Phakic intraocular lenses are indicated for patients with high refractive errors when the usual laser options for surgical correction (LASIK and PRK) are contraindicated.

[1][2] Phakic IOLs are designed to correct high myopia ranging from −5 to −20 D if the patient has enough anterior chamber depth (ACD) of at least 3 mm.

Due to the risk of higher order aberrations there is a current trend toward reducing the upper limits of LASIK and PRK to around -8 to -10 D.[4] Phakic intraocular lenses are safer than excimer laser surgery for those with significant myopia.

[5] Phakic intraocular lenses are contraindicated in patients who do not have a stable refraction for at least 6 months or are 21 years of age or younger.

Although PIOLs for hyperopia are being investigated, there is less enthusiasm for these lenses because the anterior chamber tends to be shallower than in myopic patients.

In the case of PIOLs made of polymethylmethacrylate (PMMA), surgical insertion requires a larger incision, which may result in postoperative astigmatism.

By comparison, PIOLS made of a foldable gel-like substance require a very small incision due to the flexibility of the material and thus significantly reduces astigmatism risk.

[citation needed] Another concern is progressive shallowing of the anterior chamber which normally occurs with advancing age due to the growth of the eye's natural lens.

[6][7] If a phakic IOL patient is assumed to have a 50-year lifespan, the overall decline in ACD may add up to 0.6–0.85 mm, long-term data about this effect are not available.

[citation needed] Anterior chamber depth (ACD, i.e. the distance between the crystalline lens and cornea including the corneal thickness) is required before the surgery and measured with the use of ultrasound.

Rather it depends on central corneal power, anterior chamber depth (ACD) and patient refraction (preoperative spherical equivalent).

Once in the anterior chamber and while firmly holding the lens with forceps, temporal and nasal iris tissue is enclavated with a special needle.