28
Safety
G-30-1529-en
OPMI® VISU 160 on S8, S81 & S88 Suspension Systems
Issue 5.0
Printed on 09. 10. 2006
In the following, comments on these aspects are given and a description
of how Carl Zeiss, as a manufacturer, makes allowance for them in its
systems.
Illumination characteristics (spectral composition)
Studies on exposure of the eye to light of varying spectral composition
date back to the early 1950s. These studies suggest that the potential
hazard of phototoxic injury to the patient's retina can be reduced by
blocking out the blue and ultraviolet light below a wavelength of 475 nm.
Carl Zeiss provides a GG 475 retina protection filter for surgical micro-
scopes recommended for use in ophthalmic surgery. This reduces not
only the light exposure of the patient's eye, but also that of the surgeon's.
It should be noted in this context that the use of filters inevitably leads to
a change in the color of the light. The surgeon may therefore have to get
used to the changed appearance of anatomical structures.
Illumination intensity
The majority of researchers suggest that the surgeon should use the
lowest light intensity required at the patient's eye to guarantee good
viewing during surgery.
Carl Zeiss has addressed this aspect by providing its systems with a de-
vice for continuously varying the brightness of the light source. This per-
mits the surgeon to optimally adapt the light intensity at the patient's eye
to the conditions existing in each case.
Angle of illumination
A number of publications
1)-4)
suggest that the microscope should be tilted
to reduce the exposure of the macula to direct illumination.
Carl Zeiss ophthalmic surgical microscopes are therefore equipped with
the following:
–
Tilting mechanism for the microscope body
–
Oblique illumination with brightness control
Focus of the light source
Studies show that injuries are likely to occur if the filament of the light
source is imaged on the patient's retina. The peak intensity of a filament
is considerably higher than that of an even and extended light source
such as a light guide.
