Is myopia genetic? While lifestyle factors have long been closely associated with this condition, it is important to recognize that genetics also plays a significant role in determining myopia susceptibility and severity.
We all know genetics plays a crucial role in many aspects of our physical makeup — from the color of our eyes to whether or not we have earlobes, or when we are hardwired to avoid certain types of foods. If our genes contribute to our ‘nature’, then it’s also fair to say that ‘nurture’ plays a crucial part in determining who we are as people, and some of the most common conditions around are very much caused by nurture.
In the debate about optometry’s great pandemic — myopia, environmental components like time spent outside and away from screens are well-accepted determining factors. What has been discussed less, however, is the role genetics plays in making people more likely to develop myopia. And while it’s understandable to focus on environmental factors that can be altered, it’s also important to study DNA’s influence.
Gene therapy is developing at a rapid pace and new treatments are beginning to emerge for myopia — such welcome news as both ophthalmology and optometry deal with one of the most formidable public health crises in the century.
So let’s examine the relationship between myopia and genetics and consider what optometrists can learn as a result.
Genetic loci and associated syndromes
Dr. Cheryl Chapman, president of the American Academy of Orthokeratology and Myopia Control (AAOMC) and the owner of Gretna Vision Clinic in Gretna, Nebraska, is a renowned orthokeratologist. Her dedication to advancing myopia management is evident through the establishment of a comprehensive myopia management clinic within her practice. She reports that genetics plays a major role in the presence of myopia.
“It is clear that genetics plays a role in the development of myopia,” Dr. Chapman said. “Heritability studies generally estimate the inheritance of myopia to range somewhere between 60% and 80%. At this time, nearly 200 genetic loci linked to myopia have been identified.”
“We know that a family history of myopia not only increases the risk of a child developing myopia but also increases the risk of them experiencing a fast progression of myopia. A child with one myopic parent has a 1.5-times greater risk of developing myopia. A child with two myopic parents has a three-times greater risk of developing myopia,” she continued.
Dr. Chapman said that it’s important for optometrists to remember that there are several inheritable syndromic conditions that are often associated with myopia and that the pathogenesis of secondary syndromic myopia in these conditions is often different from that of primary myopia.
As such, these cases often respond differently to standard myopia management therapies, which can have a considerable impact on patient outcomes. Examples of such conditions include Marfan’s Syndrome and Ehler’s Danlos Syndrome, both genetic conditions that affect the body’s connective tissue; and Stickler’s Syndrome, a hereditary condition characterized by a unique facial appearance, abnormalities in the eyes, hearing loss, and joint issues.
Early intervention is key
“An alternate treatment that may sometimes be more effective in these cases is the use of ophthalmic pharmaceuticals that lower intraocular pressure, such as prostaglandin analogs. Secondary syndrome myopia cases can be very severe and onset at a young age, so it is important for clinicians to be aware of these details and should consider it a red flag if a young child has myopia where the dioptric power reads higher than the patient’s age,” Dr. Chapman explained.
“For example, if you have a four-year-old that is a -5.00D or higher myope, that would warrant communication with the child’s pediatrician and should include a recommendation for a genetic workup,” she continued. “Another red flag for clinicians to watch out for would be if the myopic patient exhibits other signs of syndromic conditions that could manifest with variations in physical attributes or developmental milestones,” she said.
“Eye care providers should proactively work with primary care providers like pediatricians to perform genetic testing when appropriate to uncover syndromic conditions associated with myopia. Implementing patient intake forms and questionnaires to determine the genetic risk of myopia based on parental myopia and to screen for signs and symptoms of syndromic conditions is important,” she added.
The good news, however, is that according to Dr. Chapman, there is a constant stream of new science and study outcomes for optometrists to examine the relationship between genetics and myopia. She recommends seeking membership resources and continuing education from entities like the AAOMC as an actionable and sustainable step. She added that the alignment organizations like hers can limit the amount of time required to research new developments and how to implement them.
Don’t be a skeptic about epigenetics
This is important, as Dr. Chapman is keen to emphasize that practitioner education and consumer awareness campaigns are two of the most important things that can help shift more providers to being highly trained in modern-day myopia treatment.
Practitioner education is important because it improves access to care. Consumer awareness about treatments currently available is key to ensuring that they can have an open discussion with their provider on new options like epigenetics.
“Epigenetics is a fascinating area of study that can shed light on the combined impact that genetics and environment can play on the development of myopia. Put very simply, epigenetics refers to certain genes being turned on or off due to environmental influences. Interestingly, it has been found that epigenetic changes can be heritable,” Dr. Chapman said.
“Even though epigenetic changes don’t change the DNA code, the changes that affect what genes are turned on and off can be passed down in families. Attempts to reveal how epigenetic changes impact myopia development are underway and may provide great insight into future myopia treatments,” she said.
“I believe we will see massive developments in our ability to screen for myopic risk factors, as well as our ability to halt the progression of myopia. I anticipate our understanding of the role of genetics in myopia will drive some of these developments. In fact, I would not be surprised to see the advent of buccal swab testing to pinpoint those individuals most at risk,” she concluded.
Editor’s Note: This article was published in COOKIE magazine Issue 12.