A cataract is clouding of the eye's natural crystalline lens, which normally focuses light onto the retina. As lens proteins aggregate and the lens yellows and hardens with age, vision becomes progressively blurred and dim, colours appear faded or yellowed, glare and haloes around lights increase (often first noticed with night driving), and reading becomes harder. It is painless and gradual. The overwhelming majority are age-related, but cataracts also result from diabetes, corticosteroid use, trauma, uveitis, previous intraocular surgery, radiation, and congenital or genetic causes. Cataract is the leading cause of blindness worldwide — and, uniquely among the major causes, it is completely reversible with one operation.

When should cataract surgery be done?

When the cataract interferes with the activities that matter to the patient — not at any particular visual acuity threshold. Older systems used rigid acuity criteria (such as 6/12 or worse), but modern guidance is function-based: difficulty driving, particularly at night; difficulty reading, watching television or recognising faces; loss of confidence, restricted activity or increased falls risk; and inability to perform work or hobbies. Additional indications independent of symptoms: when the cataract prevents adequate view or treatment of the retina (for example in diabetic retinopathy needing laser); when the lens itself is causing glaucoma (phacomorphic or phacolytic); and in children, urgently, to prevent amblyopia. Waiting until the cataract is "ripe" is outdated and makes surgery technically harder and riskier.

What does cataract surgery involve?

Modern cataract surgery is a day-case procedure, usually under local anaesthesia (topical drops or a peribulbar block) with the patient awake, taking around 15-20 minutes. In phacoemulsification, a 2.2-2.8mm incision is made, a circular opening is created in the front of the lens capsule, an ultrasound probe emulsifies and aspirates the cloudy lens, and a foldable intraocular lens is implanted into the empty capsular bag. The incision is usually self-sealing without stitches. An antibiotic is injected into the eye at the end of the operation (intracameral prophylaxis), which reduces the risk of infection approximately five-fold. Most patients see an improvement within a day or two, use anti-inflammatory and antibiotic drops for around four weeks, and are refracted for new spectacles at around four to six weeks.

Can a cataract come back after surgery?

No — the natural lens has been removed and cannot regrow. However, around 20-30% of patients develop posterior capsule opacification (PCO, sometimes called "after-cataract") within two to five years: residual lens cells grow across the thin capsule left behind to support the implant, causing gradual blurring and glare that feels exactly like the original cataract returning. It is treated with Nd:YAG laser capsulotomy — a painless outpatient laser procedure lasting a few minutes that creates a clear opening in the capsule, with immediate visual improvement. It is done once and does not need repeating. Rarely it can raise eye pressure temporarily or, very uncommonly, contribute to retinal detachment or macular oedema.

Why are so many people still blind from cataract?

Not because the operation is difficult or expensive to perform, but because health systems fail to deliver it. The barriers are consistent across low- and middle-income settings: too few trained ophthalmic surgeons and, critically, too few functioning surgical teams and theatres; cost to the patient, including transport and lost income for an accompanying family member; distance from services; lack of awareness that the blindness is curable; fear of surgery; and, importantly, poor outcomes in some programmes that damage community trust. This last point is why WHO shifted to measuring effective cataract surgical coverage — counting only operations that produce good vision — and why high-volume models such as Aravind and Tilganga, which combine low unit cost with rigorously audited outcomes and active community case-finding, are the reference examples.

How does GMJ News cover cataract?

GMJ News covers global cataract blindness burden, effective cataract surgical coverage (eCSC) as the WHO indicator, phacoemulsification and MSICS as complementary techniques, biometry and IOL power calculation as the determinant of refractive outcome, IOL types and counselling trade-offs, intracameral antibiotic prophylaxis and endophthalmitis, posterior capsule opacification and YAG capsulotomy, posterior capsule rupture management, congenital cataract as an amblyopia emergency and the newborn red reflex, comorbidity and expectation setting, and high-volume surgical delivery models. Directly relevant to PHIG's eye health, health systems and surgical capacity programmes.

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Cataract

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

Cataract — opacification of the crystalline lens — is the leading cause of blindness worldwide, responsible for approximately 17 million cases of blindness and around 94 million cases of moderate to severe vision impairment, overwhelmingly concentrated in low- and middle-income countries where surgical capacity, not surgical technique, is the binding constraint (WHO). The remarkable feature of cataract is that it is entirely and permanently curable by a single operation — phacoemulsification with intraocular lens implantation, typically under local anaesthesia in under 20 minutes, restoring vision in over 90% of eyes without comorbidity — making cataract surgery among the most cost-effective interventions in all of medicine and the WHO's flagship example of the gap between what medicine can do and what health systems actually deliver, with effective cataract surgical coverage (eCSC) now adopted as a global monitoring indicator precisely because volume alone conceals poor visual outcomes.

Key messages

The leading cause of blindness worldwide — and entirely curable

Cataract accounts for approximately 17 million cases of blindness and around 94 million cases of moderate to severe vision impairment globally (WHO World Report on Vision). The burden is overwhelmingly concentrated in low- and middle-income countries — not because the disease differs, but because surgical capacity, affordability and access differ. Cataract surgery restores vision in over 90% of eyes without other ocular comorbidity, making it one of the most cost-effective interventions in all of medicine.

Effective cataract surgical coverage (eCSC) — the indicator that exposed the quality gap

WHO adopted eCSC as a global monitoring indicator precisely because counting operations conceals poor outcomes. Cataract surgical coverage (CSC) measures how many people needing surgery received it; effective CSC (eCSC) counts only those who achieved a GOOD visual outcome (presenting visual acuity 6/12 or better). The gap between CSC and eCSC in many countries is large — reflecting inadequate biometry, poor refractive correction after surgery, uncorrected astigmatism, and unrecognised comorbidity. WHO's 2030 target: a 30 percentage-point increase in eCSC.

Phacoemulsification with IOL is the standard — MSICS is the appropriate alternative at scale

Phacoemulsification: ultrasonic fragmentation and aspiration of the lens through a 2.2-2.8mm incision, with a foldable intraocular lens (IOL) implanted in the capsular bag; sutureless, rapid visual recovery, typically under 20 minutes with local anaesthesia. Manual small incision cataract surgery (MSICS): a sutureless scleral tunnel technique achieving comparable visual outcomes at substantially lower cost and without dependence on phaco machine consumables — making it the appropriate technique for high-volume, resource-constrained settings. Neither is "second-best": the choice is a systems decision, not a quality compromise.

Intracameral antibiotic prophylaxis prevents endophthalmitis

Postoperative endophthalmitis is the most feared complication of cataract surgery — rare (approximately 0.03-0.1%) but potentially blinding. The landmark ESCRS multicentre RCT demonstrated that intracameral cefuroxime at the end of surgery reduced endophthalmitis rates approximately five-fold. Intracameral antibiotic prophylaxis (cefuroxime, or moxifloxacin where cefuroxime is unavailable) is now standard of care internationally. Presentation: pain, reduced vision, hypopyon and increasing inflammation within days of surgery — a same-day ophthalmic emergency requiring vitreous tap and intravitreal antibiotics.

Posterior capsule opacification — the "after-cataract" treated by YAG laser

PCO occurs in approximately 20-30% of eyes within 2-5 years of surgery (higher in younger patients and children): residual lens epithelial cells proliferate and migrate across the posterior capsule, causing gradual blurring and glare that mimics the original cataract. Patients frequently believe "the cataract has come back" — it has not; the lens cannot regrow. Treatment: Nd:YAG laser capsulotomy — a painless outpatient procedure taking minutes, with immediate visual improvement. Complications are uncommon but include IOP spike, cystoid macular oedema and (rarely) retinal detachment.

Congenital and paediatric cataract — an amblyopia emergency

A dense congenital cataract is a time-critical emergency, not an elective problem. Deprivation of a clear retinal image during the critical period of visual development causes irreversible deprivation amblyopia. Dense unilateral congenital cataract should ideally be operated within approximately 4-6 weeks of birth, bilateral within approximately 6-8 weeks. This is why the red reflex examination in the newborn and infant checks is one of the highest-value screening tests in paediatrics — an absent or abnormal red reflex requires same-week ophthalmology referral (and also raises retinoblastoma, which is life-threatening). Postoperative management requires prolonged optical correction and amblyopia therapy.

Key statistics

~17M

people blind from cataract worldwide — the leading cause of global blindness

WHO World Report on Vision

>90%

of eyes without comorbidity achieve good vision after cataract surgery

WHO/ICO

eCSC

effective cataract surgical coverage — WHO indicator counting only GOOD visual outcomes

WHO 2021

~5-fold

reduction in endophthalmitis with intracameral cefuroxime (ESCRS RCT)

ESCRS/J Cataract Refract Surg

20-30%

develop posterior capsule opacification within 2-5 years — treated by YAG laser

RCOphth/AAO

4-6 weeks

target age for surgery in dense unilateral congenital cataract — amblyopia emergency

AAPOS/RCOphth

Global blindness — leading causes (WHO World Report on Vision)

Source: WHO. Cataract remains the single largest cause of blindness globally and is curable by one operation.

Glossary of key terms

Cataract morphology
OphthalmologyNuclear sclerotic: the commonest age-related type — yellowing and hardening of the lens nucleus; causes gradual blurring, reduced contrast, and a characteristic "second sight" phase (index myopia temporarily improving near vision in a previously presbyopic patient — a useful clinical clue). Cortical: wedge-shaped spoke opacities from the periphery; prominent glare and haloes, especially night driving. Posterior subcapsular (PSC): a plaque immediately in front of the posterior capsule; disproportionate visual disability for its size because it sits on the visual axis; causes severe glare and poor near vision; associated with corticosteroid use (topical, inhaled, oral), diabetes, radiation and younger patients. Congenital: lamellar, nuclear, polar, or total — requires urgent assessment.

Biometry and IOL power calculation
Ophthalmology/OpticsThe measurement step that determines refractive outcome. Optical biometry (partial coherence interferometry or swept-source OCT — IOLMaster, Lenstar) measures axial length, keratometry, anterior chamber depth and lens thickness; ultrasound biometry is used when dense cataract prevents optical measurement. Modern formulas (Barrett Universal II, Kane, Hill-RBF, Olsen) substantially outperform older-generation formulas (SRK/T, Hoffer Q, Holladay), especially in very long and very short eyes. Post-refractive-surgery eyes (previous LASIK, PRK, RK) require dedicated formulas — using standard formulas produces large refractive surprises. Poor biometry is a principal reason why cataract surgical coverage exceeds EFFECTIVE coverage in many programmes.

Intraocular lens types
OphthalmologyMonofocal: a single focal point — the standard, giving excellent quality distance (or near) vision with spectacles for the other range; the default in most public systems. Toric: corrects corneal astigmatism; requires accurate axis alignment. Multifocal and extended depth of focus (EDOF): provide spectacle independence across ranges at the cost of reduced contrast sensitivity, haloes and glare — unsuitable for patients with macular disease, glaucoma or high visual quality demands (night driving). Monovision: one eye set for distance, the other for near. Accommodating IOLs: aim to shift focus with ciliary muscle contraction; results remain modest. Counselling on trade-offs is essential — dissatisfaction after premium IOLs usually reflects expectation mismatch rather than technical failure.

Posterior capsule rupture and vitreous loss
Surgical complicationsThe most significant intraoperative complication (approximately 1-2% in experienced hands; higher with pseudoexfoliation, small pupils, dense white or brunescent cataract, previous vitrectomy, trauma and in training cases). Consequences if unmanaged: retained lens fragments, vitreous to the wound, cystoid macular oedema, retinal detachment, endophthalmitis. Management: anterior vitrectomy, careful IOL placement (sulcus fixation with optic capture, or anterior chamber/scleral-fixated IOL), and close postoperative follow-up. Recognised early and managed correctly, most eyes still achieve good vision — which is why intraoperative recognition and a rehearsed rescue plan matter more than the complication rate itself.

Cataract surgery and other ocular comorbidity
ClinicalVisual prognosis depends on the rest of the eye, and honest preoperative counselling prevents the commonest cause of postoperative dissatisfaction. Age-related macular degeneration: surgery removes the media opacity but cannot improve macular function — expectations must be set explicitly. Glaucoma: cataract surgery modestly lowers IOP and may be combined with MIGS procedures. Diabetic retinopathy: surgery can accelerate progression of retinopathy and macular oedema — optimise and treat retinopathy before operating where possible. Pseudoexfoliation: zonular weakness increases the risk of capsule rupture and late IOL subluxation. Fuchs endothelial dystrophy: risk of postoperative corneal decompensation — may require combined or staged endothelial keratoplasty.

High-volume cataract surgical models
Health systemsThe delivery challenge, not the surgical challenge, defines global cataract blindness. High-volume, high-quality models — Aravind Eye Care System (India), Tilganga (Nepal), the Fred Hollows Foundation programmes and others — have demonstrated that per-case cost can be reduced by an order of magnitude while maintaining outcomes, through: task-sharing and dedicated surgical teams; standardised instrument sets and parallel operating tables; local IOL manufacture; cross-subsidy from paying to non-paying patients; and active community case-finding with transport, rather than passive waiting for presentation. These are directly transferable health-systems lessons and are the reason cataract is a WHO exemplar of the gap between clinical capability and delivered care.

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