Topcon ALADDIN HW3.0, User Manual

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ALADDIN
- User manual Rev. 19 EN of 10/07/2019
101

Curvature Irregularity: Irregularity of curvature calculated on the standard deviation of the
instantaneous readings for a 4.5mm diameter cornea area

Asy SAI: Asymmetry between the most curved hemisphere and the flattest one calculated
for 4.5mm diameter cornea area and an SAI (Surface Asymmetry Index) that represents the surface
asymmetry index of the 4.5mm diameter cornea area.
12.1.3 Keratoconus
Press the “ KC ” button to open Apex keratometry with the following information:
Figure 62

AK: Apical curvature.
Represents the power of the cornea in its apex

AGC: apical gradient of curvature.
Represents the corneal power average variations (per unit of length), taking the apical power as
reference.

SI: difference between the average power of two circular zones centered in the vertical axis of the
ruler and placed in the lower hemisphere and in the upper hemisphere of the cornea respectively.

Kpi: Keratoconus diagnosis probability index.
Based on the combined evaluation of the first three indices with the probability index, there are three
different possibilities: topographic picture not compatible with keratoconus (green); suspected keratoconus
(yellow); topographic picture compatible with keratoconus (red).
If the topographic picture is compatible with keratoconus or indicates a suspected keratoconus, the
numerical values of the geometric parameters of the cone are shown at the bottom of the panel. These are:

A: area of the keratoconus (mm²)

D: average diameter of the keratoconus (mm)

r, ø: polar coordinates (mm, °) of the barycentre of the keratoconus in relation to the centre of the
map

RND: circularity factor of the keratoconus