Discussion
In the present study, we demonstrated that multiple chalazia that need surgical treatment were prevalent in Chinese young children. The mean number of lesions per person was 8.3. Bilateral chalazia and internal chalazion were most common, external chalazion occurred in more than half of the patients, and marginal chalazion was relatively rare. In addition, the abundance of internal chalazia in upper lids was higher than that in lower lids, whereas the abundance of external chalazia was similar in each eyelid.
Nemet et al demonstrated a high incidence of chalazion in people from urban areas and in females aged from 10 to 29 years.19 Chen et al found that the proportion of multiple chalazia was significantly higher in younger children (6 months to 6 years of age) compared with older children (7–12 years of age).5 Wagner mentioned that children with multiple and bilateral chalazia were often between 3 and 5 years old.4 In our study, multiple chalazia were more common in children aged 1–3 years than in those aged 3–7 years; however, the number of multiple chalazia did not differ by gender, age category or residence groups. The reason that multiple chalazia were more prevalent in younger children than in older children may be due to decreased serum vitamin A in the younger group, and the consequent keratinization of the ducts of the meibomian glands.5
The anatomical distribution of internal chalazia correlates with the characteristics of meibomian glands. Shirakawa et al studied the meibography of Japanese children (aged 1 month to 12 years) and found the numbers of meibomian glands in the upper and lower tarsal plates were approximately 26.9 and 22.0, with no statistically significant difference.20 However, the upper lid had much denser, thinner, and longer meibomian glands,20 21 which were supposed to be the main anatomical traits responsible for the higher numbers of internal chalazia in upper eyelids. Our study showed that bilateral upper lids presented 1.4 times more internal lesions than the lower lids.
Compared with internal chalazia, the proportions of patients with external and marginal chalazia were lower (99.2% vs 61.7% and 2.3%), the number of external lesions per patient was smaller (7.4 vs 1.0), and the anatomical distribution of external type showed no difference between the lids (p<0.001 vs p=0.581). Little information is available on the precise number of Zeis glands. However, given the Zeis gland opens into eyelash follicles and that there are more upper eyelashes than lower eyelashes,22 we speculated that more Zeis glands should be present in the upper lids although we did not demonstrate a higher proportion of external chalazia in the upper lids. The anatomical distribution of external or marginal chalazia totally differs from that of internal lesions. There could be three possible reasons: (1) Compared with the meibomian gland, the Zeis gland is less likely to be plugged due to its shorter duct;23 (2) The sebum secreted by the Zeis gland can inhibit bacterial growth,24 which may play a role in chalazion formation;25 26 and (3) It would be more difficult for a lump from blocked Zeis gland to penetrate through skin than one from blocked meibomian gland to penetrate through conjunctiva because skin is thicker and stronger than conjunctiva. Besides, though a chalazion from meibomian gland could grow big enough to be external, it would more likely extend towards conjunctiva than towards skin because conjunctiva is closer to tarsus and softer than skin.
To our knowledge, the relationship between internal and external chalazion has not been reported previously. Sometimes an external chalazion comes from a growing internal chalazion that penetrates the tarsus and appears superficial on the skin. This can be proven by a hole running through the tarsal plate after the removal of a chalazion. However, our study showed no relationship between these two types of chalazia for each lid, which could indicate that the formation of internal and external chalazion is relatively independent.
Sometimes, doctors may only focus on the eyelid with external nodule or big internal lump that is especially conspicuous when the patient closes his eyes and may overlook the other eyelids that appear to be normal. Though doctors should evert each eyelid for examination during I&C, we still may find hidden internal chalazion in a seemingly normal eyelid that patients or primary care providers have not noticed. The present study highlights the facts that children are susceptible to multiple chalazia and that the nodules tend to grow bilaterally and internally. It should be emphasized that during I&C, especially in young children, an examination of both eyelids, especially the upper lids, should be conducted to detect any internal chalazion.
Our study was the first to describe the detailed anatomical distribution of multiple chalazia in Chinese children. The strength of the study lies in a large sample size focusing on chalazion distribution in young pediatrics whose eyes are difficult to be examined, and our results highlight the importance of examining every eyelid even if it seems to be normal. However, there are some limitations: (1) All the patients in our study came from one hospital in southeast China, and they all underwent I&C operations. Thus, the patients who did not receive surgery under general anesthesia were not included; (2) The subjects included in the present study were all preschoolers because cooperative old children might receive operations in the outpatient clinic; (3) Patients with two or more external chalazia on one lid were quite rare in our study, possibly because parents would opt for early treatment due to cosmesis as soon as they developed external lesions. For the external chalazion, the parents have two extreme attitudes: some people are eager for surgery because the growing external chalazion may cause more significant scar on the lid, while the others believe that spontaneous resolution with conservative management may leave smaller scar than surgical excision; (4) We did not assess the localization of chalazion in the eyelid, such as medial, central or lateral, because the classification is complex if the nodules are large or are adjacent to each other. However, this information is valuable because medial chalazion might lead to canaliculitis, which requires more complicated medical and surgical treatments or even destroys the structure of puncta or lacrimal canaliculi; (5) We did not collect the follow-up results, which would give us recurrence information. In the future, a multicentered study with a longer observation time and better definition of localization would help us learn more about the distribution of multiple chalazia.
In conclusion, among the children who needed I&C, multiple chalazia were more common in patients aged 1–3 years. Different types of chalazion presented different distributional characteristics. Multiple chalazia often occurred bilaterally and internally. Internal lesions were more abundant in the upper eyelids. There was no correlation between the distributions of internal and external chalazia. Our study provides a deeper understanding of the anatomical distribution of multiple chalazia in young pediatrics that need I&C. We would like to reinforce the importance of checking every eyelid, especially the upper lids in a young patient with chalazion, because the nodules tend to grow and multiply internally, therefore requiring careful examination in this age group.