Data show 38% of young adults in the study population experienced a myopia shift of 0.50 D or more in at least 1 eye over 8 years.
Although myopia typically develops and progresses during childhood with a stabilization around 15 years old, previous research has shown myopia may continue to progress or onset during young adulthood which has been noted may be driven by more time spent indoors.
However there is limited data on its progression in young adulthood, resulting in a recent study which set out to describe the 8-year incidence of myopia and high myopia and change in ocular biometry in young adults, as well as the association with known risk factors for childhood myopia.
Led by Samantha Sze-Yee Lee, PhD, Lions Eye Institute, the study’s findings showed the development progression of myopia continued for more than one-third of adults during their third decade of life, while at a lower rate compared to childhood.
Data was obtained from the prospective single-center cohort Raine study, which has observed a cohort of participants since prenatal periods in 1989 - 1991. A total of 2900 pregnant women were recruited from the King Edward Memorial Hospital in Perth, Australia, with 2868 offspring born and forming the original study cohort now in young adulthood.
At the 20-year follow-up (ages 18 - 22 years), patients underwent their first Raine study eye examination and were invited to return for an eye examination at the 28-year follow-up. The first was conducted from January 2010 - August 2012, with the second from March 2018 - March 2020.
Both eye examinations included conjunctival ultraviolet autofluorescence (CUVAF) photography, ocular biometry, post mydriatic autorefraction/keratometry, and lens thickness measurement. A participant was considered to have myopia or high myopia if either or both eyes had a spherical equivalent of 0.50 D or less, or 6.00 or less, respectively.
Through a self-administered questionnaire, participants identified their highest level of education, parental myopia, race, and ocular history.
From 1344 participants who attended at baseline, a total of 1328 had refractive data, including 342 with myopia and 19 with myopia, at a prevalence of 25.8% (95% CI, 23.5% - 28.2%) and 1.4% (95% CI, 0.9% - 2.2%), respectively.
After excluding those without refraction data at baseline or follow-up, myopia at baseline, keratoconus, or recent use of orthokeratology contact lenses, a total of 516 participants (50.6% male) were included in the incidence analysis. Cumulative 8-year myopia incidence was 14.0% (95% CI, 11.5% - 17.4%) with 72 patients developing myopia.
Through univariable logistic regression, myopia incidence was associated with female sex (OR, 1.81; 95% CI, 1.02 - 3.22, P = .04), East Asian versus White race (OR, 6.13; 95% CI, 1.06 - 35.25, P = .04), smaller conjunctival ultraviolet autofluorescence area (OR, 9.86; 95% CI, 9.76 - 9.97, P <.009), and parental myopia (per parent; OR, 1.57; 95% CI, 1.03 - 2.38, P = <.05). Additionally, eyes with incident myopia had lower spherical equivalent, longer axial lengths, and thinner lens at baseline, compared to those that did not become myopic.
A total of 683 participants (49.5% male) were available for high myopia incidence analysis. Data show the incidence of high myopia was 0.7% (95% CI, 0.3% - 1.2%), with 5 participants who progressed to high myopia.
Additionally, investigators found a total of 261 participants (37.8%) experienced a myopic shift (≥0.50 D) in at least 1 eye over 8 years, with 152 patients experiencing myopic shift in both eyes.
A statistical significant was observed in longitudinal changes in spherical equivalent (-0.04 D per year; -0.055 to -0.027, P <.001), axial length (0.020 mm per year; 0.014 - 0.025), and lens thickness (0.020 mm per year; 0.017 - 0.024, P <.001).
The rates of myopia progression and axial elongation were shown to be faster in female participants (estimate SE, 0.02 D per year; 95% CI, 0.01 - 0.02 and AL, 0.007 mm per year, 95% CI, 0.00 - 0.011; P ≤.001) and those with parental myopia (estimate per parent SE, 0.01 D per year; 95% CI, 0.00 - 0.02 and AL, 95% CI, 0.002 - 0.008, P ≤.001). However, education level was not associated with myopia incidence or progression.
“The eye continues to elongate axially in some participants during young adulthood, which may contribute to the increased risk of myopia-related complications as these young adults reach middle and older age,” investigators wrote.
The study, “Incidence and Progression of Myopia in Early Adulthood,” was published in JAMA Ophthalmology.