Vision is a dynamic sense that undergoes continuous transformation throughout a person’s life. These changes often manifest as shifts in refractive error, such as myopia (nearsightedness), hyperopia (farsightedness), or astigmatism, which affect how clearly light focuses on the retina. Visual acuity, or the sharpness of vision, also evolves, influenced by the eye’s growth and various physiological processes.
Vision Development Through Childhood
Vision begins its remarkable development even before birth, continuing its maturation throughout childhood and adolescence. At birth, an infant’s vision is quite blurry, with eyes measuring about 16.5 millimeters in length. The visual system is still immature at this stage. Rapid eye growth occurs during the first two years of life, and the eye’s length increases, along with changes in corneal curvature and lens power.
By approximately two years of age, a child’s eyes perceive images more clearly. The cornea, which has a significant refractive power, largely stabilizes by this age. However, the eye continues to grow at a slower pace until early adulthood, reaching an approximate adult size of 24 millimeters. During this period, conditions like infantile hyperopia often lessen as the eye develops.
When Refractive Errors Typically Stabilize
For many individuals, significant changes in refractive errors, particularly myopia, tend to slow down or cease in late adolescence or early adulthood. This stabilization commonly occurs between the ages of 18 and 25. The primary reason for this is that the eye generally reaches its full adult size and shape by this time, typically around 20 or 21 years of age. As the eye’s physical growth stabilizes, the refractive error also tends to become more consistent.
This period of stabilization is considered by eye care professionals when evaluating a person for vision correction surgeries, such as LASIK, as a stable prescription is a requirement for such procedures.
Vision Changes in Adulthood and Later Life
Even after refractive errors stabilize, vision continues to change throughout adulthood due to distinct physiological processes. One of the most common age-related changes is presbyopia, which begins around age 40 and progresses until age 65. This condition, sometimes called age-related farsightedness, results from the natural hardening and loss of flexibility of the eye’s lens, making it difficult to focus on close objects. People with presbyopia often find themselves holding reading material farther away to see clearly.
Another widespread change is the development of cataracts, which involves the clouding of the eye’s naturally clear lens. This clouding can lead to blurry or hazy vision, reduced color vibrancy, and difficulty with night vision. Other age-related conditions, such as glaucoma, which damages the optic nerve and is often linked to increased eye pressure, and age-related macular degeneration (AMD), which affects central vision, also become more prevalent with advancing age.
Key Influences on Vision Changes
Various factors, beyond the natural aging process, can influence the timing, extent, and nature of vision changes. Genetic predispositions play a significant role, with conditions like myopia, hyperopia, astigmatism, glaucoma, and macular degeneration often having a familial link.
Environmental factors also contribute to vision changes. Prolonged near work and increased screen time have been associated with eye strain and can influence the progression of myopia. Lifestyle choices, including diet, smoking, and sun exposure, can impact eye health. For example, excessive ultraviolet (UV) radiation exposure and smoking increase the risk of cataracts and macular degeneration.
Underlying health conditions, such as diabetes and hypertension, can also affect vision and increase the risk of various eye diseases, including cataracts and glaucoma. Certain medications can also lead to changes in vision.