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Quick and Accurate Determination of Presbyopic Addition
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The optical correction of presbyopia must be handled individually. Our aim was to compare the methods used in addition to the refractive near vision, with the final addition used in presbyopic patients.
Eighty healthy subjects with a mean age of 49.7 years (range 40 to 60 years) were studied. Tentative near additions were determined using four different techniques: one-half amplitude accommodation with minus lenses (AAL); one-third accommodative demand with positive lens (ADL); balanced range of accommodation with minus and positive lenses (BRA) and crossed cylinder test with initial myopisation (CCT). The power of the addition was then refined to arrive at the final addition.
The mean tentative near additions were lower than the final addition for ADL and BRA addition methods. The mean differences between tentative and final additions were low for all the tests examined (less than 0.25 D). The intervals between the 95% limits of agreement differed substantially and were always higher than ±0.50 D.
All the methods used displayed similar behavior and provided a tentative addition close to the final addition. The coefficient of agreements (COA) detected suggests that every tentative addition should be adjusted according to the particular needs of the patient.
From a previous study at the Optometric Center of Fullerton, it was found that 17.5% of the review clinic population returned due to improper presbyopic reading adds. The population sample for the present study consisted of patients between 40-60 years of age who returned to the clinic between September 1983 and May 1985 due to improper add power. The add power originally prescribed was compared to each of four commonly used methods of add power determination. Our results indicate that the age expected add powers account for the fewest errors while the binocular cross cylinder the most. Upper and lower limits for an acceptable range of add powers versus age were determined.
Clinical Optics and Refraction: A Guide for Optometrists
- C Christie
Christie C. Clinical Optics and Refraction: A
Guide for Optometrists. [Internet].