Tomey UD-600, Operator'S Manual

Page: 207 / 262

4-15
4.4.2 Dense cataract
Measured axial length is calculated in the similar manner to
that using the normal average sound velocity.
4.4.3 Aphakic
Measured axial length is calculated in the same manner to
that using the normal average sound velocity.
4.4.4 Pseudophakic (1 to 3)
The factory setting of the IOL ultrasound velocity is the refer-
ence assumed from the below table. The IOL ultrasound ve-
locity varies depending on the material, manufacturer and other
conditions, such as room temperature.
Axial length is calculated by the following formla.
Lp: Axial length
Th: IOL thickness in the center (Input by user)
V
acd
: ACD ultrasound velocity
V
vit
: Vitreous ultrasound velocity
t
acd
: ACD measurement time
t
vit
: Vitreous measurement time
V
acd
·
t
acd
V
vit
·
t
vit
LP = ————— + Th + ————
2 2
Material IOL sound velocity (Default)
Pseudophakic1 PMMA 2718m/s
Pseudophakic2 Silicon 1049m/s
Pseudophakic3 Acryl 2200m/s
4.4 Axial length calculation of Biometry