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F. Barra, B. Antona, A. Barrio, A. Gutierrez, E. Piedrahita, Y. Perez; Comparison of Methods to Determine Tentative Presbyopic Add . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5846.
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Near adds are the most common clinical method to compensate the diminution in the accommodation amplitude associate to presbyopia. The presbyopic add moves the near point of accommodation to a comfortable distance to do near tasks. Usually, the determination of the near add begins finding a tentative add by using the phoropter. Then, trial–frame add refinement is recommended because it is difficult to determine appropriate near working distances and ranges of near clear vision in the phoropter. The purpose of this study was to compare the most common procedures to determine tentative near add in presbyopic patients.
The experiment was carried out with 60 normal subjects with a mean age of 51 years (range 40 to 60 years). Tentative near add was determined using seven different techniques, including the dynamic retinoscopy, one–half amplitude of accommodation (AA), based on the patient age, binocular fused cross–cylinder with and without adding plus lens power, near duochrome and balance of negative and positive relative accommodation. Next, the tentative near add was modified according to other test results, the patient’s history, and the clinical experience to arrive at the final add. This definitive add will be the reference add or "gold standard". The concordance between tests was estimated by using the statistical method of Bland y Altman.
It was studied the concordance between the tentative add from every tests and the final add, with these results: The mean tentative near additions are higher than the gold standard (final add) for every tentative adds except for the fused cross–cylinder without adding plus lens power. The biases are small in clinical terms, always below to 0.25 D. Nevertheless, the difference sometimes has statistical significance. The interval between the 95% limits of agreement correspond to substantial differences, always higher than ±0.50 D. The highest interval corresponds to the comparison of the tentative add from AA with negative lenses and the final add.
We can say that all the techniques perform similar to give a tentative add. On average, tentative adds adjust quite well to the final add. However, due to the intervals of concordance are wide, the probability of error is high. This suggests that, if possible, the tentative add has always to be adjusted according to the particular needs of the patient.
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