Uveitis-Glaucoma-Hyphema (UGH) Syndrome: Given the presence of edema and blood in the eye post-IOL cataract surgery, UGH syndrome is a strong consideration. The normal IOP and absence of pain are consistent with this diagnosis, as the condition can present with variable symptoms.

Cystoid Macular Edema (CME): This condition is a common complication after cataract surgery, characterized by edema in the macula. The patient's symptoms of edema and the absence of other severe symptoms like flashes or floaters make CME a plausible diagnosis.
Hyphema: Blood in the eye (hyphema) can occur post-surgery due to various reasons, including iris or ciliary body damage during surgery. The presence of blood without significant pain or elevated IOP supports this diagnosis.
Iridocyclitis or Anterior Uveitis: Inflammation of the iris or uvea can cause edema and discomfort. Although the patient is not using eye drops, which could indicate a lack of treatment for inflammation, this condition remains a possibility, especially if the patient had pre-existing uveitis or if the surgery induced an inflammatory response.

Endophthalmitis: Although less likely given the absence of severe pain and the patient not reporting any significant decrease in vision, endophthalmitis is a potentially devastating infection that must be considered in any post-surgical complication. It requires immediate attention and treatment.
Suprachoroidal Hemorrhage: This is a rare but serious complication that can occur post-surgery, characterized by bleeding into the space between the sclera and choroid. It is crucial to rule out this condition due to its potential for severe vision loss and need for urgent intervention.

Scleritis or Episcleritis: Inflammation of the sclera or episclera, respectively, can cause edema and discomfort. These conditions are less common post-cataract surgery but should be considered if other diagnoses are ruled out.
Vitreous Hemorrhage: Although the patient does not report flashes or floaters, a vitreous hemorrhage could still be considered, especially if there was trauma or complication during surgery that could have led to retinal or vascular damage.