Magnesium (ocular fluids)

Interpretation of Magnesium Concentration in Ocular Fluids of Cattle and Sheep
In aqueous humour, values of <0.25 mmol/l in cattle and <0.33 mmol/l in sheep are suggestive of clinical disease.
In vitreous humour, values of <0.55 mmol/l in cattle and <0.65 mmol/l in sheep are suggestive of clinical disease.

Low magnesium concentrations in ocular fluids are usually clinically significant, unless bacterial growth has caused the decrease. Normal or elevated levels of magnesium in AH or VH do not rule out the possibility of hypomagnesaemia, as magnesium contamination of the sample can occur as a result of autolysis, contamination with cells or cellular debris or the use of contaminated containers. A low result is highly suggestive of hypomagnesaemia, but should not be regarded as an absolute diagnosis. Further investigation, such as blood sampling of animals in the cohort should be carried out to confirm the diagnosis. Interpretation should always take into account the case history and circumstances in which sampling took place.
Reference: Edwards, Foster and Livesey, In Practice, Volume 31, Issue 1, 2009