Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Seek emergency care for sudden loss of vision, severe eye pain, difficulty moving the eye, a bulging eye, or severe illness with swelling around the eye.
These symptoms are not typical of a simple tarsal cyst.
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Seek urgent medical advice if swelling or redness is rapidly spreading around the eye, particularly with fever or increasing pain.
This may be a sign of infection that needs treatment.
3
Does any of this apply?
Book an appointment
Arrange a routine appointment with an optometrist, GP, or eye-care professional if:
The lump lasts for several weeks without improving
It is large, uncomfortable, or affecting your vision
You are unsure whether it is a tarsal cyst
Cysts keep developing, especially in the same place
The lump bleeds, forms an ulcer, looks irregular, or causes eyelash loss
A child has a large or persistent eyelid lump
Every sign above is quoted from the sofidex article on Tarsal cyst. If you are not sure, err upward — it is always reasonable to be checked.