Topcon ALADDIN HW3.0, User Manual

Page: 39 / 170

ALADDIN
- User manual Rev. 19 EN of 10/07/2019
39
o
Unknown
o
Silicon
o
PMMA
o
Acrylate
o
Memory
The measured axial eye length depends on the measuring mode selected. Depending on the measuring mode
selected, ALADDIN HW3.0 corrects the measurement with a constant defined as follows.
ALADDIN HW3.0 device takes into consideration two conditions of the eye that can alter the measurement
of axial length:
-
Vitreous body filled of silicone oil
-
Implant of intra ocular lens
The difference of the measurement is caused by a different group refraction index considered in the formula.
According to bibliographic data, the calculations have been performed to assess the amount of correction
that must be applied to correct the measurement in these special cases.
The correction data have been compared with predicate device assumptions and a table of corrections has
been elaborated as follows:
The correction values (in mm) of the natural vitreous body
Phakic 0
Aphakic 0.21
Pseudophakic Unknown material 0.11
Pseudophakic Silicone IOL 0.12
Pseudophakic PMMA IOL 0.11
Pseudophakic Acrylic IOL 0.1
Pseudophakic Memory IOL 0.11
For the vitreous body you can choose between:

Natural: the vitreous body has never been operated or treated such as to alter its composition.

Silicon Oil: the vitreous body has been filled, even only partly, with silicon oil.
The correction values (in mm) of the vitreous body filled by Silicon Oil
Phakic -0.74
Aphakic -0.86
Pseudophakic Unknown material -0.75
Pseudophakic Silicone IOL -0.74
Pseudophakic PMMA IOL -0.75
Pseudophakic Acrylic IOL -0.76
Pseudophakic Memory IOL -0.75
All this information is required because, on the basis of the artificial materials and their optical properties
present inside the eye, the instrument always corrects the measurements obtained to the most precise value
possible.
Once this information has been entered, you can access the acquisition environment.