Preoperative Levator Function Assessment in Blepharoplasty
- IFAAS Ops
- 12 hours ago
- 7 min read
Accurate assessment of levator function is a fundamental step in planning successful upper eyelid surgery, particularly in blepharoplasty. The levator palpebrae superioris muscle plays a central role in eyelid elevation, and variations in its strength directly influence both surgical technique and postoperative outcomes. Inadequate preoperative evaluation can lead to asymmetry, persistent ptosis, or lagophthalmos—complications that may require revision surgery.
This article reviews the clinical methods used to measure levator function, highlights key diagnostic tests, and outlines how findings guide surgical decision-making. It also addresses the management of patients with poor levator function and emphasizes the importance of postoperative monitoring to ensure optimal recovery and long-term results.
Figure 1. Demonstrates the Levator Function Test, which is the gold standard for assessing the strength and excursion of the levator palpebrae superioris muscle—the primary muscle responsible for lifting the upper eyelid.
Understanding Levator Anatomy & Function
The levator palpebrae superioris is the primary elevator of the upper eyelid. It originates from the lesser wing of the sphenoid bone and inserts into the tarsus through the levator aponeurosis. The muscle includes both voluntary (striated) fibers and an involuntary component, Müller’s muscle.
Its main function is to elevate the upper eyelid, with normal excursion of approximately 15 mm from downward to upward gaze. This movement is essential for protecting the cornea, maintaining the visual field, and ensuring proper tear film distribution.
The levator aponeurosis also forms the upper eyelid crease by attaching to the pretarsal orbicularis and skin. Weakening or dehiscence of this attachment can cause ptosis and changes in crease position. Understanding this relationship is crucial for preoperative assessment in blepharoplasty.
Figure 2. Shows the Relationship to Superior Rectus: Notice in the diagram how the levator runs directly above the superior rectus muscle. These two muscles are physically connected by a thin layer of connective tissue (fascia), which is why your eyelid naturally lifts even higher when you look upward.
Figure 3. A. Outline of upper eyelid skin ellipse for excision. B. Elevation of skin–orbicularis flap to dissect beneath the suborbicular fascial plane, protecting the levator aponeurosis. C. Conservative sculpting of medial and central fat with tenotomy scissors. D. Alternative 1: Identify disinserted levator aponeurosis edge; place 5-0 Vicryl sutures through the superior tarsal border and aponeurosis. E. Alternative 2: Fatty infiltration of the levator aponeurosis without discrete disinsertion. F. Excision of pretarsal orbicularis to expose superior tarsal plate. G. Elevate levator aponeurosis from Müller’s muscle to the desired level. H. Place 5-0 Vicryl sutures through the superior tarsal border and levator aponeurosis at the chosen height. I. Excise redundant levator aponeurosis. J. Secure 5-0 Vicryl sutures.K. Close skin with interrupted 6-0 plain gut sutures.
How Is Levator Function Measured in Clinical Settings?
Levator function is measured using standardized techniques that quantify upper eyelid excursion from maximal downgaze to maximal upgaze, with the frontalis muscle manually neutralized. The clinician blocks brow elevation with a thumb or finger, then records the eyelid margin position in downgaze and again in upgaze. The difference in millimeters represents levator function.
Function is typically classified as:
Excellent: >15 mm
Good: 12–15 mm
Fair: 5–11 mm
Poor: <4 mm
This assessment is essential for surgical planning in ptosis and blepharoplasty, as accurate measurement guides the choice of technique and helps prevent postoperative complications.
Key Tests for Evaluating Eyelid Muscle Strength
Several specialized tests help assess eyelid muscle function:
Marginal Reflex Distance (MRD): Measures the distance from the corneal light reflex to the eyelid margin in primary gaze. MRD-1 is normally 4–5 mm, and MRD-2 is typically 5 mm. Abnormal values may indicate ptosis or retraction.
Fatigue Test: The patient maintains upgaze for 1–2 minutes. Progressive drooping suggests myasthenia gravis and may warrant medical treatment rather than surgery.
Ice Test: Applying a cold pack for 2 minutes can temporarily improve myasthenic ptosis, supporting diagnosis.
Phenylephrine Test: Instilling phenylephrine evaluates Müller’s muscle function. A 1–2 mm elevation indicates potential benefit from Müller’s muscle-conjunctival resection for mild ptosis.
Snap Test: The eyelid is pulled down and released; delayed return suggests aponeurotic stretching or dehiscence.
These tests, combined with levator function assessment, guide surgical planning and technique selection.
Impact of Levator Function on Blepharoplasty Outcomes
Levator function is a major determinant of upper blepharoplasty outcomes. Patients with normal levator function (>15 mm) typically achieve predictable, symmetrical results with standard blepharoplasty. In contrast, unrecognised levator weakness can cause postoperative asymmetry, persistent ptosis, or lagophthalmos.
For mild to moderate ptosis with good levator function, combined blepharoplasty and levator advancement can correct both excess skin and drooping. Patients with poor levator function often require alternative procedures such as frontalis sling surgery to elevate the eyelid.
Levator strength also guides the amount of tissue that can be safely removed; reduced function necessitates conservative excision to avoid lagophthalmos. If levator dehiscence or disinsertion is present, repair may be required during surgery to achieve optimal results.
Preoperative detection of asymmetric levator function enables appropriate surgical planning and patient counselling, making it a critical element of the preoperative evaluation.
Figure 4. A 46-year-old woman with difficulty opening her upper eyelids underwent upper blepharoplasty (MRD-1 +4.0 mm bilaterally) and extended transconjunctival lower blepharoplasty. Symmetrical eyelid apertures were achieved intraoperatively, and at 1 year postoperative she had a balanced crease, improved brow position, resolved upper eyelid hollowing, and complete symptom relief.
Surgical Planning Based on Levator Assessment Results
Levator function directly guides surgical strategy for upper eyelid procedures. In patients with excellent levator function (>15 mm) and no ptosis, standard blepharoplasty focusing on skin and orbicularis excision is typically sufficient.
For mild ptosis (1–2 mm) with good levator function (12–15 mm), levator advancement can be performed through the blepharoplasty incision to elevate the eyelid. Moderate ptosis with fair function (5–11 mm) may require a more substantial levator advancement or resection, adjusted intraoperatively to achieve symmetry.
Severe ptosis with poor levator function (<4 mm) usually necessitates frontalis suspension using autogenous or synthetic material, bypassing the levator and relying on brow elevation.
Surgical planning must also consider eyelid laxity, brow position, and ocular surface health, as these factors affect technique selection and outcomes.
Figure 5. Levator advancement performed during an upper blepharoplasty to correct mild ptosis. For patients with mild ptosis and healthy muscle function, levator advancement is performed by accessing the levator aponeurosis through a standard blepharoplasty incision. The surgeon advances and reattaches this tendon to the tarsal plate, effectively shortening the lifting mechanism to elevate the lid margin by the desired 1–2 mm. This surgical correction restores mechanical efficiency, creates a more symmetrical and "refreshed" eye appearance, and eliminates the need for compensatory forehead straining.
Impact of Poor Levator Function on Blepharoplasty Outcomes
Figure 6. Performing a standard blepharoplasty on a patient with poor levator function without additional correction often results in under-correction (the lid remains too low) or poor crease formation because the weak muscle cannot pull the skin inward to create a deep, natural fold.
Poor levator function can undermine blepharoplasty outcomes by producing persistent ptosis, asymmetry, and unpredictable results. When levator excursion is <4 mm, standard blepharoplasty alone is often insufficient, and alternative techniques such as frontalis suspension may be required. If levator weakness is not addressed, both cosmetic and functional improvements may be limited or worsened.
Blepharoplasty in Patients with Poor Levator Function: Feasibility and Considerations
Patients with very poor levator function can still undergo blepharoplasty, but the procedure must be modified and expectations must be realistic. Standard skin-and-muscle excision alone is typically insufficient; instead, surgical planning usually involves frontalis suspension to connect the eyelid to the brow elevator. This approach restores eyelid elevation through forehead muscle action while allowing for cosmetic improvement. Careful tissue preservation is essential to avoid complications such as exposure keratopathy, and the primary goal becomes a balance between functional correction and aesthetic enhancement.
Considerations
Procedure modification is required
Standard blepharoplasty alone is insufficient for levator function <4 mm.
Frontalis suspension is typically necessary to achieve eyelid elevation.
Functional goals take priority
Primary objective is to restore eyelid opening and visual function.
Aesthetic improvements are secondary but remain important.
Choice of suspension material
Options include autogenous fascia lata, preserved fascia, silicone rods, or PTFE sutures.
Material selection depends on age, durability, and risk of infection or recurrence.
Risk of exposure and ocular surface complications
Reduced levator function increases the risk of lagophthalmos.
Careful tissue preservation and conservative skin excision are essential to prevent exposure keratopathy.
Patient selection and counselling
Patients must understand realistic outcomes and the potential need for revision surgery.
Expectation management is critical due to functional limitations.
Neurological and systemic factors
Underlying conditions such as myasthenia gravis or third nerve palsy should be optimised medically before surgery.
Temporary non-surgical measures (e.g., crutch glasses) may be considered in selected cases.
Timing considerations in congenital cases
Early intervention may be required if there is a risk of amblyopia.
Less severe cases may be deferred until later childhood.
Figure 7. In cases of poor levator function (excursion < 4 mm), a standard blepharoplasty must be modified because simple advancement of the weak muscle is often insufficient to provide adequate lift. While surgery remains feasible to improve the palpebral aperture and create an aesthetic crease, clinicians must consider more aggressive techniques like maximal resection or a frontalis suspension to bypass the non-functional muscle. These procedures carry a higher risk of lagophthalmos—an inability to fully close the eye—requiring careful postoperative management to protect the ocular surface.
Conclusion Preoperative assessment of levator function is essential for achieving predictable and satisfactory outcomes in upper eyelid surgery. Accurate measurement and standardized testing enable surgeons to distinguish between normal, borderline, and poor levator strength, which directly informs surgical planning and technique selection. While patients with excellent levator function can typically undergo standard blepharoplasty with reliable results, those with compromised function require tailored approaches such as levator advancement or frontalis suspension. Failure to identify levator dysfunction can lead to persistent ptosis, asymmetry, or lagophthalmos, underscoring the importance of thorough evaluation and patient counseling. Postoperative monitoring and realistic expectation-setting are crucial, particularly for patients with poor levator function who may need additional interventions to optimize both function and aesthetics. Reference:
Sofiadellis, F. (2025, July 16). Levator function assessment in eyelid surgery. Dr Foti Sofiadellis. https://fotisofiadellis.com/levator-function-assessment-in-eyelid-surgery/
MCAN Health. (2026). Ptosis (eyelid drooping). MCAN Health Glossary. https://www.mcanhealth.com/plastic-surgery-glossary/ptosis-eyelid-drooping/
(2023). Modified levator resection technique for moderate congenital blepharoptosis. Oculoplastic. https://link.springer.com/article/10.1007/s00266-023-03382-3
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