Differential Diagnosis for Post-Photocoagulation Visual Phenomena

Single Most Likely Diagnosis

• Vitreous Floaters: The description of "blobs" that appear as "smudges" and are in a fixed position, especially after a procedure like photocoagulation, suggests vitreous floaters. These are common after eye surgeries or laser treatments and can be particularly noticeable when blinking due to the movement of the vitreous gel.

Other Likely Diagnoses

• Posterior Vitreous Detachment (PVD): Symptoms like seeing floaters that move with eye movements and are more noticeable when blinking can also indicate a PVD, which can be precipitated by photocoagulation.
• Vitreous Hemorrhage: Although less likely given the description of "smudges" turning bright with blinking, a vitreous hemorrhage could cause sudden onset of floaters. However, it would typically be associated with more severe visual disturbances.

Do Not Miss Diagnoses

• Retinal Detachment: This is a medical emergency that can present with sudden onset of floaters, flashes of light, and a curtain or shadow descending over the field of vision. While the description doesn't perfectly match, any new onset of visual phenomena post-photocoagulation warrants consideration of retinal detachment.
• Endophthalmitis: An infection within the eye, which is a rare but serious complication of eye surgery or injections. Symptoms can include severe eye pain, redness, decreased vision, and floaters, although the latter might not be the primary complaint.

Rare Diagnoses

• Intraocular Inflammation (Uveitis): While uveitis can cause floaters due to inflammatory debris in the vitreous, it is less directly associated with photocoagulation and would typically present with other symptoms like eye pain, redness, and light sensitivity.
• Choroidal Neovascularization: This condition involves the growth of new, fragile blood vessels in the choroid layer of the eye and can be a complication of certain retinal diseases treated with photocoagulation. However, it would more commonly present with visual distortion or loss rather than just floaters.