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Is tear calcium an indicator of ocular calcification in patients with chronic renal failure?
1Department of Ophthalmology, Baskent University Medical School, Ankara, Turkey.
Background:
In patients with chronic renal failure (CRF) on regular dialysis treatment, limboconjunctival degeneration and calcifications are common. The mechanisms of ectopic conjunctival and corneal calcification remain largely speculative. The aim of the present work was to study tear calcium levels in patients with chronic renal failure, which could alter calcium excretion patterns, and to examine whether the calcium level in tear fluid is of more diagnostic importance than static calcium levels in blood.
Methods:
Tear calcium levels were measured in 25 patients with chronic renal failure, compared with 14 normal subjects. Conjunctival and corneal calcium deposits were graded by the Porter and Crombie classification.
Results:
While 11 of the 25 patients had no clinically apparent calcium deposits, six had Grade 1 or 2, and eight had Grade 3 and over limboconjunctival calcification. Mean tear calcium levels were 1.436 +/- 0.165 mg/dl in the patients and 1.307 +/- 0.155 mg/dl in the normal group. The difference was not significant (P = 0.572). No correlation was found between the grade of the calcium deposits and tear calcium levels.
Conclusions:
Tear calcium level has no diagnostic importance for the development of ocular calcification in chronic renal failure.