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J. Nemeth, B. Csakany, B. Erdelyi; Five Sequence-patterns of Corneal Surface-topography Variations in the First Minute after a Complete Blink . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2561.
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Purpose: To observe the corneal topographic changes in healthy subjects during the first minute after a total blink. Methods: The right eye of each of 36 healthy subjects was examined 5, 15, 30 and 60 seconds after a complete blink using the TMS-1 corneal topograph. The main outcome measures were changes in the surface regularity values (Klyce indices: SRI, SAI, PVA) and simulated keratometry values (K1, K2, MinK). In addition, the topographic pattern of each image was assessed from the color-coded topographic map, and was classified in 5 groups (in order of decreasing regularity: round, oval, symmetric bow-tie, asymmetric bow-tie, irregular) according to the terminology of Bogan et al. The time-sequence of the changes was analysed. Results: The surface regularity (Klyce indices) changed significantly during the 60 seconds after blinking (p<0.001), and five distinct sequences of regularity changes were found: stable; initially stable then decrease; continuous decrease; initial increase then decrease; continuous increase of regularity. There were no changes in the simulated keratometry values (p>0.7). At 15 seconds after blinking there were more eyes with topographic patterns of regular form (round, oval, symmetric bow-tie) than there were initially (at 5 seconds); but at later times the irregular forms became predominant (p<0.003). Conclusions: After a total blink the corneal surface regularity changes over time according to five different sequence-patterns in healthy eyes; this may be due to the individual characteristics of the build-up and stability of the tear film in different subjects. The ocular surface initially becomes more regular, which probably can be correlated with the building-up of the tear film. Later on the more irregular surface is a sign of thinning and break-up of the tear film.
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