Impact of the New R2L/R2H Diabetic Retinopathy Grading System on Hospital Referrals and Service workload: A Two-Year Comparative Study.

Reham Shehada, Leah Oconnell, Kimberley Turner, Chintan Sanghvi

 

Introduction

• In October 2024, the Diabetic Eye Screening Programme introduced a revised national referral pathway for patients graded as R2 pre-proliferative diabetic retinopathy.
• Previously, referral practice varied between programmes:
  • Some referred all R2 patients to the Hospital Eye Service (HES).
  • Others referred only patients considered to be at higher risk.
• This variation created inconsistency between Diabetic Eye Screening Programmes and contributed to avoidable capacity pressure within HES.
• The revised pathway introduced a two-tier R2 grading system:
  • R2L: R2 lower-risk pre-proliferative diabetic retinopathy, usually retained within digital surveillance if there is no referable maculopathy.
  • R2H: R2 higher-risk pre-proliferative diabetic retinopathy, referred to HES because of higher risk of progression.
  • Ungradable R2: Retinal images are of insufficient quality to confidently assign the R2 grade or exclude higher-risk features; these cases may require HES assessment depending on local pathway and clinical concern.
• R2L is defined by the presence of any one of the following lower-risk R2 features:
  • 8 or more blot haemorrhages across the four quadrants.
  • More than 20 haemorrhages or microaneurysms of any size per quadrant in 1–3 quadrants.
  • Venous beading in one quadrant.
  • Intraretinal microvascular abnormalities (IRMA) smaller than ½ disc diameter in any quadrant.
• R2H is based on the 4-2-1 principles, where the presence of any one of the following features is sufficient to classify the eye as R2H:
  • More than 20 haemorrhages or microaneurysms in each of the four quadrants.
  • Venous beading in two or more quadrants.
  • IRMA larger than ½ disc diameter in one or more quadrants.
• This service evaluation assessed the impact of the revised R2L/R2H pathway at East Lancashire Hospitals NHS Trust (ELHT) on:
  • Referral activity to HES.
  • Agreement between screening and hospital assessment.
  • Hospital management outcomes.       

    Methods

    • A retrospective comparative service evaluation was conducted within the Diabetic Eye Screening Programme at ELHT
    • Screening and hospital outcomes were reviewed before and after introduction of the revised R2L/R2H referral pathway.
    • Pre-implementation cohort:
      • Screening period: September 2023 to September 2024.
      • Included patients graded R2M0 or R2M1 under the previous DESP classification.
      • These patients were referred to the Hospital Eye Service under the previous pathway.
    • Post-implementation cohort:
      • Screening period: October 2024 to November 2025.
      • Included patients graded R2HM0, R2HM1, or ungradable R2 cases referred to HES.
      • Included R2LM0 patients retained within screening surveillance.
    • Data sources:
      • Local diabetic eye screening databases.
      • Hospital clinical records.
    • Analysis was based on the worst eye classification, in keeping with standard DESP referral criteria.
    • Collected variables included:
      • Screening grade.
      • Maculopathy status.
      • Hospital grading
      • Management outcome.
    • Referral activity before and after implementation was compared to assess the impact of the pathway change on HES workload.
    • Agreement between screening grade and hospital diagnosis was reviewed to assess referral accuracy.
    • Hospital documentation was reviewed to assess whether the revised terminology, particularly R2L and R2H, was used consistently after implementation.       

      Results

      • Results are presented graphically.
      • The graphs compare:
        • HES referral volume before and after implementation.
        • Screening grade distribution.
        • Hospital diagnosis and management outcomes.
      • Following implementation, fewer R2 patients were referred to HES, with more lower-risk cases retained within screening surveillance.
      • Most referred patients required monitoring rather than treatment.
                  

      Conclusion

      • Introduction of the R2L/R2H risk-stratified grading pathway at ELHT was associated with:
        • Reduced referrals to HES.
        • Increased retention of lower-risk R2 patients within screening surveillance.
      • The revised pathway appears to improve triage between diabetic eye screening and hospital eye services while maintaining patient safety.
      • Most patients referred to HES required monitoring rather than active treatment, and some were downgraded after specialist review.
      • Some patients downgraded to R1M0 were not clearly discharged back to DESP, suggesting that referral outcomes and discharge pathways require further review.
      • Hospital documentation frequently recorded the grade as R2 only, without distinguishing between R2L and R2H.
      • This highlights the need for:
        • Greater clinician awareness of the revised R2L/R2H pathway.
        • Consistent use of updated grading terminology.
        • Clearer discharge processes between HES and DESP.
      • Ongoing evaluation and clinician engagement will be important to optimise implementation of the revised pathway across the screening–hospital interface.