Microscopic and Ultrastructural Changes of Müller’s Muscle in Patients With Simple Congenital Ptosis

Advances in the genetics of congenital ptosis

Congenital ptosis, a birth defects presents at birth or by 1 year of age, is characterized by the drooping of the upper eyelid. either in isolation (non-syndromic) or with many different systemic disorders (syndromic). The estimated prevalence of ptosis (congenital & acquired) ranges from 0.79 to 1.99 per 10,000 people in different populations, and it is more prevalent in males. The underlying pathogenesis of congenital ptosis are myogenic and neurogenic, related to the development of muscles and nerves. Although most cases are sporadic, there are familial transmission characteristics, including autosomal dominant, recessive mode and X-linkage inheritance patterns. Moreover, some forms are due to chromosomal aberrations and mutations and deletions in mitochondrial DNA. Genes involved in simple congenital ptosis are ZFHX4 and COL25A1. The clinical aspects of various syndromes involving congenital ptosis are partly caused by single gene mutations. However, the pathogenesis of congenital ptosis is not fully understood. We review the reported epidemiology, genetics and clinical features of congenital ptosis and associated syndromes here.

Surgical Observations of the Levator Aponeurosis Fibrotic Changes in Simple Congenital Ptosis Suggest Complex Pathogenesis

PURPOSE

To shed light upon the possible role of the levator aponeurosis (LA) developmental fibrotic changes as an added etiology for simple congenital ptosis, which causes limitation of the levator function (LF).

METHODS

This retrospective cohort study included patients with simple congenital ptosis who underwent skin approach LA resection as a primary intervention with an intraoperative photographic documentation of LA fibrotic changes. Preoperative demographics and clinical data were reviewed. The effect of LA fibrotic changes on the LF was assessed in different LA fibrotic changes with or without levator palpebrae superioris (LPS) muscle fatty infiltration.

RESULTS

A total of 56 eyelids of 49 patients with a mean age (±SD) 6.7 (±3.2) years were enrolled in this study. The fibrotic changes of LA were observed as a sheet of fibrosis (19 eyelids) or fibrous bands (23 eyelids). Fatty infiltration of LPS was noticed in 28 eyelids, either with or without fibrotic changes of LA. Preoperative LF was diminished in LPS fatty infiltration compared with LA fibrotic sheets (P = 0.026). Postoperative LF improved significantly in both LA fibrotic sheets and LA fibrotic bands (9.4 ± 2.5 mm and 9.6 ± 2.8 mm, respectively) compared with LPS with fatty infiltration (6.4 ± 1.8 mm) (P = 0.004).

CONCLUSIONS

Although our data are inconclusive due to lack of embryologic studies, the observed LA fibrotic changes may suggest a complex pathogenesis of simple congenital ptosis. The meticulous observation of the LA and the releasing of any adhesion or band to the surrounding structures could improve postoperative LF.

[The role of Muller's muscle in the occurrence and surgical treatment of the upper eyelid ptosis]

Muller's muscle of the upper eyelid (MM) remains a poorly understood anatomical structure, so its role in the emergence of upper eyelid ptosis provokes certain interest. This literature review examines the gradual rise of attention devoted to MM and describes existing methods of its surgical treatment. Despite progress in ptosis surgery, much remains unsolved. Taking into account the available literature data, it is necessary to further advance histological studying of MM, which will help develop pathogenetically founded surgical treatment of acquired upper eyelid ptosis.

[Fatty degeneration of upper tarsal muscle as etiological factor of acquired upper eyelid ptosis]

PURPOSE

To study the histological structure of the upper tarsal muscle (Müller's muscle of the upper eyelid) in patients with acquired ptosis and to confirm the presence of its fatty degeneration as an understudied etiological factor of upper eyelid ptosis.

MATERIAL AND METHODS

A retrospective analysis was performed covering 79 biopsy samples of Müller's muscle of the upper eyelid obtained intraoperatively. Histological examination was performed with samples prepared by waxing. Planning the surgery included determination of basic parameters and the 'transparency' symptom; the Müller's muscle projection area was examined in the inverted upper eyelid, and ultrasound biomicroscopy (UBM) of the upper eyelid structures was performed.

RESULTS

Among the study subjects, a group of 11 patients with isolated fatty infiltration of the upper tarsal muscle was identified. At the preoperative stage, in the group of patients with upper eyelid eversion, visibly thickened Müller's muscle advancing on the tarsus could be observed, as well as negative 'transparency' symptom; UBM showed thickened 'conjunctiva - Müller's muscle' complex, and a large number of hypoechogenic inclusions in the muscle in comparison with the intact eye. The removed muscle was thickened, yellow, with increased density and rigidity. Microsection of the histological preparations revealed fat cells located among bundles of smooth muscle fibers of the upper tarsal muscle and dispersion of smooth myocytes on the background of fat infiltration.

CONCLUSION

The presence of dystrophic changes in the upper tarsal muscle is proved with clinical, macromorphological and pathohistological methods; they can be one of the independent causes of acquired upper eyelid ptosis.

Timing of surgical correction for the treatment of unilateral congenital ptosis: Effects on cosmetic and functional results

The authors analyzed the cosmetic and functional results of a series of patients with unilateral congenital ptosis who underwent levator resection, to compare the outcome of surgery according to the age of intervention, and to evaluate the chance of ptosis recurrence in different age groups. Analysis of the clinical charts of 44 patients who underwent a unilateral levator muscle resection under the care of one surgeon from February 2000 to March 2012 was performed. Age at the time of surgery ranged from 2.1 to 12 years. The study population was divided into different groups according to the age of surgery. Preoperative evaluation included measurements of upper eyelid margin reflex distance (MRD1), levator function, frontalis function, and complete extraocular motility examination. This study adheres to the principles outlined in the Declaration of Helsinki. The patients' follow-up ranged between 2 and 12 years. The outcome of surgery was more satisfactory (MRD1 increase: p < 0.002) and the increase of levator function was better (p < 0.0001) when surgery was performed in children aged 2 to 4 years. No ptosis recurrence was observed in children aged 2 to 4 years, as opposed to 6 (22%) children of other groups (p = 0.067). Unilateral levator resection effectively reduces the asymmetry between eyelids. The age of the operation appears to influence the outcome of surgery, as in this series cosmetic and functional results are better and the rate of ptosis recurrence is lower if the child is operated on before the age of 4 years.

Proprioceptive Phenomenon With Involutional Ptosis: Evidential Findings in Anophthalmic Ptosis

PURPOSE

To determine the effect of ptosis on compensatory frontalis contraction in patients without visual input and to identify if a sensory stimulus contributes to brow elevation.

METHODS

A prospective study. Clinical photographs were measured by 2 masked oculoplastic surgeons to determine brow height in 8 patients with unilateral ocular prosthesis in 3 conditions: at baseline, after a gold weight was applied to the upper eyelid inducing acute ptosis, and with the gold weight plus topical anesthetic. The measured brow height was then compared between the 3 scenarios.

RESULTS

Mean brow height increased after application of the gold weight when compared with baseline, and this difference reached significance (p = 0.012). After topical anesthetic was applied, the mean brow height decreased but not back to baseline. When mean brow height during the gold weight with topical anesthesia was compared with baseline and with the gold weight only scenarios, the difference was not significant (p > 0.05).

CONCLUSIONS

Frontalis contraction is observed when acute ptosis is simulated in anophthalmic patients, confirming that a contracted visual field cannot be the only stimulus for compensatory brow elevation. A sensory or proprioceptive mechanism is suggested but not confirmed by the trend of reduction in brow elevation with topical anesthesia.