Aim: To measure the distance from the eye and the
refraction of the eye at the point at which print blurs
and the point at which it becomes unreadable.
Methods: Subjective accommodation in 7 early
presbyopic subjects (mean age 45 years), with no
additional near correction, was tested using 6/12
reduced Snellen and 6/12 Lea symbols. The point at
which blur was first noticed and the point at which
the print became indistinguishable were noted in
centimetres. Objective measures of refraction were
taken at each of these points.
Results: Subjective and objective results for reduced
Snellen and Lea symbols were similar ( p = 0.91;
p = 0.81) as were the points where the print was no
longer distinguishable ( p = 0.23; p = 0.72). The difference between the blur point and the indistinguishable
point measured in centimetres for both the
reduced Snellen text and Lea symbols were statistically
significant ( p = 0.005; p = 0.0001). The objective
measures for these points, however, were not
statistically different ( p = 0.32 and p = 0.63, respectively).
Conclusion: A clinically significant difference exists
in the distance from the eyes between the point at
which text blurs and the point at which it becomes
indistinguishable. No significant change occurs in
accommodation when measured objectively after the
blur point. It is recommended that the end point of
this test is the point at which print starts to blur
