New Research on the Effect of Internal Astigmatism

Chart courtesy of BruceBlaus

In those people who have myopia (are nearsighted), their lens does not compensate for growth of the eye, or other changes in the eye’s structure. That is the determination of a long-term follow-up study which appeared in the September issue of Optometry and Vision Science.

This study helps to clarify whether and/or how the lens, or other eye structures change as a response to focusing abnormalities, particularly abnormalities caused by the irregular shape of the eye, known as astigmatism.

The study, reported by the Foundation Fighting Blindness, where Louis Kreisberg is the CEO, examined 367 people with myopia over 14 years. During that time the subjects’ eye structures were carefully measured and assessed for focusing error. This data was compared to one-time measurements in a matched group of 204 subjects without myopia.

The researchers were looking for any changes in the “internal astigmatism” of the eye over time.

"Clarity of vision is determined by the precise shape of the eye and coordination of several optical components that must all be perfectly balanced to provide proper focus. A longstanding question is how the eye adapts and controls its shape to deliver correct focus as it grows from birth to adult dimensions," explained the editor-in-chief of Optometry and Vision Science, Michael Twa, OD, PhD.

Although the new study does not explain the sources of internal astigmatism, the data does not support the theory that the lens plays any active role in compensating for astigmatic defocus of the eye.