Cataracts
Also known as: Age-related cataract, Nuclear sclerosis, Lens opacity
Overview
A cataract is any opacification of the crystalline lens that degrades vision, most commonly from age-related changes. It is the leading cause of reversible blindness worldwide and is treated definitively with surgical lens removal and intraocular lens (IOL) implantation. Modern phacoemulsification is among the most frequently performed and successful procedures in medicine.
- Definition
- Opacification of the crystalline lens
- Most common cause
- Aging
- Definitive treatment
- Phacoemulsification + IOL
- Outcome
- Reversible with surgery
Key clinical points
- The main morphologic types are nuclear sclerotic, cortical, and posterior subcapsular; each affects vision differently.
- Symptoms include glare, reduced contrast, dimming or yellowing of colors, and progressive blur.
- Surgery is indicated when lens opacity impairs the patient’s functional needs, not at a fixed acuity threshold.
- IOL selection (monofocal, toric, extended depth of focus, multifocal) is tailored to the patient’s refractive goals.
- Biometry accuracy is the single largest driver of refractive outcomes.
Types and pathophysiology
Age-related cataract results from cumulative oxidative and biochemical changes in lens proteins. Nuclear sclerotic cataracts harden and yellow the central lens and often induce a myopic shift; cortical cataracts form spoke-like opacities from the periphery; posterior subcapsular cataracts sit at the back of the lens and disproportionately affect near vision and cause glare.
Non-age-related causes include trauma, corticosteroid use, diabetes, intraocular inflammation, and congenital factors, and these should be considered when cataract appears early or asymmetrically.
Evaluation
Assessment includes best-corrected acuity, glare testing, slit-lamp grading of lens changes, and a dilated fundus exam to identify coexisting pathology that may limit visual potential. Optical biometry measures axial length and keratometry for IOL power calculation.
Corneal topography or tomography helps identify irregular astigmatism and screen candidacy for toric or presbyopia-correcting lenses. The macula should be scrutinized, often with OCT, because unrecognized maculopathy is a common cause of disappointing postoperative vision.
Surgical management
Phacoemulsification through a small incision, with implantation of a foldable IOL, is the standard of care. Femtosecond laser assistance is an option for specific steps. The decision to operate is functional: surgery is offered when the cataract interferes with the activities and goals that matter to the patient.
IOL technology now allows surgeons to address astigmatism and presbyopia at the time of surgery. Careful counseling about the trade-offs of premium lenses—particularly potential dysphotopsias with multifocal designs—supports realistic expectations and high satisfaction.
Cataracts videos
Why do they call it a cataract?
Office Based Cataract Surgery - Parag Majmudar, MD
Co-managing patients with your cataract surgeon
Cataract and Refractive Surgery Fellowship
Cataract Surgery Explain in 20 Seconds
Diabetic Patient and Cataract Surgery
Underutilized Cataract SX Metric
Self Sealing Wounds- Cataract Surgery Pearls
Frequently asked questions
- When should cataract surgery be performed?
- Surgery is appropriate when the cataract reduces vision enough to interfere with the patient’s daily activities and goals. There is no universal acuity cutoff; the decision is individualized to functional need.
- What is the difference between monofocal and premium IOLs?
- Monofocal lenses provide clear vision at a single focal distance, while toric lenses correct astigmatism and presbyopia-correcting lenses (multifocal or extended depth of focus) aim to reduce dependence on glasses across ranges, with some optical trade-offs.
- Is cataract surgery permanent?
- Yes. The natural lens does not regrow. Some patients later develop posterior capsule opacification, which is easily treated in the office with a YAG laser capsulotomy.
References & further reading
Related conditions
Presbyopia
Presbyopia is the gradual, age-related loss of the eye’s ability to accommodate and focus on near objects, resulting from stiffening of the crystalline lens and changes in the ciliary apparatus. It becomes noticeable in the early-to-mid 40s and is universal. Correction options span spectacles and contact lenses, pharmacologic miotic drops, and lens- or cornea-based surgery.
Clinical overviewCataract & RefractiveAstigmatism
Astigmatism is a refractive error in which the cornea or lens has unequal curvature across meridians, so light focuses at multiple points rather than one, blurring vision at all distances. Regular astigmatism is correctable with cylindrical lenses, while irregular astigmatism—often from corneal disease—requires specialty contact lenses. It commonly coexists with myopia or hyperopia.
Clinical overviewGlaucomaGlaucoma
Glaucoma is a group of progressive optic neuropathies characterized by retinal ganglion cell loss and corresponding visual field defects, most often associated with elevated intraocular pressure (IOP). It is a leading cause of irreversible blindness worldwide, and because early disease is asymptomatic, detection depends on structural and functional screening. Lowering IOP remains the only proven, modifiable way to slow progression.
Clinical overview