People of East Asian ethnicity may get presbyopia earlier than previous estimations, according to a new study in Clinical & Experimental Ophthalmology.

Investigators enrolled 303 participants who were 35 years and older from Guangzhou, China in this prospective cohort study. Subjects underwent visual acuity testing and non-cycloplegic automated refraction at baseline in 2008 and again in a six-year follow-up. Participants with presenting near visual acuity of 20/40 or less also underwent distance subjective refraction and add power measurement by increasing plus lens at a standard distance of 40 cm at each visit.

“To the best of our knowledge, the age-related add power requirement for East Asian population as well as the longitudinal progression of add power have never been reported,” investigators said.

The study noted the mean add power at baseline for specific age groups was 1.43 (ages 35-44), 1.73 (ages 45-54), 2.03 (ages 55-64) and 2.20 (age 65+) diopters.

“In our study, there was no gender difference in add power requirements at baseline, and the longitudinal change in add power was also similar between genders,” researchers said.

Investigators found participants who were older and had a lower educational level had significantly higher add power requirements. Additionally, researchers reported the overall six-year increase in add power was 0.15D and was smaller in myopic subjects. Also, baseline age and add power—but not changes in biometric factors—were associated with longitudinal change in add power.

The study reported a rapid increase in add power requirement from age 40 to 50, but with slower progression after that.

“Our study found an earlier onset of presbyopia compared to the norms recommended by Hofstetter and Pointer,” researchers said, referring to previous research based on mostly Caucasian populations.

They added: “Distribution and progression of add power in Chinese was different from that previously suggested by Caucasian studies. More studies are needed to establish up-to-date age-related add power prescription norms for population of different ethnicities.”