APPASAMY ASSOCIATES KMS 6, Руководство пользователя

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meridians nearest is established for the cornea in the meridians nearest to 0-180 degree.
On the right, or vertical measuring drum the power it established form the cornea in the
meridian nearest to 90 degree. The difference between these two readings is the amount of
corneal astigmatism in the eye under examination. If they are the same, there is no
measurable corneal astigmatism.
Axis of Astigmatism
The meridian indicators of the keratometer tube are white lines on the instrument body
facing the operator. The horizontal marks on each side indicate the meridian measured on
the vertical drum. The vertical mark on top indicates the meridian measured on the vertical
drum. If the astigmatism is to be corrected in a minus cylinder from, take for its axis the
mark representing the drum having the/lower dioptric reading. If the astigmatism is to be
corrected in a plus cylinder from, use the axis mark representing the drum having the
higher dioptric reading. The keratometer axis will usually corroborate that found with the
Retinoscope.
“With” and “Against” the Rule Astigmatism
The power as read at or 90 degree is usually greater than that at or near 180 degree. In
other words, the reading on the vertical measuring drum is usually greater than that on the
horizontal drum, if the power in the vertical is greater than that in the horizontal meridian,
the astigmatism is said to be “With the rule”. If the power at or near 30 degree is less than
that at or near 180 degree, the astigmatism is said to be “against the rule”.
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