OCULUS Pentacam Interpretation Manual page 130

17 Holladay Report & Holladay EKR65 Detail Report
Front elevation near min RP*
elevation upper limit
(μm)
mean +1.0
+SD +2.1
+2 SD +4.2
+3 SD +6.2
Table 5: Front elevation near min RP
(*N = 1243 normal eyes,
internal, unpublished data
by J. T. Holladay)
The lower right map [elevation (back)]
relative to the BFTEF over an 8 mm zone. The eccentricity of the ellipsoid is fixed at 0.45 (Q-value
= -0.20) and the principal radii are again varied for the best least square fit of the surface. Plus (+)
values are above the reference surface and negative values (-) are below, and are all given in μm.
Normal values for back elevations near the minimum RP
location on the back surface
Back elevation near min RP*
elevation upper limit
(μm)
mean +6.8
+SD +4.2
+2 SD +8.4
+3 SD +12.6
Table 7: Back elevation near min RP
(*N = 1243 normal eyes,
internal, unpublished data
by J. T. Holladay)
The asphericity quotient (Q-value) and eccentricity (ε) describe the shape of the elliptical surface
(Q = - ε
). These and the computed Zernike as well as the Seidel Longitudinal SA for a 6 mm zone are
2
shown in Table 9.
Variables indicating shape and SA of cornea front surface*
Q-value
-0.54
-0.26
0.00
+0.26
+0.54
Table 9: Variables indicating the shape and SA of the corneal front surface
(* All variables are computed over a 6 mm corneal zone based on an
anterior corneal apical radius of 7.71 mm, a corneal index of refraction
of 1.376 and a wavelength of 0.555 µm, using an elliptical model.)
128
(μm)
--
+3.1
+5.2
+7.2
(Figure 157)
(Table 8) are given.
(μm)
--
+11.0
+15.2
+19.4
Eccentricity (ε)
+0.73 (Q = -ε )
2
+0.51 (Q = -ε 2 )
0.00
0.51 (Q = -ε )
2
0.73 (Q = -ε 2 )
Maximum front elevation*
mean
+SD
+2 SD
+3 SD
Table 6: Maximum front elevation
(*N = 1243 normal eyes,
internal, unpublished data
by J. T. Holladay)
shows the elevation of the back surface in μm
(Table 7) and maximum elevations at any
Maximum back elevation*
mean
+SD
+2 SD
+3 SD
Table 8: Maximum back elevation
(*N = 1243 normal eyes,
internal, unpublished data
by J. T. Holladay)
Zernike (4,0) -- SA Seidel Longitudinal SA (D)
0.00
+0.19
+0.38
+0.59
+0.81
elevation upper limit
(μm) (μm)
+1.0 --
+1.3 +4.3
+2.6 +5.5
+3.8 +6.8
elevation upper limit
(μm) (μm)
+8.5 --
+3.3 +11.8
+6.5 +15.0
+9.8 +18.3
0.00
+1.03
+2.10
+3.24
+4.46