assess the effects of spectacles or orthokeratology on dry eye parameters in children and adolescents.

Conditions: Dry Eye Disease

Summary: orthokeratology(ok) is currently one of the effective methods for treating myopia, reshaping the corneal epithelium to change refractive power. due to its contact with the ocular surface, long-term wearing could lead to symptoms and signs of dry eye disease(ded) , as well as changes in tear film stability. this prospective study randomly divided 300 children and adolescents with myopia into ok group and spectacles group, with a follow-up of 12 months. at baseline, 1, 3, 6, and 12 months, non-invasive tear breakup time (nibut), ocular surface disease index (osdi) and visual analogue score (vas) score, tear meniscus height (tmh), conjunctival hyperemia (rs score) and meibomian gland (mg) scores, tear mmp-9 concentration, and point-of-care lymphotoxin alpha (lta) test.

this study will be conducted in compliance with the tenets of the declaration of helsinki and the institutional review board of he eye specialist hospital, shenyang, china \[ethics approval number: in recent years, the prevalence of myopia has significantly increased nationwide, the incidence rate of myopia among adolescents in china has risen significantly, causing blurred vision. severe myopia can cause complications that threaten vision, such as glaucoma and macula disease. it would be highly undesirable to increase the social burden. myopia can be corrected by orthokeratology (ok) and spectacles. it has been shown in numerous researches that orthokeratology lens are recognized as one of the effective methods in the treatment of myopia, has been widely used nationwide. in current years, the clinical treatment of myopia by ok lens in adolescents are increasingly confirmed to prevent the progression. traditional ok lenses change refractive power by reshaping the corneal epithelium (leading to the redistribution of corneal epithelium). as the overnight ok lens directly contact the ocular surface, the patients may endure symptoms and signs of dry eye disease (ded), which may even have some impact on the health of the ocular surface, including potential complications such as keratitis. in addition, corneal staining often has occurred in ook wearers. according to previous studies, it has shown that wearing contact lens will affect the tear film stability, damage the function of the meibomian gland, tear film thinning, its affect ocular inflammation. recent studies have also shown that ok continuous wearing has the least impact at 12 months. in order to ensure the safety of long-term wearing ok lenses in children and adolescents, the effect of ok lens on tear film and meibomian gland demonstrated further exploration. the aim of this study is to evaluate the effect of ok on the ocular surface and meibomian gland function in children and adolescents. to assess the effect of ok on ocular surface and meibomian gland function in children and adolescents, so as to improve the application of the clinical.

Eligibility criteria:
inclusion criteria: (i)myopia up to -5.5d; and with-the-rule astigmatism of up to 1.5 dc or against-the rule astigmatism of \<-0.5dc with keratometry from 40 to 45d ; (ii)participants and guardians agree to be randomly assigned and are willing to cooperate with doctors for follow-up and examination. exclusion criteria: (i) existing ocular trauma, infectious diseases, recent surgical history; (ii) keratitis or any ocular inflammation or infection; recently wearing contact lenses; allergy history; (iii) glaucoma, active uveitis or retinal disease; (iv) systemic diseases.

Keywords: myopia orthokeratology tear film dry eye