Applanation tonometry on a watery red eye in a busy lane
A 38-year-old man walks into the OPD lane with a two-day history of a red, watery right eye, gritty sensation and a tender node in front of the ear. He had a cold last week, and his son and two neighbours have had "pink eye". The lane has 14 patients waiting for applanation tonometry on the single slit lamp. Your supplies are one Goldmann prism, a box of 70% isopropyl alcohol wipes, a bottle of 5% povidone-iodine, a Schiotz tonometer in a drawer, gloves in size M with six pairs left, and no disposable tonometer tips. The doctor is 40 minutes behind and asks you to "just get the pressures done fast". The patient has already rested his chin on the slit lamp and rubbed his eye with his fingers.
1. What is the infection-control problem here, and what do you do about the request to "just get the pressures done"?
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The problem: a watery red eye with a tender pre-auricular node in a patient whose son and neighbours have the same illness, one week after a cold, is epidemic keratoconjunctivitis (adenovirus) until proved otherwise. Adenovirus is highly contagious by fingers, tonometer tips, chin rests, door handles and shared towels, and it survives on dry surfaces for days. Applanation on this man, in this lane, with this equipment, would put 14 waiting patients and the staff at risk.
What I do:
- Ask whether the pressure is actually needed now. In a watery red eye without pain, photophobia or reduced acuity, intraocular pressure is rarely the urgent question, and the diagnosis is clinical. I would propose that the doctor see him first and that tonometry be deferred until the infection settles - this is a clinical decision for the doctor, but the infection-control consequence is mine to raise.
- Separate him immediately: seat him away from the waiting area, give him tissues, ask him not to touch his eyes, and have him wash his hands. Hand hygiene for me before and after any contact.
- If the doctor insists on a pressure today, I would use a disposable tonometer tip or cover if any can be sourced, or a clean dedicated instrument (the Schiotz, which can be processed separately), rather than the shared Goldmann prism in a shared lane. The doctor's instruction to be fast does not override the need to protect the next 14 patients.
- Document the finding, the advice given and the decision taken, and tell the doctor why the sequence changed. Speed is served better by preventing one adenovirus case from closing the OPD for a week than by shaving five minutes off a list.
2. When the Goldmann prism is used on a red eye in an outbreak setting, how should it be decontaminated - and why is an alcohol wipe not enough?
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Why alcohol alone is not enough: 70% isopropyl alcohol is the routine between-patient wipe and is effective against many bacteria and enveloped viruses, but adenovirus is non-enveloped and comparatively alcohol-resistant. In an outbreak or known adenovirus case, alcohol wipes alone are not a reliable barrier.
A workable sequence for a shared prism:
- Gloves on, and handle the prism by its mount, not the optical face.
- Mechanical cleaning first - visible mucus and tear film must be removed with a soft lint-free wipe; a disinfectant cannot act through a layer of protein.
- Disinfection: for adenovirus-risk situations, soak the prism in freshly prepared 1:10 dilution of household bleach (about 0.5% sodium hypochlorite) for 10 minutes, or use 3% hydrogen peroxide, or a validated proprietary disinfection system per the manufacturer's instructions. Alcohol at 70% remains the standard rapid wipe between ordinary patients.
- Rinse and dry thoroughly - residual bleach or alcohol on the prism is toxic to the cornea and will distort the mires. Rinse with sterile saline or water and dry before the next use.
- Clean the surrounding surfaces too: chin rest, head rest, joystick, slit lamp knobs and the table, because those are touched by every patient.
Also remember the hands: glove use does not replace hand hygiene. Hands must be washed or alcohol-rubbed before and after patient contact and after removing gloves. In an outbreak, a single overlooked chin rest undoes a perfectly cleaned prism.
3. How do you manage the waiting room, the equipment and the record while this patient is in the department?
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Waiting room:
- Move him out of the queue and, if possible, to a separate area or a designated red-eye slot at the end of the list, with his own tissue and instructions not to rub his eyes.
- Ask him to keep his hands away from shared surfaces and to wash his hands before leaving. Advise (as the doctor directs) that he stay away from work or school while the eye is watering, and that towels at home should not be shared - this is how the family outbreak is being sustained.
- Protect staff: anyone examining him should glove and, if a true outbreak is suspected, use a mask and eye protection, and the slit lamp should be reserved for him at the end of the session.
Equipment: after any contact, wipe the chin rest, headband and joystick; set the prism aside for the full bleach or peroxide cycle rather than a quick alcohol wipe; do not put the Schiotz tonometer back into the shared drawer without processing it.
Record: date and time, laterality, symptoms (watery discharge, gritty feeling, pre-auricular node), the epidemic context (son and two neighbours affected), visual acuity, any drops instilled, tonometry performed or deferred and by whose decision, infection-control advice given, work/school exclusion advice, review date, and the name of the doctor informed. Write it so that if a second case appears in the same lane next week, the link is already visible in the notes rather than discovered too late.