Tomey TMS-5, Instruction Manual

Page: 115 / 216

3-65
● SK2
The SK2 is the refractive power of the meridian
at a place where a meridian of SK1 is rotated 90
degrees.
● CYL (Simulated Keratometric Cylinder)
The CYL value of corneal astigmatism can be
obtained from the SimK value (SK1 – SK2). When
the CYL value is larger than the standard, diseases,
external injuries, or surgeries may be the cause.
● SAI (Surface Asymmetry Index)
The SAI is the difference between the refractive
powers measured at two different points opposite
each other (180°) on each ring on the corneal
surface. The value is larger than the normal eye in
the case of keratoconus, penetrating keratoplasty,
refractive power correction operation for miss-
centered myopia, external injuries, and CL warpage.
When the SAI value is large, glasses may not be
sufficiently effective for correction.
● DSI (Differential Sector Index)
The DSI is the largest difference in the standard
refractive power between two sections out of eight
divisions of the cornea. A keratoconus eye shows a
larger value than a normal eye.
● SRI (Surface Regularity Index)
The SRI is related to the eyesight. This is a
measurement of the local fluctuation of refractive
power at the corneal center. When the SRI value is
large, the corneal surface within the pupil diameter
shows an irregular shape and the maximum value
of the eyesight with refractive power corrected by
glasses becomes small.
The SRI value is large in the case of a dry eye,
eyes with contact lenses, external injuries, and
penetrating keratoplasty.