Investigate the effect of 3% Diquafosol on tear film and vision-related quality of life in dry eye patients wearing orthokeratology lenses(OK lens), and to provide reference for clinical treatment.This prospective, open label study will include 60 eyes of 30 OK lens related dry eye patients.Participants will receive 3% Diquafosol ophthalmic solution. The dosage for both drugs will be one drop, six times per day for 4 weeks. Pediatric Refractive Error Profiletear(PREP), tear film lipid layer (TFLL),non-invasive breakup time (NITBUT), corneoconjunctival staining score (CS), tear meniscus height (TMH), objective visual quality,ocular surface disease index (OSDI) will be assessed and compared at baseline, day-14, and day-28

Keratoplasty is gaining popularity worldwide as a method of controlling myopia progression. Several clinical studies have shown that overnight wear of Orthokeratology lenses (OK) is an effective method of slowing myopia progression in adolescents.However, wearing corneal contact lenses tends to interfere with tear homeostasis, which may lead to ocular discomfort, dryness, and ocular surface disorders. More than 50% of contact lens wearers report symptoms of dry eye.Prolonged contact with the cornea can have an effect on the corneal layer.With the rapid increase in the use of OK lenses worldwide, potential complications have become a major concern for parents. Potential complications include keratitis and corneal epithelial damage. In addition, overnight OK lens wear has been associated with decreased tear production and reduced tear film stability. Recently, a four-week study by Carracedo et al. demonstrated that OK lens wear did not significantly change fluorescein-stained tear film breakup time or Schirmer's test I results, but subjects had increased dry eye symptoms one month after wear Decrease in cupped cell density.

Diquafosol Ophthalmic Solution (DQS) is a potent purinergic P2Y2 receptor agonist, a stabilized synthetic derivative of the naturally-occurring nucleotide uridine 5'-triphosphate; it stimulates the secretion of mucin and tears by conjunctival cup cells and conjunctival epithelial cells. Several studies have shown that Diquafosol sodium is effective in the treatment of dry eye. In addition, some studies have shown that Diquafosol sodium eye drops have significantly alleviated dry eye symptoms and improved ocular surface parameters in children wearing keratomileusis lenses at night. However, the available research lacks the ability of the DQS to assess the effect of DQS on visual acuity and quality of life improvement in patients with dry eye after wearing OK lenses. The results would inform clinicians to improve comfort and compliance with keratoplasty lenses in adolescents.

Inclusion Criteria:

• Age 8-18 years old
• Wearing corneal shape mirror more than one year and at least eight hours every night
• Myopia -5.50 to -1.00 D, astigmatism < 1.75 D, or curvature between 41.00 and 46.00D, astigmatism < -0.75D, and best corrected visual acuity ≥1.0.
• Diagnosis of dry eye: patients complained of dry eye, foreign body sensation, burning sensation, fatigue, discomfort, envy, subjective symptom such as vision fluctuation; (a) OSDI questionnaire score >13 points, and (b) NITBUT <10 s or (c) ocular surface dyeing assessment > 5 corneal spots/more than nine conjunctival spots.
• Participants were able to use eye drops as required, complete examinations, and return to the hospital for follow-up examinations within the specified time to complete follow-up.

Exclusion Criteria:

• Suffering from allergic or autoimmune disease associated with dry eye of the participants are not suitable for wearing OK lens
• Pathological changes in the corneal rim
• Eyelid rim lesions, cornea, uveitis, retina and other systemic diseases may affect the ocular surface. Examples include severe ocular surface diseases (Sjögren's syndrome, allergic conjunctivitis, ocular papules, conjunctival chafing, conjunctival scarring, and chemical damage);
• Received any dry eye treatment within 14 days prior to the start of this study or continued use of other topical eye drops that would affect the results of the study.
• Have received any other eye treatment or surgery