Have you noticed that you need to hold reading material further away? Can't read messages on your phone easily? Struggle to read the menu in a dimly lit restaurant? Colours do not appear as sharp or bright as they used to? No, it is not that print is getting smaller or of poorer quality, or that manufacture of light bulbs and cell phones has deteriorated, or that you are using the wrong washing powder! It is more likely presbyopia, a common vision disorder that is part of the natural aging process. Just as our bodies show signs of aging as we get older, our eyes decline in performance, too.
The lens inside the eye is elastic and changes its shape so that we can focus at various distances, depending on whether we are looking at something close up or further away. In the young eye the lens and tiny muscles surrounding it are flexible and the lens is able to change shape quickly in order to change focus. As we age, the lens becomes more rigid and is unable to change its shape as easily, making it more difficult to focus close up and to change focus rapidly. As well as this, the muscles lose their ability to control the size of the pupil effectively so that the eyes are less responsive to differences in lighting. Older people need more light for reading and tend to adapt less quickly to changes in light, for example when moving indoors from bright sunlight. Added to this, cells in the retina that are responsible for colour vision decline in sensitivity as we age, causing colours to appear less bright and the contrast between colours to be less noticeable.
Being part of the aging process, presbyopia is not regarded as a disease of the eyes, but it may be coupled with other age-related conditions of the eyes which could be more serious, particularly if they are not treated early. These include cataracts (clouding of the lens), age-related macular degeneration (gradual decrease in central vision), and glaucoma (build up of eye pressure and damage to the optic nerve). At times, floaters or flashes of light may be experienced. These are caused by changes to the gel-like liquid inside the eyes as we age, as it pulls away from the retina at the back of the eye. They are usually harmless but can sometimes indicate a retinal detachment which needs to be treated immediately. Chronic medications and certain medical conditions such as diabetes and cardiovascular disease may impact on eye health and should be controlled to prevent permanent damage and possible loss of vision.
The progress of presbyopia is gradual, and one usually becomes aware of it over time in certain situations. The signs may include blurred vision at normal reading distance, having to hold reading material at arms' length, eye strain or headaches after close work, difficulty reading in dim lighting, decreased colour sensitivity, increased sensitivity to glare, and needing time to adjust to changes in light between bright and darker areas. If you are short-sighted, you will find that you can read more easily by taking your distance glasses off, although you may have to hold things very close to see them clearly. Because presbyopia affects close up vision first, problems with seeing further away, for example on the computer, are generally noticed later. If any of these symptoms are affecting day to day activities, see your optometrist for a comprehensive eye examination. Seek immediate medical intervention if sudden changes occur, for example sudden loss of vision with or without pain, double vision, persistent floaters or flashes of light. These may indicate a more serious problem.
After a comprehensive eye examination, your optometrist will discuss treatment, the goal of which is to compensate for the inability of your eyes to focus on nearby objects. Treatment options include wearing corrective glasses or contact lenses, undergoing refractive surgery, or having lens implants.
Glasses are the simplest solution to correct presbyopia. Over the counter reading glasses are available and may be helpful for you if you had uncorrected vision before developing presbyopia, and if both eyes require the same correction. Check with your optometrist if these would be suitable. When selecting them, try different powers and test them on reading material held at a comfortable distance. If you have no other vision problems, your optometrist may suggest glasses with lenses for reading only. If you need prescription lenses for other vision problems, the alternatives are bifocals, trifocals or progressive multifocals. Bifocals have a visible horizontal line which separates the distance and reading prescriptions. Trifocals have corrections for close, middle and distance vision, which are separated by two horizontal lines. Progressive lenses have different focusing strengths for distance, middle distance and close-up work, but no obvious dividing line between them. Some people choose to have separate pairs of glasses for distance and reading and maybe also for middle distance.
People who prefer not to wear glasses often opt for contact lenses to improve the vision problems caused by presbyopia. Several options are available. Bifocal contact lenses provide both distance and close-up corrections. With monovision contact lenses, a lens for distance vision is worn in one eye, and one for close work in the other. Modified monovision involves wearing a bifocal or multifocal contact lens in one eye and one for distance vision in the other, so that both eyes are used for distance vision and one eye for reading. Because conditions like dry eye syndrome are common in older people, contact lenses may not be recommended for everyone. Your optometrist will guide you.
Surgery is an option to correct presbyopia. Your optometrist will refer you to an ophthalmologist who will discuss the different surgical options, pros and cons, and whether it is advisable for you. Refractive surgery is a non-reversible procedure which changes the shape of the cornea. Some ophthalmologists use a procedure in which they remove the lens in each eye and replace it with a synthetic intraocular lens. Several types of lens implants are available for correcting presbyopia.
Presbyopia can't be prevented but certain lifestyle factors can help to protect and care for your eyes:
- Have your eyes checked regularly, even if you feel you have no vision problems. If you use ready-made reading glasses it is still important to see your optometrist for regular eye examinations as people over 40 years of age are more at risk for eye diseases such as glaucoma and age-related macular degeneration.
- Control chronic health conditions some of which can affect vision and eye health.
- Protect your eyes from the sun by wearing sunglasses that block ultraviolet (UV) radiation. This is especially important if you spend long hours in the sun or are taking a prescription medication that increases your sensitivity to UV radiation.
- Prevent eye injuries by wearing protective eyewear when performing certain tasks, such as playing sports, mowing the lawn, or using products with toxic fumes.
- Eat healthy foods which contain high levels of antioxidants as well as vitamin A and beta carotene, which are vital to maintaining eye health.
- The right glasses optimise vision. As vision changes over time, having regular eye examinations will ensure that your prescription is always correct.
- Use good lighting.
- See your optometrist immediately if you experience sudden loss of vision in one eye with or without pain, sudden hazy or blurred vision, double vision, or persistently see flashes of light, black spots or halos around lights. Any of these symptoms may signal a serious medical or eye condition.