Types of IOL
Reading File
Finding Sources
Searching PubMed
"intraocular lenses"[MeSH Terms]
Searching the Web
AAO intraocular lens types monofocal multifocal toric EDOF accommodating
Types of intraocular lenses (IOLs)
IOLs are artificial lenses implanted most commonly after cataract removal. They can be classified by optical function, material, site of fixation, and design.
1. By optical function
| Type | Main purpose | Key point |
|---|---|---|
| Monofocal IOL | Focus at one distance, usually distance | Most commonly used. Reading glasses are often needed for near work. |
| Multifocal IOL | Distance and near vision | May reduce spectacle dependence, but can cause glare, halos, and reduced contrast sensitivity. Includes bifocal and trifocal IOLs. |
| Extended depth-of-focus (EDOF) IOL | Distance plus intermediate vision | Often provides good computer-distance vision; reading glasses may still be required for fine print. |
| Accommodative IOL | Attempts to change focus using ciliary-muscle movement | Designed to provide a range of focus, though near vision results can vary. |
| Toric IOL | Corrects corneal astigmatism | Can be monofocal, EDOF, or multifocal. Accurate alignment is required. |
| Light-adjustable IOL | Postoperative adjustment of refractive power | Power can be altered after surgery using ultraviolet light treatment. |
| Aspheric IOL | Reduces spherical aberration | Often incorporated into monofocal and premium IOLs to improve image quality and contrast. |
The American Academy of Ophthalmology describes monofocal, multifocal, EDOF, toric, accommodative, and light-adjustable lenses as main clinical options. AAO lens overview
2. By material
- Rigid PMMA IOL: Requires a larger incision. Used less often in routine phacoemulsification.
- Foldable silicone IOL: Can be inserted through a small incision.
- Foldable hydrophobic acrylic IOL: Widely used; good capsular-bag stability.
- Hydrophilic acrylic IOL: Foldable and injectable; has different risks of deposits or opacification depending on the model.
3. By position or fixation in the eye
- Posterior chamber IOL (PCIOL): Placed in the capsular bag or ciliary sulcus. This is the usual location after uncomplicated cataract surgery.
- Anterior chamber IOL (ACIOL): Placed in the anterior chamber when posterior capsular support is inadequate.
- Iris-fixated or iris-claw IOL: Attached to the iris.
- Scleral-fixated IOL: Secured to the sclera when capsular support is absent. It may be sutured or sutureless.
4. By design
- One-piece IOL
- Three-piece IOL
- Spherical IOL
- Aspheric IOL
- Blue-light filtering IOL
- UV-filtering IOL
- Phakic IOL: Implanted without removing the natural crystalline lens, usually for refractive correction in high myopia or other refractive errors.
- Pseudophakic IOL: Implanted after the natural lens has been removed, usually after cataract extraction.
Exam-oriented summary
IOL types in cataract surgery:
- Monofocal
- Multifocal or trifocal
- EDOF
- Toric
- Accommodative
- Light-adjustable
- Aspheric
According to placement: posterior chamber, anterior chamber, iris-fixated, and scleral-fixated IOLs.
A 2024 systematic review found meaningful trade-offs among presbyopia-correcting IOL types, especially between spectacle independence and risks such as dysphotopsia or changes in contrast sensitivity. Systematic review
Cataract types
Reading File
Finding Sources
Searching PubMed
"cataract"[MeSH Terms] AND classification
Searching the Web
AAO types of cataracts nuclear cortical posterior subcapsular congenital traumatic
Types of cataract
A cataract is an opacity of the natural crystalline lens. The common age-related forms often coexist in the same eye.
A. By anatomical location and morphology
| Type | Appearance and key feature |
|---|---|
| Nuclear sclerotic cataract | Central lens nucleus becomes yellow, then brown. Causes gradual distance-vision reduction and may produce a temporary myopic shift, called second sight. |
| Cortical cataract | Opacity in the lens cortex, classically wedge-shaped or radial spokes extending toward the centre. Glare and night-driving difficulty are common. |
| Posterior subcapsular cataract (PSC) | Central opacity just beneath the posterior capsule. Causes marked glare and poor near vision, often worse in bright light. It can progress relatively quickly. |
| Anterior subcapsular cataract | Opacity beneath the anterior lens capsule, often associated with inflammation, trauma, atopy, or other causes. |
| Anterior polar cataract | Small central anterior capsular opacity, commonly congenital. |
| Posterior polar cataract | Central posterior capsular opacity, often congenital. Important surgically because of a higher risk of posterior-capsule weakness. |
| Lamellar or zonular cataract | Layered opacity surrounding the nucleus, with clear and opaque lamellae. A common congenital cataract. |
| Coronary cataract | Peripheral cortical opacities around the equator, often with little visual effect initially. |
| Christmas-tree cataract | Multicoloured, needle-like crystalline opacities, classically associated with myotonic dystrophy. |
| Sunflower cataract | Central disc with radiating petals, associated with Wilson disease. |
| Snowflake cataract | White cortical opacities that may occur in poorly controlled diabetes, especially in younger people. |
Kanski describes nuclear sclerosis as yellowing from urochrome pigment, while cortical cataract develops through hydration clefts and vacuoles that become wedge-shaped or radial spoke-like opacities. Kanski's Clinical Ophthalmology, 10th ed., cataract section. The common clinical types are nuclear, cortical, and posterior subcapsular cataracts. AAO EyeWiki overview
B. By cause
-
Age-related or senile cataract
- Most common
- Usually nuclear, cortical, or PSC
-
Congenital/developmental cataract
- Present at birth or develops in childhood
- Examples: lamellar, polar, sutural, cerulean cataract
-
Traumatic cataract
- Blunt trauma: classically rosette-shaped cataract
- Penetrating trauma may directly damage the lens
-
Complicated cataract
- Secondary to chronic intraocular disease, especially uveitis, retinal detachment, or high myopia
- Often begins as a posterior subcapsular opacity
-
Metabolic cataract
- Diabetes mellitus: snowflake cataract
- Galactosaemia: oil-droplet cataract
- Wilson disease: sunflower cataract
- Hypocalcaemia: cortical cataract
-
Drug-induced cataract
- Most notably long-term corticosteroids, commonly causing PSC
- Also associated with some other drugs, depending on exposure and patient factors
-
Radiation or electric cataract
C. By maturity
- Immature cataract: Lens is partially opaque, with some clear cortex remaining.
- Mature cataract: Entire lens becomes opaque.
- Hypermature cataract: Advanced mature cataract with liquefied cortex and a shrunken or sinking nucleus.
- May be Morgagnian cataract if the nucleus sinks in liquefied cortex.
Exam answer in one line:
The three common age-related cataracts are nuclear sclerotic, cortical, and posterior subcapsular cataract.
The three common age-related cataracts are nuclear sclerotic, cortical, and posterior subcapsular cataract.
This is a shared conversation. Sign in to Orris to start your own chat.