Differential Diagnosis• Secondary angle closure• Neovascular glaucoma• Phacomorphic glaucoma• MigraineAlways do gonioscopy for the fellow eye

To answer the question step by step, we will first discuss the possible differential diagnoses for the given scenario:

1. Secondary angle closure: This refers to a condition where the angle between the iris and the cornea becomes blocked, leading to increased intraocular pressure. It can be caused by various factors such as inflammation, trauma, or certain medications.

2. Neovascular glaucoma: This is a type of glaucoma that occurs as a result of abnormal blood vessel growth in the eye. It is often associated with conditions such as diabetes or retinal vein occlusion.

3. Phacomorphic glaucoma: This type of glaucoma occurs due to a rapid increase in lens size, usually caused by a cataract. The enlarged lens can push the iris forward, leading to angle closure and increased intraocular pressure.

4. Migraine: While not directly related to glaucoma, migraines can sometimes cause temporary visual disturbances, including blurred vision or visual field defects. It is important to consider this as a possible cause, especially if the patient has a history of migraines.

In addition to considering these differential diagnoses, it is recommended to perform gonioscopy for the fellow eye. Gonioscopy is a procedure that allows the ophthalmologist to examine the angle of the eye and determine if there are any abnormalities or blockages present. This can help in confirming the diagnosis and guiding further management.

It is important to note that a comprehensive evaluation by an ophthalmologist is necessary to accurately diagnose and treat the patient's condition.