Optic Disc Pit

Retina

Apr 25

Congenital defects arising from failure of fetal fissure closure in embryogenesis
Mostly unilateral. 10-15% bilateral
No gender predilection

PATHOPHYSIOLOGY:

Occur due to incomplete closure of the optic fissure resulting in a micro-communication between the subarachnoid space and the pit.
Communication of optic pits and Cerebral Spinal Fluid (CSF) is controversial and Beta-2 Transferrin levels (found in CSF) of submacular fluid associated with optic pits has been variable.
Histologically, there is herniation of a dysplastic retina into the subarachnoid space through a defect in the lamina cribrosa at the pit.

SYMPTOMS:

Usually asymptomatic.
Found on routine examination incidentally.
Patients may complain of metamorphopsia, micropsia, blurred or decreased vision, or a blind spot if the optic pit is associated with a serous detachment.

SIGNS:

Usually found inferotemporally within the nerve, ⅓ are central.
Appear as a round or oval depression that differs in colour from the surrounding disc (grey, yellow or black).
Colour variation depends on the amount and location of glial tissue in the pit.
Size can vary from 0.1-0.7 disc diameters and depth from 0.3-0.5 diopters.
Associated macular edema, serous macular detachment; schisis or pigmentary changes in the macula.
Shallow serous macular detachments can be seen in upto ¾ eyes with inferotemporal pits
Source of the retinal fluid in optic disc pit maculopathy is controversial; the reports in literature describe it to be vitreous, cerebrospinal fluid, and even in some cases fluid from blood vessels in the pit.

INVESTIGATIONS:

OCT: to determine if trace amounts of subretinal fluid is seen, can show schisis-like separation between inner and outer retina.
Visual fields – Enlarged blind spot, arcuate scotomas .
Amsler grid can be used to monitor the onset of macular involvement of an optic pit with serous detachment.

MANAGEMENT:

No medical therapy indicated unless it is associated with optic disc maculopathy

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Image from Rajan Eye Care Hospital

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