This is part of the “Bascom Beta” series – rough drafts of articles that are not yet ready for prime time but that residents can use as a quick reference guide in clinic.
Tapping the anterior chamber is a key skill to have in your back pocket when managing high IOP. Some people will do this at the slit lamp – this is not necessary. It may actually be easier with patient leaned back in an exam chair.
- Eye pad
- 1 cue tip
- Lidocaine gtts
- Betadine gtts
- 32 gauge needle on a 1cc tuberculin syringe
- 1) Patient prep
- Remove plunger from the syringe
- Tape eye pad to pt’s ear to catch extra drops
- Alternate giving lido and Betadine gtts, 4 rounds total
- Place lid speculum
- 2) The tap
- Stand or sit at head of pt’s bed
- Use cue tip to press down on sclera opposite of your planned tap site – this well help anchor the eye in place
- Insertion path of your needle should be:
- Roughly parallel to the iris
- Just anterior to the limbus
- Entering at the lateral clock hour (9 o’clock for OD and 3 o’clock for OS) and travelling in either the 12 o’clock or 6 o’clock directions. The tip of the needle should never travel over the pupil.
- Brace your hand on the patient’s forehead
- Insert the needle gently until you feel a slight pop as it goes through the cornea
- Watch the cornea as the AC fluid drains. When you see dimpling, remove the needle. Draining ~0.05 cc for pt w/ IOP of 50 should bring pressure down to the 10s or lower.
- Recheck IOP. If it remains too high, repeat the tap.