Differential Diagnosis for Enlargement of Blind Spots and Ring Scotoma around Fixation
- Single most likely diagnosis:
- Retinitis Pigmentosa (RP): This condition often presents with night blindness, followed by a gradual decline in peripheral vision, which can lead to ring scotoma. The enlargement of blind spots can be attributed to the degeneration of the retina, particularly affecting the rod cells.
- Other Likely diagnoses:
- Chorioretinitis: Inflammatory conditions affecting the choroid and retina can lead to scotomas, including ring scotomas, and enlargement of the blind spots due to the formation of chorioretinal scars.
- Retinal Detachment: A retinal detachment can cause visual field defects, including scotomas. If the detachment is near the macula, it might cause a ring scotoma around fixation, and the enlargement of blind spots could be due to the detachment itself or associated retinal damage.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Optic Neuritis: Although less common, optic neuritis can present with sudden vision loss and visual field defects, including central or peripheral scotomas. It's crucial to diagnose and treat promptly to prevent permanent vision loss.
- Pituitary Tumors: Tumors affecting the pituitary gland can compress the optic chiasm, leading to visual field defects, including bitemporal hemianopia, but in some cases, they might cause enlargement of blind spots and scotomas if the tumor compresses or invades the optic nerves.
- Rare diagnoses:
- Leber's Congenital Amaurosis: A rare inherited eye disease that appears at birth or in the first few years of life, leading to severe visual impairment. While it primarily affects central vision, advanced cases could potentially lead to widespread retinal degeneration, affecting peripheral vision and causing scotomas.
- Bassen-Kornzweig Syndrome (Abetalipoproteinemia): A rare inherited disorder affecting fat absorption and leading to vitamin deficiencies, which can cause retinal degeneration similar to retinitis pigmentosa, potentially resulting in ring scotomas and enlarged blind spots.