Use adequate magnification with a magnifying loupe, ideally those with an inbuilt light source. Use local anaesthetic (e.g. benoxinate HCl).
Attempt removal of the foreign body (FB) by using a sterile cotton bud, lightly moistened with a drop of local anaesthetic, to gently lift it off.
Use a sterile, disposable needle (25- or 23-gauge) with a small syringe attached to steady the needle. It is best to bend the end of the needle so that it forms a scoop.
Hold the unit with a pen grip and keep the bevel upwards. Introduce the needle horizontally so that the tip lifts the edge of the FB (Fig. 14.3a).
Removal of foreign body: (a) disposable needle steadied with syringe using a horizontal approach; (b) dental burr rotated once, using a direct vertical approach
The needle can lift loosely bound rust.
A sterile dental burr can be used. The burr, which is applied vertically, should be rotated gently once and then the cornea inspected after each rotation (Fig. 14.3b). This should not be attempted on deep rust or central FBs.
An ‘automatic’ safety burr can be used.
Assessing the depth of injury—Seidal test
This test can evaluate suspected global rupture but a slit lamp with a cobalt blue filter is ideal. Apply 2% fluorescein eye drops and observe to see if the dye is diluted by leaking aqueous fluid. The ruptured area stains weakly while bright green concentrated dye surrounds the leak site.
Instil antibiotic drops and pad the eye for 30 minutes only. Review at 24 hours. Inspect and stain the cornea with fluorescein. Continue to instil antibiotic drops 3 times a day for 3 days. (Drops are preferable to ointment.)
Do not give LA for pain relief.
Refer deep rust stains to experts.
Never forcibly rub the cornea.
Do not use corticosteroids on the eye initially.
Get patients to wait until LA wears off (about 20 minutes). They should drive home without an eye pad.