Researchers in Belgium recently discovered a patient’s scleral shape can impact their corneal astigmatism, upending previous assumptions that only the corneal shape was important.

With the hypothesis that asymmetry in scleral contour may influence the topography of the corneal periphery, the study looked at the scleral shape of 22 participants, 11 with astigmatism and 11 without. Using three-dimensional maps from a corneoscleral topographer, the researchers calculated elevation differences and compared that with decentration and astigmatic values.

They found corneal and scleral asymmetry were highly correlated in astigmatic eyes but independent of each other in eyes without astigmatism. “Although the scleral shape is not significantly different between nonastigmatic and astigmatic participants, scleral and corneal asymmetry are related in astigmatic eyes,” the study says.  

“To the best of our knowledge, this work is the first evidence to show that scleral astigmatism ‘follows’ corneal astigmatism, which suggests that astigmatism is not restricted to the cornea but should rather be considered a property of the entire eye globe,” the researchers conclude.