It is a compromise because the distance eye does not read without glasses and the near eye cannot see in the distance. There may still be times when top-up glasses will be required such as:
- Driving a car in poor light conditions, particularly when it is raining.
- Prolonged reading, as it can be tiring to read with only one eye.
The main advantages of monovision are that using modern aspheric monofocal IOLs or toric IOLs usually gives good optical quality without halos, ghosting or glare. With monovision you can still wear glasses that correct both eyes for distance or both eyes for near vision and achieve good optical quality. Achieving monovision with monofocal IOLs or toric IOLs is cheaper than using either multifocal or accommodating IOLs.
Aspheric IOL’s correct for aberrations resulting from a change in curvature between the centre and edge of the pupil. These aberrations can causes multiple focal points and thus blurry vision.