The role of limbal stem cells in corneal epithelial maintenance: testing the dogma.
OBJECTIVE
To study and characterize the epithelial cells in patients with a central "island" of normal epithelial cells surrounded with 360 degrees of clinically apparent limbal stem cell (SC) deficiency with conjunctivalization of the limbus and peripheral cornea.


METHODS
Observational, prospective, consecutive case series.


METHODS
Five human subjects (8 eyes) who presented with total limbal SC deficiency in 1 or both eyes with a central area of normal corneal epithelial cells.


METHODS
Clinical slit-lamp examination, aided with fluorescein staining, for evidence of conjunctivalization and in vivo confocal microscopy (IVCM) of the conjunctivalized limbus and peripheral cornea and the normal central corneal epithelium.


METHODS
Long term survival of normal stratified corneal epithelial cell sheet in the presence of total limbal SC deficiency.


RESULTS
In all 8 eyes the diagnosis of limbal SC deficiency was confirmed by clinical and IVCM examination. The conjunctivalized area extended circumferentially along the entire limbus, seen clinically by the presence of fluorescein staining cells, epithelial irregularity, and vascularization and by IVCM showing bright conjunctival epithelial cells, superficial and deep blood vessels, and goblet cells. The central corneal epithelial cells had a normal appearance with polygonal superficial cells, well-defined wing cells, and smaller basal cells. The central "islands" of normal epithelial cells remained unchanged over the mean follow-up period of 60 months (range, 8-12 years).


CONCLUSIONS
The existence and survival of a healthy sheet of corneal epithelial cells over the follow-up period, in the presence of clinically apparent total limbal SC deficiency, suggests a limited role of limbal epithelial SC in physiologic homeostasis of the corneal epithelium.


BACKGROUND
The authors have no proprietary or commercial interest in any materials discussed on this article.
Division of Ophthalmology and Visual Sciences, Queens Medical Centre, University Hospital, Derby Road, Nottingham, UK. Harminder.dua@nottingham.ac.uk
Harminder S
HS
Dua
Ammar
A
Miri
Thaer
T
Alomar
Aaron M
AM
Yeung
Dalia G
DG
Said
D000293:Adolescent; D000328:Adult; D000368:Aged; D002470:Cell Survival / Q000502:physiology; D003228:Conjunctiva / Q000473:pathology*; D003316:Corneal Diseases / Q000473:pathology*; D004847:Epithelial Cells / Q000166:cytology*; D019573:Epithelium, Corneal / Q000166:cytology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016850:Limbus Corneae / Q000473:pathology*; D008297:Male; D008679:Metaplasia; D018613:Microscopy, Confocal; D008875:Middle Aged; D011446:Prospective Studies; D013234:Stem Cells / Q000502:physiology*; D014792:Visual Acuity