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Background: The ocular ferning test is used as a diagnostic aid to evaluate patients with dry-eye disease. The ferning phenomenon is a dendritic growth form of dried tear fluid. The influence of temperature and relative humidity (rH) on the morphology of tear ferning patterns was investigated. Methods: Two microliters of tear fluid of 5 volunteers with normal tear function were dropped onto a microscope slide with a pipette and were dried in a climatic chamber at four different temperatures (20, 22, 24 and 26°C) and at four different grades of rH (30, 40, 50 and 60%) at each temperature. The dried droplet was divided according to distinct morphological features into a center, transition zone and margin. The center of the dried droplet was classified into four types according to the system of Rolando. Results: In the temperature range between 20 and 26°C, rH has a strong influence on the ferning patterns. At these temperatures, increasing rH resulted in a deterioration of type I ferning obtained at 30% rH to type II or type III at 60% rH in all subjects. Otherwise, at rH of 30, 40 and 50%, no definite influence of temperature between 20 and 26°C was observed. At an rH of 60%, the ferning patterns changed with increasing temperature from 20 to 26°C from type II to type III. Conclusion: High humidity can modify and deteriorate the ferning patterns of tear fluid from subjects with normal tear function. To obtain reproducible results using the ocular ferning test, stable conditions are necessary. An rH not higher than 50% at a temperature range between 20 and 26°C produced ferning patterns without interstitial spaces which could be related to the best quality according to the system of Rolando.

We describe opacification of a plate-haptic silicone intraocular lens (IOL) caused by calcification in a diabetic patient with asteroid hyalosis. The IOL was explanted 48 months after uneventful phacoemulsification because opacification of the posterior surface was causing significant visual disturbance. Light and scanning electron microscopy and x-ray spectrometry of the explanted IOL showed the opacification consisted mainly of calcium and phosphate, presumably hydroxyapatite, in the form of precipitations on the posterior surface of the optic.

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Electron-microprobe analyses of hydroxylellestadite from the Cioclovina Cave (Romania) gave the composition Ca 10.27 [(SiO 4 ) 2.53 (SO 4 ) 2.17 (PO 4 ) 1.27 ] Σ=5.97 [(OH) 1.66 F 0.21 Cl 0.16 ] Σ=2.03 . The mineral is translucent to transparent, light orange, slightly fl uorescent, has a vitreous luster and <1.5 mm in length. A singlecrystal X-ray structure investigation gave the average space-group symmetry P6 3 /m [R1(F) = 0.038 for 783 refl ections up to 2θ MoKα = 70° and 42 variables, a = 9.496 (2), c = 6.920(2) Å, V = 540.4 Å 3 , and Z = 2]. Some atoms exhibit large anisotropic displacements. Ordering of atoms along with a symmetry reduction is not verifi ed. Fourier-transformed infrared (FT-IR) and micro-Raman spectra exhibit a distinct contribution from (PO 4 ) 3-modes along with the characteristic (SO 4 ) 2-and (SiO 4 ) 4-modes. The occurrence is quite unusual and suggests that an intense thermal process affected a restricted area within the cave. Hydroxylellestadite is associated with berlinite, another high-temperature mineral. It is likely to have formed within highly phosphatized, silicate-rich, carbonate-mudstone sediments heavily compacted and thermally transformed due to in situ bat guano combustion.