**Core Concept**
Sphenoid sinus surgery is a complex procedure that involves the removal of the sphenoid sinus, a paranasal sinus located in the sphenoid bone. The sphenoid sinus is in close proximity to several critical structures, including the cavernous sinus, the internal carotid artery, and the cranial nerves. Due to its location, sphenoid sinus surgery carries a high risk of complications.

**Why the Correct Answer is Right**
The complications of sphenoid sinus surgery can be categorized into immediate and delayed complications. Immediate complications include cerebrospinal fluid (CSF) leak, cranial nerve injury, and bleeding. Delayed complications include meningitis, sinusitis, and cerebrovascular accidents. The risk of these complications is increased due to the proximity of the sphenoid sinus to critical structures.

**Why Each Wrong Option is Incorrect**
**Option A:** Cavernous sinus thrombosis is not a direct complication of sphenoid sinus surgery. However, it can occur as a result of other complications such as CSF leak or cranial nerve injury.
**Option B:** Intracranial hemorrhage is a potential complication of sphenoid sinus surgery due to the proximity of the sphenoid sinus to the internal carotid artery and the cavernous sinus.
**Option C:** Meningitis is a potential complication of sphenoid sinus surgery, particularly if there is a CSF leak or contamination of the surgical site.
**Option D:** Visual loss is not a direct complication of sphenoid sinus surgery. However, it can occur as a result of other complications such as cranial nerve injury or intracranial hemorrhage.

**Clinical Pearl / High-Yield Fact**
It is essential for surgeons to have a thorough understanding of the anatomy of the sphenoid sinus and its surrounding structures to minimize the risk of complications. A detailed preoperative evaluation and careful surgical technique are crucial in preventing and managing complications.

**Correct Answer: D. Visual loss**