Glaucoma Referral Filtering and Co-management Schemes in Optometry

Context of Glaucoma Involvement in Optometry

• NHS Resource Pressures:

  • Glaucoma management accounts for approximately $25\%$ of eye outpatient attendances in the UK (pre-NICE data), potentially increasing post-NICE.

  • There are more than 1 million glaucoma-related outpatient visits to the Hospital Eye Service (HES) annually.

  • Diagnostic accuracy for initial optometrist referrals regarding suspect glaucoma has historically been low.

  • An aging population predicts a significant future increase in clinic loads and a substantial cost burden for the NHS.

  • There is a persistent shortage of ophthalmologists available to meet this demand.

• Ophthalmic Workforce Dynamics:

  • The "Modernising Medical Careers" (MMC) project replaced the Senior House Officer (SHO) grade with a seven-year Ophthalmic Specialist Trainee (OST) grade.

  • The UK has significantly fewer ophthalmologists per $10,000$ population compared to countries like Greece, Italy, and Spain.

  • Optometry represents a growing profession with approximately $14,000$ practitioners, many pursuing post-graduate training (e.g., Independent Prescribing (IP), Glaucoma Certificates).

Glaucoma Referral Filtering Mechanisms

• Definitions and Objectives:

  • Referral Filtering: Includes repeat measurement, enhanced case finding, and Glaucoma Referral Refinement (GRR) schemes. These apply to patients before they are accepted into the Hospital Eye Service.

  • Goal: Minimize unnecessary referrals (reduce false positives) to increase the specificity of case detection.

  • Two-Tier Testing: A strategy that uses a second layer of testing to confirm findings before HES referral.

• Patient Safety and Delays:

  • In $2014/15$, there were $7.07$ million ophthalmology outpatient department (OPD) appointments in England.

  • The Royal College of Ophthalmologists (RCOphth $2016$) highlighted that approximately $20$ patients per month suffer unnecessary sight loss due to delays and follow-up cancellations.

Historical Context of Optometric Referrals

• Performance $30$ Years Ago: Studies (e.g., Steinmann $1982$, Tuck and Crick $1991$) showed optometrists initiated most referrals. Glaucoma was confirmed in only $40\%$ of cases, while $28\%$ were discharged immediately.

• Performance in the Last $20$ Years: Optometrists initiate >90-95\% of glaucoma cases. Information quality remained variable (especially visual fields), and false-positive rates remained high (approx. $40\%$).

• MREH Data: Historically, $2.33$ hospital visits were required for every patient subsequently discharged.

Manchester Glaucoma Enhanced Referral Scheme (GERS)

• Core Concepts: Established at Manchester Royal Eye Hospital (MREH) to reduce waiting times and involve primary care.

• Clinical Protocol: Peer-accredited optometrists perform routine use of Goldmann Applanation Tonometry (GAT) and Binocular Indirect Ophthalmoscopy (BIO) along with repeated field tests.

• Performance Data ($N = 670$):

  • $41\%$ of patients were referred to HES; $59\%$ were not referred (discharged or watched in primary care).

  • Outcomes for referred patients: POAG ($24\%$), NTG ($8\%$), OHT treated ($6\%$), ACG ($2\%$), Others ($2\%$), Discharged ($43\%$), and Watch ($11\%$).

  • Reduced waiting times: Patients were typically seen within $2$ weeks by accredited optometrists.

Regional Variations and Scotland's Model

• NHS Education for Scotland: Includes specific "Teach and Treat" clinics and regional training centers.

• GOS Contract Changes: A shift in the General Ophthalmic Services (GOS) contract led to:

  • Increase in true positive referrals from $18\%$ to $31.7\%$.

  • Decrease in false positive referrals from $36.6\%$ to $31.7\%$.

  • Improved clinical data: GAT information increased from $11.8\%$ to $50\%$; dilated exam info from $2.2\%$ to $24.2\%$; and repeat visual fields (VF) from $14.8\%$ to $28.3\%$.

NICE Guidelines and Their Impact

• NICE $2009$ (CG85):

  • Advised referrals for intraocular pressures (IOP) exceeding $21\,\text{mmHg}$ even with normal discs and fields.

  • Resulted in an estimated >500,000 additional referrals per year.

• NICE $2017$ Update (NG81):

  • Explicitly addresses case finding and referral.

  • Referral Criteria: Refer if there is optic nerve head damage, a field defect consistent with glaucoma, or GAT-confirmed IOP of $24\,\text{mmHg}$ or more.

  • Mandatory Tests Before Referral:

    1. Central visual field assessment (standard automated perimetry).

    2. Optic nerve assessment/fundus exam (slit-lamp biomicroscopy, OCT if available).

    3. IOP measurement using Goldmann-type applanation tonometry.

    4. Peripheral anterior chamber depth assessment (gonioscopy or van Herick test).

  • Restrictions: Do not refer solely based on non-contact tonometry (NCT) or if a patient was previously discharged unless clinical circumstances change.

Co-management (Shared Care) in Glaucoma

• Definition: Sharing management responsibilities between professionals (HES and community).

• Levels of Shared Care:

  • Parallel Care: Data collection only.

  • Protocol-led: Data collection and decision-making governed by strict protocols.

  • Autonomous: Data collection and autonomous decision-making.

• BSCG Study ($1993-97$):

  • Shown that optometrist and HES measurements are equally reliable.

  • Clinical outcomes were comparable, with high patient satisfaction in both settings.

HES Extended Role Clinic Models

• Clinic Types:

  • Virtual Clinics: Clinicians review data for OHT/suspects or low-risk glaucoma (e.g., stable patients over $75$ years with Mean Deviation (MD) worse than $-15\,\text{dB}$ but not threatening fixation).

  • Medical Glaucoma Clinics: For complex or high-risk cases (bilateral defects, younger patients).

• Scope of Practice Survey: Hospital optometrists are heavily involved in follow-ups for Cornea, Glaucoma, Medical Retina, and Cataracts. Autonomy in management decisions varies, with many "often" or "always" consulting medical colleagues depending on the sub-specialty.

Professional Competencies and Training

• Entry-Level Gaps: New optometrists may lack experience in gonioscopy, analyzing complex glaucomatous discs, or interpreting subtle VF defects.

• Post-Graduate Pathways:

  • College of Optometrists Higher Qualifications (Certificate, Higher Certificate, and Diploma in Glaucoma).

  • Independent Prescribing (IP) Specialty Registration with the General Optical Council (GOC).

  • Local Optical Support Unit (LOCSU) pathways.

Case Study: Patient AW

• Referral Data: $54$-year-old presbyope. Asymmetric CD ratio ($0.4$ Right Eye (RE), $0.6$ Left Eye (LE)) with inferior notching/pallor. Superior VF defect. Normal IOPs (RE $20$, LE $14$).

• Medical History: Hypertension (Lisinopril), migraines, and maternal uncle with glaucoma. History of blunt trauma to the LE in childhood.

• Examination:

  • IOP: RE $22\,\text{mmHg}$, LE $20\,\text{mmHg}$ (at $13:45$).

  • CCT: RE $532\,\mu m$, LE $533\,\mu m$.

  • Gonioscopy: Wide open angles (Grade $4$).

  • VF: Both eyes "Outside Normal Limits". RE: MD $-8.45\,\text{dB}$, PSD $14.91\,\text{dB}$. LE: MD $-5.63\,\text{dB}$, PSD $12.73\,\text{dB}$.

• Diagnosis Consideration: Congenital Optic Disc Pit (prevalence $1$ in $10,000$) vs. Normal Tension Glaucoma (NTG). Acquired pits in NTG are often inferior and closer to fixation.

• Management: Review as a COAG/NTG suspect. No treatment at initial visit. Planned review in a virtual clinic in $3$ months.