IOL Power Selection
Click to IOL in the starting menue. After that a new window displayes the
supported IOL types. Choose one of them, then click to ok. Now a window
opens in which the biometric data can be entered. If a corneal topography
is loaded (see previous section), the corneal radii are already preset. They
may be altered here anyway. In addition axial length and target refraction
have to be entered.
After entering the axial length value the measuring device has to be
selected from a menue. This selection menue is presented each time a new
value is entered for the axial length. It is not presented, however, if only
other data (e.g. the IOL model) have been modified. In this case, the old,
previously entered value is shown left from the transformed one which is
used for internal calculations.
If the axial lengths are taken from a biometry device directly connected
by a cable, the transformation is done automatically.
After IOL calculation (and optional printout) the axial length of the second eye is to be measured. Because of the higher probability of operating errors the eye selection (right/left) preset in the biometer is not used in OKULIX. In OKULIX installations with integrated topography (TMSworkstation) the program askes whether topographic measurement is wanted (with topography or without topography) and whether axial length shall be measured or entered (measure length or enter length). In the next window the ACD is given which is proposed instead of the mean value of the corresponding IOL type. In most cases the proposed value will be agreed to by the user. He may, however, enter another one, e.g. in case of special anatomical conditions. The IOL power level is determined for just this ACD and indicated togther with the scaling factor (in mm/deg.) of the imaging on the retina if the option calculate scaling of retinal image size is selected. Entering different values shows the strong influence of the ACD on the result. The whole process of IOL power selection can also be performed inside the Retinal Image module. Different IOL (types as well as power levels) can easily be compared to each other. A spherical prescription glass with the target refraction should be applied for this comparison. If a topography is loaded, also the astigmatism should be corrected by a prescription glass. A printout of the results of the IOL calculation can be produced by pressing the print button. The printout also contains the topography, if present, and the meridional refraction error with the selected IOL. Also the plot of the ultrasound measurement is printed if the measurement of the axial eye length has been performed by a directly connected ultrasound device. The data of up to two different IOL types can be printed on one page. It should be noticed that the refraction error map is valid only for the first one of these IOL. |