No Chemical Injury
80 patients were retrieved from a search for ‘chemical injury’ in the PAS. Twelve patients were found to have ‘no chemical injury’. Diagnoses of chemical injury were either accidental (i.e., inputted instead of another diagnosis such conjunctivitis/trauma/etc.) or were recorded because the patient had reported contact of the eye with a chemical but there were no abnormal findings on clinical examination. No written records were found for 3 patients.
Mild Chemical Injuries
55 patients were found to have mild chemical injuries. 53% of the patients were male and 55% were in the 15–35 year age group. The average age was 37 years (SD: 22 years, range: 1–91 years).
31 patients had a non-work-related injury; 4 had a work-related injury. In the other 15 patients, it was not possible to determine if the nature of the injury was work-related.
29% had an epithelial defect (ED), 67% had no ED, and no comment was made about the presence or absence of an ED in the other 4%.
66% of the patients presented within 12 h of the chemical burn, and 87% of patients presented within 24 h (Fig. 1).
Severe Chemical Injuries
Eleven eyes of 10 patients were found to have severe chemical injuries. 90% of patients were male and 80% were in the 15–35 years age group. The average age was 23 years (range 2–39 years, SD 10 years), and there was only one female patient.
The initial presentation findings that led to the categorisation of these eyes into the severe chemical injuries group are summarised in Table 1.
The clinical notes with the initial clinical findings were not found for patient 5; only the findings at first follow-up, performed 6 days postinjury, were available for this patient.
Patients 6 and 8 presented to the emergency department 4 days after the eye had been splashed with ammonia, and the initial clinical findings were first recorded on day 4. The extent of the injury (e.g. limbal staining) may have been worse in the 24 h following injury.
Five out of 10 (50%) patients presented within 12 hours of the chemical burn. Three patients presented at 48 hours, and 2 patients presented 4 days following the chemical burn (Fig. 1).
Cause of Injury
The chemical burns were due to assault in 7 out of 10 patients. In 3 of those 7 assault cases, ammonia was confirmed as the causative chemical agent. The agent was not known in the other 4 assault cases, but was documented as an alkali in 1 case. In the 3 non-assault-related cases, the chemicals were washing machine detergent liquid (accidental injury), methyl ethyl ketone peroxide (alkali, work-related injury), and unknown, respectively.
Treatment: Prescription and Compliance
All patients were treated in line with the Moorfields Eye Hospital NHS Foundation Trust protocol for severe ocular chemical burns. This is summarised in Table 2.
Nine out of 10 patients were treated according to the hospital protocol. However, a child was initially treated with chloramphenicol eye drops only; following the first follow-up appointment, prednisolone 0.5% four times daily was added.
Most patients were prescribed all the medications in the protocol, as shown in Table 3. Two of the patients were prescribed lower doses of ascorbic acid tablets and doxycycline tablets than the protocol. The reason for this was not documented.
One patient had poor compliance with the medication due to pain and polypharmacy. Three patients could not tolerate the burning sensation with citrate and ascorbate eye drops, and 1 patient stopped cyclopentolate drops due to pain.
The recorded visual acuity at first and last presentation are shown in Table 4. The best-corrected visual acuity (BCVA) improved to 6/6 or better in 4 out of 9 eyes. Five eyes had a vision of 6/18 or worse, for reasons mentioned below. It was not possible to test visual acuity in the child, but the epithelial defect and inflammation resolved fully, and there was no evidence of residual complications.
Patient 2 was only followed up for 14 days, as he failed to attend further appointments. His vision at 14 days was poor due to persistent corneal haze.
Patient 5 had a severe assault-related chemical burn from from ammonia, and developed poor vision due to limbal stem cell failure (corneal neovascularisation/conjunctivalisation), corneal scarring and cataract formation. Vision at 5 months was still counting fingers.
Patient 7 had a visual acuity of 6/18 at 1 month postinjury due to anterior stromal and subepithelial scarring of the cornea.
Patient 9 only attended one follow-up visit, in which his visual acuity (VA) was 6/36 and the corneal epithelial defect edges were opposing (i.e. a closed epithelial defect). It is not known if he suffered long-term complications (namely, limbal stem cell deficiency) due to 9 clock hours of limbal staining at presentation.
Although patient 8 attained a vision of 6/6 at last follow-up, there was inferior corneal conjunctivalisation due to inferior limbal stem cell failure.
Patient 10 developed left upper lid cicatricial entropion, cornea conjunctivalisation, persistent corneal epithelial defect, fungal keratitis and left cornea perforation. The BCVA was therefore hand movements. Vision in the less severely affected eye was 6/6 at last follow-up, and the only complication was mild upper lid entropion.
The number of patients was too small to permit any meaningful statistical analysis of visual outcomes. It is worth noting, however, that the 2 cases (patient 5 and the left eye of patient 10) with the worst initial BCVA ended up with very poor vision.
Four (40%) out of 10 patients failed to attend follow-up visits, despite only one of them having a visual acuity of 6/6 and the others having last recorded visual acuities of 6/18, 6/24 and 6/36. Patients who did not attend were not called, and it is not known why these patients failed to attend. All 4 of these patients were victims of alleged assault. The time to first emergency department presentation was 48 h or more in 3 of those 4 patients.
Of the 4 patients who failed to attend, one attended 3 follow-up visits (up to 14 days postinjury) and 2 attended 4 follow-up visits (up to 1 month following injury). One attended only 1 follow-up visit 4 days postinjury.