Introduction
It is caused by the accumulation of plasma ornithine in the retina. This is very toxic to the RPE and choroid.
- Occurs in the first decades of life
- Nyctalopia is very common, followed by visual field loss and central field loss
- Has an associated with high astigmatism, high myopia and early onset cataracts
- May be clinically associated with neovascularisation, macular oedema and macular hole formation
Dead Giveaways
The main diagnostic features unique to gyrate atrophy include the fundus autofluorescent images and the OCT.
In FAF:
It is very common to see areas of hypo-AF
Buildup of plasma ornithine in the peripheral retina causes death and chorioretinal atrophy
This forms a scallop border between the normal and abnormal retina
Note the macular sparing + round border (looks like scallops). The bright red lines are the visible choroidal vessels, more pronounced in areas of atrophy This understandably would lead to poor constricted peripheral fields. The macular is relatively spared.
In OCT:
Chorioretinal atrophy can be clearly seen
It also spares the macular, but is typically closer to the optic disc
Note the cystic spaces marking macular oedema. The ONL, EZ, RPE and choroid are relatively normal, until the far left, to which all attenuate and disappear
diagnostic features
A feature that is also present is the fundus photograph is the very visible choroidal vessels:
That being said, many other conditions show exposed choroidal vessels.
Another possible feature is outer retinal tubulations, which are similarly present in choroideraemia
This is when the Muller cells wrap around the photoreceptors in order to protect them from death, as a temporary measure against atrophy