This article was originally published in a sponsored newsletter.

Limbal stem cells (LSCs) are adult stem cells that are responsible for maintaining the corneal epithelium and facilitating wound healing.¹ The limbus serves as a barrier between the cornea and conjunctiva and supports the continuous centripetal renewal of corneal epithelial cells, in alignment with the XYZ hypothesis.¹ In this hypothesis, X stands for limbal basal cell proliferation and stratification, Y for basal cell centripetal migration, and Z for superficial cell desquamation.

LSCs are closely controlled by their microenvironment, which is made up of stromal cells, melanocytes, soluble factors, and an extracellular matrix in a stroma that is abundantly vascularized and innervated.² The regulation of LSCs involves a coordinated effort that includes cell-to-cell contacts, signaling via extracellular matrix components and interactions between epithelial and niche cells, as well as the influence of soluble factors.³ The loss of LSCs occurs due to any damage to either the LSCs or the niche components. The hallmark sign of limbal stem cell deficiency (LSCD) is the insufficient presence of LSCs, leading to the substitution of corneal epithelial cells by conjunctival cells.⁴ Individuals who have LSCD may endure persistent or recurrent epithelial defects, surface inflammation, and corneal scarring that may cause vision loss and eventually lead to blindness.

There has been substantial progress in accurately diagnosing and managing individuals who have LSCD.⁵ Using currently available techniques, individuals can obtain better vision.⁵ Ongoing research using new cell culture and tissue engineering techniques could lead to significant breakthroughs in improving outcomes for challenging cases.⁵

Ocular surface diseases can be effectively managed with scleral lenses. One study reported that 10% to 16% of scleral lenses are prescribed for protection of the ocular surface or to improve comfort due to ocular surface disease.^6-8 Scleral lenses have been successfully prescribed to manage LSCD. Scleral lenses have also been shown to delay or prevent surgical intervention in individuals who have LSCD.⁹

In another study, the clinical and visual outcomes were evaluated with a retrospective case series of 27 eyes that had LSCD confirmed by in vivo confocal microscopy and fitted with scleral lenses.10 Vision improved in seven eyes (25.9%), remained stable in 13 eyes (48.1%), and decreased in seven eyes (25.9%, p = 0.16). The stage of LSCD stage improved in seven eyes (25.9%), did not change in eight eyes (29.6%), and worsened in 12 eyes (44.4%, p = 0.10). Five eyes were evaluated with anterior segment optical coherence tomography and anterior segment fluorescein angiogram, which demonstrated limbal compression and delayed fluorescein filling and which may be due to limbal hypoxia. The authors recommended meticulously monitoring the scleral lens fit in compromised eyes with LSCD.

Reference(s):

1. Tseng SC. Concept and application of limbal stem cells. Eye (Lond). 1989;3(Pt 2):141-157.
2. Dziasko MA, Daniels JT. Anatomical features and cell – cell interactions in the human limbal epithelial stem cell niche. Ocul Surf. 2016 Jul;14:322-330.
3. Bonnet C, Gonzalez S, Roberts JS, et al. Human limbal epithelial stem cell regulation, bioengineering and function. Prog Retin Eye Res. 2021 Nov;100956.
4. Deng SX, Borderie V, Chan CC, et al. Global consensus on definition, classification, diagnosis, and staging of limbal stem cell deficiency. Cornea. 2019 Mar;38:364-375.
5. Holland EJ. Management of Limbal Stem Cell Deficiency: A Historical Perspective, Past, Present, and Future. Cornea. 2015 Oct;34 Suppl 10:S9-S15.
6. Nau CB, Harthan J, Shorter E, et al. Demographic Characteristics and Prescribing Patterns of Scleral Lens Fitters: The SCOPE Study. Eye Contact Lens. 2018 Sep;44 Suppl 1:S265-S272.
7. Schornack M, Nau C, Nau A, et al. Visual and physiological outcomes of scleral lens wear. Cont Lens Anterior Eye. 2019 Feb;42:3-8.
8. Nau CB, Harthan JS, Shorter ES, et al. Trends in Scleral Lens Fitting Practices: 2020 Scleral Lenses in Current Ophthalmic Practice Evaluation Survey. Eye Contact Lens. 2023 Feb 1;49:51-55.
9. Schornack MM. Limbal stem cell disease: management with scleral lenses. Clin Exp Optom. 2011 Nov;94:592-594.
10. Bonnet C, Lee A, Shibayama VP, Tseng C-H, Deng SX. Clinical outcomes and complications of fluid-filled scleral lens devices for the management of limbal stem cell deficiency. Cont Lens Anterior Eye. 2023 Feb;46:101528.

Melissa Barnett, OD, FAAO, FSLS is the director of optometry at the University of California, Davis. She has received remuneration from ABB, Acculens, Abbvie, Azura, Bausch + Lomb, BCLA, Bruder, Bruno Vision Care, CooperVision, Dompé, Epion, JJVC Vistakon, Lentechs, Ocusoft, Orasis, RVL Pharmaceuticals, Sight Sciences, Science Based Health, STAPLE Program, Sun Pharma, Taursus, and Visus.