Cataract Surgery
When, IOL Choice, Complications & Recovery

1. What is cataract?

The crystalline lens sits behind the iris and consists of an outer capsule, an inner cortex and a central nucleus. It focuses light onto the retina and provides roughly 4 diopters of accommodative range in youth — the ability we lose to presbyopia.

Mechanistically, cataract is the oxidation, glycation, aggregation and crystalline-protein disruption of normally transparent lens fibers — the resulting tissue scatters and absorbs light. Different anatomic locations of opacity define the three main clinical types (see hero figure):

• Nuclear cataract: most common. Lens nucleus turns yellow, then brown, sometimes deeply brunescent. Slow progression over years. Distance vision is most affected; classic clue is a sudden myopic shift — older patients who suddenly read without their glasses are often developing nuclear cataract.
• Cortical cataract: spoke-like peripheral opacities, can mature into entirely white cortex. Hallmark is glare — oncoming headlights blow out at night; daylight is overwhelming.
• Posterior subcapsular cataract (PSC): just inside the posterior capsule — squarely in the visual axis. Even small opacities cause major deficits. Fastest progression. Near vision worse than distance (pupil constricts during reading, concentrating light through the opacity). Bright-light vision worst (same mechanism). More common in younger patients, steroid users, diabetics, and after radiation.

Natural history: cataracts do not regress. The protein changes are irreversible. The 2021 AAO PPP cites a 2017 Cochrane review showing N-acetylcarnosine drops (a widely marketed cataract eye drop) lack evidence of efficacy. Once a cataract is functionally bothersome, the only effective treatment is surgery.

2. Who gets it? Epidemiology & risk factors

Epidemiology:

• Globally: cataract is the leading cause of blindness worldwide (AAO 2021 PPP).
• United States: ~24.4 million people aged 40+ have cataract; projected to double to 50 million by 2050.
• Taiwan: 2020 NHI data — about 1.1 million people sought cataract care, over 80% aged 60+. 2002-2010 data showed an annual rate of ~5,350 surgeries per million population (~130,000/year then; substantially more now given ageing).
• Age distribution: prevalence rises sharply each decade after 40; almost all over-70s have some lens opacity, though symptoms and need for surgery vary.

Non-modifiable risk factors: age (strongest single factor), female sex, family history.

Modifiable risk factors:

• Diabetes mellitus: increases all three types with earlier onset.
• Smoking: dose-response with nuclear sclerosis. Risk declines after cessation.
• UV-B: cumulative exposure linked most to cortical cataract. UV-blocking sunglasses and brimmed hats are reasonable.
• Corticosteroids (any route): oral, inhaled, topical, intravitreal — strongest link to PSC. Long-term users should have periodic eye exams. Intranasal carries relatively lower risk.
• High myopia: increases nuclear and PSC risk; earlier onset.
• Trauma: blunt and penetrating injuries induce cataract, sometimes months to years later.
• Prior pars plana vitrectomy: nuclear sclerosis often accelerates.
• Others: hypertension, obesity, metabolic syndrome, prolonged inactivity, ionizing radiation.

On prevention: AAO 2021 PPP cites a 2012 Cochrane review of 9 RCTs showing no evidence that high-dose vitamin E, C or beta-carotene prevent cataract. A newer review suggested multivitamins may modestly reduce risk (moderate evidence). Practical: balanced diet rich in fruits and vegetables, smoking cessation, diabetes/BP control, UV protection.

3. Symptoms & warning signs

Cataract is gradual and painless; early stages are often missed. Common symptoms:

• Gradual blurring — like looking through frosted glass; not fully correctable.
• Glare and night halos — bright light overwhelms; lights at night appear haloed or starburst.
• Yellowing & reduced contrast — whites appear cream, blues dull. Often only recognized retrospectively after first-eye surgery.
• Sudden myopic shift (classic nuclear): older patients with presbyopia suddenly read without glasses; refraction shifts 1-2 D over months.
• Monocular diplopia (ghosting): uneven opacity creates multiple focal points; the moon and lamp posts develop a 'ghost'. Persists when one eye is covered — intraocular cause (commonly cataract), not stroke.
• Vision worse in bright light (classic PSC): pupillary constriction directs light through the central plaque.
• Contrast sensitivity loss: Snellen may still be 0.7-0.8 yet reading in fog, twilight or low contrast is hard. Standard charts miss this.

Important: cataract does not cause pain or redness. Eye pain, red eye, sudden vision loss, or new floaters with flashes are not typical of cataract — they may signal acute angle-closure glaucoma, retinal detachment, uveitis or another emergency. Seek immediate care.

4. When should you have surgery?

Reasonable indications for surgery:

• Driving safety — disabling night glare, blurred signage, poor depth judgment. Cataract drivers have ~2.5× the crash rate of non-cataract drivers; surgery roughly halves this (cited in AAO PPP).
• Falls & fractures — poor acuity plus reduced contrast sensitivity is a major modifiable risk factor for falls and hip fracture. An RCT showed 34% reduction in falls/fractures after first-eye surgery; observational data show a further 73% drop after second-eye surgery.
• Inability to read or work — near tasks impaired, can't read or use phone, affecting occupation.
• Cataract obscures monitoring or treatment of other ocular disease — fundus details (AMD, diabetic retinopathy, glaucoma changes) are obscured, or laser and intravitreal therapy can't be performed safely.
• Subjective bother — patient feels quality of life is meaningfully reduced even when the Snellen number looks fine. This is a legitimate indication; acuity does not capture glare, contrast loss, or aberrations.
• Anisometropia after first-eye surgery — large refractive disparity degrades stereopsis and balance.

Situations needing prompt or urgent attention:

• Lens-induced glaucoma: intumescent or leaking lens material causing acute angle closure or phacolytic glaucoma — urgent surgical management.
• Diabetic retinopathy requiring laser or intravitreal injection obscured by cataract — proceed with cataract surgery first.

Both-eye timing & ISBCS: traditionally each eye is done 1-4 weeks apart. Immediate sequential bilateral cataract surgery (ISBCS) is increasingly performed in Europe and Canada and has GRADE + endorsement from ESCRS 2024. Pros: fewer visits, faster binocular balance, less interval fall risk. Cons: cannot pause if first eye has a complication, cannot fine-tune second-eye power. Sequential surgery remains the mainstream in Taiwan.

5. Preoperative evaluation

A full workup serves two purposes: (1) confirm cataract is the main cause of visual impairment; (2) calculate precise IOL power and select an appropriate IOL.

① Standard eye examination

• Visual acuity (corrected, with optional glare testing)
• Slit-lamp exam — cataract type/density, corneal endothelium (Fuchs dystrophy), iris and pupil
• Intraocular pressure — screen for coexisting glaucoma
• Dilated fundus exam — retina, macula, optic nerve, peripheral retina
• Macular OCT — ESCRS recommends when clinically indicated (AMD, diabetic retinopathy, glaucoma, or symptoms disproportionate to cataract). Detects ERM, macular edema, subtle AMD — all affect prognosis.
• Corneal topography/tomography — astigmatism magnitude/regularity, posterior corneal power, prior refractive surgery — essential for toric IOL planning.

② Biometry — the foundation of IOL power calculation

Modern formulas need: axial length, K, ACD, lens thickness, white-to-white, age, sex. Optical biometers (PCI or swept-source OCT) are substantially more accurate than ultrasound A-scan and are strongly recommended by AAO PPP and AAPPO consensus.

IOL formulas: Barrett Universal II, Hill-RBF (AI), Kane, Olsen, PEARL-DGS. ESCRS 2024 (GRADE +): (1) prefer newer-generation formulas over SRK-T; (2) special formulas for extreme axial length; (3) keratoconus-specific formulas; (4) ASCRS or ESCRS online calculators after refractive surgery.

③ Systemic considerations

• Diabetes: aim for HbA1c < 8.5% (AAPPO 2025); significant retinopathy should be assessed for preoperative anti-VEGF or laser.
• Antiplatelets & anticoagulants: aspirin, clopidogrel, warfarin, NOACs (apixaban, rivaroxaban) need not be stopped under topical anesthesia (AAO/AAPPO/ESCRS consistent). Some centers adjust if peribulbar block is used.
• Tamsulosin & other α1-antagonists (prostatic hypertrophy meds): cause intraoperative floppy iris syndrome (IFIS) — pupillary miosis and iris billowing complicate surgery. Stopping doesn't reverse exposure; tell the surgeon in advance so iris hooks/rings can be readied.
• Dry eye treatment: dry eye destabilizes K readings. Treat before final biometry.
• Informed consent: discuss risks, IOL options, expected outcomes, possible secondary procedures (YAG, IOL exchange). AAPPO 2025 consensus 100% agreed consent should be obtained before the day of surgery.

6. Surgical method comparison

Three main surgical methods are used today:

On Taiwan's heavily marketed 'self-pay femtosecond laser' option: the laser is real and effective, but it is not an 'upgraded surgery' — it just replaces one step (incision, capsulotomy or fragmentation) with a laser. Major trials (FEMCAT, FACTS, ESCRS FLACS registry) have not shown better visual outcomes or fewer complications. There may be modest benefit in very dense nuclei, small pupils or floppy iris syndrome, but for most patients standard phaco suffices.

7. Intraocular lenses — no universally best option

① Main IOL categories

◆ Monofocal — most reliable, NHI-covered

• Single focal point, typically set for distance (no distance glasses, but reading glasses needed).
• Best optical quality — highest contrast sensitivity, least night glare/halo.
• Fully NHI-covered.
• Suits: most patients, night drivers, those with macular disease, perfectionist personalities.

◆ Toric (astigmatism-correcting)

• Built-in astigmatism correction added to a monofocal or multifocal lens.
• ESCRS 2024 thresholds: against-the-rule (ATR) ≥ 1.0 D or with-the-rule (WTR) ≥ 1.5 D meaningfully benefits (GRADE ++); ≥ 2.0 D has strong evidence (GRADE ++).
• Not suitable for irregular astigmatism (keratoconus, severe dry eye, post-LASIK).
• Self-pay: NTD 30k-60k depending on brand and power.

◆ Extended Depth of Focus (EDOF)

• Stretches a single focal point into a range; mainly strengthens intermediate vision (computer, phone, dashboard).
• Near vision modestly improved but reading glasses may still be needed.
• Less glare/halo than multifocal but more than monofocal.
• ESCRS recommends EDOF for patients wanting good intermediate acuity with relatively fewer dysphotopsias (GRADE +).
• Self-pay: NTD 60k-80k.

◆ Multifocal / Trifocal

• Multiple focal points (distance + intermediate + near). Lowest spectacle dependence postoperatively.
• Trade-off: pronounced halos, glare, starburst at night (light split among foci); reduced contrast sensitivity; 6-12 month neuroadaptation in some patients.
• Avoid in: frequent night drivers, perfectionist personality, macular disease, advanced glaucoma, irregular astigmatism, monocular amblyopia.
• ESCRS recommends multifocal for patients wanting spectacle independence at all distances (GRADE +), with explicit counseling on increased halo/glare (GRADE +).
• Self-pay: NTD 80k-150k.

◆ Light-Adjustable Lens (LAL)

• Post-implant power can be tuned with UV light over multiple in-office sessions, then 'locked in'.
• Pros: can correct refractive surprise; valuable in post-refractive eyes where calculation is hard.
• Cons: expensive; UV-filter glasses required for 2-3 months until lock-in; more visits.
• Limited availability in Taiwan.

② IOL trade-off radar (visual comparison)

③ How to choose? Four key questions

1. Personality? Perfectionists and detail-oriented patients often struggle with multifocal neuroadaptation — monofocal or EDOF is safer.
2. Predominant working distance? Mostly reading → near-set monofocal or multifocal; computer-heavy → EDOF; professional/night driver → monofocal to avoid halos.
3. Coexisting eye disease? Macular degeneration, diabetic retinopathy, advanced glaucoma, irregular astigmatism, monocular amblyopia → avoid multifocal — already-compromised vision plus multifocal contrast loss is a double hit.
4. How important is glasses-independence? If reading glasses for near are acceptable, monofocal does the job. If spectacle independence is a strong priority and you accept night halos, consider EDOF or multifocal.

Monovision as an alternative: instead of multifocal, implant monofocals targeting different distances — dominant eye for distance, non-dominant for near (~-1.5 to -2.0 D). The brain switches automatically. AAO PPP cites ~90% success rate with preserved optical quality (no halo/glare). Particularly well-suited for those who previously did well with monovision contact lenses.

8. The day of surgery

Pre-surgery (arrive 1-2 hours before):

• Identity and surgical eye verification; eye is marked above the brow
• Dilating drops (3-4 instillations, 30-40 minutes) to widen the pupil
• Topical anesthetic drops (proparacaine or tetracaine)
• Periorbital skin and conjunctival cul-de-sac prepped with 5% povidone-iodine (ESCRS GRADE +++ strongly recommended for endophthalmitis prevention)
• Sterile drape; lid speculum keeps the eye open

Surgical steps (about 10-20 minutes):

1. Corneal incision: 2.2-2.75 mm clear corneal entry (Taiwan practice mostly 2.75 mm)
2. Ophthalmic viscosurgical device (OVD): protects corneal endothelium, maintains anterior chamber
3. Capsulorhexis: a 5-5.5 mm circular opening in the anterior capsule
4. Hydrodissection: fluid wave separates lens nucleus from cortex and capsule
5. Phacoemulsification: ultrasonic tip fragments and aspirates the nucleus — the most critical and demanding step
6. Cortex aspiration: removes residual cortex while preserving the capsular bag
7. IOL implantation: foldable IOL is injected through the same incision and unfolds inside the capsular bag
8. OVD removal: irrigate/aspirate to remove the viscoelastic
9. Intracameral antibiotic: cefuroxime or moxifloxacin (ESCRS GRADE +++ — the highest-evidence endophthalmitis prevention)
10. Wound seal check: confirm watertight closure; no sutures needed

What does the patient experience?

• Bright microscope light (uncomfortable but not painful)
• Blurred shadows of instruments moving
• Mild pressure, fluid flow and instrument contact — but no sharp pain
• The surgeon's voice and machine sounds
• No general anesthesia required; mild oral or IV sedation is offered for highly anxious patients

After surgery: an eye shield or protective glasses are placed; you rest ~30 minutes and go home with a companion. Vision is already useful that day but may be hazy (mild corneal edema); by the day-1 visit it is usually noticeably clearer.

9. Postoperative recovery

① Follow-up schedule

• Day 1: confirm wound integrity, intraocular pressure, no signs of infection, IOL position (strongly recommended by AAO PPP)
• Week 1: visual acuity, inflammation
• Week 4: refraction stable, new glasses prescribed
• Month 3: comprehensive evaluation; plan second-eye surgery if needed

② Eye drops

Three classes of drops are typically used for 4-6 weeks:

• Antibiotic drops (fluoroquinolone): 1-2 weeks, prevent wound infection
• Topical corticosteroid: 4-6 weeks tapered, controls postoperative inflammation
• Topical NSAID: 4-6 weeks, prevents cystoid macular edema (ESCRS GRADE +/++ recommends NSAID + steroid combination over either alone)

For diabetics with retinopathy: ESCRS 2024 (GRADE +) suggests adjunctive triamcinolone (injectable steroid) for enhanced CME prevention, with IOP monitoring. Preservative-free artificial tears are also often prescribed for postoperative dryness.

③ Don'ts — avoid these for the first month

• Rubbing the eye (especially in first 4 weeks) — can dehisce the wound
• Contaminated water (first week) — tap, rain, pool; clean facial towels OK
• Heavy lifting, vigorous exercise, deep bending (2-4 weeks) — IOP fluctuation may stress the wound
• Sauna, swimming, eye massage (1 month)
• Heavy eye makeup (eyeliner, shadow — avoid 2 weeks)

④ Do's — what to do

• Daytime: wear sunglasses for bright light and dust
• At night: wear the protective shield for the first 1-2 weeks to prevent unconscious rubbing
• Use phone reminders for drop schedules
• Light activity (walking, household tasks) is fine from day 1 — no bed rest needed
• Non-physical work (computer, desk) can resume in week 1
• Physical work and exercise (excluding swimming) — 2 weeks
• Driving: individualized; daytime driving usually OK in week 1-2, night driving may require longer

10. Possible complications (real numbers)

Cataract surgery is now very safe. The AAO 2021 PPP compiles multiple studies showing low overall complication rates with very rare permanent vision loss. Below are real published rates, so you can think about risk in numbers rather than fear:

11. Posterior capsular opacification (PCO) — not a recurrence

What is PCO? The original cataract is removed and the IOL is in place, but a few lens epithelial cells remain on the posterior capsule (deliberately preserved at surgery to support the IOL). These cells proliferate and migrate centrally, clouding the capsule and again degrading vision.

Incidence & timing: 5-50% depending on follow-up duration and IOL design (per AAO PPP). Most arise 1-3 years post-op; multifocal IOL patients may notice it earlier because their light is already split among foci. Sharp-edged hydrophobic acrylic IOLs have the lowest PCO rate.

How YAG laser works:

• Dilating drops
• Seated at the slit-lamp YAG laser, chin in the rest
• A circular opening is made in the central posterior capsule (the IOL is not damaged)
• About 30-50 shots over ~5 minutes — light flashes and small audible pops, but no pain.
• Vision improves immediately; you may see floating dark fragments (capsule debris) for days to weeks

Possible YAG complications (rare): transient IOP rise (especially in glaucoma patients — prophylactic IOP-lowering drops can be given); retinal detachment (higher in high myopia — ~0.3-0.9% within 2 years per AAO PPP); very rare IOL damage or positional change.

12. Taiwan NHI Coverage (April 2026)

Current NHI coverage of cataract-related medications:

IOL coverage — NHI monofocal vs self-pay toric / EDOF / multifocal / trifocal / LAL — falls under medical device regulations, not the drug coverage referenced here. Hospitals publish their own IOL price lists. See the 'NHI vs Self-pay' section in the Cataract Surgery Selection article.

* Source: NHIA Drug Coverage Regulations, April 2026, Sections 14.4.1 and 14.8. Confirm latest at NHIA.

13. Common myths — QA

Key references

1. [AAO 2021 主要指引] American Academy of Ophthalmology. Cataract in the Adult Eye Preferred Practice Pattern. Ophthalmology. 2022;129(1):P1-P126. Approved Oct 2021.
2. [AAPPO 2025 亞太共識] Srinivas SP, Young AL, Behndig A, Chang DF, et al. Controversies, consensuses and guidelines on modern cataract surgery by the Academy of Asia-Pacific Professors of Ophthalmology (AAPPO). Asia-Pac J Ophthalmol. 2025;14:100224. doi:10.1016/j.apjo.2025.100224
3. [ESCRS 2024 31 條 GRADE 建議] European Society of Cataract and Refractive Surgeons. ESCRS Recommendations for Cataract Surgery. Executive Summary. 2024. Available at: https://www.escrs.org/escrs-recommendations-for-cataract-surgery
4. ESCRS Endophthalmitis Study Group. Prophylaxis of postoperative endophthalmitis following cataract surgery: results of the ESCRS multicenter study. J Cataract Refract Surg. 2007;33(6):978-988（per AAO 2021 PPP）.
5. Day TJ, Donachie PHJ, Sparrow JM, Johnston RL. The Royal College of Ophthalmologists' National Ophthalmology Database study of cataract surgery: report 1, visual outcomes and complications. Eye. 2015;29(4):552-560（per AAO 2021 PPP）.
6. Schein OD, Cassard SD, Tielsch JM, Gower EW. Cataract surgery and the 5-year incidence of late-stage age-related maculopathy. Ophthalmology. 2014;121(7):1428-1431（per AAO 2021 PPP）.
7. Day AC, Donachie PHJ, Sparrow JM, et al. The Royal College of Ophthalmologists National Ophthalmology Database. Femtosecond laser-assisted vs phacoemulsification cataract surgery (FACT): outcomes. JAMA Ophthalmol. 2020;138(6):572-579（per AAO 2021 PPP / AAPPO 2025 引述）.
8. National Health Insurance Administration, Taiwan. NHI cataract care utilization data, 2020. Available via: https://www.nhi.gov.tw/
9. Hsu CC, Hsu CY, Chen YH, et al. Time trends in cataract surgery and after-cataract laser capsulotomy in Taiwan: A population-based retrospective cohort study. J Formos Med Assoc. 2018.
10. Marcocci C, Kahaly GJ, Krassas GE, et al.（為一般 Cochrane 引述背景之歷史標誌；本文僅引述 AAO PPP 內已確認的 Cochrane 系統性回顧結論：N-acetylcarnosine 2017 systematic review 與 vitamin C/E 2012 review）。