Histopathological changes in involutional lower eyelid entropion: the tarsus is thickened!

OBJECTIVE: Evaluation of histopathological changes in lower eyelid involutional entropion.

DESIGN: Case-control, comparative study at a single institution.

PARTICIPANTS: A total of 20 consecutive patients with previously untreated involutional lower eyelid entropion and 20 matching patients with lateral lower eyelid basal cell carcinoma (BCC).

METHODS: Patients with involutional entropion were operated using our modified surgical method, and patients with BCC underwent full-thickness pentagonal excision with 3-mm surgical margins. Histopathological analysis of the full-thickness eyelid specimens of both groups included measurements of tarsal thickness and height, thickness of the pretarsal orbicularis oculi muscle, diameter of muscle fibres, and qualitative changes in lower eyelid retractor attachment.

RESULTS: The tarsus was significantly thicker in the entropion group (p = 0.006). The mean tarsal thickness was 1.40 ± 0.32 mm, whereas in the BCC group it was 1.16 ± 0.19 mm. There was no statistically significant difference in the tarsal height and the thickness of the pretarsal orbicularis oculi muscle between the 2 groups. In the entropion group, 60% of the lids had total and 35% partial dehiscence of the retractor, whereas in the BCC group, dehiscence was found in only 45% of the lids. The difference was statistically significant (p = 0.002).

CONCLUSIONS: To the best of our knowledge, this is the first histopathological study documenting thickening of the tarsus in involutional lower eyelid entropion. Moreover, dehiscence of the lower eyelid retractor was proven histopathologically in 95% of the entropic lids. With this in mind, correction of vertical instability should be mandatory in involutional lower eyelid entropion repair.