The data from the biometry results are fed into a few lens implant power calculation formulae. The most common formulae include the Barret Universal II, SRK-T, Hoffer-Q, and the Hagis.

Based on the biometry results, the surgeons will decide on the artificial lens power to produce the target refraction (glasses prescription).

Surgeons commonly choose a lens implant power to achieve long-distance vision without glasses (emmetropia). Patients will typically need to wear reading glasses after the operation. However, some patients may want to opt for other types of lens implants that could offer some reading vision without glasses. 

In most cataract operations, the surgeons aim to achieve patients focusing long-distance (emmetropia). Therefore, most patients should be able to walk about or even drive without needing glasses. Standard lens implants cannot change the focus, so patients must wear reading glasses unless they opt for a multifocal lens implant.

Some patients may want to remain short-sighted, reading without needing glasses but wearing glasses for distance. Some patients may even want to keep one eye on the distance and one eye focused on the near. The surgeons must discuss these options before surgery to agree on the resulting refraction.

Patients with significant astigmatism (the eyeball is an oval shape rather than a perfectly round shape) before the operation may still need to wear glasses for distance and near after the cataract operation, as routine cataract operation and standard lens implants do not correct for astigmatism. However, some surgeons may perform unique incision techniques (limbal relaxing incision) during surgery to reduce the amount of astigmatism. Still, this technique can only cure a small amount (1-2 diopters) of astigmatism. 

Correction for a higher degree of stigmatism will require toric lens implants. These implants have astigmatic correction incorporated into their optics. However, accurate positioning of the lens implants during surgery is critical to achieving optimal results with minimal residual astigmatism post-operatively. Before surgery, this must be discussed with the surgeons before ordering a particular lens implant.

This lens implant type uses spherical aberration theory to extend the depth of focus. This will allow the patients to be less dependent on reading glasses after the cataract operation. However, this is not a fully multifocal lens implant, so patients will still need reading glasses when engaging in near-vision tasks for long periods.

Generally speaking, surgeons may make one eye more distance dominant and one eye more near dominant to increase the range so that patients can achieve clear vision in a broader distance range.

Most patients are delighted with the outcome of the EMV lens implants. They tend to be satisfied with long-distance and intermediate-distance vision. Most patients can read a magazine or the price tags when shopping. However, most still need reading glasses. Patients are advised to discuss this with the surgeons before deciding to use this lens implant. 

Multifocal lens implants are designed for more spectacle-independent vision. These lens implants' optical section has rings focusing on different focal lengths. They generally divide the focus into long-distance, intermediate and near-vision zones. However, because the focus is shared between three distinct zones, patients may complain of some visual disturbances, mainly when driving at night. Also, there will be some loss of contrast sensitivity.
Nevertheless, most patients can achieve spectacle-independent vision. However, these implants may not be suitable for patients with pre-existing eye conditions that may have already caused problems with their vision, e.g. age-related macular degeneration, and glaucoma. The choice of these lens implants must be carefully discussed with the surgeons to ensure they suit the patient's expectations and lifestyle.