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Overview :
Central lens opacities are likely to interfere with vision
clinically. The method of Mehra and Minassian for grading central lens opacities
is based on the area of the lens opacity obscuring the red reflex relative to
the area of the clear red reflex. This is a rapid test that is useful in
prevalence and epidemiological studies and which gives consistent results
between observers.
Method:
• The pupil is undilated.
• A direct
ophthalmoscope is used to observe the red reflex, set at +2 D and held
approximately 33 centimeters from the eye.
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Finding |
Grade |
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clear red reflex, no opacities |
0 |
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few small dot opacities in the lens appearing as tiny
scattered dark spots in the red reflex. Maximum area occupied by dots 1
square mm. |
1 |
|
lens opacity obscuring part of the red reflex. Area
obscured is smaller than area of clear red reflex |
2A |
|
lens opacity obscuring part of the red reflex. Area
obscured equal to or larger than area of clear red reflex. |
2B |
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lens opacity totally obscuring the red reflex |
3 |
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aphakia or displaced lens |
4 |
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unable to assess red reflex due to corneal opacity,
etc. |
5 |
after Table 1, page 802, Mehra (1988)
where:
• aphakia = absence of the lens
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