Final answer:
The first suspicion for a patient who presents with ocular pain and visual loss after a cataract extraction operation must be endophthalmitis, a serious inflammatory condition requiring immediate treatment.
Step-by-step explanation:
After a cataract extraction operation, if a patient complains of ocular pain and visual loss accompanied by symptoms like eye redness with ciliary injection, corneal edema, hypopyon, and absent red reflex, the first suspicion must be of endophthalmitis. Endophthalmitis is a serious eye infection that can occur after eye surgery. It is characterized by inflammation, often due to bacterial or fungal infection, which can lead to severe visual loss if not promptly treated. Ocular pain and visual loss are alarming symptoms that necessitate immediate medical attention to limit damage to the eye and preserve vision.