Abstract
Purpose::
Functional results of keratoplasty are often not as good as expected, according to slit lamp graft appearance. Corneal confocal microscopy is used for "in vivo" evaluation of the morphological changes induced by lamellar (LK) and penetrating keratoplasty (PK) performed for keratoconus using different surgical techniques.
Methods::
25 eyes of 25 patients were submitted to LK (17 to anterior LK and 4 to deep anterior LK using Intralase®, 2 to excimer laser LK and 2 to automated therapeutic LK with microkeratome) and 12 patients were submitted to PK (10 using Hanna suction system and 2 using Intralase® for trephination of both donor and receiving corneas). All patients were submitted to Confoscan 4 (Nidek Technologies, Tokyo, Japan) confocal microscopy to investigate corneal biomechanical and ultrastructural alterations.
Results::
Postoperative digital slit lamp examination showed clear graft in all cases and with a good interface in LK cases. In LK patients, BSCVA resulted unsatisfying during the early follow up but improving after suture removal (mean time 3 to 5 months).According to Confoscan 4 outcomes these factors are determinant for visual rehabilitation after keratoplasty:1) interface quality2) cell and nerve density of the graft3) presence and gravity of inflammatory or scarring reaction4) regularity and stability of the residual stromal bed5) modifications and steadiness of stromal biomechanical forces recognized with linear hyporeflective stromal lines6) biomechanical changes during the follow-up after suture removal and stabilization of the graft.Each of these plays a different role depending on the technique performed. Improved LK BSCVA after suture removal seems to be related to the reduction and regularization of hyporeflective stromal lines. Severe reduction of keratocyte and endothelial cell density seems to be directly correlated to visual acuity.
Conclusions::
Confocal microscopy seems to be an effective, safe and predictive imaging method to justify the visual outcome and functional failure of different keratoplasty techniques, more than the only slit lamp exhamination.
Keywords: transplantation • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • microscopy: confocal/tunneling