19
DEUTSCH
ENGLISH
FRANÇAIS
ITALIANO
ESPAÑOL
NEDERLANDS
PORTUGUÊS
SVENSKA
DEUTSCH
ENGLISH
FRANÇAIS
ITALIANO
ESPAÑOL
NEDERLANDS
PORTUGUÊS
SVENSKA
© HAAG‑STREIT AG, 3098 Koeniz, Switzerland ‑ HS‑Doc. no. 1500.7220055‑04150 – 2022 – 09
7.5 Technical data of T-Cone (option)
Type designation:
T-Cone
Weight:
0.2 kg
Diameter:
ø 84 mm
Placido rings:
11
Length:
63.5 mm
Covered optical zone:
≤ 6 mm
7.5.1 Normative considerations
• The T-Cone complies for the central and medial measuring zones with the
standard EN ISO 19980 for corneal topography systems, type B. The T-Cone
does not cover the peripheral measuring zone.
• The T-Cone complies for the central and medial measuring zones with the
standard ANSI Z80.23 for corneal topography systems, type B. The T-Cone
does not cover the peripheral measuring zone.
7.5.2 Measuring accuracy
Test surface (axial curvature difference in mm / elevation difference in μm)
Central zone (Diameter ≤ 3 mm)
Middle zone (3 < Diameter ≤ 6 mm)
Mean value
Curvature
diff.
2 σ
Curvature
diff.
2 σ
Elevation
diff.
Mean value
Curvature
diff.
2 σ
Curvature
diff.
2 σ
Elevation
diff.
Toric (mm)
R
1
=7.987
R
2
=7.584
0.006
0.065
0.66
0.004
0.044
0.33
Ellipsoid (mm)
R=7.79
k=−0.255
0.001
0.083
0.78
0.020
0.038
1.51
Sphere 1
(mm)
R=6.448
0.013
0.037
0.61
0.012
0.025
1.12
Sphere 2
(mm)
R=7.804
−0.008
0.034
0.33
−0.008
0.026
0.75
Sphere 3
(mm)
R=8.844
−0.017
0.056
0.46
−0.024
0.038
1.61
Sphere 4
(mm)
R=10.501
−0.040
0.082
0.48
−0.069
0.044
0.58
2 σ = Two standard deviations
Sphere 1: ø11.5 mm
Toric, ellipsoid, sphere 2,3,4: ø14 mm
All surfaces: Precision ± <1 μm
Test surfaces were centred within ± 0.1 mm and their symmetry axes aligned within ± 0.5° with regard to their
measuring axis.
7.5.3 Reproducibility
Human cornea (axial curvature difference, D / elevation difference, μm)
Central zone (Diameter ≤ 3 mm)
Middle zone (3 < Diameter ≤ 6 mm)
Mean value
1 σ
2 σ
Mean value
1 σ
2 σ
−0.001 / −
0.38 / 0.66
0.76 / 1.31
−0.020 / −
0.36 / 3.22
0.72 / 6.45
n = 42 eyes
1 σ = One standard deviation
2 σ = Two standard deviations
8 Software / Help menu / Error messages
The software’s help section contains instructions and help for performing an examin-
ation and descriptions of the error messages. The help can be opened via the F1
key or in the [?] – [Help] menu.
WARNING!
The software must be installed by trained personnel in accordance with
the separate installation instructions.
