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Hannah Timlin, Pearse Keane, Alex Day, Mohamed Abdullah, Daniel Ezra; Characterisation of the Lacrimal Punctum using Spectral Domain Anterior Segment Optical Coherence Tomography: An Exploratory Study. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2792.
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© ARVO (1962-2015); The Authors (2016-present)
The aim of this study is to improve our anatomical knowledge of the normal healthy punctum in physiological conditions by using an imaging technique novel to the lacrimal system. Optical Coherence Tomography has been extensively used on the retina to provide detailed in vivo cross sectional images. Adapting this imaging technique for use on the lacrimal punctum can improve our anatomical understanding of this structure in vivo and allow baseline descriptions of OCT images of a healthy normal punctum. The method of acquiring these images and data obtained can then be used in the future for comparing healthy with diseased puncti or puncti pre and post-surgical intervention.
22 inferior puncti from 11 healthy volunteers had previously been imaged using Anterior Segment Spectral Domain Optical Coherence Tomography. These images were collated and qualitative characteristics were analysed.
OCT images reveals three layers of tissue presumed to be; epithelium, substantia propria and orbicularis. The epithelium is visible extending from the surface of the lid down into the punctum and showed variation in thickness from person to person with a mean of 70μm (SD 19, range 41 to 141). The second layer of tissue is hyperreflective in comparison to the first and third layer, with an irregular anterior interface and a relatively flat inferior interface. The medial wall of the punctum shows a graduated, curved approach to the internal punctum suggestive of a papilla. In comparison, the lateral wall shows a more acute angled approach without evidence of a papilla. The mean external punctal opening size was 615μm (SD 367, range 410 to 872) and the mean internal opening size was 18 μm (SD 30, range 0 to 99). The OCT images revealed that in physiological conditions, the internal punctum is closed at a depth of 500μm in the majority of puncti. In the 8 open puncti, the internal diameter size at 500μm depth ranged from 22μm to 99μm in diameter. A fluid level was visible inside 18 puncti, and 5 of these had multiple visible fluid levels. The first fluid level was visible at a mean depth of 279μm (SD 299, range 14 to 1138). The horizontal cannaliculus was not visualised.
Optical Coherence Tomography can be used to image and measure the lacrimal punctum and the surrounding tissue layers.
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