Achieving spectacle independence is the holy grail of cataract surgery. To achieve this, a patient requires the ability to focus at near, intermediate and long distance without the need for glasses or contact lenses. In an eye that has not had cataract surgery, this is occurs via a process called accommodation. The natural lens within the eye changes shape when gaze is directed from far to near or visa verse. This brings the object to which gaze is directed into focus.
Following cataract surgery the ability to accommodate is lost. To overcome this, several options are currently available:
- Monovision: one eye is corrected for distance vision and the other eye is corrected for near vision. When the 2 eyes are used together, the patient can see both near and far without the need for glasses
- Multi-focal: At the time of cataract surgery, intra-ocular lenses with multiple focal lengths are placed in the eye. This allows the patient to see both near and far for both eyes without glasses.
Given the different options for achieving spectacle independence, it is not clear whether one option is better than the other. A recent study by Labiris et al compared mono vision to multifocal correction in 38 and 37 patients respectively. They found no difference in visual acuity for distance or near between groups however spectacle correction for near was more frequent in the mono vision group. This was offset by the finding of increased adverse side-effects such as glare and shadows in the multi-focal group. The authors conclude that whilst visual outcomes are excellent in both groups, spectacle independence is more often achieved with multi-focal intra-ocular lenses but this is at the expense of increased visual symptoms.
Labiris et al. J Cataract Refract Surg. 2015; 41(1):53-7