Introduction
The optic fissure, classically closing in week 7 around day 44, fails to close, leading to a failed formation of the ocular tissues.
- Is equally bilateral and unilateral
- Has systemic associations 30% of the time
- Commonly associated with the other colobomas, such as chorioretinal
Dead Giveaways
The biggest giveaway is in the fundus examination and the OCT.
Fundus:
Temporally, a scleral crescent can sometimes be seen
Nasally, a pigmented margin can typically be seen (thinning is inferonasal)
While the superior rim is discernible, the inferior rim is significantly more distorted and larger. On VF testing, this would lead to a corresponding increased superior blindspot. Also note the numerous BV emerging from the edges
OCT:
Retinal herniation is seen. In H, the top band is the herniated retina, and the second band is the bottom of the coloboma. The red arrow points to the subarachnoid space In G, the red line indicates regions of retinoschisis and the white arrow points to the region of herniation and excavation
diagnostic features
Systemic Associations
CHARGE --> coloboma, heart defects, atresia of choanae, retardation of growth, genitourinary defects and ear deficits
Retinal hypoplasia
Transpheroidal encephalocele
Jain Johnson
Describes a pathophysiology
The incomplete closure of a fissue leads to the herniation of dysplastic retina
This herniation leads to maculopathy if IOP and ICP are too great. The IO and IC fluid pushes through the cavity and into the retina, leading to rhegmatogenous retinal detachment and retinoschisis.