent association with central and peripheral visual impairment and an increased risk of falls (Patino et al: 2010). Haymes et al (2007) noted that patients with glaucoma were over three times more likely than control subjects to have experienced a fall in the previous 12 months. An increase of postural sway in older patients with glaucoma was reported by Black et al (2008) who surmised that this may be a contributing factor in the increased risk of falls.
Benefits of early detection were highlighted in research undertaken by Bayer & Farrari (2002). They reported that in a group of 886 nursing home residents, there was a higher rate of glaucoma amongst the 112 residents with Alzheimer’s disease. The course of sight loss due to glaucoma was also found to be swifter and more aggressive in these patients than in those residents without dementia possibly due to non-compliance regarding daily eye drop medication.
Interestingly, (Glynn et al: 1991) in another study of falls in older patients with glaucoma found that the use of glaucoma medications could pose as great a risk of falls as visual impairment. Although they concluded that further research was needed to explore this connection, nonetheless they advised physicians to be alert to the possibilities of toxic reaction to medication in this population.
Age related macular degeneration (AMD) is the greatest cause of visual loss in older people (Macular Disease Society: 2010). It is caused by progressive damage to the macular which is the central part of the retina. The condition is traditionally divided into two forms – ‘wet’ and ‘dry’. ‘Dry’ AMD is the most common, develops slowly, and accounts for up to 80 per cent of cases of which 20 per cent of sufferers develop severe visual impairments. There is currently no cure or treatment for dry AMD. In contrast, there has been significant development in treatment for ‘wet’ AMD. However, this type is more aggressive and can progress much more quickly and can have a severe impact on visual functioning (Redmond and While: 2008).
People with AMD have reported decreased central vision, mobility, physical activity and quality of life (Klein et al: 2003; Hassell et al: 2006; Williams et al: 1998) but often remain living independently within the community (Brezin et al: 2004). Research by Szabo et al (2010) concluded that the condition was an overlooked risk factor in injurious falls, stating that older women with AMD were particularly more at risk as they had shown to have impaired balance, slower visual reaction times and poorer vision, compared with age-matched controls.
Diabetes is the leading cause of blindness in the UK. Retinopathy occurs when blood vessels in the retina of the eye become blocked, leaky or grow haphazardly. This damage reduces light passing through to the retina and if left untreated can cause blindness. Retinopathy can be treated by laser which is very successful if the condition is caught early and is generally pain free (Diabetes UK:2010). However, people with diabetes are also more likely to develop cataracts and glaucoma (Nazarko: 2010).
Dhital et al (2010) reported that there was a paucity of evidence relating to the effects of diabetic retinopathy to falls. Although this population has been included in a number of studies of falling and people with visual impairments, the condition has not been studied separately.
Because retinopathy does affect an individual’s visual field, this in its self may increase the risk of falling. However, other diabetic factors also need consideration such as lower limb neuropathy which could affect balance as well as any concurrent morbidity such as heart disease which may affect walking and mobility. A review conducted by Lord et al (2006) found that reduced edge contrast sensitivity may predispose older people to trips due to lack of observation of hazards both within the home and in the external environment. Poor control and high glucose levels have been shown to affect the ability to distinguish colours and contrasts (Nazarko: 2010)’ and therefore may affect a person’s risk of falling.