Glaucoma Co-Management
Evidence-based clinical pathway for glaucoma detection, monitoring, and co-management by optometrists in Singapore, developed in accordance with international guidelines and Singapore optometry regulatory scope.
Last updated: March 2026
Purpose: This clinical pathway provides evidence-based guidance for optometrists in Singapore to deliver comprehensive glaucoma detection, monitoring, and co-management services. The pathway follows European Glaucoma Society (EGS) guidelines and American Academy of Ophthalmology Preferred Practice Patterns, adapted for the Singapore regulatory context and adapted for shared-care arrangements with ophthalmology.
Scope of Practice — Singapore: Optometrists can detect glaucoma, monitor stable glaucoma under ophthalmology supervision, and participate in shared-care arrangements. Treatment decisions, surgical interventions, and management of unstable or progressing glaucoma remain under ophthalmology purview. This pathway focuses on screening, risk stratification, monitoring protocols, and appropriate referral timing.
Clinical Pathway Overview
Risk Assessment and Patient Identification
Glaucoma Suspect Categories
Initiate full glaucoma assessment for patients presenting with any of the following:
Low-Risk Glaucoma Suspect
- •IOP 21–24 mmHg with no other risk factors
- •Normal optic disc appearance (CDR ≤0.6, symmetrical)
- •Normal visual field testing
- •Central corneal thickness (CCT) ≥555 μm
- •No family history of glaucoma
High-Risk Glaucoma Suspect
Criteria (≥2 factors):
- •IOP ≥25 mmHg
- •CDR >0.6 or asymmetry >0.2 between eyes
- •Disc hemorrhage present
- •Thin CCT (<555 μm)
- •First-degree family history of glaucoma
- •Age >60 years with additional risk factors
Additional Risk Factors
Demographic
- •Age >60 years (risk doubles each decade)
- •Chinese ethnicity (higher PACG prevalence)
- •Family history (5× increased risk)
Ocular
- •High myopia (>−6.00D)
- •Thin central corneal thickness
- •Narrow angles (Van Herick Grade 1–2)
- •Previous ocular trauma
Systemic
- •Diabetes mellitus
- •Cardiovascular disease
- •Migraine
- •Prolonged corticosteroid use
Baseline Examination Protocol
Essential Components — All Patients
| Assessment | Method | Key Findings |
|---|---|---|
| Intraocular Pressure | Goldmann applanation tonometry (GAT) — gold standard | Normal: 10–21 mmHg. Document time of day. Repeat if >21 mmHg or asymmetry >3 mmHg. |
| Central Corneal Thickness | Ultrasonic or optical pachymetry | Average 540 μm. Thin CCT (<555 μm) = IOP underestimation; thick CCT (>590 μm) = overestimation. |
| Gonioscopy | 4-mirror goniolens in dim illumination | Grade angle with Shaffer (0–4) or Scheie systems. Identify PAS and angle closure risk. Essential in Asian populations. |
| Optic Nerve Assessment | Stereoscopic fundus exam (90D/78D lens, slit lamp) | CDR (vertical & horizontal), ISNT rule, disc hemorrhages, peripapillary atrophy, notching, RNFL defects. |
| Fundus Photography | Color optic disc photos (stereo preferred) | Document baseline disc appearance. Both eyes centered on optic nerve. Enables serial comparison. |
Structural Imaging (Recommended)
Optical Coherence Tomography (OCT)
- ▪RNFL thickness: Peripapillary scan (3.4–4.0 mm diameter)
- ▪Macular GCL analysis: Ganglion cell–inner plexiform layer thickness
- ▪ONH parameters: Rim area, disc area, CDR
Detects structural change before functional VF loss. Average RNFL <70 μm or focal loss is highly suspicious.
Anterior Segment OCT / UBM
Indications:
- ▪Narrow angles (Van Herick Grade 1–2)
- ▪Suspected plateau iris configuration
- ▪Angle closure risk stratification
- ▪Measure AOD, TISA
Particularly important in Singapore: high prevalence of PACG in Chinese population.
Functional Testing — Visual Fields
Standard Automated Perimetry (SAP)
Recommended Protocol:
- 24-2 SITA Standard or Faster
- Size III white stimulus on white background
- Correct refractive error
- Ensure pupil ≥3 mm
Reliability Indices (Accept if):
- Fixation losses <20%
- False positives <15%
- False negatives <33%
Key Parameters:
- MD: Overall sensitivity loss (Normal: >−2 dB)
- PSD: Focal loss (Abnormal: p <5%)
- GHT: Outside normal limits = suspicious
Best Practice: Obtain 2 baseline visual fields to establish reliability and confirm defects.
Classification & Staging
Established Glaucoma Severity — Hodapp-Parrish-Anderson Criteria
Classify using visual field mean deviation (MD) and structural findings:
| Severity | Visual Field MD | Defect Characteristics | RNFL/ONH Changes |
|---|---|---|---|
| Early/Mild | MD > −6 dB | Nasal step, arcuate defect, paracentral scotomas not within 5° of fixation | Localized RNFL thinning, early notching |
| Moderate | MD −6 to −12 dB | Defects within 5° of fixation in one hemifield, double arcuate | Diffuse RNFL loss, increased CDR (0.7–0.8) |
| Severe/Advanced | MD < −12 dB | Defects within 5° in both hemifields, sensitivity <15 dB within central 5° | Severe RNFL loss, CDR ≥0.9, disc pallor |
Target Intraocular Pressure by Severity
Target IOP is individualized based on baseline IOP, severity, risk factors, and rate of progression (EGS recommendations):
Early/Mild Glaucoma: 25–30% IOP reduction from baseline
Typically 15–18 mmHg. Lower target if rapid progression or additional risk factors.
Moderate Glaucoma: 30–40% IOP reduction
Typically 12–15 mmHg. Aim for low-normal range.
Severe/Advanced Glaucoma: ≥40% IOP reduction
Target <12 mmHg or lower. Single-digit IOP may be necessary. Requires ophthalmology management.
Monitoring & Follow-Up Schedule
Monitoring Schedule by Risk Category
| Patient Category | IOP Check | Visual Field | OCT/Imaging | Disc Photos |
|---|---|---|---|---|
| Low-Risk Suspect | 6–12 months | 12–24 months | 12–24 months | Baseline, then as needed |
| High-Risk Suspect | 3–6 months | 6–12 months | 6–12 months | 6–12 months |
| Early/Mild Glaucoma (Stable) | 3–4 months | 6 months | 6–12 months | 12 months |
| Moderate Glaucoma (Stable) | 2–3 months | 4–6 months | 6 months | 6–12 months |
| Severe/Advanced Glaucoma | 1–2 months | 3–4 months | 3–6 months | 6 months |
Note: More frequent monitoring required if: progression detected, IOP above target, treatment change, severe disease, only-seeing eye, or patient preference.
Progression Detection Criteria
Structural Progression
- ⚠OCT RNFL: Progressive thinning exceeding measurement variability (Guided Progression Analysis)
- ⚠Optic disc: Increased CDR, new notching, disc hemorrhage, progressive rim loss
- ⚠Photography: Serial disc photo comparison showing change (requires standardized imaging)
Functional Progression
- ⚠VF MD decline: >−1.0 dB/year over 2 years (3+ tests)
- ⚠Glaucoma Progression Analysis (GPA): “Likely progression” on 3 consecutive tests
- ⚠Expansion of defects: Deepening or enlargement of existing scotomas
- ⚠New defects: Reproducible scotomas in previously normal areas
Any detected progression warrants immediate ophthalmology consultation for treatment modification.
Co-Management & Referral Protocols
Urgent Referral — Same Day / Within 24 Hours
Acute Angle Closure Attack
IOP >40 mmHg, severe eye pain, headache, nausea/vomiting, blurred vision with halos, mid-dilated fixed pupil, corneal edema, shallow AC.
Very High IOP
IOP >35 mmHg in previously undiagnosed patient, or >30 mmHg with optic nerve changes.
Neovascular Glaucoma
Rubeosis iridis, neovascularization of angle — typically with diabetic retinopathy or CRVO.
Routine Referral — Within 1–4 Weeks
Initial Diagnosis
- ►New glaucoma diagnosis requiring treatment initiation
- ►High-risk suspect requiring baseline ophthalmology assessment
- ►IOP consistently 25–30 mmHg with risk factors
- ►Narrow angles requiring laser peripheral iridotomy consideration
Secondary Glaucoma
- ►Pigment dispersion syndrome with elevated IOP
- ►Pseudoexfoliation syndrome
- ►Traumatic glaucoma or angle recession
- ►Steroid-induced IOP elevation
Progression / Treatment Failure Referral
Documented Progression
Structural or functional progression despite treatment (see Step 4 criteria).
IOP Above Target
Failure to achieve target IOP on maximum tolerated medical therapy.
Rapid Progression
VF MD decline >2 dB/year, or significant structural change over 6–12 months.
Advanced Disease
MD < −12 dB, only-seeing eye, central fixation threat, or patient <60 years with moderate+ disease.
Special Populations — Singapore Context
Angle Closure Disease in Asian Populations
Singapore has one of the highest PACG prevalence rates globally due to Chinese ethnic majority — heightened vigilance is required.
Screening Priorities:
- •Mandatory gonioscopy for all patients >40 years, especially Chinese ethnicity
- •Van Herick test at slit lamp for all routine exams
- •Anterior segment OCT for narrow angles (Grade 1–2)
Risk Factors:
- •Age >50 years (risk increases exponentially)
- •Hyperopia (short axial length <22 mm)
- •Female gender (3:1 ratio), family history
- •Plateau iris configuration
Refer all narrow angles (Shaffer Grade 0–1) for prophylactic laser peripheral iridotomy consideration, even if asymptomatic.
High Myopia & Glaucoma
High myopia (>−6.00D) is highly prevalent in Singapore and significantly increases glaucoma risk. Diagnostic challenges due to disc morphology.
- •Large, tilted discs mimic glaucomatous cupping
- •OCT RNFL normative database less accurate
- •Emphasize serial disc photography for comparison
- •Lower threshold for VF testing and earlier referral
Normal-Tension Glaucoma (NTG)
Higher prevalence in East Asian populations. Glaucomatous optic neuropathy with IOP consistently ≤21 mmHg.
- •Disc hemorrhages more common; focal inferior RNFL defects
- •Refer all suspected NTG for ophthalmology assessment
- •Target IOP typically <15 mmHg or 30% reduction
- •May progress despite low IOP — monitor closely
Clinical Decision Algorithm
Documentation and Communication
Essential Record-Keeping — Every Visit
Must Document:
- IOP (method, time of day, corneal factors)
- Optic nerve appearance (CDR, hemorrhages, ISNT rule, changes from baseline)
- RNFL assessment (clinical and OCT if performed)
- Current medications and compliance
- Visual field summary if tested
- Assessment (stable/progressing) and management plan
Trend Analysis:
- IOP trend graphs (identify patterns, diurnal peaks)
- VF MD progression analysis (rate of decline)
- OCT RNFL thickness tracking over time
- Side-by-side disc photo comparison
- Regular review of progression toward target endpoints
Referral Letters and Co-Management Communication
- Current and historical IOP readings (with dates, time of day, method)
- CCT measurements and gonioscopy findings (angle grading all quadrants)
- Optic nerve description (CDR, hemorrhages, RNFL defects)
- Visual field results (MD, PSD, GHT, pattern deviation plots)
- OCT RNFL/GCL analysis if available
- Risk factors, family history, and current medication list
- Reason for referral and urgency level clearly stated
Quality Metrics and Practice Audit
Detection Metrics:
- % patients >40 years receiving IOP measurement
- % patients >40 years receiving optic nerve assessment
- % elevated IOP patients receiving gonioscopy
- % suspects receiving baseline visual fields
Management Metrics:
- % glaucoma patients at target IOP
- % patients monitored per recommended frequency
- Time to progression detection
- Appropriate referral rate and timeliness
References
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Document Version: 1.0 | Last Updated: March 2026
This clinical pathway follows European Glaucoma Society guidelines and AAO Preferred Practice Patterns, adapted for Singapore optometric practice. Practitioners should apply clinical judgment and local protocols. Regular updates will be provided as new evidence and regulatory guidance emerge.
Changelog: v1.0 — Initial release. Restructured from section-based to 5-step clinical pathway format. Added Clinical Decision Algorithm flowchart, Singapore-specific PACG guidance, NTG and high myopia subsections, and documentation/quality audit framework.