Grading diabetic retinopathy: Who can do it?

Grading determines the level of disease present in the retina using a nationally agreed classification system and management protocols. Depending on the local setting, grading can be done by studying digital images of the retina or through slit lamp biomicroscopy and each grader follows a specific, and feature based technique

Grading must achieve both a high sensitivity and high specificity for a diabetic retinopathy (DR) programme to successfully prevent vision loss in a population. Trained DR graders use screening software or guidelines to assign the correct grade for the level of DR they see in each eye. There are four possible outcomes for the patient depending on the grade provided for each eye:

1. Recall for routine digital screening
2. Further slit lamp biomicroscopy by a senior grader or assigned clinician
3. More frequent monitoring by the screening unit
4. Referral to the hospital eye service

It is straightforward to define thresholds between levels of disease but, in practice, there will be areas of uncertainty within some grading decisions that need further consideration. Therefore, each DR programme needs to ensure there are clear systems and protocols and that these are followed.

The role of the grader is demanding and needs considerable training to maintain a high and consistent sensitivity and specificity. Each person undertaking grading needs a:

• Clear job description
• Support system to ensure they can provide the best service.

Who can be a grader, can vary across different settings, e.g. non clinical specialist technicians, optometrists or clinical nurses assistants. Each grader needs to be linked with and supported by an ophthalmologist, ideally a retinal specialist.

Local programmes need to constantly review their grading staff capacity and facilities to adjust for changes in demand for, and capacity of, the service and to make contingency plans for long-term sickness, maternity leave and annual leave. Ultimately, programmes need to work towards ensuring that enough accredited graders are employed at any given time to meet the service objectives and provide an effective service to patients.

As you watch this video, consider the different grading roles in your own setting. What are the challenges for quality assurance? In the future, do you think grading could be assigned to artificial intelligence systems instead of trained graders?