Figure 1. Foreign body Photo: Dr Henry Heron
Bachelor of Medical Science (Vision Science)/Master of Optometry, Ocular Therapeutics
Corneal foreign body (FB) removal results in corneal nerve exposure, manifesting as pain and blepharospasm.1 The remaining epithelial defect may also increase the risk of microbial keratitis.1 Consequently, the literature focuses on managing corneal abrasions following FB removal; however, it has not arrived at a consensus.
Management aims at reducing pain, accelerating epithelial healing and preventing infections. The choice depends on patient symptoms, FB material, factors affecting epithelial healing and size of the epithelial defect after removal. It is important to perform a dilated examination and Seidel test to investigate signs of a penetrating injury or intraocular FB.
A 35-year-old male presented with an uncomfortable RE and no noticeable changes to his vision. Two days prior, he had felt something enter the eye while grinding metal.
He had not been wearing protective eyewear. As the eye had been feeling uncomfortable, he had presented to the pharmacy that afternoon and been given saline. He had used saline as needed that day and the following day.
He presented to the optometrist two days after the injury because the discomfort had not resolved. He had no significant ocular history, unremarkable general health and was not taking medications.
BCVA OD 6/6 OS 6/6. Pupils PERRL, no RAPD.
• OD: Grade 2 diffuse bulbar conjunctival hyperaemia (CCLRU) with 0.5 x 0.5 mm metal FB at 10 o’clock 1.5 mm from the limbus surrounded by a rust ring, without corneal infiltrate. Sodium fluorescein (NaFl) staining showed a positively stained ring surrounding the FB. Lid eversion clear, Seidel test negative, AC quiet, lens clear.
• OS unremarkable
IOP 14 mmHg OU (iCare 12:15 pm). Fundus examination unremarkable.
Corneal metal foreign body.
Management and review
1 drop oxybuprocaine 0.4% instilled OU to remove OD FB.
• Spud used for FB and Algerbrush for rust ring removal, NaFl post removal
• 1.5 x 2 mm epithelial defect extending to Bowman’s layer
• Seidel test negative.
1 drop chloramphenicol 0.5% 4x/day RE only. Review in 24 hours expecting smaller epithelial defect and less discomfort.
On review, the patient was experiencing minimal discomfort. He used two drops 0.5% chloramphenicol before returning to the practice. OD Grade 1 bulbar hyperaemia (CCLRU). NaFl revealed diffuse SPK in region of epithelial defect but otherwise epithelium had healed.
The edges of healed defect site were irregular and slightly hazy. No infiltrate or rust ring and AC quiet. IOP 15 mmHg OU (iCare 12:30 pm). Patient was instructed to instil another two drops of 0.5% chloramphenicol that day only, and then cease. Additionally, the patient was advised to use Polyvisc ointment once in the evening for one week. The patient was reminded to wear protective eyewear during hazardous industrial work and return to care if problems arose.
Ocular foreign bodies (FB) account for the most common occupational-related ocular injury.2 In Australia, ocular FBs accounted for 63.5 per cent of 7,000 work-related eye injuries presenting to emergency,3 predominantly affecting 20-40 year old males due to their work and hobbies.3,4 On average, two days are missed from work, causing patient morbidity and socio-economic burden.4,5 In Australia, eye injuries are estimated to cost $155 million each year.3
Corneal FB removal results in corneal nerve exposure, manifesting as pain, tearing, photophobia and blepharospasm.1 Other sequelae may include rust ring, traumatic uveitis, microbial keratitis, corneal scarring and recurrent corneal erosion.1,3,4,6
Corneal abrasions usually heal within 24-96 hours; however, this depends on their size, patient immune status and rust ring removal.1,5,6 Incomplete rust removal can delay healing.6 Treatment options are exhaustive and include lubricating eye-drops for comfort, prophylactic antibiotics, and topical non-steroidal anti-inflammatories (NSAIDs), oral analgesia or cycloplegia for pain management.7
Role of antibiotics
Topical antibiotics are prescribed post-FB removal as prophylaxis against infection,1,2,4 with 14-20 per cent of corneal FBs having positive bacterial culture.3,4,6 The type of corneal FB can help guide management. In the presence of a heated metallic FB, lubricating eye-drops may be sufficient as heat sterilises the FB.8 Similarly, glass and plastic are inert materials.8,9 Small epithelial defects may not warrant antibiotics, as they will heal within hours.1,5,6 Fingernail and decomposing matter corneal FBs can introduce bacteria into the eye; therefore, antibiotics would be recommended.
Time of injury can affect prescribing methods. If occurring in the morning, the practitioner may choose not to prescribe antibiotics if the defect is small, and review at the end of the day, to see whether healing has occurred. In comparison, if the injury occurs in the evening, the ocular environment is soon to undergo a hypoxic state due to lid closure, increasing risk of infection; therefore, antibiotics could be prescribed.
Evidence recommends chloramphenicol for corneal FBs as it exhibits greater sensitivity over ciprofloxacin against isolated micro-organisms, with 95 per cent and 90 per cent, respectively.4 Chloramphenicol is a primarily bacteriostatic broad spectrum, affordable antibiotic which is widely available.9,10 Chloramphenicol has staphylococcal cover, which has been identified as the most frequent isolated pathogen from corneal FBs.6 However, chloramphenicol is resistant against Pseudomonas species and therefore, is not recommended as prophylaxis in contact lens wearers.8,10 Antibiotics with pseudomonal cover such as tobramycin 0.3%, gentamicin 0.3%, ciprofloxacin 0.3% or ofloxacin 0.3% should be prescribed.1,9,12
Indications for antibiotic prescribing following corneal trauma include contact lens wear and vegetative matter, as they are associated with higher risk of secondary bacterial keratitis.12 Others include immunocompromised patients, extension to the stroma and dry eye, due to reduced corneal healing.
At the Royal Victorian Eye and Ear Hospital, chloramphenicol is the most commonly prescribed antibiotic for corneal metal FBs.3 Chloramphenicol use for corneal abrasions is a common practice in accident and emergency departments.6,11,13 There is no consensus on dosage frequency with 2-5x/day suggested.6,10,13,15 Given this patient was not a contact lens wearer, chloramphenicol 0.5% 4x/day was appropriate to use. Chloramphenicol ointment could have been prescribed instead as it is preservative free and therefore, less likely to cause surface irritation but its increased viscosity would blur vision. As undertaken in this case, prophylactic antibiotic use can continue until the epithelium heals, to minimise risk of microbial keratitis.7
As patients can be non-compliant, an initial antibiotic, in-office, loading dose can be considered in addition to providing the patient with a prescription.
Other management options
A meta analysis found that topical NSAIDs reduce pain at 24 hours; however, studies demonstrated variability with co-interventions and pain scales used.5 Interventions included ketorolac 0.5% 4x/day, diclofenac 0.1% 4x/day and diclofenac six-hourly while awake for 24 hours, or until the defect closed.5 Although co-interventions have a potential role, they confound results. Topical NSAIDs use may allow earlier return to work, reducing socio-economic burden,11,14 and enables less dependence on oral NSAIDs.16 However, literature has not compared oral to ophthalmic NSAIDs.17 Oral NSAIDs are more affordable than topical equivalents, but contraindications and precautions such as gastrointestinal ulcers must be considered.7,16,17
There is limited evidence surrounding the use of oral analgesics for corneal abrasions.1 Corneal FBs have a good prognosis, therefore pain is often the primary concern due to nociceptor activation. Pain can be addressed with oral analgesia.1 However, it is important to ask about concomitant medications due to drug-drug interactions, and comorbid conditions such as kidney and liver disease, which affect drug metabolism, prior to recommending oral analgesia. Analgesia was shown to be more effective with 400 mg ibuprofen (two tablets) with 56 per cent achieving 50 per cent pain relief, while reducing to 46 per cent for 500 mg paracetamol (two tablets).
Patching reduces mechanically-induced trauma from lid-cornea interactions;1 however, a Cochrane review favoured no patching in the first 24 hours following corneal abrasion.18 When considering pain, two studies favoured no patching, while none favoured patching.18 There was no difference in the time to healing, and there were no complications.1
Multiple studies have administered cycloplegia;15,16,19 however, co-interventions confound results. Comparing homatropine 5% six-hourly to placebo, there was no difference in pain 24 hours following the abrasion.19 Similarly, flurbiprofen 0.03% 4x/day for 48 hours, with or without a stat dose of homatropine 2%, had lower pain scores than the control group, or those given a stat dose of 2% homatropine.15
Potential sequelae of corneal FBs include recurrent corneal erosion (RCE), rust rings and traumatic uveitis. A retrospective chart review of RCE identified 45 per cent as having a history of trauma.20 Lacrilube ointment was prescribed for one week, to reduce the risk of a future RCE. However, literature suggests that epithelial-stromal adhesion can take at least six weeks to heal21 and therefore, longer treatment duration would be suggested. Nightly Lacrilube for two months has been investigated for preventing RCE following fingernail-induced corneal abrasion.22 Those patients prescribed Lacrilube had a higher prevalence of symptoms suggestive of RCE.22 Although this suggests ointment is not beneficial, outcomes were based on symptoms not signs, and included only fingernail injuries.22 A Cochrane review acknowledges that further research is required for prophylactic regimens following traumatic corneal abrasion.23
Rust rings form within three to four hours of the foreign body; however, removal is easier 24-48 hours later.24 The burr is superior to manual removal of a rust ring and therefore, as inadequate removal can delay visual outcomes, a burr should be used, as performed in this case.3
Traumatic uveitis accounts for approximately 12 per cent of uveitis presentations, and the most common treatment modality is local steroids;25 however, treatment may not be required as immune response reduces as healing occurs. Therefore, signs and symptoms should guide management.
Protective eyewear is important to discuss with patients presenting with ocular injuries, as 90 per cent can be prevented with adequate protection.3 It is important to be specific with recommendations because 45 per cent of corneal metallic FB injuries occurred while wearing eye protection.3
Corneal abrasions heal within 24-96 hours, depending on their size and patient immune status.1,11,5 Given there is a risk of microbial keratitis while a breach in the corneal barrier exists, it is feasible to review a patient daily until the epithelium is healed. The other option is to inform the patient to return to care if symptoms worsen as in most cases, abrasions resolve. If symptoms are worsening, considerations include retained FB material and penetrating injury.
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