Introduction

The correction of drooping eyelids (blepharoptosis) is one of the most commonly performed procedures on the eyelid [1,2]. Blepharoptosis is not only a cosmetic problem, but primarily a medical one [2]. Drooping eyelids obstruct the visual field, can modify the shape of the ocular surface inducing refractive errors, and in children can be the cause of underdeveloped vision [3]. There are many surgical methods for the correction of blepharoptosis. Clinically, they can be divided into 3 groups: methods performed on the levator muscle of the upper eyelid via the skin, methods performed from the inside of the eyelid (from the conjunctiva), and methods whose essence is the suspension of the upper eyelid on the frontalis muscle [2–4]. Methods performed from the conjunctival side, in addition to the absence of a visible skin scar, have advantages over traditional transcutaneous methods in terms of shorter surgery and recovery time, a more natural shape of the upper eyelid crease after surgery, and a shorter learning curve for the surgeon [1–7]. Disadvantages include, according to some authors, limited efficacy in the correction of minor blepharoptosis (up to 3mm with at least good levator function (LF)) [4,8,9]. There are also ongoing discussions about the algorithms used to estimate the amount of eyelid lift after surgery, since the exact mechanism of action of transconjunctival blepharoptosis surgery is not fully elucidated [4,10–12]. Clinicians wonder about the role of LF, Muller’s muscle, as well as the tests of thein preoperative administration of phenylephrine eyedrops [13–15]. Among the numerous papers on both the topic and the increasingly widely used procedures, there is a lack of prospective comparative research focusing on updating the indications for this type of procedure [12,16,17].

This study aims to update current knowledge by prospectively analyzing how severity of ptosis, levator function, and phenylephrine response influence surgical outcomes. To our knowledge, this is the first and largest prospective study on this topic.

Materials and methods

Results

A total of 231 eyes (111 left and 120 right) were included in this study. Demographic data of the study group are presented in Table 1.

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Table 1. Baseline characteristics of the study group.

https://doi.org/10.1371/journal.pone.0343505.t001

MRD1 changed significantly from 0.14 ± 1.5 mm to 4.0 ± 0.8 mm at a 3-month follow-up (Wilcoxon pair order test, V-statistics 0 with p-value <0.001). Overall patient satisfaction ranged from 1 to 2 (on a scale of 0–2). The majority of patients (98.3%) presented good eyelid contour at a 3-month follow-up. Mild residual medial ptosis was observed in 4 patients with both a high grade of ptosis and impaired preoperative LF. No patient was dissatisfied with the results of the procedure at the endpoint of the study. Inter-eyelid symmetry within 1 mm was achieved in 226 out of 228 cases (99%). Surgery time averaged 23 minutes (range 14–34). Indications for blepharoplasty were noted in 40 out of 141 patients (28.4%). Twenty-three patients (16%) reported eye discomfort despite the use of a dressing contact lens at a 2-week follow-up, which improved during further follow-ups. No significant complications were reported in the study group. Results of subgroups analyses are presented in Table 2 and Fig 1.

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Table 2. The relationships between the compared subgroups used to compare MRD1 changes, Mullerectomy range, tarsectomy range and patient satisfaction scores.

https://doi.org/10.1371/journal.pone.0343505.t002

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Fig 1. Boxplot demonstrating MRD1 changes, Mullerectomy and tarsectomy changes and patient satisfaction scores across different subgroups.

https://doi.org/10.1371/journal.pone.0343505.g001

Comparing outcome measures in subgroups, there was a statistically significant difference of ΔMRD1 in patients with preoperative MRD1 ≥ 1 mm compared to patients with preoperative MRD1 < 1mm. (Table 2, Fig 1).

The tarsectomy range differed significantly in all 3 subgroup analyses. The tarsectomy range was significantly smaller in patients with preoperative MRD1 ≥ 1 mm compared to patients with MRD1 < 1mm (P < 0.0001). In patients with LF ≤ 8 mm, there was a statistically significant difference in both the Muellerectomy range and tarsectomy range compared to patients with LF > 8mm. In patients with a positive 10% PT result there was a statistically significant difference in tarsectomy range compared to patients with a negative 10% PT result. (Table 2, Fig 1).

There was no difference in patient satisfaction, surgery duration, cosmesis or complications between subgroups (P > 0.05) (Table 2, Fig 1).

Results of linear regression modeling are presented in Table 3 and S1 File.

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Table 3. Linear regression analysis of the impacts of potential limiting factors: preoperative MRD1, LF and PT result on ΔMRD1.

https://doi.org/10.1371/journal.pone.0343505.t003

Discussion

Our study shows that preoperative ptosis severity, LF, and PT results influence the surgical plan but do not affect outcomes of posterior-approach blepharoptosis surgery.

It was thought that only minimal ptosis with very good LF could be corrected by a transconjunctival approach [8,9]. Current reports confirm that transconjunctival methods of ptosis correction can also be successfully used in moderate to severe ptosis, usually in procedures combining Mullerectomy and tarsectomy [5,10–12]. The aim of our study was to identify how potential limiting factors influence the outcome of posterior-approach blepharaptosis surgery. We compared outcomes in patients with minimal to moderate ptosis to those with moderate to severe ptosis. In general, we observed similar outcomes, although it should be noted that the difference in the amount of tarsectomy and Muellerectomy was significantly greater in the group of patients with moderate to severe ptosis. Another difference was noted in patients with a positive 10% PT result. The tarsectomy range was significantly smaller in this subgroup compared to patients with a negative 10% PT result (Table 2, Fig 1). Linear regression results show individuals with a positive test have a ΔMRD1 larger by 0.56 mm on average compared to individuals with a negative test (Table 3, S1 File). The only statistically significant difference in postoperative MRD1 change resulted from a comparison between the outcomes in patients with upper eyelid ptosis>3mm to patients with upper eyelid ptosis ≤3 mm (Table 2, Fig 1). Although both groups show the same median value (4.0), mild-to-moderate ptosis cases showed greater eyelid elevation than moderate-to-severe cases (4.31 vs. 3.94 mm, Table 2, Fig 1), which results from the size of the desired correction. In moderate-to-severe ptosis ΔMRD1 was significantly larger by 1.85 mm compared to the subgroup with mild to moderate ptosis (Table 3, S1 File). In patients with LF < 8mm both the Muellerectomy range and the tarsectomy range were greater than in patients with LF ≥ 8 mm (Table 2, Fig 1), but LF does not affect ΔMRD1 based on linear regression analysis (Table 3, S1 File). Most patients presented good eyelid contour at a 3-month follow-up, hovever mild residual medial ptosis was observed in 4 patients with both severe ptosis and impaired LF. This mild medial undercorrection was determinared by the anatomy of the upper eyelid and the possibility to secure and place appropriately the Putermann clamp. Thus, special care should be taken when qualifying patients with severe ptosis and impaired LF. It may be appropriate to allow for a 1:2 mm tarsectomy in these patients rather than a 1:1 ratio as suggested by some authors [18,19]. In our opinion Mueller’s anatomy and the size of the upper eyelid tarsus should be assessed before surgery in order to plan the appropiate blepharoptosis correction in this group of patients. It should be noted, however, that procedure satisfaction and cosmetic effect were not impacted by blepharoptosis size, LF and the amount of tissue resected, or results of the preoperative 10% PT. No patient was dissatisfied with the procedure outcome at the endpoint of the study (Table 2, Fig 1). Extension of the range of correction through a transconjunctival approach was achieved by combining 2 mechanisms: Mueller muscle resection and tarsectomy. It appears that additional submaximal safe tarsectomy affects the extent of blepharoptosis correction and cosmetic outcome, as described by other authors for the correction of severe blepharoptosis with poor LF via an anterior approach [20,21]. Statistically significant differences in the Mullerectomy range and tarsectomy range in subgroup comparisons may confirm this assumption (Table 2, Fig 1). Minor complications such as keratitis reported in 0.85%, undercorrection and asymmetry >1mm in 5% of cases and visible change in the contour of the upper eyelid in 1.7% of cases were noted in the previously described series of 118 eyes [12] and were to avoid with the learning curve of the surgeon. It is important to note, however, that some patients from the current study (16%) reported eye discomfort despite the use of a bandage contact lens at a 2-week follow-up, which improved during further follow-up and completely resolved at the endpoint of the study.

With the trend toward minimally invasive surgery, surgical techniques for posterior-approach ptosis repair are increasingly being turned to as quick, effective and safe procedures.

This study provides updated evidence that posterior-approach blepharoptosis surgery can achieve successful outcomes even in cases of moderate to severe ptosis and impaired LF (4–8 mm).

While greater initial ptosis and reduced LF necessitate larger tissue resections, these factors do not negatively impact final eyelid position or patient satisfaction. This challenges traditional restrictive indications and supports expanding the use of posterior-approach techniques. This may result in an increase in the popularity of transconjunctival methods in the correction of moderate to severe blepharoptosis rather than only in minimal blepharoptosis, as was standard practice in the past.

Like any study, ours also has its limitations.

One such limitation is certainly the lack of comparison stemming from blepharoptosis etiology and the lack of a comparison group treated with a different surgical technique. This is due to the fact that the study group included adult patients, mostly with involutional blepharoptosis, where there is no standard of care. We intended to check how different clinical factors, which may also be considered limiting factors, could influence final outcomes. To make our results reliable and show dependencies between subgroups, it was necessary to involve a big cohort, which we managed to achieve. Secondly, there was lack of child study participitats, what derminates the ethic’s reqiurements. Our conclusions were made based on a standard, but relatively short follow-up. Results would benefit from confirmation in a long term study. An advantage of this study is undoubtedly the large sample size, which allowed us to measure relationships in a reliable prospective manner.

Conclusion

Preoperative ptosis severity, LF and PT results influence the surgical plan but do not affect outcomes of posterior-approach blepharoptosis surgery. These findings suggest that posterior-approach techniques can reliably be used beyond traditionally limited indications, providing a valuable contribution to the evolving practice of minimally invasive eyelid surgery.

Supporting information

Acknowledgments

This manuscript was created as part of the Capstone Project at Harvard Medical School within the Polish Clinical Scholars Research Training Program 2023/2024 at Harvard Medical School in cooperation with the Medical Research Agency, Warsaw, Poland(ABM).