Intraocular lenses (IOLs) are implanted to replace a cataractous lens or, as phakic IOLs, to correct refractive errors without removing the natural lens. Types include monofocal, toric, multifocal, and phakic designs placed in the anterior or posterior chamber. Preoperative testing (corneal topography, endothelial cell count, anterior chamber depth) determines candidacy. Procedures are usually outpatient and brief, but risks such as infection, elevated eye pressure, lens rotation, endothelial cell loss, and cataract formation (with some phakic lenses) require follow-up. Regulatory approvals for specific devices vary by country and have evolved since the 2000s .
What an implantable contact lens is
An implantable contact lens is commonly called an intraocular lens (IOL). IOLs either replace the eye's natural crystalline lens after cataract removal or are implanted in front of the natural lens to correct refractive errors. The latter are usually called phakic intraocular lenses (phakic IOLs or pIOLs).
IOLs are small corrective lenses made of biocompatible materials (acrylic, silicone, or collamer). They have supporting arms called haptics that center and hold the lens inside the eye.
Types and common uses
- Replacement IOLs: Implanted during cataract surgery when the cloudy natural lens is removed. Modern options include monofocal, toric (for astigmatism), multifocal, and accommodating designs.
- Phakic IOLs: Implanted without removing the natural lens to correct high myopia, some hyperopia, or astigmatism when corneal laser surgery is unsuitable.
- Anatomic placement: IOLs may sit in the posterior chamber (behind the iris) or the anterior chamber (in front of the iris), and some are iris-fixated.
A brief history
Sir Harold Ridley implanted the first successful intraocular lens in London on November 29, 1949. Phakic IOLs and modern foldable replacement IOLs became more widely used from the 1980s onward.
Preoperative evaluation
Surgeons perform a thorough eye exam before implantation. Typical tests include corneal topography, endothelial cell count, anterior chamber depth measurement, pupillary size, and retinal evaluation. Stable refraction (little or no change in prescription) is important for refractive procedures.
Contraindications commonly include shallow anterior chamber depth, low endothelial cell count, active uveitis, uncontrolled glaucoma, and a history of retinal detachment.
The procedure
Cataract surgery with IOL implantation is most often done under local or topical anesthesia. Modern phacoemulsification techniques use a small incision and a foldable replacement IOL; many procedures take 10-30 minutes. Phakic IOL insertion is also typically an outpatient procedure and may involve a small incision.
Surgeons choose lens type and size based on biometric measurements. Proper sizing and placement are important: misalignment can cause residual astigmatism, rotation (especially for toric lenses), or other complications.
Risks and follow-up
Common risks include infection (rare), inflammation, increased intraocular pressure, lens rotation (toric IOLs), endothelial cell loss (notably with some anterior-chamber phakic lenses), and, for phakic IOLs, a small risk of early cataract formation. Regular follow-up exams monitor visual outcome, intraocular pressure, and corneal health.
Modern notes
Phakic IOLs are a valuable option for patients who cannot have corneal refractive surgery. Advances in lens materials and designs have broadened choices for both cataract and refractive correction. Specific device approvals and indications vary by country; ask your ophthalmologist for the most current, locally relevant options and regulatory information. Some regulatory milestones for phakic IOLs in the United States occurred in the 2000s and later .
- Confirm specific US FDA approval dates and labeled indications for major phakic IOL devices (e.g., Visian ICL/EVO) and update text accordingly.
- Verify any recent regulatory milestones or name changes for phakic IOL models referenced (device names and approvals vary by country).