Efficacy and Safety of the New Defocus Spectacle Lens in Preventing Progression of Myopia

Myopia has become the focus of global attention.

There has been a lot of evidence that soft bifocal contact lenses, corneal plastic lenses, low-concentration atropine and outdoor time can reduce the incidence and progress of myopia, while the clinical effects of new technical spectacles with refractive correction function are mixed. Among the strategies of myopia control through optical intervention, the clinical researches of the bifocal spectacle lens showed that the myopia progression can be slowed by about 50% in two years. However, for active children, wearing 1.50D binoculars may increase the risk of injury caused by falls. Moreover, DIMS (Defocus Incorporated Multiple Segments) spectacle lens which also reported that myopia can be effectively controlled is the effect of reducing the far-sighted defocus of omnidirectional off-axis aberration. Although the DIMS lens do not have the discomfort of wearing like the bifocal lens, because several small defocusing areas divide the imaging, the field of vision will feel uncomfortable vibration, or feel scattered light, which will hinder the field of vision.

Like DIMS lens, defocus spectacle lens aims to suppress hyperopia defocus caused by omni-directional off-axis aberration. The method is to set the focal depth extension area and optical center (refractive correction area) of astigmatism with relatively positive refractive power in the surrounding concentric circle area. The precise focusing position of astigmatism, that is, the defocusing amount of the forward refractive force as the equivalent spherical lens, is about 2.75D as the same as the DIMS lens. The change from the two straight focus lines in the front and back directions of astigmatism to the point image distribution of precise focus is very gentle, so there will be no sharp point image change like the DIMS lens, which can inhibit the discomfort of the field of vision being divided.

This study plans to design a randomised trial to compare the effects of new defocusing spectacle lenses and traditional aspheric spectacle lenses on myopia progression in Chinese children aged 6-14 years.

Inclusion criteria

• Aged 6 to 14 years;
• Under the condition of bilateral cycloplegic autorefraction, the spherical refractive error of -1.00 to -3.50 D in each eye and astigmatism of not more than 1.50 D and anisometropia of not more than 1.00 D;
• Best-corrected visual acuity of equal or better than 0.00 LogMAR (>= 1.0 as Snellen).
• The intraocular pressure of 10 to 21mmHg.
• Volunteer to participate in this clinical trial with signature of the informed consent form.

Exclusion criteria

• History of eye injury or intraocular surgery;
• Clinically abnormal slit-lamp findings
• Abnormal fundus examination
• Ocular disease, such as uveitis and other inflammatory diseases, glaucoma, cataract, fundus diseases, eye tumors, dominant strabismus, and any eye diseases that affect visual function;
• Systemic diseases causing low immunity (such as diabetes, Down's syndrome, rheumatoid arthritis, psychotic patients or other diseases that researchers think are not suitable for wearing glasses);
• Participation of the drug clinical trial within three month and the device clinical trial within one month;
• Only one eye meets the inclusion criteria;
• Unable to have regular follow-up
• Participation of any myopia control clinical research trial within three months, and currently using rigid contact lenses (including nursing products), multifocal contact lenses, progressive multifocal lenses and other specially designed myopia control lenses, atropine drugs, etc.