Aging’s Effect on Eyesight
As one of the five senses, vision allows us to see the world around us. Everything we see comes in the form of light, and the structures inside our eyes convert that light and display that image to what we’re seeing now. With that being said, not everyone has the ability to see pictures clearly, and on top of that, it is possible for vision to degrade with age, which is our main focus of this article.
To start, the basic anatomy of the eye consists of a few structures as light enters the eye. It begins by hitting the cornea, a transparent tissue at the outermost layer that acts as a protective barrier that passes light, allowing the lens to focus the light entering our eyes. As the light travels, it then encounters the retina, which lines the back of the eye, and converts the light into a signal/image, waiting to be interpreted by the brain. That signal is then carried to the brain by the optic nerve, allowing you to see the article you’re reading right now. With degrading vision by aging, many conditions affecting the above structures can be to blame. Below are some examples of eye conditions that might come with aging.
This condition is an inflammation of oil glands in the eyelids and is also the most common cause of dry eyes. The smooth surface of the cornea is maintained by a thin layer of tears coated around the surface, which is produced by various cells lining the inner surface of the eyelid. Blepharitis interferes with the tear film, which causes the degradation of the images displayed by damaging the surface of the cornea. This comes with age, depending on the person, and the inflammation ultimately damages the cells that produce tears for our cornea, causing blurry vision.
Cataracts are a very common condition in elders, and it’s said that about half of all 65-year-old Americans have some degree of cataract formation in their eyes. It occurs when the lens in the eyes is broken down by proteins, causing the lens to be cloudy and blurry. As children, our lenses were crystal clear; however, as we age, our lens clouds up. Fortunately, cataracts are very treatable, as cataract surgery is one of the most performed surgeries in the world.
Other than the condition of the cataract, the lenses also degrade in pliability over time, as the crystalline lens becomes less flexible at refracting light onto the retina. In most cases, these hardening lenses make it difficult to view and focus on nearby objects, which is the reason why many elders need to read from further distances.
Age-related macular degeneration
Age-related macular degeneration (AMD) is the gradual damage of the macula, which is a part of the retina. This controls sharp and straight-ahead vision and makes it difficult to see objects clearly. According to the Centers for Disease Control and Prevention, AMD is the most prevalent cause of blindness and vision loss in people over age 65 in the United States. More specifically, the National Eye Institute (NEI) stated that more than two million Americans currently have AMD, and the number can be expected to double to 5.4 million by 2050.
In addition, damage to the optic nerve is a severe issue that can lead to blindness. Glaucoma is one of the conditions that damage the optic nerve by fluid buildup in the anterior chamber of the eye. The increase in fluid creates more pressure on the optic nerve, which is also known as the increase in intraocular pressure. The development risk of glaucoma increases with each decade after age 40, from around 1 percent in your 40s to up to 12 percent in your 80s.
Other than these more serious conditions, there are also less severe changes that occur to our vision and eye structure as we age.
Reduced pupil size: One aspect that comes with aging is the loss of muscle strength, which also applies in this case. The size of our pupils is controlled by muscles in our vision system, and as those muscles weaken, the pupil decreases in size. Signs can be shown from the responsiveness of one’s eyes to ambient lighting change, causing older people to need more ambient light than younger adults for comfortable reading.
Loss of peripheral vision: Another natural effect would be the decrease in the spectrum of peripheral vision. Our visual field reduces one to three degrees per decade, resulting in a total decrease of 20-30 degrees by the age of 80 years old.
Decrease colour vision: Other than the decrease in peripheral vision, our colour vision also decreases with time. Colour vision is provided by cells in the retina, and aging reduces its sensitivity to colour, causing the image to be displayed with less contrast, especially for blue tone colours.
Even though these issues may seem distant to you, it is still very important to recognize the possibilities of these conditions for later on in life. It is much easier to prevent than treat poor eyesight, so start early and care for your vision!
Article author: Kacy Zhao
Article editors: Sherilyn Wen, Victoria Huang