Cycloplegics

Concise summaries of cycloplegic and mydriatic eye drops used in ophthalmic and optometric practice in Singapore, including clinical guidance on pharmacology, dosing, patient selection, myopia control (low-dose atropine), and safe monitoring.

Last updated: March 2026

What are cycloplegics?

Cycloplegics are topical ophthalmic agents that temporarily paralyse the ciliary muscle (cycloplegia), eliminating the eye's capacity to accommodate. Most agents in this class also produce mydriasis (pupil dilation) by blocking the iris sphincter muscle. Both effects are mediated through competitive antagonism of muscarinic acetylcholine receptors (primarily M3) in the ciliary body and iris.

In Singapore, cycloplegics are a cornerstone of paediatric optometric and ophthalmic practice. Given Singapore's extraordinarily high myopia prevalence — exceeding 80% in young adults — cycloplegic refraction in children and low-dose atropine for myopia control are among the most clinically significant applications of this drug class in the region. The landmark ATOM1 (2006) and ATOM2 (2012) randomised controlled trials, conducted at the Singapore National Eye Centre (SNEC), established the global evidence base for low-dose atropine as a myopia control intervention.^[1,2]

Drug classes

Anticholinergic cycloplegics (muscarinic antagonists) — the core class; produce complete or near-complete cycloplegia and mydriasis by blocking muscarinic receptors in the ciliary body and iris sphincter. Duration ranges from short (cyclopentolate: 6–24 h), intermediate (homatropine: 1–3 days), to long (atropine: 7–14 days).
Pure mydriatics (adrenergic agonists) — dilate the pupil via stimulation of the iris dilator muscle (α1-agonist); do not cause cycloplegia. Phenylephrine 2.5% and 10% are the primary agents. Used as adjuncts for diagnostic dilation, not for cycloplegic refraction.
Low-dose atropine (myopia control) — sub-therapeutic atropine formulations (0.01%–0.05%), compounded at licensed hospital pharmacies, act via a distinct proposed mechanism (retinal/choroidal M4 receptor modulation) to slow axial elongation without causing clinically significant cycloplegia or accommodation loss at the lowest doses.

Who are they for?

Cycloplegics and mydriatics are indicated across a broad range of diagnostic and therapeutic clinical scenarios. In Singapore, the high burden of myopia among children and young adults — driven by intensive near-work demands, an urban indoor lifestyle, and limited outdoor time — means that myopia control indications represent a particularly important and rapidly growing segment of cycloplegic use. The Myopia in Singapore children longitudinal cohort data demonstrate myopia onset as early as age 6–7 years, making early cycloplegic assessment and timely initiation of myopia control essential.^[3]

Patient profiles and common indications

Cycloplegic refraction — children

Mandatory for accurate refraction in children <10–12 years to eliminate accommodative spasm; essential for diagnosing latent hyperopia, accommodative esotropia, and anisometropia.

Myopia control — progressive paediatric myopia

Low-dose atropine 0.01%–0.05% OD at bedtime; supported by ATOM1/ATOM2 (SNEC); widely prescribed in Singapore by ophthalmologists and paediatric optometrists under medical supervision.

Anterior uveitis / iritis

Therapeutic cycloplegia with atropine 1% or homatropine 2% prevents formation of posterior synechiae, reduces ciliary spasm pain, and stabilises the blood-aqueous barrier.

Diagnostic mydriasis — fundal examination

Tropicamide 1% ± phenylephrine 2.5% for diabetic retinopathy screening, vitreoretinal assessment, optic nerve evaluation, and dilated anterior segment examination.

Amblyopia penalization therapy

Atropine 1% instilled to the fellow (sound) eye blurs central vision, promoting use of the amblyopic eye — an established alternative to occlusion patching (PEDIG trials).

Post-operative / traumatic iritis

Cycloplegia with cyclopentolate or homatropine reduces photophobia and ciliary spasm pain following intraocular surgery, corneal procedures, or blunt ocular trauma.

Caution — contact lens wearers

Cycloplegic and mydriatic drops should not be instilled while contact lenses are in situ. Advise patients to remove lenses before instillation. Given the prolonged duration of mydriasis and accommodation loss — particularly with cyclopentolate (6–24 h) or atropine (up to 14 days) — contact lens wear should be suspended for the full duration of effect. Singapore's high contact lens-wearing population (estimated >1.2 million wearers) makes this a highly relevant counselling point. Patients should be strongly advised to arrange transport rather than drive after mydriatic instillation, due to photophobia and impaired near vision.

When should they be used?

Diagnostic cycloplegic refraction

Cycloplegic refraction is indicated whenever manifest refraction may be confounded by active accommodation — particularly in children under 10–12 years, patients with suspected latent hyperopia or accommodative esotropia, and any patient whose non-cycloplegic refraction is inconsistent with symptoms or visual acuity findings. Cyclopentolate 1% is the standard agent; atropine 1% (3-day pre-instillation) is reserved for infants, very high hyperopes, or patients where cyclopentolate achieves inadequate cycloplegia. Examination should occur 30–45 minutes after the final cyclopentolate dose.

Myopia control — ongoing low-dose atropine

Low-dose atropine (0.01%–0.05%) is initiated by an ophthalmologist in children with documented myopia progression (≥0.50 D/year or increasing axial length on biometry). Therapy is ongoing and typically continued until myopia stabilises or the patient reaches adulthood. Axial length review every 6 months is recommended. Concentration selection (0.01% vs. 0.025% vs. 0.05%) is guided by the balance of efficacy and tolerability — ATOM2 demonstrated that 0.01% achieves meaningful slowing of progression with minimal functional side effects.^[2]

Therapeutic use and urgent referral

Therapeutic cycloplegia (atropine or homatropine) for uveitis, traumatic iritis, or post-operative management must be prescribed and initiated by an ophthalmologist. Any Singapore optometrist detecting signs of anterior uveitis, iritis, or acute angle closure must refer the patient urgently — same-day to the nearest ophthalmic emergency service. Do not attempt to manage these conditions within an optometric setting.

Indication	Recommended agent	Referral / Duration
Routine fundal examination (adult)	Tropicamide 1% ± phenylephrine 2.5%	Single visit; ophthalmologist
Cycloplegic refraction — child ≥1 year	Cyclopentolate 1% (×2 drops)	Examine at 30–45 min; refer to ophthalmologist
Cycloplegic refraction — infant <12 months	Cyclopentolate 0.5% or atropine 1% (home pre-instillation)	Ophthalmology/paediatric referral
Progressive myopia — myopia control	Low-dose atropine 0.01%–0.05% OD	Ongoing; ophthalmologist; 6-monthly axial length review
Anterior uveitis / iritis	Atropine 1% or homatropine 2% BD–TID	URGENT ophthalmology referral — same day
Amblyopia penalization	Atropine 1% to fellow eye (as prescribed)	Ophthalmologist-directed; ongoing monitoring

Where are they available in Singapore?

In Singapore, all cycloplegic and mydriatic eye drops are regulated by the Health Sciences Authority (HSA) under the Medicines Act (Cap. 176). All agents in this class are classified as Prescription-Only Medicines (POM) and may only be prescribed by a registered medical practitioner (typically an ophthalmologist, paediatrician, or GP with ophthalmic experience). Low-dose atropine formulations (0.01%, 0.025%, 0.05%) are compounded preparations prepared by licensed hospital pharmacies — they are not commercially available as off-the-shelf products and require a valid prescription from a doctor.^[4]

Scope of practice — Singapore optometrists

Under the Optometrists and Opticians Act (Cap. 213A) and regulations administered by the Optometrists and Opticians Board (OOB), Singapore-registered optometrists are authorised to examine eyes, measure visual function, and prescribe optical appliances (spectacles and contact lenses). They do not have the authority to prescribe, supply, administer, or compound any therapeutic medications — including cycloplegics and mydriatics. Optometrists must refer any patient requiring cycloplegic refraction, mydriatic examination, myopia control pharmacotherapy, or therapeutic cycloplegia to a registered medical practitioner. Performing cycloplegic refraction by self-administering or supervising drug instillation outside a medically supervised context is outside the current Singapore optometric scope of practice.^[5,6]

Prescription-only (POM): All cycloplegics and mydriatics — cyclopentolate (Cyclogyl), atropine (Isopto Atropine), tropicamide (Mydriacyl), homatropine (Isopto Homatropine), and phenylephrine (Minims Phenylephrine) — require a valid prescription from a registered medical practitioner. No cycloplegic is available OTC or as a Pharmacy medicine in Singapore.
Hospital formularies: Cyclopentolate 1%, atropine 1%, tropicamide 1%, and phenylephrine 2.5% are standard formulary items at major public eye centres. Low-dose atropine 0.01%/0.025%/0.05% is dispensed by hospital pharmacies following ophthalmologist prescription via myopia management clinics.
Private ophthalmology clinics: Cycloplegic eye drops may be prescribed and administered during clinic visits, or prescribed for home use prior to a scheduled refraction appointment (atropine pre-instillation protocol). Dispensing is through licensed retail pharmacies with valid prescription.
Compounding pharmacies: Low-dose atropine formulations are prepared by licensed compounding pharmacies (including hospital-affiliated units) under strict pharmaceutical standards. Patients must present a valid medical prescription. Quality, sterility, and shelf-life considerations mean compounded products should be obtained only from HSA-licensed outlets.
HSA product verification: Current HSA registration status for commercially available cycloplegics and mydriatics can be verified via the HSA product registration portal (hsa.gov.sg). Note that compounded low-dose atropine formulations are not individually registered products — they are prepared under the prescribing physician's responsibility at licensed compounding facilities.^[4]

Why use topical cycloplegic agents?

Topical ophthalmic cycloplegics deliver high local drug concentrations directly to the ciliary body and iris with faster onset, more complete ciliary muscle relaxation, and a significantly lower systemic drug load compared with oral anticholinergics. Targeted topical delivery is both clinically superior for the intended ocular effect and substantially safer from a systemic adverse-event standpoint.

Accurate paediatric refraction

Complete cycloplegia eliminates accommodative spasm, revealing true refractive error — particularly critical for detecting latent hyperopia and accommodative esotropia in Singapore children.

Myopia control — population-level benefit

Low-dose atropine is the best-evidenced pharmacological myopia control agent globally. Singapore-generated ATOM data underpin international clinical guidelines (IMI, BCLA, AAO). Benefits on axial length slowing are clinically meaningful.

Prevention of posterior synechiae

In uveitis, cycloplegia prevents iris adhesion to the anterior lens capsule, preserving pupil mobility and preventing irreversible structural complications.

Ciliary spasm pain relief

Paralysing the ciliary muscle eliminates the photophobic pain of ciliary spasm in traumatic iritis and post-operative inflammation — a rapid and effective analgesic mechanism.

The topical route is preferred over systemic anticholinergics (e.g., oral atropine) for ocular indications because topical agents achieve far higher intraocular drug concentrations at a fraction of the systemic dose, dramatically reducing systemic anticholinergic adverse effects (tachycardia, urinary retention, confusion, fever). Nasolacrimal occlusion and eyelid closure further reduce systemic absorption and are best practice for all cycloplegic instillations, particularly in children and infants.^[7]

How to use cycloplegics — patient instructions

Instillation technique

Wash hands thoroughly with soap and water before handling the bottle or touching the eye area.
Tilt head back and gently pull down the lower eyelid with one finger to create a small pocket (lower fornix).
Hold the bottle inverted above the eye and instil one drop into the lower fornix — do not allow the bottle tip to touch the eye, eyelid, or eyelashes to prevent contamination.
Immediately after instillation, gently close the eye and apply nasolacrimal occlusion by pressing a fingertip firmly to the inner corner of the eye (nasolacrimal duct area) for at least 1–2 minutes — this is critical to reduce systemic absorption, particularly in children and infants.
If a second drop is required (e.g., for cycloplegic refraction), wait at least 5 minutes before instilling the next drop to allow the first dose to be absorbed and to reduce overflow loss.
Recap the bottle immediately after use. Store as directed on the label (most at room temperature, away from direct heat and light). Discard as indicated — single-use Minims units must be discarded after each use.

Contact lens guidance

Remove all contact lenses (soft and rigid gas-permeable) before instilling any cycloplegic or mydriatic drop. Do not reinsert lenses until cycloplegia and mydriasis have fully resolved.
For low-dose atropine 0.01% (nightly use), insert the drop after lens removal at bedtime. Morning lens insertion is acceptable as effects at this concentration are minimal; however patients should be counselled on individual variation in pupil response.
Do not drive or operate heavy machinery while mydriasis persists — important counselling point given Singapore's high contact lens usage and active working population. Arrange transport or allow full recovery time before driving.
Wrap-around sunglasses are strongly recommended following mydriatic or cycloplegic instillation — especially relevant in Singapore's high-UV tropical environment where bright outdoor light after dilation causes significant photophobic discomfort.

Monitoring and red-flag referral

All patients after mydriatic instillation: Van Herrick or gonioscopic assessment of anterior chamber angle depth is advisable before dilation in any patient with a shallow anterior chamber, high risk of angle closure, or relevant family history — to avoid precipitating acute angle-closure glaucoma.
Children on atropine 1%: Instruct parents to apply nasolacrimal occlusion rigorously. Refer urgently if child develops fever, flushing, tachycardia, confusion, or extreme agitation after instillation — signs of systemic atropine toxicity. Seek emergency medical review immediately.
Myopia control (low-dose atropine): Review every 6 months; measure axial length and best-corrected visual acuity; reassess spectacle prescription; consider concentration stepping (0.01% → 0.025% → 0.05%) if progression continues. Monitor for allergic conjunctivitis or hypersensitivity reactions.
Uveitis patients on therapeutic cycloplegia: IOP monitoring at each review — steroid use (often co-prescribed) carries IOP-raising risk; anterior segment assessment for synechiae formation; refer urgently to ophthalmologist if worsening or new visual symptoms develop.
Red flags requiring same-day referral: Severe eye pain after mydriatic instillation (possible angle closure); corneal haze or oedema; sudden vision loss; fixed mid-dilated pupil with pain and vomiting — refer immediately to the nearest ophthalmic emergency service.

Common cycloplegics in Singapore

All commercially available agents listed are, or have been, registered with HSA Singapore or are available through registered importers. Low-dose atropine formulations are compounded at licensed hospital pharmacies and are not individually listed on the HSA product register. Verify current product registration status at hsa.gov.sg before prescribing or referring for any specific product.

Brand (Generic)	Mechanism / Class	Dosing	Min. Age	Side Effects & Precautions	Clinical Notes
Cyclogyl Cyclopentolate HCl 1% POM	Anticholinergic (M3 antagonist) — ciliary muscle + iris sphincter block	1–2 drops; repeat after 5–10 min; examine at 30–45 min	≥3 months	Stinging, mydriasis, photophobia; CNS effects in young children	Gold standard for cycloplegic refraction; nasolacrimal occlusion mandatory
Isopto Atropine Atropine Sulfate 1% POM	Long-acting anticholinergic — maximum cycloplegia and mydriasis	Refraction: 1 drop BD ×3 days pre-visit. Uveitis: 1 drop BD–TID.	Caution <3 months	Mydriasis 7–14 days, fever, flushing, tachycardia; toxicity risk in children	Reserved for high hyperopia, infants, or uveitis; keep out of children's reach
Low-Dose Atropine 0.01%Atropine Sulfate 0.01% (compounded) POM	Proposed M4 retinal/choroidal modulation — slows axial elongation	1 drop OD at bedtime (both eyes)	≥6 years	Minimal; slight mydriasis, negligible accommodation loss	Myopia control; ATOM1/2 evidence base; compounded POM; not interchangeable with atropine 1%
Mydriacyl Tropicamide 1% POM	Short-acting anticholinergic — primarily mydriatic, weak cycloplegia	1–2 drops; onset 15–30 min; effects resolve in 4–6 h	Caution in infants	Photophobia, blurred near vision, stinging; angle-closure risk	Diagnostic dilation only — not adequate for cycloplegic refraction
Minims Phenylephrine Phenylephrine HCl 2.5% POM	α1-adrenergic agonist — iris dilator stimulation; no cycloplegia	1 drop; onset 15–30 min; duration 2–5 h	2.5% any age with caution; avoid 10% <1 year	Hypertension, tachycardia; rebound miosis; angle-closure risk	Mydriatic only — no cycloplegic effect; adjunct to tropicamide for dilation
Isopto Homatropine Homatropine HBr 2% POM	Intermediate-acting anticholinergic muscarinic antagonist	1–2 drops; repeat after 5–10 min; duration 1–3 days	≥3 years	Photophobia 1–2 days, blurred near vision, dry mouth	Intermediate duration; occasional use in mild uveitis or traumatic iritis

Legend

POMPrescription Only Medicine — Sold or supplied to the public on prescription only.

PPharmacy Medicine — Sold or supplied from any licensed retail pharmacy under pharmacist supervision.

OTCGeneral Sales List (GSL) — Sold or supplied to the public without restriction.

Dosing reflects standard clinical doses unless otherwise noted. Always refer to the approved product insert for full prescribing information. OD = once daily, BD = twice daily, TID = three times daily, QID = four times daily, PRN = as needed. Low-dose atropine formulations are compounded products — confirm preparation, concentration, and shelf-life with the dispensing pharmacy.

References

[1] Chua WH, Balakrishnan V, Chan YH, et al. Atropine for the prevention of childhood myopia progression. Ophthalmology. 2006;113(12):2285–2291. PMID: 17020591. (ATOM1)
[2] Chia A, Chua WH, Cheung YB, et al. Atropine for the treatment of childhood myopia: safety and efficacy of 0.5%, 0.1%, and 0.01% doses (ATOM2). Ophthalmology. 2012;119(2):347–354. PMID: 21963266.
[3] Saw SM, Gazzard G, Shih-Yen EC, Chua WH. Myopia and associated pathological complications. Ophthalmic Physiol Opt. 2005;25(5):381–391. PMID: 16101943.
[4] Health Sciences Authority Singapore. Medicines Act (Cap. 176). Singapore Statutes Online. Available at: sso.agc.gov.sg (accessed March 2026).
[5] Republic of Singapore. Optometrists and Opticians Act 2007 (No. 16 of 2007). Singapore Statutes Online. Available at: sso.agc.gov.sg/Act/OOA2007 (accessed March 2026).
[6] Optometrists and Opticians Board Singapore. Scope of practice guidelines. Ministry of Health Singapore. Available at: moh.gov.sg (accessed March 2026).
[7] Bartlett JD, Jaanus SD, eds. Clinical Ocular Pharmacology. 5th ed. Butterworth-Heinemann; 2008. Chapter 7: Cycloplegics and Mydriatics.
[8] Chia A, Lu QS, Tan D. Five-year clinical trial on atropine for the treatment of myopia 2: myopia control with atropine 0.01% eyedrops. Ophthalmology. 2016;123(2):391–399. PMID: 26271839.
[9] Shih YF, Chen CH, Chou AC, Ho TC, Lin LL, Hung PT. Effects of different concentrations of atropine on controlling myopia in myopic children. J Ocul Pharmacol Ther. 1999;15(1):85–90. PMID: 10048351.
[10] Twelker JD, Mutti DO. Retinoscopy in infants using a near noncycloplegic technique, cycloplegia with tropicamide 1%, and cycloplegia with cyclopentolate 1%. Optom Vis Sci. 2001;78(4):215–222. PMID: 11347294.
[11] Lovasik JV. Pharmacokinetics of topically applied cyclopentolate HCl and tropicamide. Am J Optom Physiol Opt. 1986;63(10):787–803. PMID: 3024293.
[12] International Myopia Institute. IMI — Myopia Control Reports Overview and Introduction. Invest Ophthalmol Vis Sci. 2019;60(3):M1–M19. PMID: 30817827.

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