Abstract
Purpose: :
To compare the confocal microscopic features of the lamellar interface after 2 types of deep anterior lamellar keratoplasty (DALK): descemetic with total stromal resection versus pre-descemetic with deep stromal dissection.
Methods: :
Thirty eyes of 30 patients who had keratoconus with healthy endothelium were treated by DALK using the air technique. Baring of Descemet membrane (DM) was achieved for 18 eyes (Descemetic group). A fine stromal layer was left in 12 eyes (pre-Descemetic group). Interface clarity, corneal topography, confocal microscopy, and endothelial cell count were analyzed
Results: :
In all the patients a deep lamellar interface was identified. Microscopic features of the interface were different in the two groups studied. In the descemetic group the interface was identifiable as an homogeneous hyper-reflectivity, with variable transparency and possible presence of bright microdots. In the pre-descemetic group the interface was represented as an evident discontinuity in the deep stromal extracellular architecture with absence of keratocites associated with hyper-reflectivity, and possible presence of microdots. Also the Z-scan curve were different between the two groups. In the descemetic patients we observed just one unique deep peak of hyper-reflectivity, just above the descemet membrane. In the pre-descemetic group we observed two peaks of reflectivity, at the level of the endothelium and in the deep stroma.Measuring the reflectivity of the interfaces at one months follow up we observed a grater reflectivity of the pre-descemetic group (165,12± 30,71) compared with the descemetic patients (140,15± 22,31). After six months of follow up the peak of reflectivity were comparable in the two groups (134,71±29,15 and 142,71±20,23 respectively).
Conclusions: :
The depth of the lamellar bed, smoothness, and healing process at the interface are the keys to optimal visual acuity.At 1 months follow up the keratocyte activation and interface haze were less in the descemetic group. This diffecence in the microscopic features disappear after 6 months follow up. At mid-time follow up the of cornea that undergone DALK surgery still presented a moderate postoperatory interface haze and a residual activation of keratocyte independently from the kind of lamellar surgery performed.
Keywords: keratoconus • cornea: stroma and keratocytes • microscopy: confocal/tunneling