What is cataract? Symptoms, causes & treatment

A cataract is an opacification of the crystalline lens that degrades image quality and reduces visual acuity. Most cataracts are age-related; others follow trauma, inflammation, medications (notably corticosteroids), metabolic disease, or are congenital. Cardinal symptoms are painless, progressive blur, glare/halos, reduced contrast, color desaturation, and sometimes monocular diplopia. Diagnosis is clinical with slit-lamp biomicroscopy after dilation. Treatment is surgical lens extraction with intraocular lens (IOL) implantation when visual function is limited and nonsurgical measures are inadequate.

Key Points

• Cataract is the most common cause of reversible vision impairment worldwide and a leading indication for ophthalmic surgery in the US.
• Symptoms include painless blur, glare and halos (especially with night driving), progressive myopic shift, and reduced contrast; exam shows lens opacities on slit-lamp.
• Surgery (phacoemulsification with IOL) restores vision in most patients; preoperative evaluation must assess ocular surface, cornea, macula, optic nerve, and biometry.
• Posterior capsule opacification is the most frequent late complication and is treated with Nd:YAG laser capsulotomy.
• No proven medical therapy prevents or reverses age-related cataract; risk factor control (UV protection, smoking cessation, glycemic control) is recommended.
• Congenital/infantile cataract threatens visual development and requires urgent pediatric ophthalmology evaluation.

Anatomy and Physiology

The crystalline lens is an avascular, biconvex structure suspended by zonules from the ciliary body. It consists of a capsule, anterior epithelium, cortex, and central nucleus. Lens transparency depends on ordered fiber architecture and water-soluble crystallin proteins; metabolism is anaerobic, with active ion pumps maintaining dehydration. With aging, lens fibers compact (nuclear sclerosis), proteins aggregate, and light scatter increases, reducing optical quality and accommodation.

Etiology

• Age-related (senile) cataract: nuclear sclerosis, cortical, posterior subcapsular (PSC)
• Metabolic/systemic: diabetes mellitus, hypocalcemia, galactosemia (pediatric), myotonic dystrophy
• Medication-induced: corticosteroids (systemic, inhaled, topical), phenothiazines
• Ocular comorbidity (“complicated”): chronic uveitis, retinitis pigmentosa, high myopia, pseudoexfoliation
• Trauma: blunt (rosette), penetrating, intraocular foreign body
• Radiation: ionizing radiation, ultraviolet-B
• Congenital/infantile: hereditary (e.g., autosomal dominant), intrauterine infections (e.g., rubella), metabolic errors

Pathophysiology

Age-related cataract is driven by oxidative stress, post-translational modification and aggregation of crystallins, advanced glycation end products (exacerbated by hyperglycemia), and disruption of lens microcirculation. Nuclear sclerosis increases refractive index causing myopic shift. Cortical cataracts arise from osmotic and electrolyte imbalance forming clefts and spokes. PSC cataracts form from posterior migration of aberrant epithelial cells with granular opacities near the visual axis, disproportionately affecting acuity and glare.

Epidemiology

In the US, cataract prevalence rises steeply with age. The National Eye Institute reports that by age 80, more than half of Americans have a cataract or have had cataract surgery [2]. Tens of millions of adults are affected, with higher prevalence among persons with diabetes and among some racial/ethnic groups [2]. Cataract surgery is among the most commonly performed procedures in Medicare beneficiaries [1].

Classification

• By morphology:
  • Nuclear sclerosis
  • Cortical (spoke-like)
  • Posterior subcapsular (PSC)
  • Anterior/posterior polar; cerulean; rosette (traumatic)
• By etiology:
  • Age-related, congenital/infantile, traumatic, complicated (secondary), metabolic, drug-induced, radiation
• By maturity (historical, descriptive):
  • Incipient/immature, mature (“white”), hypermature/morgagnian (liquefied cortex, sinking nucleus)

Symptoms and Signs

• Age-related nuclear sclerosis
  • Symptoms: gradual distance blur, improved near vision without readers (“second sight”), color yellowing.
  • Signs: central nuclear brunescence/sclerosis on slit-lamp; increased myopia; decreased contrast.
• Cortical cataract
  • Symptoms: glare, halos, fluctuating vision; night-driving difficulty.
  • Signs: peripheral/central radial “spokes” that scatter light; worse with bright illumination.
• Posterior subcapsular cataract
  • Symptoms: disproportionate glare disability and near-vision loss; bright-light worse than dim.
  • Signs: granular/plaquelike opacity just anterior to posterior capsule in the visual axis.
• Congenital/infantile cataract
  • Symptoms: leukocoria (white pupil), nystagmus, strabismus; poor fixation.
  • Signs: lens opacity at birth/early infancy; abnormal red reflex; risk of amblyopia.
• Traumatic cataract
  • Symptoms/Signs: timing linked to injury; rosette pattern after blunt trauma; associated zonular weakness or capsular rupture.

Complications

• Untreated: progressive visual impairment, increased fall risk, driving hazards, impaired quality of life; amblyopia in infants.
• Surgical (intraoperative): posterior capsule rupture, zonular dialysis, dropped nucleus, Descemet membrane detachment, suprachoroidal hemorrhage.
• Early postoperative: corneal edema, intraocular pressure (IOP) spike, wound leak, inflammation, toxic anterior segment syndrome, endophthalmitis.
• Late postoperative: cystoid macular edema (Irvine–Gass), posterior capsule opacification (PCO), IOL malposition/dislocation, dysphotopsias (positive/negative), refractive surprise, posterior vitreous detachment/retinal tear or detachment.

Diagnosis

Clinical evaluation

• History: impact on activities (reading, driving, work), glare symptoms, monocular diplopia, onset/progression, prior ocular surgery/trauma, steroid exposure, systemic disease (diabetes), anticoagulants/antiplatelets.
• Examination:
  • Visual acuity (distance/near), pinhole, refraction (document myopic shift).
  • Pupils (afferent defect suggests optic nerve/retinal disease).
  • Slit-lamp biomicroscopy with dilation to grade lens opacities (e.g., LOCS III, if used).
  • IOP measurement.
  • Dilated fundus exam to assess macula and optic nerve for coexisting disease.
  • Glare testing and/or contrast sensitivity when symptoms exceed Snellen acuity loss.

Imaging and laboratory testing

• Biometry for IOL calculation: optical biometry (partial coherence interferometry/swept-source) preferred; ultrasound A-scan if dense cataract; keratometry/topography for astigmatism/irregular cornea [1].
• Macular OCT if maculopathy risk (diabetes, age-related macular degeneration, epiretinal membrane) [1].
• Specular microscopy/pachymetry if endothelial disease (e.g., Fuchs endothelial corneal dystrophy).
• B-scan ultrasonography if posterior segment view is obscured.
• Pediatric/congenital: targeted systemic workup (e.g., metabolic, infectious) based on history/exam; genetics referral when indicated [7].

Differential diagnosis

Treatment

Surgery is indicated when cataract reduces visual function (acuity, glare, contrast) and affects desired activities, and when expected benefits outweigh risks. There is no medically proven way to reverse age-related cataract.

Medical management

• Optimize refraction and lighting; anti-glare coatings; magnifiers.
• Risk factor control: UV-blocking eyewear, smoking cessation, strict glycemic control, review corticosteroid necessity [1,2].
• Topical pharmacotherapy does not reverse cataract. Antioxidant/vitamin supplements have not shown meaningful prevention or reversal in randomized trials [3].

Postoperative topical regimens (representative examples; individualize) [1,9,10]:

• Antibiotic: a fluoroquinolone (e.g., moxifloxacin 0.5% 1 drop qid for 1 week; gatifloxacin 0.5% qid; ofloxacin 0.3% qid).
• Corticosteroid: prednisolone acetate 1% 1 drop qid, taper over 2–4 weeks; or difluprednate 0.05% 1 drop bid then taper.
• NSAID (adjunct to reduce cystoid macular edema risk): ketorolac 0.5% qid or bromfenac 0.07% qd or nepafenac 0.1% tid/0.3% qd for 2–4 weeks.

Endophthalmitis prophylaxis:

• Povidone-iodine 5% to the ocular surface is standard of care [1].
• Intracameral antibiotic at the end of surgery reduces postoperative endophthalmitis in large studies (cefuroxime 1 mg/0.1 mL in ESCRS; moxifloxacin 0.5 mg/0.1 mL in other cohorts) [4,5,6]. In the US, intracameral use is common but off-label; no FDA-approved intracameral cefuroxime product is available.

Procedural and surgical management

• Phacoemulsification with posterior chamber IOL (CPT 66984; complex 66982): standard technique under topical ± intracameral anesthesia with monitored sedation. Femtosecond laser–assisted cataract surgery is an alternative without proven superior visual outcomes for most indications [1].
• IOL selection:
  • Monofocal (spherical/aspheric): target emmetropia or monovision; toric models for regular corneal astigmatism.
  • Multifocal and extended-depth-of-focus (EDOF): increased range of vision with potential for glare/halos and reduced contrast; careful patient selection.
  • Accommodating IOLs: limited true accommodation; selection individualized.
• Special situations:
  • Weak zonules (pseudoexfoliation, trauma): capsular tension ring (CTR), segment/suture fixation.
  • Dense/white cataract or small pupil: staining with trypan blue, mechanical pupil expansion.
  • Coexistent corneal endothelial disease (Fuchs): consider staged or combined endothelial keratoplasty (“triple” DMEK/DSAEK) [1].
  • Pediatric cataract: general anesthesia; lens aspiration with or without primary posterior capsulotomy/anterior vitrectomy; primary IOL selection based on age/eye growth with amblyopia therapy [7].
• Posterior capsule opacification (PCO): Nd:YAG laser capsulotomy (CPT 66821) restores clarity; monitor for IOP spike and rare retinal tear/detachment [1].

Preoperative workup and counseling:

• Ocular surface optimization (treat significant dry eye) to improve biometry accuracy [1].
• IOL power calculation with optical biometry (CPT 92136) and appropriate formula selection; consider prior keratorefractive history.
• Macular OCT when indicated; discuss realistic outcomes and dysphotopsia risk.
• Anticoagulants/antiplatelets: phacoemulsification is typically performed without stopping therapy; coordinate with prescribing clinician for individualized risk assessment [1].

Special populations

• Pediatric: Unilateral dense congenital cataract generally requires surgery in early weeks to prevent amblyopia; bilateral dense cataracts in the first months. Postoperative optical correction (contact lens or IOL) and aggressive amblyopia management are critical; evaluate for systemic/genetic causes [7].
• Pregnancy/lactation: Elective cataract surgery is usually deferred until postpartum unless urgent; topical perioperative medications have low systemic absorption but risk–benefit should be reviewed.
• Diabetes: Higher risk of rapid progression and postoperative cystoid macular edema; optimize glycemic control and consider perioperative NSAIDs; screen and treat diabetic retinopathy preoperatively [1].
• Elderly/frail: Assess support for postoperative care and fall risk; anesthesia plan tailored to comorbidities; cognitive impairment affects consent and rehabilitation.

Prognosis

Visual outcomes after modern cataract surgery are excellent for most patients when macula and optic nerve are healthy; residual refractive error, coexisting retinal disease, and surgical complications limit results [1]. Endophthalmitis is rare with antisepsis and adjunct prophylaxis [4–6]. PCO is common over time and is effectively treated with Nd:YAG capsulotomy.

Prevention and Patient Counseling

• No eyedrops or supplements are proven to prevent or reverse age-related cataract [3].
• Counsel on UV-blocking sunglasses/hat brim, smoking cessation, and glycemic control in diabetes.
• Review medication exposures (especially corticosteroids) and minimize when clinically feasible.
• For driving, discuss state vision standards and glare management; advise avoiding night driving if hazardous until treated.
• After surgery, emphasize drop adherence, eye protection, activity restrictions per surgeon, and prompt reporting of pain, sudden blur, or new floaters/flashes.

When to Seek Immediate Care

• Sudden vision loss or a “curtain” over vision
• Severe eye pain, redness, or light sensitivity, especially within days to weeks after eye surgery
• New showers of floaters or flashes of light
• Eye injury or chemical exposure
• Nausea/vomiting with severe eye pain

Call 911 or go to the nearest emergency department for these symptoms.

References

1. American Academy of Ophthalmology Preferred Practice Pattern. Cataract in the Adult Eye. San Francisco, CA: AAO; 2021. https://www.aao.org/preferred-practice-pattern/cataract-in-adult-eye-ppp-2021
2. National Eye Institute. Facts About Cataract. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/cataracts. Accessed July 24, 2026.
3. Evans JR, Lawrenson JG. Antioxidant vitamin and mineral supplements for slowing the progression of age-related cataract. Cochrane Database Syst Rev. 2017;(7):CD004567. doi:10.1002/14651858.CD004567.pub4
4. ESCRS Endophthalmitis Study Group. Prophylaxis of postoperative endophthalmitis following cataract surgery: Results of the ESCRS study. J Cataract Refract Surg. 2007;33(6):978-988. doi:10.1016/j.jcrs.2007.02.032.
5. Haripriya A, Chang DF, Namburar S, et al. Endophthalmitis reduction with intracameral moxifloxacin in 600,000 consecutive cataract surgeries. Ophthalmology. 2017;124(6):768-775. doi:10.1016/j.ophtha.2017.01.062.
6. Chang DF, Braga-Mele R, Henderson BA, Mamalis N, Vasavada A; ASCRS Cataract Clinical Committee. Prophylaxis of postoperative endophthalmitis after cataract surgery: Results of the 2014 ASCRS member survey. J Cataract Refract Surg. 2015;41(6):1300-1305. doi:10.1016/j.jcrs.2015.06.013.
7. American Association for Pediatric Ophthalmology and Strabismus (AAPOS). Cataract in Children. https://aapos.org/glossary/cataract. Accessed July 24, 2026.
8. EyeWiki (AAO). Cataract. https://eyewiki.aao.org/Cataract. Accessed July 24, 2026.
9. DailyMed. Prednisolone acetate ophthalmic suspension 1% labeling. https://dailymed.nlm.nih.gov/dailymed/
10. DailyMed. Ketorolac tromethamine ophthalmic solution 0.5% labeling. https://dailymed.nlm.nih.gov/dailymed/

Disclaimer: This article is for informational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified eye care professional about your specific condition. If you have sudden vision loss, severe eye pain, or an eye injury, seek emergency care immediately.