Evaluation Of Meibomian Gland Structure And Function In Patients With Vernal Keratoconjunctivitis (Vkc) Using A Combination Of Non Contact Meibography And Lipid Layer Interferometry

VKC however  remains a relatively unexplored entity in terms of its impact on the meibomian glands (MG’s)and contribution of these effects to dry eye disease (DED) seen in these children. The purpose of this study was to evaluate  the structural and functional impact of VKC on MG’s using the Lipiview II

(Tear Science Inc., Morrisville, N.C.) which uses a   combination of non contact meibography to image the MG’s and lipid layer interferometry to measure lipid layer thickness(LLT) .

Prospective , observational , comparative  study conducted at the Cornea and Refractive Services of a tertiary care institute comprising 50 VKC patients and 50 age matched controls. One eye per subject was evaluated using random number tables. Controls included patients visiting the outpatient services for refraction.

Inclusion criteria for VKC patients (i) age >8 yrs-<20 years (ii)  moderate persistent (grade 2B) and severe (grade3) VKC (Bonini’s classification) Exclusion criteria: use of systemic or topical drugs affecting MG function e.g. doxycycline in past 3 months. All subjects underwent ophthalmological evaluation in the following sequence: (i) Lipiview imaging for LLT and meibography (ii) dry eye evaluation comprising tear break up time (TBUT), ocular surface staining(OSS), Schirmer I scoring and meiboscoring (expressibility and quality of meibum secreted). Image J software was used to assess MG dropout in both lids. MG morphology was categorized by 2 independent observers as tortuous, hooked, ghost, thickened , fluffy or abnormal gaps.

MG loss (meibograde), OSS score, and meiboscore was higher in cases ( 2.68 ± 0.96 , 0.580 ± 1.07 and 0.56 ± 0.95 respectively) than controls (1.80 ± 0.67, 0.00 ± 0.00 , 0.22 ± 0.47 respectively)(p<0.001, 0.001 , 0.025). LLT, total blinking and TBUT was lower in cases (54.58 ± 9.43 nm, 5.64 ± 3.83 and 4.92 ± 3.09 sec respectively) than controls ( 70.14 ± 22.50nm, 7.84 ± 4.80 and 12.02 ± 2.73 sec respectively) (p =0.001, 0.013, 0.001). Both groups had comparable Schirmer I scores. Ghost glands and fluffy areas were more frequent in cases versus controls.

Children with moderate persistent and severe VKC suffer from DED which is primarily evaporative in nature, associated with a thinner lipid layer and increased ocular surface staining  indicating ocular surface damage. Significant MG dropouts, changes in gland morphology and deterioration in quality of meibum secreted is also present. VKC patients  are thus  prone to a vicious cycle of inflammation both due to the disease itself as well as to the dry eye which develops consequent to deterioration in MG structure and function. Co-management of DED and MD dysfunction warrants as much attention as the allergic component itself .