Abstract
Purpose: :
Increased host and interface scatter after Descemet-stripping with endothelial keratoplasty (DSEK) might affect endothelial image quality. We compared endothelial image quality in eyes after DSEK as recorded by three microscopy techniques: non-contact specular microscopy, non-contact confocal microscopy, and contact confocal microscopy.
Methods: :
The central corneal endothelium of 52 eyes of 43 patients was photographed at the same examination by using a non-contact specular microscope (Konan Noncon Robo, Konan Medical, Inc.), and a confocal microscope (ConfoScan 4, Nidek Technologies) with non-contact and contact objective lenses. All eyes were examined 3 weeks to 38 months after DSEK; eyes with corneal edema and eyes with corneal haze unrelated to DSEK or the preoperative diagnosis were excluded. Image quality was assessed by determining the proportion of countable cells (well-defined centers and apices) in the best image from each method: if all or nearly all cells were uncountable the image was poor, if <33% of the cells were countable it was fair, if 33-66% of the cells were countable it was good, and if >66% of the cells were countable it was excellent. Images were graded by two masked observers and disagreements were adjudicated by a third observer. Image quality was compared between microscopes by using Bowker’s test of symmetry and McNemar’s test.
Results: :
With non-contact specular microscopy, image quality was excellent in 4 eyes (8%), good in 8 eyes (15%), fair in 18 eyes (35%) and poor in 22 eyes (42%). With non-contact confocal microscopy, image quality was excellent in 37 eyes (71%), good in 11 eyes (21%), and fair in 4 eyes (8%); no images were of poor quality. With contact confocal microscopy, image quality was excellent in 47 eyes (90%) and good in 5 eyes (10%); no images were of fair or poor quality. When comparing all grades, image quality was better with contact and non-contact confocal microscopy than with non-contact specular microscopy (p<0.001), whereas quality did not differ between contact and non-contact confocal microscopy (p=0.32). When comparing excellent and non-excellent images only, image quality was better with contact than with non-contact confocal microscopy (p=0.01). Image quality with the specular microscope correlated with time after surgery (r=0.27, p<0.001).
Conclusions: :
Contact confocal microscopy provides the best endothelial image quality after DSEK. Image quality with non-contact specular microscopy improves with time after DSEK, and this might be attributed to the gradual improvement in corneal optical properties.
Keywords: cornea: clinical science • transplantation • cornea: endothelium