Until recently, eye doctors have had two primary options to evaluate patients for signs of limbal stem cell deficiency (LSCD). They could perform a slit lamp evaluation—looking for a dull and irregular reflex from the conjunctivalized corneal surface and a classic “whorled” epithelium along with the loss of limbal palisades of Vogt.1,2 The other option is fluorescein staining, which will show a stippled pattern when the conjunctival epithelium has encroached on the corneal surface.1,2
Now, researchers are saying that doctors can employ the anterior segment function of OCT angiography (OCT-A) to image the previously inaccessible structure. Using OCT-A, researchers evaluated a metric called maximum corneal vascular extension (CoVE), from the limbus to the furthest vessel over the cornea, and corneal vascular thickness (CoVT), from the most superficial to the deepest corneal vessel.3
The researchers, from Tufts University in Boston, looked at 26 eyes of 24 patients with LCSD to classify them into stage I, II and III, and 12 eyes of 12 healthy controls. Using anterior segment OCT-A, they identified significant differences in CoVE and CoVT between all stages compared with controls, and between stages I and III LSCD.
They also ascertained details that a slit lamp exam might miss. For instance, the study shows, CoVE is significantly different between stages I and II, whereas CoVT is significantly different between stages II and III. CoVE and CoVT also strongly correlate with best-corrected visual acuity, the study shows.
Specifically, CoVE was 0.27±0.10mm in the control group, 0.79±0.21mm in stage I, 1.68±0.89mm in stage II and 2.53±0.82mm in stage III LSCD. CoVT was 51.0±19.4μm in controls, 113.7±36.6µm in stage I LSCD, 129.7±39.3µm in stage II and 336.0±85.0μm in stage III.
1. Vora G, Daluvoy M. Diagnosis and management of limbal stem cell deficiency. Eyenet Magazine. www.aao.org/eyenet/article/diagnosis-management-of-limbal-stem-cell-deficienc. February 2014.
2. Dua H, Saini J, Azuara-Blanco A, Gupta P. Limbal stem cell deficiency: Concept, aetiology, clinical presentation, diagnosis and management. Indian J Ophthalmol. 2000;48(2):83-92.
3. Binottiab W, Nose R, Koseogluab D, Dieckmannab G. The utility of anterior segment optical coherence tomography angiography for the assessment of limbal stem cell deficiency. Ocul Surf. April 23, 2020. [Epub ahead of print].