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. Author manuscript; available in PMC: 2021 Dec 1.
Published in final edited form as: Cont Lens Anterior Eye. 2020 Mar 4;43(6):613–616. doi: 10.1016/j.clae.2020.02.006

Alignment of a Wavefront-Guided Scleral Lens Correction in the Presence of a Lens Capsulotomy

Lan Chi Nguyen †,*, Gareth D Hastings †, Matthew J Kauffman †, Raymond A Applegate †, Jason D Marsack †
PMCID: PMC7483213  NIHMSID: NIHMS1574899  PMID: 32146116

Abstract

PURPOSE:

To demonstrate the necessity of aligning a wavefront-guided scleral lens (WGSL) optical correction to the eye’s effective pupil, with misalignments leading to reduced performance.

CASE REPORT:

A 34 year old subject with a history of failed LASIK in the left eye, leading to penetrating keratoplasty, extracapsular extraction of the crystalline lens and neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy, enrolled in a study examining WGSL performance,. Habitual logMAR acuity OS (aided with a scleral lens) was +0.04. Residual higher order root mean square (HORMS) wavefront error (WFE) was 0.28 μm (Φ = 4.75 mm, mean age-matched norm = 0.17 μm), and objective over-refraction was −0.30 −0.54 × 008. When a WGSL (targeting aberrations up to the 5 th radial order) was manufactured with the wavefront-guided optics aligned to the center of the dilated pupil, logMAR acuity worsened to +0.15, residual HORMS WFE worsened to 0.44 μm (Φ = 4.75 mm), and objective over-refraction increased to +1.19 −0.30 × 122. Slit lamp imagery revealed that the effective pupil was no longer defined by the iris of the eye, but rather the capsular opening created by the capsulotomy. When the WGSL was redesigned to align the wavefront-guided optics to the center of the capsular opening, logMAR acuity improved to −0.14, residual HORMS WFE reduced to 0.17 μm (Φ = 4.75 mm) and objective over-refraction reduced to +0.20 −0.15 × 111.

CONCLUSION:

WGSLs are an emerging option for patients with highly aberrated, ectatic and post-surgical corneas whose visual symptoms cannot be alleviated with conventional corrections. However, alignment of the optics of the WGSL to the underlying optics of the eye over the effective pupil is critical in achieving good optical and visual performance.

Keywords: aberration, ectasia, wavefront-guided, scleral lens

Introduction

Wavefront-guided scleral lenses (WGSLs) are a model of personalized medicine as they target the unique, higher- (not correctable with sphere and cylinder) and lower-order (sphere and cylinder) aberration structures of individual eyes. In the context of current practice, WGSLs provide an additional tool to the clinician when conventional correction modalities have been exhausted and the patient continues to (1) report unsatisfactory perceived visual quality and visual performance and (2) exhibit elevated residual levels of higher order aberration (HOA) [1–3].

Patients that frequently meet these criteria include those with post-refractive surgery ectasia or other iatrogenic complications, post-penetrating keratoplasty, corneal trauma, pellucid marginal degeneration, and keratoconus [4–7]. The current non-surgical standard of care for a highly aberrated eye is a rigid contact lens such as a scleral lens (SL), which typically masks between 55 and 60% of HOAs [3,5] through (1) approximate refractive index matching of the post-lens tear layer and the cornea, and (2) by providing a new, well-formed optical first-refracting-surface for light entering the eye. While conventional scleral lenses serve some patients well, the residual 40 to 45% of HOAs are frequently elevated compared to age- and pupil-matched controls and can cause poor visual performance and patient dissatisfaction.

Several groups [1–3] have demonstrated that WGSLs decrease HOAs that remained uncorrected with conventional SLs and provide improved visual performance when compared to conventional SLs [1–3]. As these lenses become more common, it is important to emphasize that the pupil, as defined by the iris, is not always the limiting aperture of the eye and that misalignment of a wavefront-guided correction with respect to the underlying WFE (over the actual effective pupil) can reduce the optical and visual performance of the correction [8–13].

This report presents examples of such optical and visual performance data and contrasts (1) the detriment resulting from improper alignment of a WGSL with (2) the significant benefits achieved by appropriate alignment of the correction with the effective pupil. In this case, the eye had a complicated history that began with a failed laser-assisted in situ keratomileusis (LASIK) procedure, followed by penetrating keratoplasty, crystalline lens extraction, and neodymium:yttrium-aluminum-garnet (Nd:YAG) laser treatment to manage subsequent capsular opacification.

Case report

A 34-year-old subject enrolled in a study examining WGSL performance approved by the Institutional Review Board of the University and carried out in accordance with the Declaration of Helsinki. The subject signed informed consent documentation after being educated as to the potential risks associated with participating in the study and gave permission to use his/her images in publications. A history of failed LASIK in the left eye was reported as a result of a mechanical microkeratome malfunction, which subsequently required penetrating keratoplasty and extracapsular extraction of the crystalline lens followed by an Nd:YAG laser posterior capsulotomy. Presenting logMAR visual acuity in the affected eye (aided with a habitual conventional SL) was +0.04 (20/25 Snellen). Residual higher order root mean square (HORMS) wavefront error (WFE) (through the conventional SL) measured with a COAS HD wavefront sensor (Johnson and Johnson Vision, Santa Ana CA) was 0.28 μm (pupil diameter = 4.75 mm; mean age-matched norm for the same pupil size = 0.17 μm [14]) and objective over-refraction was −0.30 −0.54 × 008. Slit lamp examination showed a clear graft and a posterior chamber intraocular lens implant.

The subject reported seeing shadows around objects and letters as well as glare while wearing the habitual SL.

Following study protocol [2,3], a new conventional SL was fit and refined as a predicate lens for the WGSL. Follow-up was consistent with overall study design (weekly laboratory visits for eight consecutive weeks) and findings regarding wear time, comfort and stability of vision were unremarkable. When a stable conventional SL with a clinically acceptable fit was achieved, the lens was removed, the subject was dilated with 1 drop of 1% tropicamide and 1 drop of 2.5% neosynephrine and, after reaching full dilation, the SL was re-inserted, allowed to settle, and residual wavefront error was measured through the SL. A WGSL targeting aberrations in the 2nd to 5th Zernike radial orders was manufactured using a DAC 2X-ALM OTT ophthalmic lens lathe (DAC International, Carpinteria CA) in Boston XO material (Bausch and Lomb, Rochester NY). The wavefront-guided correction was offset from the geometric center of the lens and designed into the WGLS such that it was coaxial to the center of the dilated pupil as defined by the iris. At this stage it was not noted that the YAG capsular opening was displaced with respect to the pupil defined by the iris.

While wearing this initial WGSL, optical and visual performance was worse than with the conventional SL: logMAR visual acuity was +0.15 (20/30 Snellen), residual HORMS WFE increased (worsened) to 0.44 μm (pupil diameter = 4.75 mm), and objective over-refraction worsened to +1.19 −0.30 × 122.

This poor performance with the WGSL were initially puzzling and quite contrary to typical WGSL performance. Examination of slit lamp imagery revealed that the effective entrance pupil of the eye – defined by the Nd:YAG capsulotomy – was not concentric with the center of the physiological pupil defined by the iris. The Cartesian (rectangular) offsets from the geometric center of the scleral lens were quantified by exporting and analyzing a high-resolution photograph of the lens on the eye as follows: Engraved markings of known separation on the anterior lens surface provided a reference scale. Offsets were quantified from the geometric center of the scleral lens to (1) the center of the dilated pupil center as x = −0.85 mm and y = +0.40 mm, and to (2) the center of the capsular opening as x = −0.65 mm and y = +1.15 mm.

The difference between the locations (Euclidean distance of 0.78 mm; Figure 1) is clinically relevant because WFE (on which the WGSL was designed) was measured over the capsule opening, but the corresponding correction was positioned over the pupil defined by the iris.

Figure 1. The differences between the locations of the center of the dilated physiological pupil (red dashed lines) and the center of the capsular opening (blue dashed lines) to the geometric center of the lens (green filled circle) equated to a total vector of 0.78 mm.

Figure 1.

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Based on the offset of the capsular opening quantified from the slit lamp imagery in Figure 1, a second WGSL was designed and manufactured where the wavefront-guided correction was shifted from being centered on the dilated iris towards being centered on the capsular opening. While wearing this second WGSL, logMAR visual acuity improved to −0.14 (20/14 Snellen), residual HORMS WFE reduced to 0.17 μm (pupil diameter = 4.75 mm), which was within the 95% age-matched normal limits [14], and objective over-refraction improved to +0.20 −0.15 × 111. Differences in simulated visual image quality, HORMS WFE, and objective over-refraction between the three lenses are shown in Figure 2.

Figure 2. Residual wavefront error, objective over-refraction, and simulated retinal images for the three lenses fit in this case: (A) a conventional scleral lens showed elevated higher-order root mean square wavefront error (HORMS WFE) and poor simulated retinal image quality, (B) first iteration WGSL showed increased (worse) HORMS WFE and poorer simulated visual image quality, and (C) aligned WGSL providing a reduction in HORMS WFE to within 95% age-matched normal limits and substantially improved simulated visual image quality.

Figure 2.

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Discussion

This case report described an eye where the effective pupil was neither defined by, nor centered on, the physiological pupil defined by the iris. This complicated the fitting of a WGSL.

The tolerance for the acceptable misalignment of a wavefront-guided correction scales with the magnitude of the correction [8–13]. This concept is analogous to the tolerance of cylinder rotation where the accuracy of the axis becomes increasingly important as cylinder magnitude increases. Consequently, the appropriate alignment of a WFG correction, as illustrated in this case, becomes increasingly important as the magnitude of the targeted correction (aberrations that are residual through a conventional SL) increases.

In conclusion, WGSLs are an emerging option for patients with highly aberrated eyes whose visual symptoms cannot be alleviated with conventional optical corrections. However, practitioners should be aware that this highly personalized method of vision correction requires vigilance during assessment, fitting, and design to obtain optimal performance. In this case, aligning the optics of a WGSL to the underlying optics of the eye over the effective pupil defined by the capsulotomy was critical in achieving good optical and visual performance.

Highlights.

  • Wavefront-guided scleral lenses improve vision and decrease higher order aberrations in ectasia and post-surgical corneas

  • Alignment of wavefront-guided scleral lens corrections to the underlying optics of an eye over the effective pupil is crucial

  • The pupil, as defined by the iris, is not always the limiting aperture of the eye

Acknowledgments

This work is supported by NIH/NEI R01EY019105 (JDM and RAA); NIH/NEI P30EY0755; the Borish Endowment RAA, University of Houston, College of Optometry

Footnotes

Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Conflicts of interest and Source of Funding:

RAA and JDM are named as inventors on patents related to wavefront-guided contact lenses that are owned by The University of Houston. LCN, MJK, and GDH have no conflicts of interests.

References

  • 1.Sabesan R, Johns L, Tomashevskaya O, Jacobs DS, Rosenthal P, Yoon G. Wavefront-guided scleral lens prosthetic device for keratoconus. Optom Vis Sci 2013;90:314–23. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Marsack JD, Ravikumar A, Nguyen LC, Ticak A, Koenig DE, Elswick JD, et al. Wavefront-guided scleral lens correction in keratoconus. Optom Vis Sci 2014;91:1221–30. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 3.Hastings GD, Applegate RA, Nguyen LC, Kauffman MJ, Hemmati RT, Marsack JD. Comparison of wavefront-guided and best conventional scleral lenses after habituation in eyes with corneal ectasia. Optom Vis Sci 2019;96:238–47. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.Choi J, Wee WR, Lee JH, Kim MK. Changes of ocular higher order aberration in on-and off-eye of rigid gas permeable contact lenses. Optom Vis Sci 2007;84:42–51. [DOI] [PubMed] [Google Scholar]
  • 5.Kosaki R, Maeda N, Bessho K, et al Hori Y, Nishida K, Suzaki A, et al. Magnitude and orientation of Zernike terms in patients with keratoconus. Invest Ophthalmol Vis Sci 2007;48:3062–8. [DOI] [PubMed] [Google Scholar]
  • 6.Negishi K, Kumanomido T, Utsumi Y, Tsubota K. Effect of higher-order aberrations on visual function in keratoconic eyes with a rigid gas permeable contact Lens. Am J Ophthalmol 2007;144:924–9. [DOI] [PubMed] [Google Scholar]
  • 7.Gumus K, Gire A, Pflugfelder SC. The impact of the Boston Ocular Surface Prosthesis on wavefront higher-order aberrations. Am J Ophthalmol 2011;151:682–90. [DOI] [PubMed] [Google Scholar]
  • 8.Guirao A, Williams DR, Cox IG. Effect of rotation and translation on the expected benefit of an ideal method to correct the eye’s higher-order aberrations. J Opt Soc Am A 2001;18:1003–15. [DOI] [PubMed] [Google Scholar]
  • 9.Guirao A, Cox IG, Williams DR. Method for optimizing the correction of the eye’s higher-order aberrations in the presence of decentrations. J Opt Soc Am A 2002;19:126–8. [DOI] [PubMed] [Google Scholar]
  • 10.Thibos LN, Cheng X, Bradley A. Design principles and limitations of wave-front guided contact lenses. Eye Contact Lens 2003;29:S167–70. [DOI] [PubMed] [Google Scholar]
  • 11.López-Gil N, Castejón-Mochón JF, Fernández-Sánchez V. Limitations of the ocular wavefront correction with contact lenses. Vision Res 2009;49:1729–37. [DOI] [PubMed] [Google Scholar]
  • 12.Shi Y, Applegate RA, Wei X, Ravikumar A, Bedell HE. Registration tolerance of a custom correction to maintain visual acuity. Optom Vis Sci 2013;90:1370–84. [DOI] [PubMed] [Google Scholar]
  • 13.Shi Y, Queener HM, Marsack JD, Ravikumar A, Bedell HE, Applegate RA. Optimizing wavefront-guided corrections for highly aberrated eyes in the presence of registration uncertainty. J Vis 2013;13:1–15. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Applegate RA, Donnelly III WJ, Marsack JD, Koenig DR, Pesudovs K. Three-dimensional relationship between high-order root-mean-square wavefront error, pupil diameter, and aging. J Opt Soc Am A 2007;24:578–87. [DOI] [PMC free article] [PubMed] [Google Scholar]

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