Aysun Sanal Doğan MD
Corneal topography measurements obtained with the Sirius Scheimpflug device do not appear to be affected by the presence of dry eye, according to the results of a study presented by Aysun Sanal Doğan MD, Department of Ophthalmology, Diskapi Yildirim Beyazit Training and Research Hospital, Ankara, Turkey.
“These findings confirm that use of Scheimpflug corneal topographic is reliable for dry eye patients,” Dr Doğan told the 21st ESCRS Winter Meeting in Maastricht, The Netherlands.
In the retrospective case review study, Dr Doğan and her associates compared the performance of the Sirius Scheimpflug topographer in 33 patients with diagnosis of dry eye disease with its performance in 40 control patients.
The two groups were similar in terms of age and gender distribution. The dry eye group included four men and 29 women with a mean age of 39 years, ranging from 18 to 65 years, and the control group included eight men and 32 women with a similar age profile.
Dr Doğan noted that, compared to the control group, the dry eye group had significantly higher Meibomian gland drop-out than the control group (21% vs. 15.1%), and significantly lower tear break-up time as measured with non-invasive tear film (6.5 vs 17 seconds).
EXCELLENT REPEATABILITY
The researchers used two images with at least 95% acquisition quality to assess the reliability of measurements. They analysed intra-class coefficients (ICC), a measure of repeatability, for each corneal topography parameter within both groups using SPSS 20.0 software.
They found then that the ICCs were excellent (>0.95) for the comparison of two images in terms of all parameters in both the dry eye group and the control group. In addition, comparison in terms of topographic parameters, including the central corneal thickness, revealed that dry eye patients and controls are not different topographically.
Dr Doğan noted that dry eye leads to unstable tear film, which can affect image quality and reliability. However, the speed with which the Scheimpflug topographer acquires its images may improve the reproducibility of its measurements. In addition, the selection of high-quality images may have enhanced the repeatability of the measurements.
“Our study showed that repeated Scheimpflug corneal topographic measurements of the same patient in both dry eye group and controls are in agreement to an excellent degree. Secondly, there is no significant difference between dry eye patients and controls in terms of topographic features.
"Therefore, the device may be useful as a screening, biometric measures and diagnostic tool for various ophthalmic diseases even if dry eye syndrome also coexists. But further studies are needed to compare the repeatability of measurements in very severe dry eye patients,” she concluded.
Aysun Sanal Doğan: asanaldogan@gmail.com
