“Genomic medicine presents tremendous potential in childhood myopia research. By identifying specific risk genes, we can provide more precise prevention and management strategies for children.”
Professor Guy Chen
Specialist in Ophthalmology
Awardee of the 2023/24 HKAM-HKGI Research Excellence Grants in Genomic Medicine
Hong Kong has a high incidence of myopia. Prior to the pandemic, myopia rates among six-year-old children were approximately 12% to 15%. However, after the pandemic, the figures more than doubled to 25%, meaning that one in four Primary 1 students has myopia. “Myopia is a multifactorial disease involving both genetic and environmental factors,” Professor Guy Chen explained. “Particularly for young children with myopia, genetic factors may play a more decisive role.”
Myopia primarily follows two inheritance patterns: single-gene and polygenic. “Single-gene inheritance can be dominant or recessive. When parents don’t have myopia but a child develops severe myopia, this could be due to recessive inheritance. However, most myopia cases are a result of polygenic inheritance, where dozens or even hundreds of genes combine with environmental factors to cause myopia,” said Professor Chen.
Major Health Risks Associated with High Myopia
In addition to severely affecting vision, high myopia could trigger other serious eye diseases. “The risk of high myopia patients having retinal detachment is 100 times higher than normal people,” Professor Chen said. Other common complications include macular degeneration, glaucoma, and early-onset cataracts. “High myopia patients may develop cataracts between 40 and 50 years old, 10 to 20 years earlier than average,” Professor Chen added.
These complications also impact work and quality of life. Once the eyeball elongates to become myopic, it is essentially irreversible. Even after laser vision correction surgery, the risks associated with high myopia remain.
Making Childhood Myopia a Thing of the Past
Professor Chen and his team are dedicated to researching genes related to childhood myopia, collecting genetic data from nearly 40,000 Hong Kong children. Through genome-wide association study (GWAS), they discovered four new genes associated with childhood myopia. “These childhood myopia genes were never found in adult myopia research. Each gene variant increases myopia risk by 1.2 to 1.5 times. If a child carries all four gene variants, their myopia risk increases by more than three times.”
The research also found that children with high genetic risk scores and who engage in prolonged close-up work have a myopia risk increase of four to five times. “These findings enable us to formulate personalised myopia care strategies,” Professor Chen said. “High-risk children’s daily cumulative reading time should not exceed three hours, while low-risk children should not exceed four hours.”
New Directions in Childhood Myopia Prevention Transform Care
For treatment, besides wearing appropriate glasses, atropine eye drops can effectively slow myopia progression. Some children even experienced myopia reversal after combining Atropine eye drops with red light therapy, according to another study conducted by Professor Chen’s team: “Some children experienced complete reversal from 100 degrees of myopia after six months of treatment, no longer needing glasses, and their eye axis also shortens.”
Professor Chen emphasised the importance of establishing local genomic databases, as different ethnic groups have varying genetic characteristics, and Western research findings may not necessarily apply to local patients. Having a local database offers valuable reference for precision medicine across specialties. “By analysing local children’s genetic data, we can more accurately identify myopia risk genes and provide more precise prevention strategies for Hong Kong children. Genomic medicine enables us to identify high-risk children early. We can adjust reading habits, implement personalised treatment plans, and reduce the likelihood of high myopia,” he said.
Childhood Myopia and Genomic Analysis
As myopia often begins during school age when the eyeball is still developing, conducting paediatric myopia research reveals not only the disease’s origins but also its developmental trajectory.
Professor Chen’s research studies both the genetic and environmental factors of childhood myopia. His research team invites primary school students and their parents to participate in detailed ophthalmological examinations, including vision tests, eye pressure, and fundus examinations, while collecting oral mucosa or blood samples to gather genetic data from nearly 40,000 Hong Kong children.
With support from the HKAM-HKGI Research Excellence Grants in Genomic Medicine, Professor Chen’s team conducted genomic study on approximately 6,000 children, with the goal of discovering new childhood myopia-related genes and developing genetic risk scoring models to identify high-risk children early. In doing so, doctors will be able to implement targeted prevention and management measures, reducing myopia’s impact on the next generation.