Corresponding Author: Masoud Khorrami-Nejad, PhD. Department of Optometry, School of Rehabilitation, Tehran University of Medical Sciences, Enghelab St, Tehran 1148965141, Iran. Aging affects the eyelids and periorbital tissues, which are often a primary concern for individuals seeking facial rejuvenation [1]. While patients may focus their complaints on the eyelids, aging is a complex process that affects the entire face. The initial cosmetic concerns expressed by individuals undergoing the aging process often pertain to alterations in the lower eyelid and midface regions [2,3]. Lower eyelid blepharoplasty (LEB) is a frequently sought-after surgical procedure, with the majority of patients seeking consultation due to age-related alterations in the region, such as the presence of tear trough deformities, nasojugal folds, malar festoons, herniated orbital fat, orbicularis laxity or hypertrophy, lower lid laxity, or excess skin [4-6].
In general, there are two main techniques for LEB [7]. The first is the transcutaneous approach, which involves making an external skin incision to address excess skin while providing access to the orbicularis muscle, orbital septum, and the underlying fat pockets. The second is the transconjunctival approach, which allows the surgeon to avoid disrupting the anterior and middle eyelid lamellae while accessing the fat compartments. Historically, the decision between the two has been primarily based on a surgeon’s level of experience and the requirement for skin resection [8,9]. Regardless of the approach taken, both techniques offer the ability to address herniated orbital fat and midface volume loss. Techniques such as fat removal, fat repositioning, and augmentation using dermal fillers or autologous fat grafting have gained popularity as effective methods for addressing these concerns [10].
Complications arising from a LEB typically involve lid malpositioning, ectropion, and disruption of lamellar structures [9,11]. To provide a systematic approach to assessing and managing these complications, Lelli and Lisman [12] developed an organizational tool that categorizes these complications into early, intermediate, and late stages. The impact of corneal biomechanics on intraocular pressure (IOP) measurement, refractive surgery results, and the progression of ectatic diseases has been extensively reported in the literature. The heightened focus on corneal biomechanics has spurred the development and refinement of various in vivo measurement methods. Currently, available technologies include optical/imaging systems combined with noncontact air-puff tonometry [13,14].
Blepharoplasty procedures, which involve modifications to the extraocular tissues, may cause pressure redistribution on the corneal tissue [15-17]. Instruments that assess corneal biomechanics, such as the Corneal Visualization Scheimpflug Technology (Corvis ST; Oculus), can be employed to detect this change. The impact of corneal biomechanics on IOP measurement, refractive surgery results, and the progression of ectatic diseases has been extensively reported in the literature [18,19]. In addition, several studies have investigated the effect of upper eyelid surgery on various corneal properties, including corneal morphology and biomechanics [15-17,20-24]. These biomechanical changes can potentially influence corneal refraction and astigmatism, leading to long-standing blurred vision [25,26]. However, no study investigated the effect of LEB on corneal biomechanical properties [17]. The rationale stems from the understanding that the eyelids and cornea have a close anatomical relationship, with the eyelids exerting a certain degree of pressure on the corneal surface. LEB surgery, which involves the resection and repositioning of lower eyelid fat pads, could conceivably alter this pressure distribution. This alteration in eyelid pressure, coupled with potential changes in blinking patterns post-surgery, might lead to changes in the biomechanical properties of the cornea, such as stiffness and curvature. Therefore, this study aims to explore whether LEB surgery induces measurable changes in corneal biomechanics using the Corvis ST, a device that assesses corneal deformation in response to an air puff.
Materials and Methods
Ethics statement
The study protocol was approved by the Ethics Committee of Tehran University of Medical Sciences before data collection to review patient records and utilize the data (No. IR.TUMS.FARABIH.REC.1401.028). All participants provided written informed consent to use their data for research purposes. The study adhered to the tenets of the Declaration of Helsinki.
Study participants
The current research was a prospective study conducted in the oculoplastic division of Farabi Eye Hospital (Tehran, Iran). To be eligible for participation, individuals had to be over 35 years old, reflecting the target population for LEB, which is typically sought for age-related cosmetic concerns. Additionally, participants had to have undergone LEB surgery, the primary focus of the study. Furthermore, their best-corrected distance visual acuity had to be equal to or greater than 20 / 40, ensuring adequate visual function and minimizing the potential influence of preexisting visual impairments on corneal biomechanics. To eliminate the potential impact of previous surgeries on corneal biomechanics, only patients undergoing their first LEB procedure were included. Lastly, a minimum follow-up period of postoperative 4 months was mandatory to allow sufficient time for corneal biomechanical changes to manifest and stabilize. Patients were excluded if any of the following criteria applied: corneal ectatic diseases, history of previous corneal refractive surgery, pterygium, severe dry eye, posterior segment pathologies, such as diabetic retinopathy or age-related macular degeneration, and glaucoma. Patients were also excluded if they exhibited incomplete eyelid closure and those with poor Bell phenomenon in order to achieve a homogenous study population. In total, 38 eyes of 19 patients underwent surgery, of which only 19 right eyes were included in the study.
Examination protocols
Upon enrollment in the study, all included patients underwent a thorough medical history-taking and standard ophthalmological examination. All study participants were recruited between March 2022 and March 2023. These patients were monitored by the ophthalmologist for 4 months following the procedure. Preoperative and postoperative data of these patients who were followed up for 4 months after LEB surgery were analyzed. Biomechanical examinations were carried out before (upon the day of) and 4 months after the LEB surgery using Corvis ST. Corvis ST is a dynamic Scheimpflug analyzer that applies a concentric air-puff to deform the central cornea while concurrently monitoring the corneal response [27]. The instrument utilizes an ultrahigh-speed camera to capture 140 images of the cornea’s central horizontal meridian over a timeframe of 32 milliseconds, equivalent to the duration of the air puff. The device analyzes the images in real time to derive various dynamic corneal response parameters. These parameters have been extensively studied since the instrument’s introduction into clinical practice in 2010 [28]. This device measure various parameters related to corneal deformation and biomechanics, including: first applanation (A1) deformation amplitude (DA), second applanation (A2) DA, A1 applanation time, A2 applanation time, A1 velocity, A2 velocity, A1 deflection length, A2 deflection length, A1 deflection amp, A2 deflection amplitude, A1 delta arc (dArc) length, A2 dArc length, A1 deflection area, A2 deflection area, highest concavity (HC) dArc length, HC DA, HC deflection length, HC deflection amplitude, HC deflection area, HC time peak distance, DA max deflection amplitude, max deflection amplitude, max dArc length max, max inverse radius, IOP, biomechanical-compensated IOP (bIOP), pachymetry, pachymetry slope, whole eye movement max, DA ratio max, Ambrosio relational thickness integrated radius, stiffness parameter A1, Corvis Biomechanical Index, and stress-strain index (SSI).
Surgical procedure
The technique performed in this study was lower eyelid transconjunctival blepharoplasty with fat repositioning to subperiosteal space. The primary indication for LEB in all patients was cosmetic concerns related to aging changes in the lower eyelid. All surgeries were performed by a single surgeon (SMR). The technique of transconjunctival surgery has been well documented [29]. Before starting the surgery, the patient’s tear through the hollow was marked in a sitting position. The surgery was performed under general anesthesia. At first, traction suture was applied with silk 4-0 thread in the lower eyelid margin, and the lower eyelid was everted by placing a desmar (Moria SA). Then the conjunctiva was incised about 5 to 7 mm below the lower edge of the tarsus with a scalpel blade no. 15, and next, both the conjunctiva and lower eyelid retractors were cut with scissors. Then, the upper edge of the conjunctiva and retractors were pulled upward with silk 4-0 threads. After that, the desmar was removed and placed in the reverse position so that it pulled down the lower eyelid. Then the fat pockets were opened with Stevens scissors. Care was taken during the dissection to preserve the inferior oblique muscle between the medial and central fat pads. The prolapsed medial and lateral fats were resected and then cauterized. Central fat was considered as a flap to be transferred to the subperiosteal space. Then, the orbicularis muscle was pushed back, and the periosteum was exposed. Next, the periosteum was incised at the inferior orbital rim with a scalpel blade no. 15, and the space under the periosteum was dissected using a freer periosteal elevator. Then the central fat flap was transferred to the subperiosteal space using a double-needle Prolon 4-0 thread (Ethicon), and after passing under the tear trough hollow, the needles were removed from the skin and fixed by placing a bolster on the skin. Finally, after checking the bleeding in the surgical site, the conjunctiva was sutured with Vicryl 7-0 thread (Ethicon) and the eye was bandaged with antibiotic ointment. The day after surgery, the dressing was opened, and antibiotic ointment and betamethasone drops were started for the patient every 4 hours. Seven days after the surgery, the suture with bolster was removed.
Statistical analysis
Statistical analyses were administered using IBM SPSS ver. 24 (IBM Corp). The mean ± standard deviation and frequency values were reported for every parameter during postoperative follow-up sessions. The normal distribution of all data was first checked by using the Shapiro-Wilk test. In cases of parametric analysis, the paired t-test was administered to make a comparison between data of the preoperative and postoperative measurements or between consecutive postoperative examinations. When the parametric analysis was not indicated, the Wilcoxon ranked test was executed to compare the values of preoperative and postoperative measurements. A p-value of <0.05 was considered to be statistically significant.
Results
The mean age of 19 patients (16 female patients, 84.2%; 3 male patients, 15.8%) was 49.0 ± 10.1 years (range, 37-72 years). Comparison of the A1 and A2 DA, time, velocity, deflection length, deflection amplitude, dArc length, and deflection area parameters before and 4 months after surgery are shown in Table 1. Four months following surgery, A1 and A2 time increased by −0.328 ± 0.467 milliseconds (p = 0.007) and −0.387 ± 0.408 milliseconds (p = 0.001), respectively. Also, A1 DA increased by −0.013 ± 0.028 mm, which was nearly statistically significant (p = 0.054).
Comparison of the HC length, amplitude, area, and time parameters before and 4 months after surgery are reported in Table 2. As shown in this table, 4 months after surgery, the absolute value of the HC dArc length decreased (−0.012 ± 0.020 mm), but the HC time increased (−0.389 ± 0.505 milliseconds), which were both statistically significant (p = 0.021 and p = 0.004, respectively). Also, the reduction of the HC deflection length (0.131 ± 0.273 mm) and area (0.233 ± 0.517 mm2) following surgery were nearly significant (p = 0.058 and p = 0.065, respectively).
Comparison of the peak distance, maximum DA, deflection amplitude, maximum dArc length, and maximum inverse radius parameters before and 4 months after surgery are reported in Table 3. As shown in this table, none of these parameters changes significantly following surgery (all p > 0.05).
Comparison of IOP, pachymetry, and other biomechanics indexes before and 4 months after surgery are reported in Table 4. Of these parameters, IOP and bIOP increased significantly following surgery (IOP: −2.184 ± 3.228 mmHg, p = 0.009; bIOP: −2.042 ± 2.915 mmHg, p = 0.007). However, the SSI significantly decreased (0.138 ± 0.259) after surgery ( p = 0.037). The mean Corvis Biomechanical Index decreased by 0.070 ± 0.151 following surgery, which was nearly significant ( p = 0.075).
Discussion
The most successful cosmetic eyelid surgery is the surgery that restores the appearance of the patient’s face in a younger and natural way. The possible risks and complications are minimal, and the result is long-term, satisfying both the surgeon and the patient [26]. LEB surgery aims to counteract the effects of aging and gravity on the lid/cheek complex by resectioning and redistributing eyelid fat pockets [30].
The influence of factors like age, certain medical conditions including keratoconus and diabetes, treatments including prostaglandins, and refractive surgeries on corneal biomechanical behavior has now been well studied in the literature [31-33]. Also, numerous studies have explored the impact of corneal biomechanics on the progression of ectatic disorders, refractive surgery outcomes, and IOP measurement [34]. The Corvis ST instrument provides biomechanical parameters of the cornea that are obtained from its inward and outward deformations in response to a single air pulse [35]. Given the interaction between the upper and lower eyelids and the cornea, the LEB procedure might alter the pressure applied by the lower eyelid on the corneal tissue, thereby impacting corneal biomechanical characteristics. In the present study, we investigated the postoperative changes in various corneal biomechanical parameters measured by Corvis ST in patients who underwent LEB surgery. Our results indicated that most corneal biomechanical measurements did not show differences before and after LEB surgery, except A1 and A2 times, HC dArc length, HC time, IOP, bIOP, and SSI. Notably, all the parameters with postoperative significant changes showed a significant increase, while SSI and the absolute value of HC dArc length showed a significant decrease following LEB surgery. Most of these changes were in the direction of increasing the corneal stiffness. While statistically significant, the magnitude of these changes, particularly in IOP and corneal stiffness, might not necessarily translate to clinically significant effects on visual acuity or astigmatism in the short term. However, the long-term implications of these changes, especially in patients with preexisting risk factors for glaucoma or corneal ectasia, warrant further investigation.
Earlier techniques of LEB centered on excision of skin, muscle, and fat through skin or skin-muscle flaps to reshape the lower eyelid. While aesthetically beneficial for many patients, this approach can potentially lead to long-term issues such as abnormal eyelid position, scleral show, rounded palpebral fissures, and hollow lower eyelid area [36]. Currently, LEB surgery focuses more on less aggressive fat removal, fat repositioning using transconjunctival or subciliary approaches, minimal skin excision, and lower lid support through canthopexy and canthoplasty procedures [36,37]. To our knowledge, no study examined the postoperative changes in corneal biomechanical parameters following the LEB surgery.
Most studies on the effects of eyelid surgeries and corneal properties evaluated the corneal changes following upper eyelid blepharoplasty (UEB). They indicated that throughout the UEB procedure, the loss of orbital extra fat may lead to substantial changes in the geometry, morphology, and function of the cornea [38,39]. A comparable impact can be considered for patients who underwent LEB. Only a few studies in the literature investigated the post-operative changes in corneal biomechanical parameters following the UEB procedure. Sommer et al. [17] conducted a prospective study to investigate the effects of UEB surgery on corneal biomechanical properties, as well as topographic and tomographic specifications in 42 eyes of 35 patients. Measurements were taken both preoperatively and postoperatively, with 4-week interval between the two sets of measurements. In addition to the difference in the type of eyelid surgery between the present study and their study, we utilized the Corvis ST device for corneal biomechanical assessment, whereas Sommer et al. [17] employed the ORA device (Reichert Ophthalmic Instrument). Notably, the ORA measures fewer corneal biomechanical indices (corneal hysteresis and corneal resistance factor) compared to Corvis ST. The authors observed an increase in postoperative corneal hysteresis and corneal resistance factor measurements 4 weeks after the operation, with values rising from 9.4 ± 2.3 to 10.2 ± 2.2 mmHg and from 9.7 ± 2.1 to 10.5 ± 2.2 mmHg, respectively. However, these changes did not reach statistical significance, as evidenced by p-values of 0.100 and 0.072, respectively. Regarding corneal biomechanical indices, we found a significant increase in A1 and A2 times, HC time, IOP, and bIOP. However, the SSI and absolute value of the HC dArc length index showed a significant decrease after the LEB procedure.
Several factors may contribute to the observed changes in corneal biomechanics after LEB. A possible hypothesis is that the resection of the fat pockets and redistribution of their remaining in LEB will reduce the weight of the lower eyelid. By neutralizing this effect of gravity, the strength of the girdling effect of the eyelid, especially in the area of the lower tarsus and the medial and lateral canthal ligaments, is increased, which can increase the application of more pressure on the corneal surface. These changes, along with changes in the blinking pattern, could be the underlying cause of the alteration in corneal biomechanics to increase the cornea’s stiffness [40,41]. The observed increase in IOP after LEB may be related to changes in the eyelid-globe relationship and the dynamics of aqueous humor outflow, although further research is needed to confirm this.
It is notable that Sommer et al. [17] found no significant changes in Goldman-correlated IOP, the corneal compensated IOP after the UEB surgery 4 weeks after the UEB surgery. In contrast, we found that IOP and bIOP measurements significantly increased four months after the LEB procedure (p > 0.001). It can be inferred that the choice of device used to measure corneal biomechanical properties, as well as the timing of measurements taken after the operation, may have an impact on postoperative biomechanical outcomes. Furthermore, our study underscores the importance of preoperative evaluation of IOP in patients scheduled for LEB surgery, particularly those with borderline IOP measurements. The average of IOP increase after LEB surgery in our study was about 2 mmHg, which may not be clinically important in patients with normal IOP, but in people with a history of glaucoma, we should consider this issue.
The major limitation of the present study was its limited sample size and relatively follow-up period. It is reasonable to speculate that a larger sample size and longer follow-up periods could have yielded statistically significant findings for other corneal biomechanical parameters and provided more definitive insights into the long-term clinical implications. Although topical steroids were used for one week after surgery, they can potentially influence corneal biomechanics. Future studies with larger cohorts and extended follow-up are necessary to confirm our findings and further elucidate the long-term effects of LEB on corneal biomechanics. Additionally, future research should investigate the potential influence of preexisting conditions, such as diabetes and connective tissue disorders, on corneal biomechanical changes after LEB.
Despite the lack of prior research on the impact of LEB on corneal structure and function, including corneal biomechanics, the present study yielded noteworthy results. Specifically, significant changes in corneal biomechanical parameters, such as A1 and A2 times, HC dArc length, HC time, IOP, bIOP, and SSI, were observed following LEB surgery. These findings suggest that LEB may have an effect on corneal biomechanics and highlight the need for further investigation in this area.
This is the first study to examine the impact of LEB surgery on corneal biomechanical properties using the Corvis ST device. To assess changes in these properties, preoperative and postoperative measurements were taken using this device. Our findings indicate that the resection and repositioning of the fat pockets in LEB leads to changes in eyelid pressure on the corneal surface, which ultimately causes biomechanical changes of the cornea in the direction of increasing corneal stiffness.
PDF Links
PubReader
ePub Link
XML Download
Full text via DOI
Download Citation
Print
