Almost everyone will develop a cataract eventually. The only question is when. The surgery that treats it is the most performed operation in the world, with a success rate that is hard to match in medicine.
A cataract is simply a clouding of the natural lens inside the eye. The lens sits behind the pupil and is normally clear, bending light precisely onto the retina at the back of the eye. As a cataract develops, the lens gradually becomes cloudy, yellowed, or opaque. Light scatters rather than focusing cleanly. The result is vision that slowly becomes blurry, hazy, and increasingly difficult to work with. Cataracts are the leading cause of reversible visual impairment worldwide, and the treatment, when the time is right, restores vision reliably and quickly.
What You Need to Know About Cataracts
- Most cataracts are age-related and develop slowly over years, with no pain and gradual symptoms
- Early cataracts don’t always need treatment. Surgery is considered when the cataract affects daily life
- Surgery is highly effective: over 95 percent of patients achieve meaningfully better vision
- The operation replaces the cloudy natural lens with a clear artificial intraocular lens (IOL) and takes around 15 to 20 minutes
- Modern IOL options can correct distance, intermediate, and near vision, potentially reducing dependence on glasses after surgery
- No drops, medications, or lifestyle changes can reverse a cataract. Surgery is the only effective treatment
How Vision Changes With a Cataract
The changes happen so gradually that many people adapt without realising how much their vision has declined. You start needing more light to read. Oncoming headlights at night feel uncomfortably bright, or have halos around them. Colors look slightly washed out or yellowed. Then one day you realise that even with new glasses, things still aren’t quite right.
Typical symptoms
- Blurred or hazy vision that glasses cannot fully correct
- Increased sensitivity to bright light and glare, especially driving at night
- Colors appearing faded, yellowed, or less vivid than they used to be
- Needing a lot more light for reading or close work
- Frequent changes in glasses prescription
- A temporary improvement in near vision (called second sight) in some cataracts, followed by deterioration as it progresses
- Halos or starbursts around lights at night
Types of Cataract
Age-related cataract
The vast majority of cataracts are age-related. The lens proteins gradually break down and clump together over years or decades, clouding the lens. Most people over 65 have some degree of lens clouding, though not all are symptomatic enough to need surgery. Age-related cataracts can affect one or both eyes.
Nuclear, cortical, and posterior subcapsular cataracts
Age-related cataracts are classified by where the clouding occurs within the lens. Nuclear cataracts affect the central core and are the most common. Cortical cataracts develop in the outer layers, producing spoke-like opacities that cause significant glare. Posterior subcapsular cataracts form at the back surface of the lens and tend to progress more quickly, causing disproportionate glare and difficulty reading even when the cataract appears relatively small. This type is also associated with steroid use and diabetes.
Other types
Congenital cataracts are present from birth or develop in early infancy and require urgent treatment to prevent deprivation amblyopia. Traumatic cataracts can follow a direct eye injury. Secondary cataracts develop as a consequence of other eye conditions such as uveitis, or as a side effect of prolonged corticosteroid use. See our steroids in eye care page for more on this.
When Is Surgery Needed?
There is no medical urgency to operate on most cataracts. The right time is when the cataract is affecting your daily life in a way that matters to you: when driving has become unsafe, reading is genuinely difficult despite good lighting and glasses, or work and leisure activities are badly affected. That decision is yours, guided by your ophthalmologist’s assessment.
Waiting is not harmful in most cases. But there is no benefit to it either. The cataract won’t improve. It will slowly get worse. A more advanced cataract is technically more challenging to remove than an earlier one. And in the meantime, the vision loss affects quality of life, independence, and safety in ways that are easy to underestimate when the decline has been gradual.
Cataract Surgery
How the operation works
Modern cataract surgery, performed by the cataract and lens team uses phacoemulsification. Through a tiny self-sealing incision at the edge of the cornea, a fine ultrasound probe breaks up and removes the cloudy lens. The natural lens capsule, a thin membrane that surrounded the lens, is left in place. A foldable artificial intraocular lens (IOL) is inserted through the same small incision and unfolds inside the capsule. No sutures are needed. Fifteen to twenty minutes, local anaesthetic, awake but comfortable throughout, home the same day.
Biometry and lens selection
Precise measurements of the eye (biometry) are taken to calculate the power of the IOL needed to achieve your target refraction. You discuss with your surgeon which lens type suits your visual needs and lifestyle. This conversation matters. The choice between a standard monofocal lens and a premium option is one of the most important decisions before the operation.
What happens on the day
You arrive as a day case, receive anaesthetic drops to numb the eye, and in some cases a small injection around the eye. You’re awake throughout but feel no pain, only mild pressure. Around 15 to 20 minutes. Home the same day with a protective shield and antibiotic and anti-inflammatory drops to use for several weeks.
What to expect afterward
Vision improves within the first day or two in most cases, though it may stay slightly blurry for a week or two as the eye settles. Most people return to light daily activities within 24 to 48 hours. Avoid rubbing the eye, swimming, and dusty environments for about four weeks. A new glasses prescription is assessed around four to six weeks after surgery.
Choosing an Intraocular Lens
Standard monofocal lenses
The most commonly used IOLs are monofocal lenses set for one focal distance, usually distance vision. Most patients with monofocal lenses will still need reading glasses after surgery for near tasks. These lenses are highly reliable and are used in the majority of cataract operations worldwide.
Premium lenses
Extended depth of focus (EDOF) lenses provide a continuous range of vision from distance to intermediate with some near function. Multifocal lenses split incoming light to simultaneously focus near and far. Both types involve trade-offs, most commonly some degree of halos or glare around lights at night. Not every patient is a suitable candidate. The discussion with your surgeon about which lens fits your life is one of the most important conversations before the operation.
Toric lenses
For patients with significant astigmatism, toric IOLs correct both the cataract and the astigmatism simultaneously, producing sharper unaided distance vision than a standard lens would achieve in the same eye.
When Vision Clouds Again After Surgery: PCO
Months or years after successful cataract surgery, some patients notice their vision becoming hazy again. This is not a recurrence of the cataract. The natural lens capsule left in place during surgery can gradually thicken or cloud over, a condition called posterior capsule opacification, sometimes called a secondary cataract even though the original implant is completely unaffected.
PCO is treated with a brief laser procedure called a YAG capsulotomy. A focused laser creates a small opening in the cloudy capsule. Vision restores almost immediately. Not over weeks. Almost immediately. The procedure takes a few minutes, requires no incision, and is done in the clinic. Most patients notice the improvement the same day. Once done, it never needs repeating.
Contact Your Eye Unit If You Notice After Surgery
- Sudden significant worsening of vision in the operated eye at any point
- Increasing rather than decreasing pain or redness in the days after the operation
- A new floater, flash of light, or shadow in vision
- Discharge or unusual appearance of the eye in the first weeks after surgery
Serious complications after cataract surgery are uncommon, but they include endophthalmitis (infection inside the eye) and retinal detachment, both of which require urgent treatment. Any sudden change in vision or unexpected increase in symptoms should be reported the same day, not monitored at home.
Frequently Asked Questions About Cataract
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Can cataracts be treated without surgery?
No. There are no eye drops, medications, or lifestyle changes that reverse a cataract once it has formed. Some products are marketed as cataract treatments — particularly certain eye drops. None have proven effective in proper clinical trials, despite what the packaging implies. When symptoms are mild, managing with updated glasses and better lighting is entirely reasonable while you monitor for progression. But when the cataract is affecting your life, surgery is the only effective option.
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Is cataract surgery safe?
By surgical standards, very safe. Serious complications in experienced hands occur in roughly 1 in 1000 cases. The most common issue isn’t really a complication — it’s PCO (posterior capsule opacification), where the membrane left during surgery gradually clouds over. Happens in around 20 percent of patients, treated with a quick laser procedure in the clinic. Your surgeon will go through the risks before you consent, and you should ask about their personal complication rate, not just the national average.
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Will I need glasses after surgery?
That depends on which lens is implanted and what target refraction you and your surgeon agreed on. With a standard monofocal lens set for distance, most people still need reading glasses for close work. With premium multifocal or EDOF lenses, many patients achieve useful vision at multiple distances without glasses, though night vision side effects like halos are more common. Set your expectations clearly before the operation, based on an honest conversation about what each lens can and cannot achieve.
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Can the cataract come back after surgery?
The artificial lens cannot develop a cataract. But the thin natural capsule left in place to support the implant can become cloudy over time, causing hazy vision again. That’s posterior capsule opacification, not a new cataract. It happens in roughly 20 percent of patients and is treated very simply with a short laser procedure in the clinic that permanently restores clear vision.
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How long does recovery take?
Most people notice clear improvement within the first day or two. Full stabilization takes four to six weeks, after which a new glasses prescription can be assessed if needed. Antibiotic and anti-inflammatory drops are used as directed, and activities like swimming, rubbing the eye, and dusty environments are avoided for about four weeks. Most people return to normal daily activities within a day or two.
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Should I have both eyes done at the same time?
Most surgeons operate on one eye at a time, typically a few weeks apart. The first eye heals and its result is assessed before the second operation. This also allows the lens power calculation for the second eye to be refined based on what was achieved in the first. Bilateral simultaneous surgery on the same day is occasionally offered but sequential surgery remains the standard approach in most units.
If you would like to learn more, the American Academy of Ophthalmology’s cataracts page offers a clear overview of cataracts, symptoms, diagnosis, and treatment.
Cataract is any opacity of the crystalline lens sufficient to impair vision or interfere with daily function. It is the leading cause of reversible blindness globally, responsible for approximately 51% of world blindness, and the most commonly performed surgical procedure in ophthalmology. The vast majority of cataracts are age-related (nuclear sclerosis, cortical, posterior subcapsular), driven by oxidative damage, UV-B exposure, and protein aggregation in the crystalline lens. Surgery , phacoemulsification with intraocular lens (IOL) implantation , is curative. The challenge in modern cataract practice is not surgical but clinical: determining the right moment to intervene, selecting the optimal IOL, and managing the growing complexity of cataract surgery in eyes with prior refractive surgery, corneal disease, or macular pathology.
Clinical Overview: Cataract
- Types: Nuclear sclerosis (most common , gradual central lens yellowing/hardening; myopic shift early, reduced contrast late); Cortical cataract (spoke-like opacities from periphery; glare prominent); Posterior subcapsular cataract (PSC , at the posterior pole; disproportionate effect on near vision and glare in bright light; associated with steroids, diabetes, uveitis, myotonic dystrophy)
- Grading: LOCS III (Lens Opacities Classification System): nuclear opalescence (NO1-6), nuclear color (NC1-6), cortical (C1-5), PSC (P1-5). Clinically, describe what the patient sees and function, not just slit-lamp grade.
- Surgical indication: Symptomatic visual impairment affecting daily function. BCVA threshold varies by patient (a 6/9 that impairs driving matters; a 6/12 in a non-driver who reads large print may not). Consider also: intumescent/hypermature cataract, phacomorphic glaucoma, lens-induced uveitis, need for fundal view (diabetic retinopathy surveillance).
- Phacoemulsification: Standard technique. Corneal incision, continuous curvilinear capsulorhexis (CCC), hydrodissection, ultrasonic emulsification of the nucleus, cortex aspiration, IOL implantation in the bag. 2.2-2.4 mm clear corneal incision (sutureless). Operating time approximately 15-20 minutes.
- IOL selection: Monofocal (most common , one focal point, typically distance; patient usually needs glasses for near); monofocal toric (corrects corneal astigmatism); multifocal/EDOF (extended depth of focus, reduces spectacle dependence; higher dysphotopsia rate); light-adjustable lens (LAL , adjustable post-operatively with UV light)
- Biometry: IOL power calculation from axial length (AL), anterior chamber depth (ACD), and keratometry (K). Modern formulae: Barrett Universal II, Kane, Hill-RBF (best for average eyes); Haigis-L or Barrett TK for post-refractive surgery eyes (K reading unreliable after LASIK/PRK).
Pathophysiology and Types
Nuclear sclerosis: The crystalline lens grows throughout life by adding lens fibers from the equatorial epithelium. The central nucleus compacts and undergoes progressive protein aggregation (alpha-crystallin misfolding), increasing density and yellow-brown pigmentation. The refractive index of the nucleus rises, producing a myopic shift , patients often report that their reading vision temporarily improves (“second sight”) before contrast sensitivity deteriorates. Nuclear cataracts are graded by color (NO/NC scale) and density. Dense brunescent cataracts require higher phaco energy and carry greater surgical risk.
PSC (posterior subcapsular cataract): A plaque of granular opacity at the posterior pole of the lens, directly in the axial path of light. This location produces disproportionate visual impact, particularly in bright light (pupil constricts over the opacity) and for near tasks (convergence and accommodation direct the visual axis through the PSC). Associated with: prolonged systemic or topical corticosteroid use, diabetes mellitus, uveitis, radiation, and myotonic dystrophy. Patients may have surprisingly good Snellen BCVA but severely impaired contrast sensitivity and glare.
Preoperative Assessment
Biometry: Anterior segment OCT and optical biometry (IOLMaster 700, Lenstar) preferred over immersion A-scan. Measures AL, ACD, keratometry, white-to-white, and central corneal thickness. For post-refractive surgery eyes: corneal topography (Pentacam) for true keratometry and total corneal power. The most common cause of postoperative refractive surprise is incorrect K input or unmeasured posterior corneal astigmatism.
Slit-lamp assessment before surgery: Assess the density and type of lens opacity, pupil dilation adequacy (poor dilation increases surgical complexity), zonular integrity (pseudoexfoliation, prior trauma), corneal clarity (Fuchs’ endothelial dystrophy changes the risk profile and counseling), and anterior vitreous (presence of anterior PVD or vitreous abnormality). Document any corneal guttata , if significant, consider combined phaco-DSAEK/DMEK or staged surgery.
Macular assessment before IOL selection: OCT macula before any premium IOL recommendation. Epiretinal membrane, macular degeneration, or vitreomacular pathology contraindicate multifocal IOLs , patients with macular disease require monofocal IOL and frank counseling about expected visual outcome.
Surgical Technique and IOL Options
Standard phacoemulsification sequence: Intracameral anaesthesia (lidocaine 1%) supplemented with topical oxybuprocaine. Temporal or superior clear corneal incision (2.2-2.4 mm). Side port. Trypan blue to stain the anterior capsule for CCC in white cataracts. Hydrodissection and hydrodelineation. Divide-and-conquer or stop-and-chop nuclear technique depending on density. Cortex irrigation and aspiration. IOL loading and implantation into the capsular bag. Stromal hydration to close the wound. Intracameral cefuroxime 1 mg/0.1 mL (ESCRS PREMED protocol; reduces endophthalmitis risk approximately 5-fold).
IOL selection in complex eyes: After LASIK (myopic correction): K readings underestimate true power , use history-based or no-history formula (Barrett TK, Haigis-L). After LASIK (hyperopic): K readings overestimate , different adjustment required. After RK (radial keratotomy): extreme unpredictability; target slight myopia and plan for enhancement. Fuchs’ dystrophy: if mild, staged approach (phaco first, DMEK 3-6 months later if decompensation) or combined phaco-DMEK. Toric IOL in eyes with corneal astigmatism ≥0.75 D if corneal topography is regular (no KISA%, no irregular astigmatism pattern).
Complications
Posterior capsule rupture (PCR): The most common significant intraoperative complication, occurring in approximately 1.8-3% of cases in trainee hands, 0.5-1% in experienced surgeons. Anterior vitrectomy is required. If PCR occurs before IOL insertion: sulcus IOL placement (if adequate capsular support) or anterior chamber IOL. If nuclear fragments fall into the vitreous: close the wound, leave the cortex, and arrange vitreoretinal surgeon for pars plana vitrectomy. Do not try to retrieve posterior vitreous nuclear fragments through the anterior approach.
Posterior capsule opacification (PCO): Occurs in up to 30% of patients within 5 years. Lens epithelial cells migrate and proliferate behind the IOL (Elschnig pearls, fibrous PCO). Treated with Nd:YAG laser posterior capsulotomy , outpatient, takes 5 minutes, very safe. Significant complication of YAG: raised IOP (treat prophylactically with apraclonidine if glaucoma risk), posterior IOL displacement (rare with standard IOLs), and retinal detachment (1 in 1,000 , counsel appropriately).
Toxic anterior segment syndrome (TASS): Non-infectious sterile anterior segment inflammation 12-24 hours post-phaco from contaminated irrigating solution, OVD, or instruments. Distinguished from endophthalmitis by earlier onset, absence of pain, and diffuse corneal edema rather than vitritis. Management: intensive topical steroids. Usually resolves without permanent damage if treated promptly.
Post-operative endophthalmitis: Incidence approximately 1 in 1,000 with intracameral antibiotic prophylaxis. Presents 2-7 days post-op with pain, reduced vision, hypopyon. Emergency management: vitreous tap for culture + intravitreal vancomycin 1 mg + ceftazidime 2.25 mg. ESCRS endophthalmitis trial: intravitreal antibiotics alone or combined with systemic (EVS protocol for systemic not supported in phaco-related endophthalmitis , differs from post-trauma). Refer same day.
Clinical Decision Points
- Monofocal vs multifocal IOL: Multifocal/EDOF IOLs reduce spectacle dependence but introduce halos, glare, and reduced contrast sensitivity. Suitable for high-motivation patients with healthy maculas, regular corneal topography, and realistic expectations. Absolute contraindication: macular pathology (AMD, ERM, DR), irregular astigmatism, significant dry eye. Do not offer premium IOLs to patients who prioritize best possible distance acuity over near independence.
- Toric IOL accuracy: Requires stable corneal astigmatism above 0.75 D, regular topography, and accurate intraoperative alignment. Misalignment of 10° loses ~33% of toric effect; 30° misalignment produces net astigmatism equal to the uncorrected amount. Verify rotation with an online toric calculator at follow-up and reposition within the first 2-4 weeks if significantly rotated.
- Post-LASIK cataract: Use adjusted biometry formulas (Barrett TK Universal preferred). Target slight myopia (-0.5 D) to buffer formula uncertainty. Counsel that refractive outcome is less predictable than in virgin eyes. Enhancement options post-phaco: LASIK enhancement, PRK, or piggyback IOL.
- Dense cataract, no fundal view: If the cataract prevents adequate view for retinal disease monitoring (e.g., DR surveillance), this is an independent surgical indication even if acuity is serviceable. Document this reasoning explicitly in the referral.
Same-Day Assessment Required
- Post-phaco pain + reduced vision + hypopyon at 2-7 days , endophthalmitis until proven otherwise; vitreous tap and intravitreal antibiotics same day
- Phacomorphic glaucoma , intumescent cataract causing pupil block and acute angle-closure; IOP reduction then urgent cataract extraction
- Lens dislocation (subluxation or full luxation) causing monocular diplopia, refractive shift, and zonular instability , vitreoretinal or anterior segment specialist
Post-operative endophthalmitis has a narrow treatment window. Every hour’s delay between symptom onset and intravitreal antibiotics worsens the visual prognosis. Any patient presenting to urgent care with post-operative eye pain and vision loss within 2 weeks of cataract surgery must be referred to ophthalmology the same day, regardless of how mild symptoms appear at triage.
Clinical Pearls: Cataract
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BCVA is a poor proxy for cataract-related disability. Contrast sensitivity and glare testing matter more.
A patient with PSC cataract can have 6/9 Snellen acuity and be unable to drive safely because of incapacitating glare from oncoming headlights. Snellen acuity is measured in high-contrast conditions under controlled lighting , the conditions least likely to reproduce the real-world effect of PSC. When a patient’s reported disability seems disproportionate to their acuity, test contrast sensitivity (Pelli-Robson chart) and glare sensitivity (Brightness Acuity Tester) before concluding the cataract is not surgical. Function, not just acuity, is the right threshold.
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The first post-LASIK cataract you do is the hardest one to get right. Use the right formula.
Conventional K readings after myopic LASIK underestimate the true post-surgical corneal power because they measure peripheral rather than central curvature. Using standard SRK/T or Holladay 1 formulae produces hyperopic outcomes , sometimes by 2-3 D. The Barrett True-K formula (uses LASIK history if available) or the ASCRS online calculator (combining multiple formula results) are the current best options. If LASIK records are unavailable, the Shammas no-history formula is a reasonable fallback. Target slight myopia in these eyes to buffer the uncertainty.
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Femtosecond laser-assisted cataract surgery (FLACS) is not clearly superior to manual phaco for most cases.
FLACS uses a femtosecond laser to create the corneal incision, anterior capsulotomy, and nuclear fragmentation. Multiple randomized trials show equivalent or marginally better capsulotomy circularity compared with manual CCC, but no consistent difference in visual outcomes, PCR rate, or endothelial cell loss in standard-difficulty cases. The benefit may be more meaningful in specific scenarios: white intumescent cataracts (where CCC is high-risk), dense nuclear cataracts (less phaco energy needed), and highly astigmatic eyes requiring precise incision positioning. At its current cost premium, FLACS is difficult to justify as a routine substitute for skilled manual phacoemulsification.
Further reading: RCOphth Cataract Surgery Guidelines. For the lens anatomy context see the lens basics page. Related conditions: refractive errors (IOL planning context), uveitis (PSC association). Full subspecialty context: cataract and lens subspecialty page.