Over the years, several pathogenetic mechanisms have been proposed to explain the clinical manifestations of epiblepharon. The traditional view that epiblepharon simply occurs due to a “mechanical” push of the lashes against the cornea by a horizontal fold of extra skin²,³ has been questioned,⁴,⁵ and this challenge has recently been renewed.⁶ An alternative hypothesis suggests that the excess skin fold merely has a minor secondary etiopathogenic role and that the real culprit lies in the loss of attachment of the anterior layer of the lower eyelid retractors to the skin and tarsus.⁴,⁵,⁶ It has recently been confirmed that the lower lid retractors are composed of a definite double layer and not just one layer as was previously thought.⁷ The anterior layer emerges from the Lockwood ligament, fuses with the orbital septum, and terminates on the anterior surface of the tarsus, subcutaneous tissue, and skin up to the lid margin. Normally, this anterior insertion holds the pretarsal orbicularis and skin firmly against the tarsal plate, subsequently keeping the eyelashes in check in their normal horizontal position.⁵ Therefore, the loss of this anterior insertion not only loosens the attachment of the skin and the pretarsal orbicularis to the tarsus but more importantly it causes the eyelashes to assume a vertical orientation. The unchecked fold of skin and orbicularis further enhances epiblepharon by pushing the cilia more toward the globe. Although the presumed role of orbicularis muscle hypertrophy in epiblepharon pathogenesis has been dismissed recently,⁶ it is interesting to point out that epiblepharon is reduced by muscle relaxants that are used when the child is under general anesthesia,⁸ which argues against total dismissal of an aggravating role of the orbicularis muscle.

Epiblepharon, a disease with a strong East Asian predilection,³,⁹,¹⁰,¹¹ is characterized by the presence of a horizontal fold of skin of variable length that lies parallel to and partially overrides the lower eyelid margin (Figure 21.1). The eyelashes are either vertically oriented or inverted causing ciliocorneal touch, and frequently the latter is seen only in or more accentuated in downgaze (Figure 21.2). In its most typical form, this horizontal fold of skin usually assumes a tentlike appearance limited to the medial one-third of the eyelid with a downward and lateral slant.¹⁰ The more extensive the skin fold, the more the lower eyelid margin is concealed by the fold.¹² Epiblepharon is also associated with a faint or obliterated lower eyelid crease.

A classification system for epiblepharon based on the severity of keratopathy due to ciliocorneal touch where keratopathy is classified into four grades starting with grade 0, which shows no keratopathy, up to grade 3, where more than one-third of the cornea is involved, has been proposed.¹ However, it requires a slit lamp examination, which may not always be possible in younger children. An alternative classification system was designed to aid in clinical judgment and to lay the groundwork for proper management was proposed based on the horizontal extent of the skin fold and the degree of concealment of the lid margin.¹ In class I, the skin fold is
below the lower eyelid margin. In class II, the fold is at the level of the lower eyelid margin without concealing it. Class III is defined as the fold being above the level of the lower eyelid margin but concealing <one-third of the lid margin medially. The most severe case is class IV where the fold is above the level of the lower lid margin and conceals >one-third of the eyelid margin (Figure 21.3). We believe this classification system based on skin fold height is more clinically relevant and reportedly correlates well with the severity of ciliocorneal touch.¹ However, occasionally patients will be observed where the degree of ciliocorneal touch outweighs the skin fold grading.

Infants and young children may not express their symptoms well, and even in older children or adults, epiblepharon may be completely asymptomatic.⁹ In patients where there is significant ciliocorneal touch, photophobia, eye rubbing, and squeezing of the eyelids are frequent presenting symptoms. A more common, almost universal symptom is epiphora,⁹ but it is important not to overlook congenital nasolacrimal duct obstruction as a possible cause for tearing.¹³ Other less common symptoms only reported by older children include ocular pain and blurred vision.⁹

The natural history of epiblepharon is that most patients will spontaneously improve to the extent that by the time they reach high school, only 2% of children with untreated epiblepharon still have the condition,¹⁴ but it cannot be directly inferred from the literature the exact percentage of patients who will ultimately require surgery. Indirect evidence could be deduced from age-matched prevalence studies. A landmark study conducted on Japanese children between the ages of 1 and 18 years showed a progressive decline with advancing age (24% at 1 year, 20% at 2 years, 7% at the age of 5-6 years, and 2% at 13-18 years).⁹

An unusual finding in patients with epiblepharon is the high incidence of clinically significant astigmatism, which affects between 44% and 52% of patients. It is usually in the form of with-the-rule astigmatism typically over 1.0 D and may even end up with astigmatic amblyopia.¹⁰,¹⁵,¹⁶,¹⁷ The cause is unknown, but the most plausible explanation is that the change in corneal curvature is induced by a mechanical force created by the skin fold.¹⁷ An alternative hypothesis is that astigmatism is due to pressure on the cornea from chronic squeezing and compulsive rubbing of the eyelids, both being natural sequelae of chronic ocular irritation, a situation not unlike the induction of keratoconus by frequent eye rubbing.¹⁷ Another unusual association is the link to obesity where older children (6-15 years) with a higher body mass index have a higher incidence of symptomatic epiblepharon.¹⁸,¹⁹ One study found a female predilection,¹⁹ while another study did not find any sex predilection.¹⁸ The cause is unknown.