The IS16 fitting set has 13 lenses, K1 to K13. The reference sag is stated for the landing diameter of 13.90mm, with an incremental increase in sag provided in the fitting set.
INITIAL TRIAL LENS SELECTION Select a lens which lands on the sclera to provide about 250 to 350 microns of APICAL CLEARANCE. • For cases of mild to moderate keratoconus start with the K4 lens (4300µm at 13.90mm); • For advanced keratoconus start with the K8 lens (4700µm sag at 13.90mm).
APICAL CLEARANCE ADJUST the apical clearance by selecting a trial lens – increase sag until desired clearance is achieved. LIMBAL CLEARANCE Should be 50µm to 150µm (0.050 to 0.150mm). If the limbal clearance is not adequate when the apical clearance is correct, ADJUST in 50µm steps; ask for increased or decreased limbal clearance as a custom parameter when ordering. Each adjustment step for limbal clearance is 50µm (0.050mm) measured at a chord diameter of 11.80mm. SCLERAL LANDING ZONE The peripheral landing zone should align with the sclera in all four quadrants. The lens has a flat meridian which is marked (see diagram), Adjust peripheral alignment in steps of 25µm (0.025mm). LIMBAL CLEARANCE and the SCLERAL LANDING ZONE may be adjusted independently in each of the four quadrants. In any one quadrant these parameters may be adjusted independently of each other. LENS POWER The IS16 lens can be specified to have spherical or toric powers. For toric prescriptions note the flat meridian axis. The lens may also be specified as a bifocal. TORIC PERIPHERY All lenses have 300 microns of toricity in the periphery to allow for a better fit in a greater number of patients.
Assessment of lens fit
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