Comparison of and correlation between anterior and posterior corneal elevation maps in normal eyes and keratoconus-suspect eyes

Abstract

The posterior corneal elevation and the corneal thickness values were different in keratoconus-suspect eyes. The correlation between the anterior and posterior corneal aconic shapes was between keratoconus-suspect eyes and normal eyes.

Characterization of corneal structure in keratoconus

“…[14][15][16][20][21][22] Specifically, in keratoconus and also in keratoconus suspect, significantly larger values of BFS 14,16,21 and posterior elevation 15,16,22 have been reported (Figure 3). Schlegel et al 16 report a mean aconic astigmatism for the posterior corneal surface of 2.29 D G 1.71 (SD) in a sample of 48 keratoconussuspect patients using scanning-slit technology. In the same sample, they also found a mean maximum posterior elevation of 0.0288 G 0.0102 mm at 1.0 mm of radius from the center.…”

“…In the same sample, they also found a mean maximum posterior elevation of 0.0288 G 0.0102 mm at 1.0 mm of radius from the center. 16 De Sanctis et al 14 They obtained a mean value for this ratio of 1.874 G 0.532 in a sample of 43 keratoconus patients and of 1.103 G 0.462 in a sample of 23 keratoconus suspects using scanning-slit technology. 65 In addition, they found excellent keratoconus detection ability of the same ratio obtained using the anterior elevation data (cutoff: 0.5122, sensitivity: 99%, specificity: 95.2%).…”

“…The term keratoconus suspect was coined for designating corneas not showing biomicroscopic keratoconic signs but subtle topographic features similar to early stages of keratoconus. [14][15][16][17][18][19] In such conditions, other diagnostic tests and examinations may be helpful to confirm the potential presence of an incipient ectatic condition.…”

“…There is evidence that both anterior and posterior curvatures are affected in keratoconic eyes and also in keratoconus suspect eyes. 20 Likewise, significantly larger values of best-fit sphere (BFS) 14,16,21 and posterior elevation 15,16,22 have been reported in clinical keratoconic eyes and keratoconus suspect eyes. Therefore, manifestations of the ectasia also occur at the posterior corneal surface, even in early stages of the disease.…”

Macular corneal dystrophy and associated corneal thinning

“…Therefore evaluation of the anterior corneal surface in isolation can give indices that spuriously suggest the presence of keratoconus, and correlation with posterior corneal elevation maps and regional pachymetry is required. 20,21 The origin of the apparent anterior corneal elevation is uncertain, but the stromal deposits of MCD probably affect the quality of data capture.…”