Visual Improvement With Wavefront-Guided Scleral Lenses for Irregular Corneal Astigmatism

Abstract

Purpose:

To report interim results of a single center, randomized, double-blind, crossover-controlled clinical trial comparing wavefront-guided (wfg) scleral lenses (SLs) to traditional scleral lenses (tSLs) for patients with a history of irregular corneal astigmatism (ICA).

Methods:

Thirty-one ICA eyes of 18 participants were reviewed, 23 with keratoconus, six postcorneal refractive ectasia, and two postpenetrating keratoplasty. Patients with corneal or lens opacities were not excluded from participating. Participants underwent a diagnostic lens-based fitting with a tSL with standard spherocylindrical optics. Once the tSL was finalized, a comprehensive wavefront aberrometer-based system was used to capture the residual aberration of the tSL under scotopic conditions without pharmacologic dilation, and these data were used to create a wfgSL. Once the tSL and wgfSL were finalized, a double-blinded, randomized, crossover was conducted where the participants received lens A (tSL or wgfSL) or lens B (the alternative), each worn for a 4±1 week interval. Measurements of the visual acuity (VA) and total higher-order root mean squared (HORMS) were recorded at each interval under controlled lighting conditions. At the final visit, patient subjective preference for lens A or lens B was recorded.

Results:

The average HORMS for a fixed 5-mm pupil was 0.68±0.31 μm for tSL and 0.29±0.18 μm for wfgSL. Wavefront-guided SL provided an average HORMS improvement of 56% (P<0.001). All eyes showed a reduction in HORMS, ranging from 18% to 83%. Wavefront-guided SL provided an average VA improvement of 0.12±0.11 logMAR (P<0.01). Seventy-one percent of eyes showed one line or greater improvement, 26% showed no improvement, and 3% showed a reduction of VA with the wfgSL. The average VA with tSL was 0.14±0.16 logMAR and 0.03±0.11 logMAR for wfgSL. Seventeen of 18 patients subjectively preferred wfgSL.

Conclusion:

In eyes with ICA, wfgSL reduced HORMS and improved VA when compared with tSL. Patients subjectively preferred wfgSL to tSL. These interim results demonstrate the feasibility and generalizability of wfgSL in a typical clinical practice environment.

Irregular corneal astigmatism (ICA) may be induced by corneal disease, dystrophy, scarring, trauma, surgery, or other disorders affecting the cornea. Irregular corneal astigmatism creates higher order aberrations (HOA), significantly degrading image quality, even with optimal spherocylinder correction. Previous studies have reported that patients with ICA may have difficulty achieving satisfactory vision using spectacle or traditional soft contact lens correction.¹ This is primarily due to an increase in HOAs such as coma, trefoil, and spherical aberration, which are uncorrectable by spectacles or traditional soft disposable contact lenses because these optical aids are only designed to address lower order aberrations (defocus and astigmatism), that is, conventional refractive error.

Navarro et al.² showed that wavefront-guided custom contoured phase plates could be effectively used to compensate for ocular aberrations. Bará et al.³ showed that compensation was most negatively affected by centration, then rotation, and finally axial displacement. Guirao et al.⁴ corroborated the centration and rotation effect and suggested applications to adaptive optics, refractive surgery, and contact lenses. Sabesan et al.,⁵ Marsack et al.,⁶ and Jinabhai et al.⁷ applied these principles to custom wavefront-guided (wfg) soft contact lenses (SCL), where stability, position, and lens deformation impacted results. Chen et al.⁸ then showed the results of a custom posterior surface SCL to improve stability, and although anterior surface aberrations could be reduced, internal aberrations remained.

Rigid contact lenses have long been standard of care to improve visual acuity (VA) for patients with ICA, and although corneal RGP lenses are still the most commonly used lenses for ICA, scleral lenses (SLs) have become well adopted in clinical practice.⁹ SLs are predominately used for patients with irregular astigmatism.⁹ Both corneal RGP lenses and traditional scleral lenses (tSL) use spherocylindrical optics but partially correct for HOAs induced at the anterior surface of the cornea while leaving internal HOAs induced by the posterior cornea and both surfaces of the crystalline lens.^10,11 These uncorrected internal HOAs may still make significant contributions to retinal image quality.¹¹ Using wavefront aberrometry to measure the total ocular aberration over a tSL, wavefront-guided SL (wfgSL) can be created. This method allows for quantification of residual aberrations including lower and higher orders. For screening and evaluation, HOAs are frequently summarized as higher-order root mean squared (HORMS) a calculated measure of the magnitude of aberration measured in micron (μm) units. The measured aberrations are then used to design the surface profile of the wfgSL neutralizing the total residual aberrations present in the eye. Detailed design principles and procedures were described elsewhere.^12–14 Using a SL instead of an SCL overcomes many challenges. Scleral lenses are thought to be more stable on the eye and resistant to deformation because of the rigid material. In addition, complexity and variability caused by soft materials, specifically related to material expansion, are also overcome.

Wavefront-guided SL has been demonstrated to decrease residual HOAs effectively and improve subjective visual quality in patients with corneal ectasia, specifically keratoconus (KC). In addition to reduced residual HORMS, wfgSLs have been shown to improve both VA and contrast sensitivity compared with tSLs, in many cases to similar levels as nonectatic eyes.^12–15 Maximal improvement is contingent on both lens positional stability and a period of habituation.^14,16

In contrast to our current study, these previous studies were conducted in research laboratory settings with relatively small sample sizes of patients with predominantly KC using instruments and SL designs that are not available to practitioners. In addition, these studies controlled for media opacities such as corneal scars.^12–14 Therefore, the goal of this study is to evaluate the clinical feasibility and generalizability of this technology in a typical clinical practice environment by comparing optical and visual outcomes of tSL and wfgSL and patient subjective preference (PSP). We accomplished this goal by incorporating an appropriate period of habituation, multiple forms of ICA, and less stringent patient selection criteria when compared with previous studies. In addition, a nonpharmacologically dilated method was used with a commercially available aberrometer and SL design.

METHODS

This was a prospective, randomized, double-blind, crossover clinical trial. The protocol was conducted in conformance with the Declaration of Helsinki and approved before study initiation by WCG Institutional Review Board. Written informed consent was obtained from subjects before participation in the study. Patients 18 years of age or older with a diagnosis of ICA of any etiology were eligible to participate. Those with visually significant posterior segment pathology, those unable to apply and remove a SL, and those unable to be successfully fit were excluded. Target enrollment for the study was 100 eyes. This interim report was created once the first 50 eyes enrolled completed or exited the study.

Participants were fit with a commercially available SL with quadrant specific landing zones (ARES Scleral Lens, Ovitz, Manufactured by Valley Contax, Eugene OR) manufactured from Roflufocon D (Contamac, Optimum Extra, Grand Junction CO) with a polymer encapsulation of 90% water and polyethylene glycol (Tangible Hydra PEG, Tangible Sciences, Menlo Park, CA). The method of fitting was diagnostic lens set based. All lens selection and modifications were determined by slit-lamp assessment and practitioner judgment, with support of the laboratory consultants when necessary. No objective measurement of scleral shape, such as scleral profilometry, was used. All lens revision examinations took place after 2 weeks, with a minimum of 3 hr of lens wear before examination to ensure complete lens settling and stability.

The tSL was the version of the SL with standard best-corrected spherocylindrical optics. The wfgSL has the addition of a freeform optics patch to deliver the wfg optics. All SLs were manufactured with a dot matrix at the edge of the optic zone for positional measurement. This dot matrix was present on all lenses, on both the tSL and wfgSL, so clinician observation could not distinguish a tSL from a wfgSL.

All patients were educated on lens application and removal techniques with proper lens care using hydrogen peroxide 3% (Clear Care Triple Action, Alcon, Fort Worth, TX) for disinfection and unpreserved sterile saline, sodium chloride 0.9% (LacriPure, Menicon, North Billerica, MA), to rinse and apply the lenses. After successful training, they were instructed to wear the tSL daily.

Criteria for tSL finalization were rotational and transitional stability with a target apical clearance of 250 μm, with a predetermined acceptable range of 75 and 400 μm, full limbal clearance, without impingement at the haptic after 2 weeks of daily wear and with a spherocylindrical over-refraction that showed no VA improvement. If the criteria could not be met, the patient was exited from the study.

Once the tSL was finalized, aberrometry data were captured using a commercially available Hartmann Shack–based wavefront aberrometer (OVITZ xwave, Rochester, NY). Furthermore, the tSL must be worn at least 3 hr before the aberrometer measurement to allow the lens to stabilize to a resting position. All aberrometry measurements were performed under scotopic conditions, in an examination room without windows and with all room illumination off. Aberrometry was captured after 2 to 5 min of dark adaptation without pharmaceutical dilation. Resultant aberrometry profiles were represented using Zernike polynomials up to the sixth order.

These aberrometry data were used as a basis to generate an opposing freeform optical design to negate the subject's individual measured aberrations. The optical design was typically asymmetric in both rotation and reflection. This freeform optical design was added to the anterior optical surface of the tSL to create the wfgSL. The diameter of the freeform optical design was the same as the maximum pupil size measured by the aberrometer. In the same measurement, the aberrometer also captured an infrared spectrum anterior segment image of the eye and tSL. This image allowed precise measurement of position, rotation, and tilt of the tSL on the eye relative to the subject's pupil and visual axis. This information was used to accurately place and orient the freeform optical surface on the wfgSL such that when the lens was stabilized on the eye the correction would be directly in line with the visual axis of the subject and in the correct rotation. The wfgSL parameters and material were identical to the tSL. The only design variation of the initial wfgSL was the addition of the wavefront-guided freeform optical patch. The procedure and criteria for wfgSL finalization were the same as previously stated. If the criteria were not met, the patient was exited from the study.

Once the tSL and wgfSL were finalized, the patient and care provider were blinded, and the patient was randomly assigned. Participants received lens A (tSL or wgfSL) or lens B (the alternative lens), each worn for a 4±1 week interval. At the crossover visit, lens A was assessed and then removed, and lens B was dispensed. After time for lens stabilization and settling elapsed, then lens B was assessed. At follow-up, measurements were taken of VA and the total HORMS. At the final visit, the patient reported their subjective preference for lens A or lens B. The investigator was unmasked after the completion of the last visit.

Wavefront aberrometry data can only be compared at a common pupil diameter. Therefore, for analysis of aberrations, several pupil sizes were examined; a normalized pupil size, a 5.0-mm pupil, and a 3.0-mm pupil. In the context of this manuscript, normalized means that aberrometry data were compared using the smaller of the patient's pupil diameters at the lens A and lens B visit. A recalculation of the HORMS data was performed with a 5.0-mm pupil to provide data that can be universally compared with the established literature and a 3.0-mm pupil to represent photopic visual quality.

All VA measurements were obtained under controlled lighting conditions using a Snellen letter chart, and for statistical comparison, the values were converted to logMAR. Procedurally, all evaluations took place after a minimum of 3 hr of lens wear to ensure lens stability.

Statistical analysis was performed using Google Sheets (Google, Mountain View, CA), R (R Core Team, www.r-project.org), MATLAB (MathWorks, Natick, MA), and STATA (StataCorp, College Station, TX). Since measurements were obtained from both eyes of multiple patients, the intraclass correlation coefficients (ICC) between the two eye measurements of these subjects were assessed. Shapiro–Wilk test was performed to assess the normality of the data. A P<0.05 was used to determine statistical significance by the Mann–Whitney U test.

RESULTS

Demographics

For this interim data, 31 eyes of 18 subjects, 23 with KC, and six postcorneal refractive ectasia (ectasia) were analyzed. Two eyes with a history of KC had undergone penetrating keratoplasty (PK). Five eyes had a history of epithelial off corneal collagen crosslinking (CXL); four eyes with KC, and one eye with ectasia. Two eyes with ectasia had a history of CXL with intracorneal ring segments. One eye with KC had a history of corneal tissue addition keratoplasty (CTAK)¹⁷ followed by topography-guided photorefractive keratectomy (TGPRK). Average ICCs of logMAR and normalized HORMS before HOA correction were 0.576 and 0.191, respectively. F-tests with true value zero yielded 2.36 (P=0.078) and 1.24 (P=0.359), respectively. This indicated that no significant correlation was observed between the two eyes within subjects. As such, each eye of the patient was treated as a separate uncorrelated data point for all following data analysis.

Fifteen males and three females were analyzed. The age of subjects ranged from 22 to 63 years with an average age of 42.5±12.0 years. Nineteen eyes were dropped out, 15 due to an inadequate fitting relationship of the tSL and four were lost to follow-up.

Tomography

The average maximum keratometry (Kmax) across all eyes evaluated was 59.85 D±10.97, with an inferior to superior (I-S) ratio of 8.63 D±3.99. Stratified by disease, the KC group had an average Kmax of 59.51 D±12.16 and an I-S ratio was 8.72 D±4.05. In the ectasia group, the average Kmax was 58.33 D±6.14, with an I-S ratio of 7.56 D±1.54. For PK, the average Kmax was 68.25 D±3.89, and the I-S ratio was 10.90 D±9.44.

Aberrometry

When normalized to the patient's own pupil, the average tSL HORMS was 1.35 μm±0.69 at 4-week follow-up appointment. The average wfgSL HORMS was 0.66 μm±0.35 at the 4-week follow-up appointment. WfgSL provided an average HORMS improvement of 49% after 4 weeks of wear (P<0.001). All eyes showed a reduction in HORMS, ranging from 12% to 78%. In the eyes diagnosed with KC, the HORMS of the tSL was 1.37 μm±0.76, and 0.64 μm±0.39 for the wfgSL, a HORMS reduction of 51% (P<0.001). For the cohort with ectasia, the tSL HORMS was 1.28 μm±0.54, and 0.74 μm±0.27 for the wfgSL, a 36% HORMS reduction (P<0.05). In the eyes with PK, HORMS was 1.30 μm±0.21 for the tSL, and 0.58 μm±0.10 for the wfgSL, a HORMS reduction of 55% (P=0.12). Figure 1 displays a variety of wavefront maps and Zernike bar plot comparisons of tSLs and wfgSLs for a variety of individual eyes.

FIG. 1.

Wavefront maps and Zernike bar plots for traditional scleral lenses and wfgSLs for a variety of individual eyes. (A) Keratoconus-only, (B) keratoconus with corneal tissue addition keratoplasty and topography-guided photorefractive keratectomy, (C) ectasia-only, (D) ectasia with intracorneal ring segments, and (E) keratoconus with penetrating keratoplasty. Pupil diameter of Zernike coefficients is matched between the traditional scleral lenses and wfgSL scans, but not between patients. A reduction in higher order aberrations is observed throughout a variety of conditions. wfgSL, wavefront-guided SL.

For a 5.0-mm pupil, HORMS for the tSL was 0.68 μm±0.31 and wfgSL was 0.29 μm±0.18, a reduction of 56% (P<0.001). All eyes showed a reduction in HORMS ranging from 18% to 83%. In the eyes diagnosed with KC, the HORMS of the tSL was 0.66 μm±0.30, and 0.29 μm±0.21 for the wfgSL, a HORMS reduction of 58% (P<0.001). For the cohort with ectasia, the tSL HORMS was 0.84 μm±0.30, and 0.35 μm±0.09 for the wfgSL, a 54% HORMS reduction (P<0.01). In the eyes with PK, HORMS was 0.36 μm±0.07 for the tSL, and 0.22 μm±0.06 for the wfgSL, a HORMS reduction of 41% (P=0.12). Figure 2A shows mean Zernike coefficient magnitudes and Figure 2B shows mean Zernike coefficient values across all eyes at a 5 mm pupil.

FIG. 2.

A. Mean Zernike coefficient magnitude across all eyes. B. Mean Zernike coefficient values across all eyes. All eyes adjusted to 5-mm pupil diameter before averaging. Error bars are one standard deviation. The most common aberrations before wavefront correction are vertical coma, spherical aberration, secondary astigmatism, and secondary coma.

For a 3.0-mm pupil, HORMS for the tSL was 0.18 μm±0.09 and wfgSL was 0.08 μm±0.05, a reduction of 50% (P<0.001). In the eyes diagnosed with KC, the HORMS of the tSL was 0.17 μm±0.09, and 0.08 μm±0.06 for the wfgSL, a HORMS reduction of 52% (P<0.001). For the cohort with ectasia, the tSL HORMS was 0.24 μm±0.09, and 0.10 μm±0.03 for the wfgSL, a 48% HORMS reduction (P<0.05). In the eyes with PK, HORMS was 0.08 μm±0.01 for the tSL, and 0.06 μm±0.02 for the wfgSL, a HORMS reduction of 22% (P=0.22).

Visual Acuity

The average VA for tSL was 0.14±0.16 logMAR at 4-week follow-up. The average VA for wfgSL was 0.03±0.11 at 4-week follow-up. Wavefront-guided SL provided an average VA improvement of 0.12±0.11 (P<0.01). Approximately 71% of eyes showed a VA improvement of one line or better, 26% showed no improvement, and 3% showed a loss of one line after 4 weeks of wfgSL wear. The greatest improvement was 0.4 logMAR. The 23 eyes with KC improved 0.09±0.10 logMAR, the six eyes with ectasia improved 0.18±0.13 logMAR, and the two PK eyes improved 0.17±0.07 logMAR. Table 1 provides all visual performance data.

TABLE 1.

Higher-Order Root Mean Squared and Visual Acuity Stratified by Disease and Pupil Size

Condition	All Eyes (n = 31)	KC (n = 23)	Ectasia (n = 6)	PK (n = 2)
tSL VA	0.14±0.16	0.12±0.15	0.26±0.20	0.05±0.07
wfgSL VA	0.03±0.11	0.03±0.11	0.08±0.09	−0.13±0.00
tSL HORMS (patient normalized pupil)	1.35±0.69	1.37±0.76	1.28±0.54	1.30±0.21
wfgSL HORMS (patient normalized pupil)	0.66±0.35	0.64±0.39	0.74±0.27	0.58±0.10
tSL HORMS (5-mm pupil)	0.68±0.31	0.66±0.30	0.84±0.30	0.36±0.07
wfgSL HORMS (5-mm pupil)	0.29±0.18	0.29±0.21	0.35±0.09	0.22±0.06
tSL HORMS (3-mm pupil)	0.18±0.09	0.17±0.09	0.24±0.09	0.08±0.01
wfgSL HORMS (3-mm pupil)	0.08±0.05	0.08±0.06	0.10±0.03	0.06±0.02

Patient Subjective Preference

Seventeen of 18 patients subjectively preferred the wfgSL.

DISCUSSION

To our best knowledge, this is the first study designed to demonstrate the clinical feasibility of wfgSL. The key finding of the study is that wfgSL improved outcomes compared with tSL and patients subjectively preferred the wfgSL over the tSL. This study was conducted in a typical clinical setting. Therefore, the results demonstrated may be more generalizable than the results reported in prior studies. Moreover, our study patients had a variety of ICA, severity, corneal surgical history, media opacities, and a wide age range. In addition, the device and SL design used are commercially available to all practitioners.

There have been two key studies evaluating the performance of wfgSL in a research laboratory setting. Sabesan et al. reported tSL versus wfgSL as well, 11 eyes of six patients with KC. Visual acuity improved by 1.9 logMar and HORMS by ∼68%, normalized to a 6 mm pupil.¹³ Hastings et al. reported on conventional SL, analogous with tSL in this study, versus wfgSL in 20 eyes of 10 patients, 9 KC, and one pellucid marginal degeneration. Visual acuity improved by ∼0.6 logMar and HORMS by 43%, normalized to a 5 mm pupil.¹⁴ Although the demographics are not identical, they are similar and consistent with the results observed in this study. Importantly, the methods are not the same. The previous wfgSL studies captured aberrometry measurements to create the wfgSL after pharmacologic dilation.^12–14 This study only used physiologic dilation under scotopic conditions during aberrometry capture. Our data show that comparable results can be achieved without pharmacologic dilation, which may be more clinically efficient and provide a better experience for the patient.

The overall optical performance of the wfgSL in this study is promising. The logMAR results show statistically significant improvements and are promising. However, in this study, Snellen VA was converted to logMAR, which may introduce some error into the statistical analysis. The residual HORMS indicates that the wfgSL provided patients with ICA with the typical optical quality observed in eyes with normal corneas. However, in certain cases, the residual HOA could still be significant, thereby limiting visual performance, especially for a larger pupil size under mesopic and scotopic light conditions. It has been shown that achieving diffraction-limited performance in both normal and abnormal eyes is possible in a research laboratory by using adaptive optics.^18–20 It is important to understand current limitations to achieving diffraction-limited visual performance with wfgSL. Lens positional stability has been well documented in reducing the performance of wfgSL.¹⁶ Various strategies have been described to improve stability, including use of toric and elevation specific haptics.^21,22 Other potential limitations of wfgSL are similar to those of tSL, including SL surface condition, tear film abnormalities, manufacturing tolerances, and lens reservoir clarity.²³ Two factors related to SL surface condition have already been researched, wfgSL optics are unaltered by daily cleaning or the addition of lens polymer coatings.^24,25 The effect of changing pupil size, accommodative status, binocular balancing, and lens settling effects on wavefront-guided optics remain largely unknown.²⁶

Regarding PSP, all but one patient preferred wfgSL. The patient who preferred the tSL noted a loss of depth of focus with the wfgSL. When specifically asked about distance VA the patient reported preference for the wfgSL. The patient was a 56-year-old man with KC in both eyes. Right eye tomography showed mild KC with a Kmax of 51.2 D and an I-S Ratio of 6.45 D. Visual acuity was 0.1 logMAR with tSL and wfgSL was 0.00 logMAR, a one-line improvement. Higher-order root mean squared was reduced from 0.74 μm for tSL to 0.43 μm with wgfSL, a 42% reduction. Left eye tomography showed severe KC with a Kmax was 85.0 D and an I-S Ratio of 14.98 D. Visual acuity was 0.1 logMAR with tSL and 0.2 logMAR with wfgSL, a loss of one line. However, HORMS improved, 2.08 μm with the tSL and 0.62 μm with the wgfSL, a 70% reduction. This case highlights that reducing HORMS to the absolute minimum in every patient may not always achieve the best overall outcome for the patient. The PSP of this patient may be explained by reduced depth of focus from correcting HOA in presbyopic eyes and poor neural adaptation to wfg optics. The effect of higher order aberration correction on intermediate and near vision in presbyopic patients has not yet been explored. Furthermore, the effect of neural adaptation was not explored in this study. Sabesan et al.²⁷ used an adaptive optics system (AOS) to show that even with full correction, patients with KC displayed reduced VA, likely because of long-term neural adaptation to poor retinal quality. Years later, Sabesan et al.²⁸ showed that using an AOS to train patients with KC, the best-corrected VA could be improved by just over one logMAR line. Hastings et al.¹⁴ reported on patients adapted after 8 weeks of wfgSL. Although our adaptation period was shorter, we did not study this difference, and it is possible this patient simply did not have enough time to neural adapt. The PSP data may be influenced by several factors, such as which lens was received first, daily visual tasks, environment illumination, or disparity of ICA severity.

Although this study increases the clinical applicability of wfgSL, several questions requiring further studies remain. The first is to directly compare results of pharmacologic versus physiologic dilation. The goals of pharmacologic dilation are to create the largest pupil size possible so the wfg optics can address all natural lighting conditions and to prevent instrument induced accommodation; however, this induces changes in crystalline lens shape by modulating ciliary body tone. Physiologic dilation, on the other hand, leaves natural tone intact; however, if the physiological pupil size used to design the wfgSL is smaller than the largest scotopic pupil size, it is possible that the visual performance during scotopic conditions could be less optimal because the wfg optic zone is smaller than the largest physiologic pupil. In addition, instrument-induced accommodation is also possible. Another remaining question to study is a more clinically representative SL fitting relationship. As previous studies have shown, misalignment of wfg optics degrade vision; thus, efforts were made to ensure that all SLs in this study were designed to have an ideal and stable fitting relationship.¹⁶ In clinical practice, not all SL fits must show complete stability to be deemed successful so it is possible an acceptance of instability should be studied. Furthermore, the impact of visual performance related to opacity of both cornea and crystalline lens needs to be explored and serve to set guidelines, expectations, and inform candidates for wfgSL. The same applies to the severity of the condition and surgical history. Moreover, patients with lid or lash positions that partially cover the scotopic pupil may need to be instructed to open their eyes wide or may need to have the lid retracted. This may lead to lens displacement from the habitual position with natural lid position and tone leading to unreliable HOA data and position of optics. Finally, the effect of wfgSL on VA throughout a range of distances should be explored.

Although our study expands on the type of ICA and has more eyes than the previous studies, the number of eyes is still small. When subdivided into smaller cohorts, such as the ectasia cohort (n=6 eyes), determining statistical significance is limited. These are interim results with more data being collected as the study continues, this may lead to more robust statically significant results. In addition, a variety of correlation statistics will be performed and reported.

CONCLUSION

Wavefront-guided SL reduced HORMS and improved VA compared with tSL. Subjectively, patients prefer wfgSL over tSL. This study demonstrates the clinical feasibility of wfgSL technology and the generalization of its use across multiple etiologies of ICA. Further studies of wfgSL are required to address potential limitations and to continue to broaden the use cases for wfgSL clinically.