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LIMBAL STEM CELL DEFICIENCY

Limbal stem cell deficiency (LSCD) is a potentially blinding disease in which there is a breakdown at the limbus (the junction of the clear corneal tissue and the white conjunctival tissue) and the corneal surface becomes replaced by hazy conjunctival tissue. The limbus is located at the peripheral edge of the cornea and acts as a physical barrier separating the clear cornea from the surrounding conjunctiva and its blood vessels that cover the sclera, or white part of the eye.1 In normal, healthy eyes, superficial corneal epithelial cells shed naturally and are replaced by stem cells located at the limbus.2 In people who have LSCD, this renewal does not occur as it should and tissue is instead replaced by conjunctival epithelial cells, which lack the transparency needed for clear vision.3 This growing problem is made worse by the fact that it is easily overlooked in the early stages when vision-saving treatment can be most effectively applied. Such delay can lead to epithelial defects, corneal ulcers and scars, conjunctivalization of the cornea, vision loss and pain.

WHAT CAUSES LIMBAL STEM CELL DEFICIENCY?

The corneal epithelium completely regenerates every three to ten days.4 This repair process requires constant cell renewal from peripheral limbal stem cells.5 However, individuals who have LSCD lack these vital cells, which compromises corneal epithelium renewal and leads to injury and vision loss. There are many possible reasons why limbal stem cells might be in short supply. Causes fall into one of two categories: congenital or acquired. Congenital causes for LSCD include aniridia, keratitis associated with multiple endocrine deficiency, dyskeratosis congenita, and epidermal dysplasia. 678910111213 Acquired causes include burns, ocular surgery, contact lens misuse and ocular surface inflammatory diseases.

HOW IS LSCD DIAGNOSED?

In some cases, LSCD develops slowly and your doctor can detect it before it starts to interfere with your vision or cause significant discomfort. However, unfortunately patients often present with both pain and blurry or decreased vision. Other symptoms can include contact lens intolerance, photophobia, tearing, and blepharospasm.20 In addition to patient-reported symptoms, your doctor can determine whether you have limbal stem cell deficiency based on your history and clinical signs, such as a hazy epithelium and/or epithelial staining, indicating breakdown of the epithelial cells. If any of these signs and symptoms point toward LSCD, laboratory tests will likely be used to confirm a diagnosis. When LSCD is treated early, cell loss can usually be halted or reversed. On the other hand, if LSCD progresses to total limbal deficiency, surgery may be the only option.

MEDICAL AND SURGICAL TREATMENTS FOR LSCD

If left untreated, limbal stem cell deficiency can cause recurrent epithelial erosions and infection, as well as pain and loss of vision. LSCD is often medically treated when it’s caught early on. Artificial tears, punctual occlusion, Vitamin A ointment, autologous serum, cyclosporine and topical cortical steroids might be recommended in such cases. Other options include debridement and amniotic membrane transplantation. If total limbal stem cell deficiency occurs or if the above measures fail, more aggressive surgical management will likely be needed.21 Furthermore, even after transplant surgery, the cornea may not remain clear and a repeat procedure may be necessary.22 There is also a risk of rejection from allogeneic transplants.

SCLERAL LENSES FOR LSCD

Scleral lenses are common for the management of ocular surface diseases, including LSCD.24 25 In patients who have not yet progressed to total limbal stem cell deficiency, scleral lenses can act as a bandage, optimizing the health of the ocular surface and helping to stabilize it. Scleral lenses feature a large-diameter that allows the lens to vault (not touch) the cornea and limbus, resting instead on the white part of the eye, known as the sclera. Beneath the lens, a fluid-filled reservoir hydrates the corneal epithelium, offering an environment conducive to cell regeneration. The lens also protects the cornea from the mechanical shearing effect of the eyelids that occurs during blinking. Scleral lenses provide excellent surface protection and continuous lubrication, potentially reducing the risk of damage to the surviving corneal epithelial cells.26 Indeed, scleral lenses might allow some patients with LSCD to delay or avoid more aggressive surgical intervention.27 If you have LSCD, visit your eye doctor to determine the most appropriate management strategy for you.

REFERENCES

  1. Ahmad S. Stem Cells Transl Med. 2012 Feb; 1(2): 110–115.

  2. Ahmad S. Stem Cells Transl Med. 2012 Feb; 1(2): 110–115.

  3. Ahmad S. Stem Cells Transl Med. 2012 Feb; 1(2): 110–115.

  4. Lim P, Fuchsluger TA, Jurkunas UV. Limbal stem cell deficiency and corneal neovascularization. Seminars in ophthalmology 2009;24(3):139-48.

  5. Gipson IK. The epithelial basement membrane zone of the limbus. Eye 1989;3 ( Pt 2):132-40.

  6. Nishida K, Kinoshita S, Ohashi Y, Kuwayama Y, Yamamoto S. Ocular surface abnormalities in aniridia. Am J Ophthalmol. 1995;120:368–75.

  7. Skeens HM, Brooks BP, Holland EJ. Congenital aniridia variant: Minimally abnormal irides with severe limbal stem cell deficiency. Ophthalmology. 2011;118:1260–4.

  8. Puangsricharern V, Tseng SC. Cytologic evidence of corneal diseases with limbal stem cell deficiency. Ophthalmology. 1995;102:1476–85.

  9. Mohammadpour M, Javadi MA. Keratitis associated with multiple endocrine deficiency. Cornea. 2006;25:112–4.

  10. Aslan D, Akata RF, Holme H, Vulliamy T, Dokal I. Limbal stem cell deficiency in patients with inherited stem cell disorder of dyskeratosis congenita. Int Ophthalmol. 2012;32:615–22.

  11. Aslan D, Akata RF. Dyskeratosis congenita and limbal stem cell deficiency. Exp Eye Res. 2010;90:472–3.

  12. Felipe AF, Abazari A, Hammersmith KM, Rapuano CJ, Nagra PK, Peiro BM. Corneal changes in ectrodactylyectodermal dysplasia-cleft lip and palate syndrome: Case series and literature review. Int Ophthalmol. 2012;32:475– 80.

  13. Di Iorio E, Kaye SB, Ponzin D, Barbaro V, Ferrari S, Böhm E, et al. Limbal stem cell deficiency and ocular phenotype in ectrodactyly-ectodermal dysplasia-clefting syndrome caused by p63 mutations. Ophthalmology. 2012;119:74–83.

  14. Nishida K, Kinoshita S, Ohashi Y, Kuwayama Y, Yamamoto S. Ocular surface abnormalities in aniridia. Am J Ophthalmol. 1995;120:368–75.

  15. Puangsricharern V, Tseng SC. Cytologic evidence of corneal diseases with limbal stem cell deficiency. Ophthalmology. 1995;102:1476–85.

  16. Sangwan VS, Jain V, Vemuganti GK, Murthy SI. Vernal keratoconjunctivitis with limbal stem cell deficiency. Cornea. 2011;30:491–6.

  17. Bhatia RP, Srivastava R, Ghosh A. Limbal stem cell study in contact lens wearers. Ann Ophthalmol (Skokie) 2009;41:87–92.

  18. Sridhar MS, Vemuganti GK, Bansal AK, Rao GN. Impression cytology-proven corneal stem cell deficiency in patients after surgeries involving the limbus. Cornea. 2001;20:145–8.

  19. Dua HS, Azuara-Blanco A. Autologous limbal transplantation in patients with unilateral corneal stem cell deficiency. Br J Ophthalmol. 2000;84:273–8.

  20. Dua HS, Saini JS, Azuara-Blanco A, Gupta P. Limbal stem cell deficiency: concept, aetiology, clinical presentation, diagnosis and management. Indian journal of ophthalmology 2000;48(2):83-92.

  21. Kim BY, Riaz KM, Bakhtiari P, et al. Medically reversible limbal stem cell disease: clinical features and management strategies. Ophthalmology 2014;121(10):2053-8.

  22. Basu S, Fernandez MM, Das S, Gaddipati S, Vemuganti GK, Sangwan VS. Clinical outcomes of xeno-free allogeneic cultivated limbal epithelial transplantation for bilateral limbal stem cell deficiency. The British journal of ophthalmology 2012;96(12):1504-9.

  23. Basu S, Fernandez MM, Das S, Gaddipati S, Vemuganti GK, Sangwan VS. Clinical outcomes of xeno-free allogeneic cultivated limbal epithelial transplantation for bilateral limbal stem cell deficiency. The British journal of ophthalmology 2012;96(12):1504-9.

  24. Rosenthal P, Cotter JM, Baum J. Treatment of persistent corneal epithelial defect with extended wear of a fluidventilated gas-permeable scleral contact lens. Am J Ophthalmol 2000; 130: 33–41.

  25. Segal O, Barkana Y, Hourovitz D, Behrman S, Kamun Y, Avni I, Zadok D. Scleral contact lenses may help where other modalities fail. Cornea 2003; 22: 308–310.

  26. Dua HS, Miri A, Alomar T, Yeung AM, Said DG. The role of limbal stem cells in corneal epithelial maintenance: testing the dogma. Ophthalmology 2009; 116: 856–863.

  27. Schornack MM. Limbal stem cell disease: management with scleral lenses. Clin Exp Optom. 2011 Nov;94(6):592- 4.

The above information was provided by The Scleral Lens Education Society

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