The Biological Basis of Myopia

"The Biological Basis of Myopia" was my senior project in my biology major. This topic was close to life more than it was just a project. I gained many information that would benefit me in my everyday life and it supplied me with some practices in order to prevent any refractive errors to occur in my life.

The eyes are the mirror of the soul, their expression change according to the inner state of our minds and bodies. Health, fear, love, worry, happiness, sadness and all other feelings are expressed within our eyes. Healthy individuals reflect their well being in their eyes, and sickness is first noticed from the eyes.

Our eyes work from the moment we wake up until the end of the day; they take in tons of images from the world and send it to our brain for processing so we can know what's going on outside our bodies.
Eyes are sense organs which detect light and convert it into electrochemical signals in the neurons which send it to the brain for analysis so that vision would occur. The light must be collected on the retina in order to see a clear image, if this does not happen, then there's a refractive error in our vision.

Myopia or nearsightedness is the most common refractive error of the eye, and has become more prevalent in the last few years. Individuals suffering from myopia have difficulty in seeing far objects. Myopia occurs when the eyeball is too long, relative to the focusing power of the cornea and lens of the eye. This causes light rays to focus at a point in front of the retina, rather than directly on its surface. Myopia typically begins in childhood and may have a higher risk if the parents are nearsighted.

Some studies suggest that people who do large amounts of reading and near work that requires a lot of focusing have higher chances of becoming myopic. However myopia has other causes like familial and genetic basis. When children with myopic parents have a higher chance of becoming myopic then definitely genes have a major role in controlling myopia.

References: 

1-Visual System, Clinical Anatomy and Physiology of the Visual system, Lee Ann Remington, third edition, 2011

2-Gross Anatomy of the eye, Helga Kolb 2005 


Now let's take a look at the Age-dependent changes in refractive errors:

Epidemiological studies show that refractive development is a dynamic process, and the refractive changes occur throughout the individual's life at variable rates. Data from human and animal studies show a highly variable distribution of refractive error during the neonatal period. During the school years and due to the excess near work the refractive errors shift more toward myopia with increasing age.
Although the rate of refractive change during late childhood can vary between populations and ethnicities, the incidence of myopia increases progressively from preschool years and generally reaches its maximum around 9–12 years. By early adulthood, the rate of change in ocular refraction tends to decline and the prevalence of myopia stabilizes. During middle age (between age 40 and 60), the prevalence of myopia gradually declines and refractive errors become more hyperopic.

References: 

1-Seeing and perception, The eyes have it, Earlyne Chaney, 1987

2- Myopia, Douglas R Fredrick, associate clinical professor of ophthalmolog