The physiological blind spot (punctum caecum) is the portion of the retina where the optic nerve passes through the optic disc. This area is devoid of photoreceptor cells. While normally small, it may become larger if certain conditions are present.
Clinically the patient may notice a scotoma.
Differential diagnosis of an enlarged blind spot:
(1) big blind spot syndrome
(2) coloboma of the optic nerve
(3) a wide range of drugs (corticosteroids, tetracycline, etc)
(4) drusen of the optic nerve
(5) glaucoma
(6) inferior conus
(7) inverted optic disc or nasally directed scleral canal
(8) juxtapapillary choroiditis
(9) medullated nerve fibers
(10) multifocal evanescent white-dot syndrome
(11) pseudotumor cerebri with papilledema
(12) papillitis
(13) progressive myopia with central crescent
(14) senile halo
(15) high-resistance musical instrument players
