Morphological and Functional Changes of Meibomian Glands in Pediatric and Adult Patients with Allergic Conjunctivitis

Abstract

Allergic conjunctivitis (AC) is one of the most common ocular disorders in clinical practice and is associated with meibomian gland dysfunction. This study aimed to explore the morphological and functional changes of meibomian glands (MGs) in pediatric and adult patients with AC and to analyze their potential predictors. In our prospective, observational cohort study, a total of 59 patients with AC were enrolled, with 30 patients aged ≤16 years in the pediatric group and 29 patients in the adult group. All patients underwent examinations at baseline and last visit when the complete resolution of conjunctival papillae was identified. An automatic MG analyzer was used to measure the morphological and functional parameters of MGs, including their area ratio (GA), tortuosity index (TI), and signal index (SI). Two groups were comparable at baseline in terms of characteristics and MG parameters (p > 0.05). The morphological (length, square, and GA) and functional MG parameters (SI) of AC patients significantly improved in the pediatric group after treatment (all p < 0.05), but not in the adult group. The change in the GA correlated with age, sex, GA, TI, and SI at baseline (all p < 0.05). Age (p = 0.001) and GA (p < 0.001) at baseline were predictors of an improvement in the GA of MGs. The findings showed that the structure and function of MGs in pediatric patients with AC seem to improve after the conjunctival papillae disappear, but not in adult patients.

Keywords: allergic conjunctivitis; child; dry eye; meibomian glands; tear film.

Figure 1

The morphological changes in meibomian glands between baseline (upper) and last visit (lower). In this study, we chose the same area (a center on the gland of the most significant change, including its left and right three glands) in the original grayscale meibography image for examination to the best of our abilities (A,B, green outline). The automatic process of reduced random noises, enhanced contrast, and visibility images (C,D), and automatic generation of the binarized and binary inverted mask image (E,F). Removal of the tarsal conjunctival area and segmentation of each gland manually (G,H). Selection of intended analysis meibomian glands (I,J).

Figure 2

Comparison of meibomian glands morphological parameters between baseline and last visit. Representative images of MGs structural changes (A–D). Meibography images showed the same upper eyelid of MGs of a 12-year-old patient with AC: (A) at baseline (meiboscore = 1) and (B) after 22-day treatment (meiboscore = 0). Meibography images showed the same upper eyelid of MGs of a 31-year-old patient with AC, (C) at baseline (meiboscore = 1), and (D) after 4-month treatment (meiboscore = 1). Note that more significant morphological improvements (white arrow) were observed in pediatric AC patients than in adult AC patients. Diameter, length, square, TI, and GA of pediatric and adult AC patients between baseline and last visit (E–I). Length, square, and GA were increased significantly at the last visit in pediatric AC patients (F,G,I), whereas no significant change was observed in the adult group. AC, allergic conjunctivitis; TI, tortuosity index; GA, glands area ratio; MGs, meibomian glands. Bars represent mean ± SD. ** p < 0.01, *** p < 0.001. The paired Wilcoxon signed-rank test.

Figure 3

Comparison of meibomian glands functional parameters between baseline and last visit in AC patients. Representative images of functional changes in MGs (A–D). Meibography images showed the same upper eyelid of MGs of a 5-year-old patient with AC: (A) at baseline (SI = 3.23) and (B) after 48 days at the last visit (SI = 6.74). Meibography images showed the same upper eyelid of MG of a 54-year-old patient with AC: (C) at baseline (SI = 5.84) and (D) after 66 days at the last visit (SI =8.07). Note that the clearer and more distinguishable gland figures were observed in the pediatric patients than in adult patients. There was a significant increase in SI at the last visit in pediatric AC patients (G), whereas no significant change was observed in adult AC patients (E,F,G). AC, allergic conjunctivitis; MGs, meibomian glands; SI, signal index; NIBUT-1st, the first time of noninvasive keratograph tear film breakup; NIBUT-avg, the mean time of noninvasive keratograph tear film breakup. Bars represent mean ± SD. * p < 0.05. The paired Wilcoxon signed-rank test.

Figure 4

Scatterplots for the correlations between age (A), GA at baseline (B), SI at baseline (C), and the percentage change in GA. Age, GA at baseline, and SI at baseline were significantly correlated with the percentage change in GA (p < 0.001, p < 0.01, and p < 0.05, respectively). The Spearman coefficients were rAge: −0.54, rGA: −0.35. rSI: −0.38. Percentage change in GA (%) (GA at last visit − GA at baseline)/GA at baseline × 100; GA, glands area ratio; SI, signal tortuosity index.