3% Diquafosol Ophthalmic Solution for Active Moderate-to-Severe Vernal Keratoconjunctivitis

The aim of the study is to investigate whether patients with moderate-to-severe VKC and keratitis will benefit from the addition of Diquafosol ophthalmic solution in terms of symptoms and signs of VKC, tear film metrics, ocular surface inflammation and quality of life. Potential beneficial effect of Diquafosol treatment on top of current standard use of topical immunosuppressant therapy in VKC would be studied. Subject at least aged 6 and above with clinical diagnosis of vernal keratoconjunctivitis would be invited to join this study and perform the following assessments: 1. best corrected visual acuity, 2. slit lamp biomicroscope examination, 3. tear meniscus height and non-invasive keratographic tear breakup time(NIKBUT) measurement, 4. cornea fluorescein staining (CFS) and 5. Schirmer's I test. Doctor will prescribe eyedrop, 3% Diquafosol ophthalmic solution and 0.1% Cyclosporin A cationic ophthalmic emulsion or 0.1% Cyclosporin A cationic ophthalmic emulsion at the end of examination. Subjects will be followed up at 4 weeks, 8 weeks, 16 weeks after treatment. All participants will be required to answer a standardised questionnaire relating to severity of VKC and dry eye disease.