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Can Cataract Surgery Cause Unequal Vision?



First, it’s important to understand the basics of cataract surgery. The process involves replacing the natural lens of the eye with an artificial one. If the process is being done on both eyes, doctors tend to favor a waiting period between the first and second operations. Inevitably, during this transitional phase, the treated eye will be out of balance with the untreated eye, a condition known more formally as anisometropia.

Wearers of contact lenses have a distinct advantage coping with this in-between phase, since they can insert one of their two contact lenses into the untreated eye. For those who favor glasses, this half-applied method is not an option. In their case, a patch or grin-and-bear-it approach are the more tangible options.

A Difference Measured in Diopters

The other major kind of vision imbalance comes after the operation on both cataracts is complete. Because of the complicated nature of the eye and the different ways that individuals react to the surgery, there is often a slight new imbalance of vision between the two eyes.

For example, one 57-year-old patient found that after the surgery, there was a difference of three diopters in the refractive error between his two eyes. A diopter is a unit of measurement for the power of the artificial lenses implanted during cataract surgery. What this patient experienced is actually something that some cataract surgery patients opt for deliberately, as part of an effort to achieve monovision (the adjustment of one eye for distant vision and the other eye for near vision).

Possible Solutions

Those, like the 57-year-old patient aforementioned, who suffer from more permanent unbalanced vision have a number of different options. They can, quite simply, choose to adjust to this mild form of monovision. Or, they can try eyeglasses with a corresponding diopter difference in the two lenses. Surprisingly, most patients cannot comfortably wear these types of glasses, which then leaves the door open for Lasik surgery on one eye or an even more expensive operation called an IOL exchange.



Oxford Radcliffe Hospitals – Vision Imbalance After Cataract Surgery, Retrieved June 9, 2011 from – Anisometropia After Cataract, Retrieved June 9, 2011 from

MSN Encarta – Definition: Diopter, Retrieved June 9, 2011 from

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