The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [312]
Figure 9.5 Visual pathways and visual fields.
An additional blind spot, or area of depressed vision called a scotoma, may be indicative of a brain tumour. For example, in pituitary gland tumours it is common to develop bilateral defects in the field of vision due to invasion of the optic chiasm (Goodman and Wickham 2005).
The ageing process
The eye changes with age. This process can start in the third decade of life, with most anatomical and physiological changes becoming more prevalent the older a person becomes (Nigam and Knight 2008) (Boxes 9.4 and 9.5).
Box 9.4 Effects of ageing on the eye
Anatomical changes
The retro-orbital fat atrophies.
Eyelid tissues become weak.
The levator muscle weakens, causing the eyelid to droop which can occlude the upper visual field.
Physiological changes
Presbyopia – the distance from which print can be read increases.
Reduced flexibility of the lens means it can no longer change shape to focus on close objects quickly.
Cataracts – the lens become dense and yellow, affecting colour perceptions; it can become so dense that the lens proteins precipitate, creating a halo effect around bright lights.
Night vision reduces.
Diminished central vision caused by cells within the retina dying.
Dry eyes from reduced tear production.
(Holman et al. 2005, Nigam and Knight 2008)
Box 9.5 Eye conditions common in the older population
Glaucoma: the optic nerve is damaged by increased pressure in the eye, resulting in reduced visual field and pain.
Cataract: as explained in Box 9.4.
Diabetic retinopathy: blood vessels connected to the retina are damaged by the disease and sight becomes blurred and patchy, and can be totally lost.
Age-related macular degeneration is a chronic disorder of the macula cells in the centre of the retina, a highly sensitive area responsible for detailed central vision. As this degenerates, central vision declines which can lead to blindness.
(Holman et al. 2005, Watkinson and Seewoodhary 2007)
Related theory
Sight provides us with important sensory input to enable self-care and pleasurable activities such as reading. ‘Early detection of changes in the eye is important to enable effective treatment and prevent long-term problems and even blindness (Holman et al. 2005, p.37).
Reduced vision or blindness can make the hospital environment very unwelcoming. When caring for patients with eye problems, it is essential to promote a safe, secure environment, where the person is supported and encouraged to communicate their needs effectively.
Evidence-based approaches
Rationale
Indications
Eye care may be necessary under the following circumstances.
After eye surgery to prevent postoperative complications.
To relieve pain and discomfort.
To prevent or treat infection.
To prevent or treat injury to the eye, for example to remove sharp objects.
For eye tests such as refraction.
For screening to detect disease such as glaucoma.
To treat existing problems such as conjunctivitis.
To detect drug-induced toxicity at an early stage.
To maintain contact lenses and care for false eye prostheses.
To optimize the eye’s visual function, especially with age-related degeneration.
(Boyd-Monk 2005, Cunningham and Gould 1998, Stollery et al. 2005, Watkinson and Seewoodhary 2007)
These problems may be experienced in isolation or in combination.
Eye care includes patient education of the eye and surrounding structures as well as health promotion and safety advice to promote quality of life (Watkinson and Seewoodhary 2007).
Principles of care
Eye care is performed to maintain healthy eyes through keeping them moist and infection free. The eye is an important organ and inadequate techniques may lead to the transmission of infection from one eye to the other or the development of irreversible damage to the eye which could lead to loss of sight (Ashurst 1997, Cunningham and Gould 1998).