Abstract
Abstract: :
Purpose: To see which accommodation factors are predictors of the presence of myopia and the amount of myopia Methods: Monocular and binocular accommodation facility were measured on 64 young adult subjects (30 myopes, 34 non–myopes, with a mean age of 20.14 + 1.55 years) at 6m using plano/–2.00 flippers and at 40cm using +2.00/–2.00D flippers (cycles per minute). Monocular accommodation response to negative lenses (–1.00D, –2.00D, –3.00D, –4.00D) and monocular and binocular response to target distance (6, 3, 1, 0.5, 0.4, 0.33 metres) were monitored using a PowerRefractor. Tonic accommodation (dark focus and pinhole), accommodative hysteresis and Near–work induced transient myopia was measured with the PowerRefractor. Amplitude of accommodation was measured with a modified push–up method. AC/A and CA/C ratios were determined with the PowerRefractor and MIM card. Results: Multiple regression analysis was carried out including all accommodative factors predicting myopia with p < 0.25. As the most explanatory model of the outcome variable (myopia) using the least number of variables was required, variables were removed starting with the least significant till all variables remaining in the model were significant at p < 0.10. The multiple regression equation was constructed from the unstandardised coefficient values. Myopia = 0.6*amplitude of accommodation –3.7* slope of accommodative response to negative lenses –0.9* pinhole accommodation –1.2* binocular lag of accommodation at 33cm. Conclusions: Four accommodation factors (amplitude of accommodation, accommodative response to negative lenses, tonic accommodation and binocular lag of accommodation accounted for 44% of the myopia present in the young adult subjects.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • myopia • optical properties