Refractive errors before and after presbyopia

Abstract Background: Some studies have shown that eyes undergo a hyperopic shift after the presbyopia, whereas others have reported a myopic shift. Objective: The purpose of this study was to determine types and the degree of refractive errors before and after presbyopia. Methods: This was a cross sectional study carried out at the department of optometry (Mashhad University of Medical Sciences) in 2001. Following routine optometric examination, the type and degree of refractive errors of 500 patients before and after presbyopia were statically analyzed using X2 and student t-tests. Findings: The prevalence of hyperopia was 19.4% before presbyopia which later increased to 40.1% (p<0.001). Following the occurrence of presbyopia, against-the-rule astigmatism increased to 12.3% whereas the with-the-rule astigmatism decreased to 12.9% (p<0.001). The distribution of oblique astigmatism was 3.7% and 3.4%before and after presbyopia, respectively. The gender had no effect on refractive errors before and after presbyopia. Conclusion: The presbyopia caused a reduction in optical power of eyes and also increased hyperopia. Reduced rigidity of the upper tarsal plate associated with presbyopia, caused an increase in the against-the-rule astigmatism.