Non-contact meibography: Keep it simple but effective
Introduction
Meibomian Gland Dysfunction (MGD) is one of the most common abnormalities in ophthalmic practice [1] and the major cause of lipid anomaly [2] and therefore of the evaporative dry eye [3]. This was also recognized by the Tearfilm & Ocular Surface Society, which launched the International Workshop on Meibomian Gland Dysfunction (www.tearfilm.org/mgdworkshop/index.html) [3]. According the MGD Workshop, it is recommended to assess MGD by lid morphology, MG mass, gland expressibility, lipid layer and MG drop-out by meibography [3].
Meibography is a technique to visualize the morphology of the MG. There are two different principals: transillumination of the everted lid [4], [5], [6] versus direct illumination, named the non-contact meibography [7], [8], [9], [10]. In transillumination the lid is everted over a light source [5], [11] while non-contact meibography [10] consist of a slit lamp equipped with an infrared charge-coupled device video camera and an infrared transmitting filter [10] to allow the observation of the everted lid without contact to the instrument. To our knowledge, Jester et al. were the first describing meibography by infrared (IR) light [12] and subsequently many other groups used the transillumination IR techniques [4], [5], [6], [10] in MG observation, but Arita et al. were the first introducing non-contact meibography [7], [8], [9], [10]. The latter is commercially available but expensive.
The aim of this pilot-study was to analyze if a simple IR security video-camera is useful in meibography instead.
Section snippets
Methods
Meibographs (Fig. 1) were taken of the lower lid of 17 subjects (female = 10, male = 7; mean age = 44.3 years ±13.3 SD), randomly selected from the patient pool of the Horst Riede GmbH, Weinheim, Germany using a IR CCD video-camera (802CHA CCD; Shenzhen LYD Technology Co. Ltd., Shenzhan, China) which was adapted for near observation by adding a lens system (Fig. 2, Fig. 3). This camera set-up was named the ‘portable non-contact IR meibograph’ (PNCM). Lipid layer and non-invasive tearfilm break-up time
Meibography
An IR CCD video-camera (802CHA CCD; Shenzhen LYD Technology Co. Ltd., Shenzhan, China) was adapted for near observation by adding a lens system (Fig. 2, Fig. 3). The camera was connected to a computer via a Video-to-FireWire Converter DFG/1394-1e (The Image Source Europe GmbH, Bremen, Germany) and photographs were captured by the according software (IC Capture 2.0 and IC Imaging Control 3.1; The Image Source Europe GmbH). Photographs were then analyzed by ImageJ 1.42q (Wayne Rasband, National
Statistical analysis
Data were tested for normal distribution by the Shapiro-Wilk test. Correlations between MGL and tearfilm and symptoms were calculated by Pearson correlation, the ability to discriminate between OSDI± was analyzed by the receiver operative characteristic curve (ROC) and area under the ROC (AUC).
The data were analyzed using SPSS 16.0 (SPSS Inc., Chicago, USA).
Results
MGL scores were significantly correlated to lipid-layer pattern (r = −0.68, p = 0.001) (Fig. 5) NIBUT (−0.46, 0.032) (Fig. 6) and age (0.61, 0.005). MGL was significantly larger in female (U-test; p = 0.001). MGL was significantly correlated to OSDI scores (r = 0.89, p = 0.001) (Fig. 7) AUC of MGL was 95.8% (p = 0.001; sensitivity = 88.9%; specificity = 87.5%; threshold = 32.3%) (Fig. 8).
Discussion
Significant correlations between MGL and lipid layer as well as non-invasive break-up time were found. MGD is commonly characterized by qualitative and quantitative changes in the glandular secretion [18]. Consequently a decrease in lipid layer thickness is reasonable in increased MDL. The lipid layer is an important component to stabilize the tearfilm [19]. This is supported by the significant correlation of MGL and non-invasive break-up time, analyzed in this study. However these findings are
Conclusions
Meibomian gland loss was significantly correlated to tearfilm and dry eye symptoms. MGL seems to be a predictive discriminator between symptomatics and asymptomatics. The portable non-contact IR meibograph (PNCM) is a useful device for meibography.
Acknowledgement
Presented at the 35th BCLA Conference, Manchester, UK.
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