II. Degenerative corneal conditions
It is bilateral peripheral lipoid infiltration of the corneal stroma. It is a very common condition in old age. Uncommonly it occurs in young age due to hyperlipidemia or juvenile diabetes (arcus juvenilis).
No symptoms, it never affect vision because it does not reach the central area.
- It starts as an ark like opacity near the upper part of limbus. This opacity has a diffuse central border and a sharp peripheral border separated from the periphery by a clear zone (the lucid interval of Vogt).
- Then a similar arc develops lower down. Then both arks extend circumferentially till they fuse with each other forming a complete ring.
Differential diagnosis: from pannus siccus.
Treatment: No treatment.