AIM: To evaluate the corneal densitometry in treatment-naive patients with keratoconus and its relevance with anterior and posterior corneal elevation.

METHODS: Keratoconic corneas were examined using the Pentacam. Corneal densitometry was measured over a 12-mm diameter area, divided by annular concentric zones and depths, more over anterior and posterior corneal elevation was measured. Keratoconus was classified according to the topographic keratoconus classification.

RESULTS: A total of 152 subjects \〖72 patients with keratoconus(46 male, 26 female)and 80 healthy control subjects(50 male,30 female)\〗 were included in the study. There were significant differences in corneal densitometry values of the groups in central 2 mm keratoconus(KC)=19.62±4.17 gray scale unit(GSU), N=15.38±1.54 GSU(P<0.0001), and in annulus of 2 to 6 mm in diameter(K=16.40±2.18 GSU, N=15.31±1.25 GSU, P<0.0001). When densitometry values for different depths were examined, the anterior layer presented the highest value(KC=23.69±3.71 GSU, N=20.91±2.52 GSU, P<0.0001), which was significantly higher than the values obtained in the central and posterior layer(KC=14.34±1.70 GSU, N=13.61±1.21 GSU, P=0.001 and KC=11.40±1.23 GSU, N=12.35±0.88, P=0.002 respectively). Analysis of the correlation between corneal densitometry for each layer depth(anterior, central and posterior)with posterior corneal elevation values demonstrated significant association(r=0.293, r=0.278 and r=0.294 respectively). The similar correlation was not found between corneal densitometry for each layer depth and anterior corneal elevation(r=-0.211, r=-0.101, r=0.99 respectively). In the control patients such a significant correlation between posterior/anterior corneal elevation and corneal light backscatter for each layer depth was not found.

CONCLUSION: The densitometry map reveals that light backscatter was higher in the central portion of the anterior keratoconic cornea. Corneal densitometry values of keratoconus patients were correlated with posterior corneal elevation in 0-2, 6-10 and 10-12 annuli and in all anterior, central and posterior layers. The densitometry level was higher in more advanced stages.