Astigmatism prevalence and biometric analysis in normal population.

PURPOSE: To analyze the magnitude, orientation, and age-related changes of corneal astigmatism and its correlation with biometric parameters in healthy eyes.

METHODS

Patients over 15 years of age were enrolled in our study. Exclusion criteria were previous ocular surgery, corneal disease, or contact lens wear. Axial length (AL), keratometric readings, and anterior chamber depth (ACD) were assessed using IOLMaster.

RESULTS

In our study, 1092 eyes were examined. The mean age was 69.64 ± 15.25 years (range 
15-100 years). The AL was 23.32 ± 1.49 mm and ACD was 3.17 ± 2.03 mm. Higher AL and ACD values were observed in male patients. The overall astigmatism was 0.89 ± 0.72 D. The magnitude of astigmatism was =0.5 D in 73.53% of the cases, =1.0 D in 32.78%, =1.5 D in 13.55%, and =2.0 D in 6.86%. In our population, 582 eyes (53.3%) showed with-the-rule astigmatism, 309 (28.3%) against-the-rule, and 201 (18.4%) oblique astigmatism, regardless of sex. Significant against-the-rule astigmatic shift was verified with aging. Significant correlation was found between age and ACD (r = <0.39, p<0.001), age and AL (r = <0.15, p<0.001), and AL and flat (r = <0.54, p<0.001) and steep keratometric readings 
(r = <0.49, p<0.001).

CONCLUSIONS

In order to obtain adequate refraction results, at the time of cataract surgery distinct attention should be drawn to ophthalmologic biometric parameters, which are continuously changing even in adulthood, and to astigmatism above 1.0 D, present in >32% of the population.