FITTING POST REFRACTIVE SURGERY PATIENTS
These patients present with corneas that are flatten
centrally in a 6-8 mm zone. It
is best to think of this fitting challenge as fitting two distinct areas –
the flatter ablated zone and the original host cornea.
STARTING TRIAL LENS:
Take the central Ks and a reading at the 4 mm temporal area.
Manual Keratometer Fitting: Take central Ks and then
get temporal measurements or use pre-surgery K readings.
The base curve of the Dyna
Intra-Limbal lens will be 1
diopter steeper than the flat central K.
To determine the amount of reverse curve needed, calculate the
difference between the base curve and the 4 mm temporal measure. * i.e.
central Ks of 40.00/42.00 and 4 mm temporal K of 44.00. Select a trial lens of 41.00 with 3 diopters or the Series B
Flat K = 40.00
One D. steeper than flat central K of 40.00 D. + 1 =
Base curve is 41.00 D.
Difference between base curve of 41.00 D. and temporal K
of 44.00 = 3D.
Try a Series B Special
Reverse Geometry Series that has a 3 D. reverse
DESIRED FLUORESCEIN PATTERN
An alignment pattern is the ultimate goal, but that is
difficult to achieve. Get as
close to an alignment pattern as possible.
You want to see minimal vaulting in the central region. The lens with an 11.2 mm diameter, will move only 1/2 - 1 mm and
should not impinge the limbus. The lens is made from Menicon Z material for
good oxygen transmission and good wetting so metabolic wastes are washed
In our example if the mid-peripheral area is pinched
off, you need less reverse curve so go to a Series A. If the mid-peripheral area is showing pooling you need more
reverse curve so go to the Series C.
Select the 11.2 mm diameter unless you have a small
cornea or a very large cornea. Lenses are available from 10.0 to 11.6 mm.
All other parameters are totally custom and all parameters are available.
No one peripheral system will work on all corneas.
You can get the edge profile in standard or any degree of flatter or
steeper. * i.e. one step flatter, two steps flatter, etc.
DO NOT fit the edge too tight. You MUST have adequate tear exchange under the lens.
REVERSE CURVE INFORMATION
Series A has 2 D. of reverse curve
Series B has 3 D. of reverse curve
Series C has 4 D. of reverse curve
Series D has 5 D. of reverse curve
Series E has 6 D. of reverse curve