Blinking and superficial punctate keratopathy in patients with diabetes mellitus.

AIM: To evaluate blinking patterns in patients with diabetes mellitus and whether blinking contributes to the formation of superficial punctate keratopathy in diabetic patients. METHODS: We examined 163 patients with type II diabetes mellitus and 76 without diabetes. Blinks were recorded, analysed using six parameters, and compared between patients with and without diabetes. Multivariate regression analysis was performed to assess the influence of other ocular factors, such as status of tear lipid layer, tear breakup time, corneal sensitivity, the result of cotton thread test, or blinking rate related to superficial punctate keratopathy. RESULTS: In patients with diabetes, the average mean and maximum interblinking times were longer, the average coefficient of variation of interblinking time was higher, and the average blinking rates were lower than those in patients without diabetes. Multivariate regression analysis revealed that the status of tear lipid layer and tear breakup time were significantly relevant to superficial punctate keratopathy (P < 0.01). CONCLUSION: Interblinking time was longer in diabetic patients, resulting in a decreased blinking rate. The prevalence of superficial punctate keratopathy cannot be predicted from blinking patterns in patients with diabetes.

Mixing Effect of Polyoxyethylene-Type Nonionic Surfactants on the Liquid Crystalline Structures.

An effective cross-sectional area per surfactant molecule at hydrophobic interfaces of aggregates, a(S), in hexagonal (H(1)) and lamellar (L(alpha)) liquid crystals was calculated in homogeneous and mixed polyoxyethylene dodecyl ether systems as a function of polyoxyethylene (EO) chain length by means of small-angle X-ray scattering. The a(S) increases with increasing the EO chain length. The a(S) in the mixed surfactant system is considerably smaller than that in the single surfactant system, even if the average EO chain length is the same. The reduction of a(S) is larger than that predicted by ideal mixing of the surfactants. Moreover, if the EO chain lengths of the surfactants are more separated, the a(S) is smaller. The shapes of surfactant self-organizing structures may be governed by the balance of the attractive and the repulsive forces acting at the hydrophobic interfaces of the aggregates. According to this consideration, the mixing effect of surfactants with the different EO chain lengths on the a(S) in the L(alpha) phase was discussed. It is considered that the surfactant molecules are tightly packed in the aggregates since the reduction in repulsion force takes place in the excess EO chain part of the hydrophilic surfactant longer than the short EO chain of the lipophilic one. The lower surface tensions and the better stability of macroemulsions and the large solubilizing capacity of microemulsions result from the mixing effect. Copyright 1999 Academic Press.