Cortical Cataract and Refractive Error

To evaluate the relationship between the presence of cortical cataract and accommodation effort, using refractive error as a proxy.

Patients between 50 and 90 years, scheduled for cataract surgery, were selected with the help of a photographic database. Nuclear and cortical cataract were graded and patients grouped having no cataract, pure cortical, mixed or pure nuclear cataract. Refraction data at the time of the photograph was converted to estimated spherical equivalent refractive error each patient would have had at the age of 45 years.

From the initial 239 eyes from 239 patients, cases with myopia below -6.5 dpt and hyperopia above 6.5 dpt were excluded, resulting in 199 cases for final analysis. Eyes with no cataract showed the lowest median refractive error (-3.65 dpt), followed by the pure nuclear group (-2.69 dpt). The median refractive error for pure cortical (-0.23 dpt) and mixed cataracts (-0.87 dpt) were close to emmetropia. Cortical cataracts were found in 37% of myopes, 82% of emmetropes, and 85% of hyperopes.

Emmetropes and hyperopes tend to develop more cortical cataract than myopes. These cortical cataracts might be caused by shear stress inside the crystalline lens due to accommodation efforts at the time of onset of presbyopia.