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 can accommodate — about 10 diopters or more in youth, declining gradually with age until presbyopia sets in.

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 relatively younger patients (often in their 40s to 60s), 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: the number of people with cataract is forecast to double from about 24.4 million to about 50 million by 2050 (AAO 2021 PPP).
• Taiwan: 2020 NHI data — about 1.1 million people sought cataract care, over 80% aged 60+. 2002-2010: an average of ~5,350 surgeries per million population per year (Hsu & Liu 2014); volume has since grown with ageing, to about 244,000 operations in 2020 (Ministry of Health and Welfare).
• 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. The PPP also notes moderate evidence that a multivitamin/mineral supplement may reduce risk. 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; the glasses prescription may change noticeably over a short time.
• 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. In studies cited by the AAO PPP, drivers with cataract were ~2.5× more likely to have had an at-fault crash in the prior 5 years (Owsley 1999), and in a cohort of 277 cataract patients those who had surgery had half the crash rate over 4-6 years of follow-up (Owsley 2002).
• Falls & fractures — poor acuity plus reduced contrast sensitivity is a major modifiable risk factor for falls and hip fracture. An RCT showed a 34% lower rate of falls in the year after first-eye surgery; a cohort study found falls were 54% lower after first-eye and 73% lower after second-eye surgery, both compared with before the first operation (cited in AAO PPP).
• 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 (ESCRS's + to ++++ ratings indicate quality of evidence, not strength of recommendation). 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) newer-generation formulas tend to give better outcomes (traditional formulas remain acceptable where newer ones are unavailable); (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) usually need not be stopped for cataract surgery (AAO PPP and the AAPPO majority view; data on newer anticoagulants are limited, so management is individualized). This is not limited to topical anesthesia: in U.K. data cited by the AAO PPP (48,862 operations), users receiving sharp-needle or sub-Tenon blocks had no increase in sight-threatening hemorrhagic complications, although subconjunctival hemorrhage was more common (warfarin 3.7%, clopidogrel 4.4%, non-users 1.7%).
• 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). The AAPPO 2025 consensus advises obtaining consent before, rather than on, 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 studies (the FEMCAT and FACT randomized trials and the ESCRS EUREQUO registry study) 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.
• Standard monofocal spherical IOLs are fully NHI-covered (no out-of-pocket cost); an aspheric monofocal carries a self-pay difference of about NT$ 30,500 per eye (median charge).
• 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: toric IOLs should be considered for corneal astigmatism ≥ 1.0 D (GRADE ++); evidence is strong above 2.0 D, moderate above 1.5 D and more limited at 1.0 D.
• Not suitable for irregular astigmatism (keratoconus, severe dry eye, post-LASIK).
• Self-pay difference: monofocal toric ~NT$ 45,000 per eye; ~NT$ 55,000-110,000 per eye combined with extended-focus or multifocal designs.

◆ 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 difference: short-range extended focus (enhanced monofocal) ~NT$ 40,000; long-range EDOF ~NT$ 75,000 per eye.

◆ 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 considering multifocal IOLs for patients wanting spectacle independence at all distances, used thoughtfully and with explicit counseling because halo/glare is more common than with monofocals (GRADE +).
• Self-pay difference: bifocal ~NT$ 60,000, trifocal ~NT$ 85,000, trifocal toric ~NT$ 110,000 per eye.

◆ Light-Adjustable Lens (LAL): available abroad only

• 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-protective glasses must be worn whenever awake until the final lock-in (several weeks after surgery, per the US FDA review); more visits.
• Not available in Taiwan: no Ministry of Health and Welfare licence has been found.

Amounts above are median per-eye IOL self-pay differences from the NHIA self-pay-difference device price lookup (queried October 2026) and exclude surgery: cataract surgery is NHI-covered, and with a special-function IOL NHI still pays 2,744 points while you pay the difference. For reference only; actual charges follow each hospital/clinic's posted fee schedule. Full table by class: 'Special-function IOLs: national reference prices' in our cataract surgery selection guide.

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 one study with ~90% acceptance 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 (recommended by ESCRS for endophthalmitis prevention, GRADE +)
• Sterile drape; lid speculum keeps the eye open

Surgical steps (about 10-20 minutes):

1. Corneal incision: clear corneal entry, commonly 2.2-2.75 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 cites cefuroxime as the example, GRADE +++ — the highest evidence rating for endophthalmitis prevention in that guideline)
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 (AAO PPP: within 24 hours for high-risk or functionally monocular patients, within 48 hours for low-risk patients)
• 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: the proportion needing YAG capsulotomy ranges from under 5% to 54%, depending on follow-up duration and IOL design (per AAO PPP). It can appear months to years after surgery; onset varies and the rate generally increases over time (AAO PPP). Multifocal IOL patients may notice it earlier because their light is already split among foci. Sharp-edged hydrophobic acrylic IOLs have lower PCO rates than hydrophilic acrylic IOLs.

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; studies cited in the AAO PPP report 0-0.4% over 1-8 years, and about 0.9% within the first 5 months in another study); very rare IOL damage or positional change.

12. Taiwan NHI Coverage (updated 22 October 2026)

Current NHI coverage of cataract-related medications:

IOL coverage — NHI monofocal vs self-pay toric / EDOF / multifocal / trifocal — 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: Taiwan NHI drug reimbursement rules (updated 2026-10-22), sections 14.4.1 and 14.8. Confirm latest at NHIA.

13. Common myths — Q&A

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(4):100224. doi:10.1016/j.apjo.2025.100224
3. [ESCRS 2024 31 個臨床問題 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 and identification of risk factors. J Cataract Refract Surg. 2007;33(6):978-988（per AAO 2021 PPP）.
5. Day AC, 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. Wang JJ, Klein R, Smith W, Klein BE, Tomany S, Mitchell P. Cataract surgery and the 5-year incidence of late-stage age-related maculopathy: pooled findings from the Beaver Dam and Blue Mountains eye studies. Ophthalmology. 2003;110(10):1960-1967.
7. Day AC, Burr JM, Bennett K, et al. Femtosecond laser-assisted cataract surgery versus phacoemulsification cataract surgery (FACT): a randomized noninferiority trial. Ophthalmology. 2020;127(8):1012-1019（AAO 2021 PPP 引述）.
8. National Health Insurance Administration, Taiwan. NHI cataract care utilization data, 2020. Available via: https://www.nhi.gov.tw/
9. Lee JS, Chung CC, Lin KK, Yu KH, Kuo CF, See LC. Time trends in cataract surgery and after-cataract laser capsulotomy in Taiwan: A population-based retrospective cohort study. Int J Surg. 2016;36(Pt A):265-273.
10. Dubois VDJ-P, Bastawrous A. N-acetylcarnosine (NAC) drops for age-related cataract. Cochrane Database Syst Rev. 2017;CD009493. doi:10.1002/14651858.CD009493.pub2.
11. Mathew MC, Ervin A-M, Tao J, Davis RM. Antioxidant vitamin supplementation for preventing and slowing the progression of age-related cataract. Cochrane Database Syst Rev. CD004567. doi:10.1002/14651858.CD004567.pub2 (Original 2012 review; the current Cochrane page lists 2022. This does not imply new 2022 trials.)
12. Hsu WM, Liu JH. Ophthalmology in Taiwan. Taiwan J Ophthalmol. 2014;4(2):59-62. doi:10.1016/j.tjo.2014.03.004
13. Owsley C, Stalvey B, Wells J, Sloane ME. Older drivers and cataract: driving habits and crash risk. J Gerontol A Biol Sci Med Sci. 1999;54(4):M203-M211（AAO 2021 PPP 引述）.
14. Owsley C, McGwin G Jr, Sloane M, et al. Impact of cataract surgery on motor vehicle crash involvement by older adults. JAMA. 2002;288(7):841-849（AAO 2021 PPP 引述）.
15. Benzimra JD, Johnston RL, Jaycock P, et al. The Cataract National Dataset electronic multicentre audit of 55,567 operations: antiplatelet and anticoagulant medications. Eye. 2009;23(1):10-16（AAO 2021 PPP 引述）.