Relationship between age and presbyopic addition using a sample of 3,645 examinations from a single private practice.

Background: This study uses information collected in a private optometric practice to describe the relationship between age and the add power needed to correct presbyopia.

Methods: Computer-assisted data analysis with a database management program, Q&A, and Microsoft Excel was used to assess the relationship between age and presbyopic addition. Data collected from 3,645 examinations by one practitioner in a single private practice--over a period of approximately 23 years--were entered into the database. The patient base was primarily white and about equally divided between the sexes. The practitioner generally used the fused cross cylinder for the tentative presbyopic addition and refined this by patient preference and best visual acuity at near, all using a carefully determined near working distance.

Results: The presbyopic addition increased rapidly in patients from ages 40 to 50 years, the rate at age 40 being about 0.22 diopters per year and the average rate during the 40- to 50-year-old decade being about 0.12 diopters per year, or approximately 0.25 diopters every 2 years. After the patient reaches 50 years of age, the presbyopic addition increased more slowly, at the rate of approximately 0.03 diopters per year--or approximately 0.25 diopters in 8 years.

Conclusions: Quantitative data taken from more than 3,600 refractions showed a nearly parabolic relationship between age and presbyopic addition from approximately the age of 40 to 75 years.