II. Degenerative corneal conditions
Arcus senilis
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).
Clinical picture:-
Symptoms:
No symptoms, it never affect vision because it does not reach the central area.
Signs:
- 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.