Accommodative amplitude using the minus lens at different near distances

Area of Science:

• Ophthalmology
• Optometry
• Vision Science

Background:

• Accurate measurement of amplitude of accommodation (AA) is crucial for understanding visual function.
• The minus lens (ML) procedure is a common method for assessing AA.
• Investigating the impact of testing distance on ML-AA measurements is important for clinical practice.

Purpose of the Study:

• To compare the mean findings and repeatability of the minus lens (ML) amplitude of accommodation (AA) measured at 33 cm and 40 cm.
• To evaluate the reliability of ML-AA measurements at different working distances.

Main Methods:

• Amplitude of accommodation (AA) was measured using the ML procedure in 120 subjects.
• Measurements were taken from the dominant eye at target distances of 33 cm and 40 cm.
• Each measurement was repeated within 24–48 hours to assess repeatability.

Main Results:

• Mean AA was significantly higher at 33 cm (10.20 D) compared to 40 cm (8.85 D) (P < 0.001).
• Repeatability coefficients were ±1.24 D at 33 cm and ±0.99 D at 40 cm.
• Retest reliability (intraclass correlation coefficient) was high at both distances (0.87 at 33 cm, 0.91 at 40 cm).

Conclusions:

• There is a lack of agreement between ML-AA measurements obtained at 33 cm and 40 cm.
• Testing at 40 cm may offer superior repeatability.
• Further research is needed to clarify if the difference in AA reflects a true proximity effect or a change in blur perception.