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R. Scotto, D. Venzano, A. Zambelli, M. Mete, C. E. Traverso; Dynamic OCT Angle Assessment (DOCTAA) as a Complement in the Different Diagnosis of Angle Closure. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5800.
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to describe a technique for the differential diagnosis among angle closure (AC) mechanisms through digital scans combined with a new dynamic test.
54 eyes of 33 patients (8 males, 25 females) were included and divided in 2 groups: group 1 defined as angle width less than 25° in both nasal and temporal sectors (n=51), and group 2 characterized by a past acute angle closure in the fellow eye (n=3). Angle OCT scans (RT 100-2, Optovue Inc., Freemont, CA, USA) were acquired on both groups at rest and during corneal indentation applied with a scleral depressor (Heine, Germany), after topical anaesthesia. Angle width in degrees was measured on the horizontal meridian (nasal and temporal sectors) and its variations under corneal indentation were also recorded. We considered a cut-off value of 25° to arbitrarily separate angles with and without the potential to occlude, and measured the variations from this angle width obtained with indentation.
In group 1, during corneal indentation an increase in angle width over 25° was observed in 20 (39%) eyes (mean 28,3°±5,6°). Among the remaining 31 (61%) eyes, in 25 (49%) eyes the widening did not reach the cut-off value (15,6±5,3°), while in 6 (12%) eyes a reduction in angle width was observed (6,7°±7°). Two eyes of the group 2 (66,6%) demonstrated an increase in angle width over 25° (25,8°±4,5°), while in the remaining eye a smaller increase was measured (9,4°). Since no significant differences between nasal and temporal sector was recorded in either group, the main of the two values could be taken for the analysis.
DOCTAA could represent a reliable technique to perform an accurate evaluation of angle structures, representing a complement to dynamic indentation gonioscopy with the possibility of quantitative recording. A significant increase of angle width during indentation is suggestive of pupillary block as the main pathomechanism, while a stable or decreased width could be suggestive of other anatomical factors for the risk of AC.
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