A differently designed pair of glasses could significantly slow the worsening of myopia during childhood.
A study published in JAMA Ophthalmology followed 159 American children aged 6 to 12. All were myopic at the beginning of the trial. Half received standard glasses correcting distance vision. The others wore lenses incorporating 1,021 tiny, specialized optical zones. The glasses were assigned at random.
A. The highly aspherical geometry prevents a single focal convergence.
B. Light rays passing through the single-vision zone converge directly on the retina, producing a sharp central image. Light rays passing through the 1,021 highly aspherical lenses generate a volume of myopic defocus (white shell) in front of the retina.
To understand the value of these lenses, it is worth revisiting myopia. In a myopic person, the image of a distant object forms in front of the retina instead of precisely on it. During childhood, the problem can worsen as the eye grows and lengthens. Conventional glasses correct vision but do not necessarily aim to slow this progression.
The new lenses retain a central zone that provides a sharp image. Around it, very small, strongly curved lenses alter the way some of the light enters the eye. They produce several focal points in front of the retina. This device is designed to limit the signal that promotes eye elongation while still allowing the child to see properly.
After two years, the difference between the groups was clear. Myopia had progressed by an average of 0.25 diopters with the study lenses, compared with 0.90 diopters with conventional glasses. This corresponds to a relative reduction of 71%. The diopter is the unit used to measure the correction required by the eye.
The researchers also directly measured eye length. It had increased by 0.21 mm in the group fitted with the new lenses, compared with 0.45 mm in the control group. Elongation was therefore reduced by 53%.
The treatment does not appear to have reduced the quality of the correction. After 24 months, the best visual acuity achieved with the glasses was comparable in both groups. Of the 159 children initially included, 135 completed the two-year assessment. The trial was conducted at nine centers in the United States, with participants and several team members unaware of the type of lens assigned.
These results add to earlier trials conducted notably in China, where this technology had already slowed the progression of myopia. The American study must nevertheless continue: the published analysis covers 24 months, while the protocol calls for follow-up through 36 months. This final year will show whether the gap between the two groups is maintained.