Lower Eyelid Position Changes Following Müller’s Muscle-Conjunctival Resection Blepharoptosis Surgery

Abstract

Background

Asymmetry of the lower eyelids and a lower position of the lower eyelid on the ptotic side are common issues in patients with upper lid ptosis. Understanding the relationship between upper lid ptosis correction and lower eyelid position will facilitate better treatment strategies for ptosis.

Objectives

The aim of this study was to assess the lower eyelid position before and after Müller’s muscle-conjunctival resection (MMCR) in unilateral myogenic ptosis (MP) and aponeurotic ptosis (AP).

Methods

This prospective interventional before-and-after study included adults with blepharoptosis. Measurements were taken before and 6 months after the surgery.

Results

A total of 47 patients were included, with 29 having MP and 18 having AP. The mean [standard deviation] ages were 31.55 [5.30] years and 50.11 [6.45] years, respectively. In the MP group, there was a significant association between baseline margin reflex distance 2 (MRD2) and the severity of ptosis (MRD1) (β = −0.739, P = .004, multivariate regression analysis). After MMCR, significant decreases were observed in MRD2 for both the MP (−0.38 [0.48] mm, P < .001) and AP (−0.39 [0.47] mm, P = .003) groups. The symmetry of MRD2 remained stable at 41.4% in the MP group, while it decreased from 44.4% to 16.7% in the AP group. The baseline MRD2 was the only factor associated with postoperative MRD2 in the MP group.

Conclusions

Patients with MP and AP often exhibit a lower position of the lower eyelid, which typically elevates after posterior upper lid ptosis surgery. In myogenic cases, the severity of preoperative lower eyelid position correlates with the severity of upper lid ptosis and predicts postoperative elevation of the lower lid.

Level of Evidence: 3

Blepharoptosis (ptosis) is a prevalent condition frequently encountered in ophthalmology and oculoplastic clinics.¹ Although it may be primarily a cosmetic issue, it can also cause functional problems such as amblyopia, refractive error, and visual field defects, significantly impacting an individual’s quality of life.^2-4

Margin reflex distance 1 and 2 (MRD1 and MRD2) have traditionally served to quantify the positions of the upper and lower eyelids and assess eyelid ptosis.⁵ They reflect the distance between the upper and lower lid margins and the corneal light reflex, generated when the corneas are illuminated and light is reflected from them.⁵ The sum of MRD1 and MRD2 corresponds to the palpebral fissure height. A decrease in MRD1 signals upper eyelid ptosis (Figure 1). Normally, the lower and upper margins of the cornea are covered by the eyelids, and the appearance of the sclera below the cornea (inferior scleral show) indicates increased MRD2.⁶

Among the various causes of ptosis, the 2 primary types are myogenic ptosis (MP) and aponeurotic ptosis (AP).⁴ MP arises from dysfunction or weakness of the muscles responsible for elevating the eyelid, mainly the levator palpebrae superioris.⁷ In contrast, AP stems from structural changes in the levator aponeurosis, the connective tissue structure that supports eyelid elevation.⁸ It is frequently age-related, occurring due to degenerative changes in the eyelid tissues over time.⁹ Measuring levator function, assessing eyelid crease height, and evaluating eyelid symmetry aid in distinguishing MP from AP.⁸ Several surgical options are available to correct ptosis, including Müller’s muscle-conjunctival resection (MMCR), levator advancement and resection surgery, and sling surgery. The choice of procedure depends on the severity of the ptosis, the function of the levator muscle, and the surgeon’s personal preference. MMCR was first described by Putterman and Urist in 1975 and has gained popularity among surgeons.¹⁰ The surgery involves excising a tissue flap containing conjunctiva, Müller’s muscle, and some levator aponeurosis fibers. Although some modifications to the technique have been proposed, such as using a single horizontal mattress suture or tissue glue, the overall outcomes appear to be similar across different variations of the surgery.^11-13

Upper blepharoptosis can lead to alterations in the lower eyelid position, which can occur in both congenital and aponeurotic subtypes.^4,14-21 This phenomenon, known as dynamic scleral show, is a common concern for patients considering blepharoptosis repair.¹⁸ During preoperative counseling, it is important to assess whether the dynamic scleral show requires repair and inform the patient accordingly.¹⁸

Previous studies have noted that upper blepharoptosis surgery can change the position of the lower eyelid. This has been reported for MMCR,¹⁴ levator resection,^4,16,21 and sling surgery.¹⁶ However, no research has identified the specific factors determining lower eyelid position changes and symmetry following MMCR ptosis surgery. Furthermore, there is a lack of research comparing outcomes between AP and MP after MMCR. Therefore, the purpose of this study was to compare the lower eyelid position in patients with AP and MP pre- and post-MMCR surgery, analyze the factors influencing these changes, and evaluate the rate of postoperative lower eyelid symmetry.

METHODS

Study Design

This was a prospective analysis of patients with upper eyelid ptosis who were referred to an oculoplastic clinic between April 2021 and October 2022. The study design was approved by the Institutional Ethics Committee of Tehran University of Medical Sciences and conducted according to the latest version of the Declaration of Helsinki. Informed consent was obtained from all of the patients. Patients were included if they were over the age of 18 years, with an MRD1 of >1 mm lower than the normal side and levator function of >5 mm, and underwent unilateral MMCR surgery for MP or AP in isolation from blepharoplasty or other surgeries. Patients with good levator function, a high eyelid crease, and a history compatible with onset of ptosis at an older age are considered to have AP. However, patients with lower levator function, a fair eyelid crease, lag in downgaze, and congenital onset were included in the MP group. Patients were excluded if they had any history of eyelid or brow surgery, previous trauma, third nerve palsy, strabismus, extraocular myopathy, or thyroid eye disease.

Surgical Technique

MMCR with intraoperative adjustment was performed for all patients. The desired crease was marked through the skin. Local anesthesia with lidocaine 2% + adrenaline 1/200,000 was injected, with 0.3 mL administered to the lid margin and 0.7 mL to the palpebral subconjunctiva. The upper lid was everted and fixed by means of 4-0 silk and a Desmarres retractor, and an incision was made just superior to the upper edge of the tarsus, transconjunctivally. The next step involved precise dissection of the conjunctiva and Muller’s muscle from the aponeurosis. Depending on the required correction for ptosis, dissection could be continued. To correct a 2-mm ptosis, approximately 8 to 10 mm of the flap needed to be resected. Once enough dissection had been performed centrally, medially, and laterally, sutures were added. Similar to the anterior approach, 3 double-armed 5-0 Vicryl sutures were used. The path of the suture was through the conjunctiva, then Muller’s muscle, then the upper edge of the tarsus, and finally exiting from the skin on the marked crease. Two arms of the suture in the same path were passed, and with butterfly-shaped tying, the height and curve could be checked, and, if needed, the sutures could be adjusted. After achieving a good result, the excess part of the conjunctiva-Muller flap was cut. Patients were advised to apply cold packs to the eyelid for the initial 3 days postsurgery for 30 minutes separated by 2-hour breaks. Antibiotic and steroid eye drops twice daily for 1 week and artificial tear drops every 4 hours for 1 month were prescribed. Postoperative examinations were typically scheduled for the first day, 2 weeks (to monitor the healing process), and the final follow-up, which occurred at least 6 months after the procedure.

Outcomes Measure

The data before surgery and at least 6 months after surgery that were retrieved by 1 experienced oculoplastic surgeon (S.M.R.) included diagnosis (MP or AP), MRD1, MRD2, levator function, and amount of MMCR. All operations were performed by a single surgeon. MRD1 and MRD2 were assessed in person using the same method and assessor for all participants. When the patient fixated on the light source in the primary position, the distance between the upper and lower eyelid margins and the corneal reflex was measured using a millimeter ruler adjacent to the eyelids (Figure 1). To assess levator function, the upper eyelid excursion was measured by pressing over the patient’s eyebrow to negate the influence of the frontalis muscle, while observing the movement from extreme downgaze to upgaze. The primary outcome of the study was to compare the lower eyelid position before and after surgery, and to identify factors that influenced these changes. The secondary outcome was to evaluate the rate of postoperative lower eyelid symmetry in both patient groups. Eyelid symmetry was defined as having the same MRD2 measurement on both lower eyelids, with the ratio of MRD2 on the ptotic side to MRD2 on the nonptotic side equal to 1.⁴

Statistical Analysis

Statistical analysis was conducted with IBM SPSS Statistics (version 27). The following statistical tests were employed for data analysis: the Mann-Whitney U-test for continuous variables; the χ² test for categorical variables; the Wilcoxon rank test for comparing preoperative and postoperative continuous variables; the Spearman correlation for examining the relationship between preoperative MRD2 and MRD1, levator function, and age; a binary logistic regression model for identifying factors influencing the change in MRD2; and a linear regression model for determining factors influencing the preoperative MRD2 and the postoperative change in MRD2. P < .05 was considered statistically significant.

RESULTS

The study included 47 subjects, 42 females and 5 males, with a mean [standard deviation] age of 38.66 [10.75] years (range, 21-62 years), consisting of 29 with MP and 18 with AP. The 2 groups did not show significant differences, except for a lower mean age and levator function observed in the MP group (Table 1). Additionally, the measurements of MRD2 for both eyes were higher in the MP group than in the AP group (Table 1). However, there was no significant difference in the MRD2 ratio between the ptotic eye and the nonptotic eye for the 2 groups. Detailed patient demographics and clinical findings for both groups are provided in Table 1. Preoperatively, 41.4% (12/29) of the MP patients (Figures 2, 3) and 44.4% (8/18) of the AP patients exhibited symmetric MRD2 values (Figure 4).

Multivariate regression analysis showed that the preoperative MRD2 of the ptotic side was significantly correlated with the preoperative MRD1 (β = −0.494, P = .008) of the ptotic side and was not significant for the age, levator function, and MRD1 and MRD2 of the nonptotic side (0.1 < P < .7). Subgroup analysis showed such a significant correlation with MRD1 only on the MP group (β = −0.739, P = .004) but not in the AP group (P = .510).

Table 2 presents the changes in MRD1 and MRD2 between pre- and postoperative visits. Both the MP and AP groups exhibited a significant reduction in MRD2, indicating a decrease in scleral show, with mean changes of 0.38 [0.48] mm (P < .001) and 0.39 [0.47] mm (P = .003), respectively. There was no significant difference in the mean changes between the MP and AP groups (P = .947). Furthermore, the MRD2 ratio of ptotic eye to nonptotic eye, which serves as an indicator of symmetry, demonstrated a significant decrease from 1.01 [0.92] to 0.93 [0.10] postoperatively (P < .001). This decrease was observed for both the MP group (0.07 [0.08], P < .001) and the AP group (0.10 [0.11], P = .001) (Figures 2-4).

The lower eyelid position did not show any change in 34.4% (10/29) of patients in the MP group (Figure 5) and in 38.5% (5/17) in the AP group postoperatively (Figure 6). Multivariate regression analysis of patients with and without postoperative changes in the MRD2 indicated that among patients in the MP group, only the preoperative MRD2 showed a significant association with postoperative changes in the MRD2 (β = 7.80, P = .028). However, this significant association was not observed in the AP group (Table 3, Supplemental Tables 1, 2). None of the patients had complications in follow-ups.

DISCUSSION

Humans, along with certain other species, tend to find symmetric patterns more appealing than asymmetric ones. These preferences likely stem from biological signals.²² Symmetry in the periocular region and eyelids is a fundamental aspect of facial aesthetics, influencing our perception of beauty and attractiveness.²³ The presence of unilateral blepharoptosis, which creates asymmetry, significantly impacts facial aesthetics negatively. Correcting this condition through oculoplastic procedures is a common practice.

Traditionally, in assessing and correcting ptosis, the focus has primarily been on upper eyelid measurements, especially the central height of the upper lid evaluated by the MRD1, as well as other upper eyelid characteristics such as contour, notches, and peak. However, recent studies have suggested that beyond upper eyelid parameters, changes in the position of the lower lid and its indicator, MRD2, may also occur in cases of both upper lid MP^4,16 and AP,^4,21 which are the most prevalent primary types of ptosis, and play a role in contributing to asymmetry in ptotic patients. Hence, there is a connection between upper eyelid ptosis and lower eyelid position. In this study, which evaluated 47 adults with unilateral MP and AP, we also found that the MRD2 was higher (more inferior lower lid and more inferior scleral show) on the ptotic side than on the nonptotic side. Similarly, in 6 previous reports,^{4,16,18,20,21,24} the lower lid position tended to move downward more on the ptotic side (associated with higher MRD2), while 2 reports^14,19 contradicted this finding.

Kim et al observed higher inferior scleral show on the ptotic side in patients with congenital ptosis, suggesting a mechanical effect of upper eyelid lift during ptosis surgery as a possible mechanism.¹⁶ Matsuo et al proposed that disinsertion (in AP) or weakening (in MP) of the levator muscle could result in an extra contraction, leading to dynamic lower scleral show.¹⁸ Teo et al suggested that reduced superior visual field in ptosis eyes may drive compensatory contraction of the inferior rectus, resulting in increased scleral show.²⁰

Contrarily, Tenzel et al found a lower MRD2 on the ptotic side in children with unilateral congenital ptosis.¹⁹ They attributed this to possible maldevelopment of both upper and lower eyelid retractors. These conflicting results could be influenced by differences in study population characteristics and measurement techniques. Moreover, these mechanisms may be operative at the same time. Regardless of the cause of this change, the lower eyelid position (MRD2) and its asymmetry should be further reviewed, documented, and considered during preoperative consultation for ptosis correction procedures.

Following the identification of asymmetry in lower lid position in upper lid ptosis, assessing predictors of this asymmetry becomes significant. This study showed the only predictor of the preoperative MRD2 is preoperative MRD1 (β = −0.494, P = .008) of the ptotic side and such a significant correlation was present only in the MP group (β = −0.739, P = .004) but not in the AP group (P = .510). This finding was similar to those of previous studies in which the amount of ptosis is correlated with the higher MRD2 (higher inferior scleral show and lower position of the lower lid) only in MP.^4,19

The next question that arises is how ptosis correction surgeries and change in the MRD1 affect the asymmetry in lower lid position and MRD2. Only 4 previous studies have investigated the impact of ptosis correction on the lower lid position.^4,14,16,21 Kashkouli et al conducted a study involving 78 patients who underwent anterior levator surgery for upper eyelid ptosis.⁴ They found that 56.8% of MP and 80% of AP patients exhibited lower scleral show (high MRD2). Following the surgery, both groups showed a significant improvement in MRD2, resulting in a symmetric MRD2 in 91.4% of the MP group and 80% of the AP group.⁴

Similarly, Kim et al evaluated pediatric congenital ptosis patients who underwent frontalis sling surgery with autogenous fascia, demonstrating a significant decrease in MRD2 show postoperatively.¹⁶ Eshraghi et al also observed improvement in MRD2 after anterior levator resection in congenital and acquired ptosis cases.²¹ Zloto et al conducted a study involving 69 patients who underwent MMCR.¹⁴ The preoperative mean MRD2 was 4.16 mm, which increased to 4.67 mm 3 months after surgery (P < .01). In our study, 6 months after modified MMCR, both the MP and AP groups showed a decrease in MRD2, with reductions of 0.38 mm and 0.39 mm, respectively.

The discrepancy with Zloto et al’s study, which utilized a classic MMCR procedure, could be attributed to the different follow-up periods and surgical techniques. In our modified MMCR, the superior edge of the resected Muller muscle-conjunctiva was connected to the anterior lamella using sutures, bypassing the levator fibers. This created an indirect tucking and advancing effect on the levator muscle, making the mechanism of action more similar to the anterior levator surgeries performed in the studies by Kashkouli et al and Eshraghi et al.^4,21 The retrospective nature of Zloto et al’s study,¹⁴ population characteristics, and measurement technique (photograph-based measurements vs our clinical measurements) may also contribute to these contradictory results.

Nevertheless, it is crucial to acknowledge that various anterior and posterior ptosis correction surgeries can impact lower lid position, necessitating consideration and discussion during preoperative consultations for ptosis surgery.

No study examined the factors influencing the severity of preoperative higher MRD2 and lower scleral show, factors predicting the improvement in the MRD2 after surgery, and the rate of postoperative symmetric lower eyelids following posterior ptosis correction. These were the main objectives of our study.

We observed that a higher degree of preoperative MRD2 was a significant predictor of postoperative MRD2 decrease in the MP group. The lack of significant correlations in the AP group may be attributed to the relatively better levator function, and the smaller sample size in this group.

Among previous reports, only Kashkouli et al evaluated postoperative symmetry and found a significant improvement in lower lid position after anterior levator surgery, resulting in an increase in the symmetry of MRD2 (MRD2 ratio of ptotic/nonptotic = 1) from 39.7% to 91.4% in patients with MP and from 20% to 80% in patients with AP.⁴ However, in our study, we evaluated this factor and found that despite a significant decrease in postoperative MRD2 (as in Kashkouli et al's study), the symmetry of MRD2 remained stable at 41.4% in the MP group and decreased from 44.4% to 16.7% in the AP group. This finding can be interpreted in conjunction with another finding of our study, which showed that the preoperative MRD1 is a predictor of the preoperative MRD2, which is itself a predictor of the postoperative MRD2. Mild ptosis, as observed in our study with a mean of 2.35 mm, which has higher MRD1 values, may result in lower preoperative MRD2 (upper position of lower lid and lower amount of asymmetry) and consequently lower postoperative MRD2. In Kashkouli et al’s study, the preoperative MRD1 was 0.5 mm, indicating higher preoperative MRD2 and higher postoperative MRD2.⁴ This finding highlights the potential asymmetry of the lower eyelid, specifically in patients with mild ptosis who do not exhibit a decreased preoperative MRD2, which can result in asymmetric postoperative outcomes (lower MRD2 compared to the normal eye). This consideration should be taken into account in ptosis management.

The limitations of this study include its small sample size, particularly in the AP group. Additionally, the study had a relatively short-term follow-up period. Conducting similar studies with larger sample sizes and longer follow-up durations would provide a more accurate assessment of changes.

CONCLUSIONS

A significant number of patients with unilateral myogenic and aponeurotic upper lid ptosis exhibited a lower position of the lower lid, more inferior scleral show, and lower lid asymmetry, which decreased significantly after posterior ptosis surgery. For MP cases, the severity of preoperative lower lid position correlated with ptosis severity and predicted postoperative improvement in inferior scleral show. This suggests that the greater the droopiness of the upper eyelid, the lower the position of the lower eyelid, and consequently, the greater the change in the lower lid position after ptosis surgery. However, for AP cases, no significant predictors for lower lid position improvement were found. Additionally, AP cases exhibited decreased lower lid symmetry after upper lid ptosis surgery, emphasizing the need for tailored preoperative documentation, counseling, and management strategies.

Supplemental Material

This article contains supplemental material located online at www.aestheticsurgeryjournal.com.

Disclosures

The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article.

Funding

The authors received no financial support for the research, authorship, and publication of this article.

REFERENCES

Author notes