Ocular Diagnostic Preparations

Last updated by Peer reviewed by Dr Doug McKechnie
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Treatment of almost all medical conditions has been affected by the COVID-19 pandemic. NICE has issued rapid update guidelines in relation to many of these. This guidance is changing frequently. Please visit https://www.nice.org.uk/covid-19 to see if there is temporary guidance issued by NICE in relation to the management of this condition, which may vary from the information given below.


  • Use - tear film assessment, identification of corneal epithelial defects/corneal disease and perforation (Seidel test).
  • Action - absorbs light in the blue wavelength and emits green fluorescence.
  • Administration - a single drop is sufficient.
  • Additional information - remember to warn patients that their eye will look yellow but that this readily wears off. They may also find that handkerchiefs stain yellow for several hours after they blow their nose. It stains contact lenses.
Seidel test to detect a wound leak:
  • Apply concentrated fluorescein (eg, 2% solution or directly from a moistened fluorescein strip) over the suspect area of the anaesthetised cornea, whilst observing the site with a slit lamp.
  • If there is a leak, the fluorescein dye appears as a bright green fluid oozing from the orange dye concentrate.


  • Use - in eye units to perform fundus angiography.
  • Administration - intravenous: it remains largely intravascular and circulates in the blood stream. Patients are monitored for allergic reactions during and after the procedure.
  • Contra-indications - renal impairment and allergy to fluorescein.
  • Side-effects[2] - discolouration of the skin (yellow tinge) and urine, vomiting, itching, sneezing, vasovagal syncope, allergic reactions including anaphylaxis (1 in 1,900: severe, 1 in 220,000: fatal).
  • Use - retinal angiography. Provides a better visualisation of the choroidal (rather than retinal) vasculature. In addition to visualising choroidal neovascularisation, it may also be helpful in assessment of inflammatory disease and choroidal tumours.
  • Administration - intravenous: remains largely intravascular.
  • Contra-indications - pregnancy, renal impairment, iodine allergy.
  • Side-effects - nausea and vomiting, sneezing and pruritus, staining of stool, vasovagal syncope and severe anaphylaxis (1 in 1,900).
  • Use - detection of corneal and conjunctival damage (desiccation or devitalised tissue, eg, good for diagnosis of keratoconjunctivitis sicca).
  • Action - stains damaged conjunctival and corneal cells.
  • Additional information - this should only be administered after applying topical anaesthetic, as it stings and may cause local irritation on application; advise patients of temporary coloured staining of the eye. The dye needs to be washed out afterwards.

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