Myopia, or near-sightedness, is an ocular condition where there is a mismatch between the optical power and length of the eye. The combined optical power of the eye is too strong for its corresponding axial length, causing incoming light to focus in front of the retina. The most common form worldwide is secondary to elongation of the axial length of the eye, termed axial myopia. Myopia is the most common ocular disorder. It affects 20-50% of the population over 12 years of age in the United Stated. The prevalence is even higher in Asian, such as Singapore and Hong Kong. Recent evidence is pointing towards an increasing prevalence of myopia. Currently, the underlying mechanism for myopia development and progression remains unclear, however it is understood that the resultant axial length is determined by a complex interplay between individual genetics and environment. Outdoor activity was protective against myopic progression, while near-work activity had a detrimental effect, even adjusted for parental myopia and ethnicity. In addition, the associated increased axial length increases the risk of eye diseases, including presenile cataract, retinal detachment, myopic retinopathy and glaucoma. Myopia has been implicated as the sixth leading cause of visual loss. The importance of myopia should not be underestimated.

Myopia is in epidemic proportion in China and many Asian cities. The prevalence of myopia is well beyond 80% in these cities. Since high myopia increases the risk of sight-threatening diseases such as glaucoma, retinal degeneration and detachments, it is important to decrease the prevalence of myopia and in particular the high myopia population. In fact, China has identified myopia as a national concern in 2018 and different ministries are joining hands in leading major initiatives to combat myopia in China. From animal studies, we now know that eye growth is modulated by optical inputs received during the early developmental phase. Apparently, optically defocused images formed behind the eye (called hyperopic defocus) would accelerate eye growth; whereas defocused image formed in front (called myopic defocus) would slow down eye growth. This feedback mechanism is universal in many different animal species. In addition, our studies have shown that the eye can integrate simultaneously presented optical defocus and that myopic defocus is a power stop signal to eye growth. Using the principle, we have attempted to incorporate and project myopic defocus in novel optical devices for controlling myopia progression in children. The Centre for Myopia Research of the PolyU has successfully produced special contact lenses as well as spectacle lenses that have incorporated myopic defocus for myopia control. They are Defocus Incorporated Soft Contact lenses (DISC) and Defocus Incorporated Multiple Segments (DIMS) spectacle lenses. Randomised control clinical trials have been conducted in schoolchildren using these lenses and they have shown to effectively slow down the myopia progression by 60%. These new optical devices could significantly decrease the high myopia population and will be useful in controlling myopia in children clinically. Acknowledgement:
The research was supported by the Edwin Leong Endowed Professorship, and industrial grants from Hoya Lens Ltd (H-ZG3B; H-ZG5N); Dean Reserve Fund (1-ZVN2), RGC/GRF PolyU 151033/15M; PolyU 151051/17M.

Orthokeratology involves the use of a specially designed contact lens to correct myopia. This treatment is popular among children since it could provide good vision without glasses during daytime. However, there could be chance of infection if the lens is handled improperly. Cases of severe infection leading to irreversible damage to vision has been reported. Parents considering using this lens should be aware of the risks.

Myopia is a global health threat. By year 2025, it is predicted approximately 50% and 10% of world’s population being myopic and highly myopic respectively. Notably, high myopia is associated with sight-threatening complications, including pre-senile cataract, glaucoma, retinal detachment, and choroidal neovascularization etc. Effective methods for myopia control is important. In this lecture, the author will present his works on Low-concentration Atropine for Myopia Progression (LAMP) Study.

Purpose: Low-concentration atropine is an emerging therapy for myopia progression, but its efficacy and optimal concentration remained uncertain. Our study aimed to evaluate the efficacy and safety of low-concentration atropine eye drops at 0.05%, 0.025%, and 0.01% compared with placebo over a one-year period.

Design: Randomized, placebo-controlled, double-masked trial.

Participants: 438 children aged 4-12 years with myopia of at least -1.0 diopter (D) and astigmatism of -2.5D or less.

Intervention: Subjects were randomly assigned in a 1:1:1:1 ratio to receive 0.05%, 0.025% and 0.01% atropine, or placebo eye drop, respectively, once nightly to both eyes for one year. Cycloplegic refraction, axial length, accommodation amplitude, pupil diameter, and best-corrected visual acuity were documented measured at baseline, 2 weeks, 4 months, 8 months, and 12 months. Visual function questionnaire CHI-VFQ-25 was administered at the one-year visit.
Main outcome measures: Changes in spherical equivalent (SE) and axial length (AL) were measured, and their differences among groups were compared using generalized estimating equation.

Results: After one year, the mean SE change was -0.27±0.61D, -0.46±0.45D, -0.59±0.61D, and -0.81±0.53D, in the atropine 0.05%, 0.025%, 0.01%, and placebo groups, respectively (P < 0.001), with respective mean increase in AL at 0.20±0.25mm, 0.29±0.20mm, 0.36±0.29mm and 0.41±0.22mm (P < 0.001). The accommodation amplitude was reduced by 1.98±2.82D, 1.61±2.61D, 0.26±3.04 D, and 0.32±2.91D, respectively (P < 0.001). The There was an increase in the pupil sizes under photopic and mesopic conditions were increased respectively by in the treatment groups (1.03±1.02mm and 0.58±0.63mm in 0.05% atropine, 0.76±0.90mm and 0.43±0.61mm in 0.025% atropine, and 0.49±0.80mm and 0.23±0.46mm in 0.01% atropine), and 0.13±1.07mm and 0.02±0.55mm compared with minimal change in the placebo group (P < 0.001). Distant or near visual acuity; and vision-related quality of life was not affected in each group. Vision-related quality of life was similar between groups.

Conclusions: The 0.05%, 0.025% and 0.01% atropine eye drops could reduce myopia progression along a concentration-related dependent response. All concentrations were well tolerated without adverse effect on vision-related quality of life. Of the three concentrations used, 0.05% atropine was more most effective in controlling myopia SE progression and AL elongation over a period of one year.