Most commonly it is attracted from vegetative foreign body like vegetables or wood.sometimes dusting in house can also cause.sometimes it can occur due to infective instruments. Can't say what has infected your uncle's eye.you said doctor has replaced the tissue,means he has done corneal transplant or patch graft?As far as reports are there what i conclude is it has not entered the eye,it's limited to cornea only.
Next Steps
you must consult any corneal as well as retinal surgeon for fungal corneal ulcer and fungal endophthalmitis. don't waste time as it's sight threatening