LENS IN THE CROSSFIRE: A MULTISITE AUDIT ADDRESSING IATROGENIC CATARACT RISK IN CT HEAD IMAGING

The ocular lens is one of the most radiosensitive structures in the human body. Even a single exposure to ionising radiation increases the risk of radiation-induced cataracts, with cumulative harm over time. CT head imaging is routinely performed across emergency and outpatient settings, yet lens protection is often overlooked. Despite clear guidelines recommending lens exclusion when clinically appropriate, this principle is inconsistently applied - contributing to preventable, iatrogenic visual morbidity. This project aimed to audit current compliance with lens exclusion protocols in CT head scans across three UK hospital sites and evaluate the impact of a structured quality improvement intervention. 

Multisite audit conducted across three hospitals within the Mid and South Essex NHS Foundation Trust (Basildon, Broomfield and Southend).

Two audit cycles were conducted. In each cycle, 150 outpatient CT head scans (50 per site) were retrospectively reviewed. Scans requiring ocular assessment (e.g. trauma, CT orbits, diplopia) were excluded. Remaining studies were manually assessed for inclusion or exclusion of the lenses using scout and axial views. Between cycles, interventions included:

1. Departmental presentations and awareness posters

2. Visual aids and refresher training on gantry tilt and scan alignment with the supraorbitomeatal line

3. Encouragement of optimal patient positioning using chin-tuck techniques and head-tilt cushions

Cycle 1:

6/150 scans (4%) excluded both lenses

144/150 scans (96%) exposed at least one les

Cycle 2 (post-intervention):

70/150 scans (47%) excluded both lenses

80/150 scans (53%) still included one or both lenses

Statistical analysis using Fisher's exact test demonstrated a significant improvement in compliance (p<0.0001). Each site showed marked gains, confirming the effectiveness of the intervention package. 

This audit identifies a systemic oversight in imaging safety - one with direct consequences for long-term visual outcomes. Lens exclusion is a cost-free, achievable intervention that significantly reduces iatrogenic cataract risk. Radiographer-led education, visual prompts and small workflow adjustments resulted in a statistically and clinically meaningful improvement in compliance. In an era of increasing CT usage, integrating lens protection into routine imaging practice should be prioritised as part of broader ophthalmic and radiation safety standards.