Method:
As part of a two-year observational prospective study in the year 2017, VKC cases and controls were recruited for one year in our tertiary eye care center, as approved by the Institutional review board. The study was conducted in strict adherence to the tenets of Declaration of Helsinki after written informed consent from all study participants.
VKC was diagnosed and graded based on the classification by Boniniet al (11). Patients with ocular itching, photophobia, presence of active tarsal/limbal papillae, bulbar congestion, Horner Tranta’s dots or superficial punctate keratitis were diagnosed as active VKC. The quiescent stage was diagnosed based on inactive or flat-topped papillae, a non -inflamed ocular surface with previous history of chronic itching. All cases were included after a complete ophthalmic examination and ruling out any other ocular or systemic morbidity or history of ocular surgery. Tear specimen and conjunctival imprints were collected in cases and controls, while blood sample was collected in a sub-set based on consent of the study participant. All cases with active VKC and age >6 years were included in the study. Patients with history of previous ocular surgery, ocular co-morbidity other than VKC, any systemic disease other than allergic disorders; age < 6 years and quiet eye at presentation were excluded from the study.
VKC cases were further graded based on their severity as non-refractory (NR-VKC) and refractory (R-VKC). On basis of Bonini’s classification, patients with grade 1 and 2 (mild to moderate form of seasonal VKC) were considered as non-refractory and those with grade 3 and 4 (severe to very severe form of perennial VKC) were grouped as refractory. Patients with refractory VKC were further sub-grouped based on the duration and/ or use of topical steroid or immunomodulator, (C) those who were on topical steroid/immunomodulator <8 weeks; (D) those without steroid or immunomodulator, who presented as fresh case with a repeat episode; (E) those who were on steroid/immunomodulator > 8 weeks. A duration of 8 weeks was considered so that the maximum effect of topical immunomodulator could be assessed. All cases had active VKC at recruitment and were advised to defer use of any topical on the day of collection. Non refractory and fresh refractory cases (group D) were only on lubricants at presentation whereas refractory (groups C and E) were on dual acting mast cell stabilizer (Olopatadine 0.2% w/v, Alcon Laboratories, India) in addition to lubricants and topical steroid / immunomodulator (Fluoromethalone 0.1% w/v, Allergan India Private Limited/ Tacrolimus ointment 0.03% w/w, Aurolab, India).