If the measured values do not match those of the test eye, check the alignment in the fixation window and
take a second measurement. You should also make sure that the lens in the patient fixation window is not
dirty (see below). If the instrument still seems to be out of calibration, call Humphrey Systems Customer
Service.
Cleaning the Patient Fixation Window
Check the fixation window regularly for dust and smudges because a dirty lens can cause erroneous
readings. Unusually high sphere or cylinder readings can be the result of dirt on the patient fixation
window.
Note: The lens in the patient fixation window has a special coating that is easily scratched. Take care
in cleaning it.
To clean the window, first use a camel hair brush to gently remove the dust from the lens. Then dampen a
lintless camera lens tissue with a camera lens cleaning solution and gently wipe the lens surfaces to remove
smudges or fingerprints.
Cleaning the Screen and Outer Casing
Wipe the screen with a clean, dry cloth. Do not use any cleaner.
Clean dirt spots and dust from the outer casing with a clean cloth and mild detergent or isopropyl alcohol.
Never spray detergent or alcohol directly on the casing.
For reasons of hygiene, be sure to wipe the forehead rest and the chin rest with an alcohol swap after each
patient.
Changing the Fuses
Two fuses are located in the fuse box on the side of the instrument just above the on/off switch and the
power cord attachment. Your Acuitus accessory kit contains two replacement fuses of the correct type and
rating.
To change the fuses:
Turn the instrument off and unplug the power cord.
Use a small screwdriver to gently pry open the cover to expose the fuse holders (marked with an arrow).
Slide out each fuse holder and check the filament for breakage. Remove the defective fuse.
Insert a new fuse in the fuse holder. Slide the fuse holders back into the housing with the arrow pointing to
the right. Push the cover up and in until it snaps in place. Plug in the power cord.
Caution: Use replacement fuses of the correct type and rating (T 2.0 slow blow, 250V). Failure to do
so could damage the instrument.
Zeiss Humphrey Systems Acuitus User Manual
PN 50648 Rev A June 2001
18