Amplitude of Accommodation and Add Power in An Adult Population of Tehran, Iran

Purpose: To determine add power (AP) and amplitude of accommodation (AA) in a sample of Iranian population and its relationship with refractive errors Methods: This cross-sectional study enrolled people of 35-70 years old by simple random sampling. Exclusion criteria were myopia or hyperopia over 6 diopter (D) and astigmatism more than 0.75 D. Those with a history of eye disorders and taking certain medicines that affect on vision were excluded. After correcting refractive errors, distance and near visual acuity (VA) and APs were determined considering subject’s age and AA at a distance of 33 cm. The AA was measured using a Royal Air Force (RAF) rule with push up method. Results: Of 422 participants, 205 (48.6%) were males with a mean age of 50.2±8.8 years old, mean AP of 1.57±0.82 D, and average AA of 3.48±2.5 D. For each year of age, AP raised 0.1 D and AA decreased to 0.23 D (p<0.001). The need for AP occurs when AA was less than 6 D. Conclusion: The results of this study showed the distributions of AP and AA in a sample of Iranian population. The AA in this study was mid-range in comparison with other studies. It was found that females became presbyopic earlier than males and hyperopes became presbyopic earlier than emmetropes and myopes. These results pointed out that decreasing in AA less than 6 D requires AP.