[Comparative analysis of the value of information provided by anterior segment optical coherence tomography and confocal laser scanning microscopy for identifying the palisades of Vogt in normal limbus]

AIM

to conduct a comparative analysis of the value of information provided by anterior segment optical coherence tomography (AS-OCT) and in vivo confocal laser scanning microscopy (CLSM) for identifying the palisades of Vogt (POV) in normal limbus.

MATERIAL AND METHODS

POV were studied in 15 healthy participants (30 eyes) without any anterior segment disease. Two examination methods were used: AS-OCT En Face imaging (RTVue XR Avanti, 3D Cornea protocol) and CLSM (HRT3). Concordance of the results was then analyzed.

RESULTS

Structural features of POV were distinguishable by both methods. CLSM was able to visualize POV in both the superior and inferior limbi of all the 15 patients (30 eyes). Within the inferior corneal hemisphere, POV had the appearance of well-differentiated hyperreflective double-contoured structures organized in parallel lines at the level of basal epithelium. The structure of the superior limbus, as judged from CLSM data, varied significantly: «classic» palisades were seen in only 13 eyes (43%), while in the other 17 cases (57%) POV were atypical. On OCT, POV structure was seen in detail in 29 eyes. By comparing the abilities of CLSM and OCT to visualize POV, a strong positive correlation (rS=0.99, p<0.05) was revealed between the results obtained in both the superior and inferior limbi.

CONCLUSION

OCT data provide a detailed understanding of POV structure and strongly correlate with CLSM results. Taking into consideration the noninvasiveness, demonstrativeness, and repeatability of AS-OCT En Face imaging as well as the high value of provided information, the method cay be recommended as an alternative in POV diagnostics.

[Diagnostic capabilities of optical coherence tomography and confocal laser scanning microscopy in studying manifestations of aniridia-associated keratopathy]

AIM

to investigate the possible use of anterior segment optical coherence tomography (AS-OCT) and laser scanning confocal microscopy (LSCM) for visualization of limbal progenitor structures and epithelial changes at different stages of aniridia-associated keratopathy (AAK) and to analyze genotype-phenotype correlations of corneal damage.

MATERIAL AND METHODS

Thirty-four patients (63 eyes) with congenital aniridia (CA) were subjected to epithelial cell density measurement in the central cornea as well as epithelial surface assessment with limbal palisades of Vogt (POV) detection in the corresponding sites of the two corneas. For that, LSCM (HRT3) and AS-OCT (RTVue XR Avanti) were performed. Central corneal and epithelial thicknesses were measured using the Pachymetry protocol.

RESULTS

There has been found an increase in the central corneal thickness (CCT) of CA patients, which correlated with the stage of AAK, and a decrease in the central epithelial thickness as compared with healthy subjects (p<0.05). The difference between the basal and wing epithelial cells density in eyes with stages I and II AAK and normal cells density at stage 0 AAK was statistically significant (p<0.05). Intact or disturbed POV were detected in all patients with PAX6 3' deletion. At that, AS-OCT findings highly agreed with LSCM images for both the inferii (r_S=0.85, p<0.05) and superior limbi (r_S=0.53, p<0.05). A negative correlation was established between the stage of AAK and in vivo morphology of POV (r_S=-0.5, p<0.05). However, no correlation was found between the stage of AAK and patient's age (r_S=0.169, p=0.174).

CONCLUSION

AS-OCT and LSCM are both important diagnostic tools for corneal surface monitoring in patients with limbal stem cells deficiency.