U M Langenauer | PubMed Health

PubMed2006

Phosphate concentration in artificial tears.

BACKGROUND: Irrigating solutions and eye drops may contain phosphates as part of their buffer system. In the presence of epithelial keratopathy, a high concentration of phosphate favours corneal calcification. Knowledge of the phosphate concentration in artificial tear products helps to prevent this sight-threatening complication. This study gives an overview on the amount of phosphate contained in artificial tears. METHODS: Fifty-nine samples of commercially available artificial tear preparations were tested. The quantification of phosphate was performed using the molybdate method on a Modular P autoanalyzer. RESULTS: Twenty-six of 59 (44%) artificial tear products had a phosphate concentration above physiological levels (>1.45 mmol/l). A phosphate concentration above 25 mmol/l was found in nine products (15%), a concentration higher than 50 mmol/l in three (5%). CONCLUSIONS: Many artificial tear formulations contain unphysiological levels of phosphate, but very high concentrations are found only in a few products. These preparations have the potential to favour the formation of insoluble crystalline calcium phosphate deposits when used on a damaged corneal surface, and should therefore be used cautiously.

Autoanalysis↗

PubMed2006

[Chronic (kerato-) conjunctivitis refractory to therapy in children].

BACKGROUND: Chronic conjunctivitis and keratoconjunctivitis account for a significant ocular morbidity. Early diagnosis and appropriate management are essential to avoid persisting structural damage and visual loss. In children, the correct diagnosis is frequently delayed because of the low individual experience with pediatric ocular inflammation, the uncommon clinical manifestations and the rarity of some conditions. This study aims to identify the problems associated with the diagnosis of chronic pediatric (kerato-)conjunctivitis. PATIENTS AND METHODS: 48 consecutive tertiary referrals (median age: 8.5 years) with chronic conjunctivitis or keratoconjunctivitis were studied. The ocular inflammation of all patients was denoted by their referring ophthalmologists as "chronic conjunctivitis refractory to therapy". The median time since disease onset was 23 months (range: 3 - 118). On average, 2.8 (range: 2 - 5) ophthalmologists were seen before the final diagnosis was made. A standardized protocol was used to classify and diagnose the ocular inflammation. Laboratory investigations were carried out to confirm the diagnosis in 20 out of 48 patients. RESULTS: In 33 out of 48 patients treatment failure was due to an inappropriate diagnosis. The most frequent diagnosis were Staphylococcus-associated inflammation (n = 21) and vernal keratoconjunctivitis (n = 12). Viral infection causing molluscum contagiosum was the most frequent condition that was missed (n = 7). Ligneous conjunctivitis (n = 2) was not recognised by the 9 ophthalmologists who were previously in charge of the treatment. Significant corneal involvement was found in 24 (50 %) patients. CONCLUSION: History taking and a thorough clinical examination of the entire ocular surface allow the correct diagnosis of and therapy for chronic surface inflammation in almost all pediatric patients. Subtle clinical changes have to be sought actively to avoid misdiagnosis. Such changes include lesions in the anterior lid margin, collarettes, follicules, papillae, and superficial punctate keratopathy.

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