Abstract
Purpose: :
to assess the kinetic of regression of corneal oedema with anterior optical coherence tomography (Visante OCT, Carl Zeiss Meditec Inc®, Dublin, USA) at the wound site after standard phacoemulsification and its correlation with induced astigmatism measured by the keratometric power (KP) using Allegro Oculyzer (WaveLight, Inc®).
Methods: :
This prospective study includes 30 eyes who presented grade 2 or 3 cataract that were all operated by the same surgeon. All incisions were performed according to a standard technique : 2.75 mm blade, selfsealing incision, 1 suture point and no stromal hydration. At 1, 7 and 30 days after surgery 2 mesurements were performed at the site of incision previously marked on slit lamp : corneal topography with measure of KP in dioptres using Allegro Oculyzer and corneal thickness in high resolution mode, using Visante OCT.
Results: :
Preoperative mean KP was 0.82 Diopters (D) ± 0.28 (SD) on a mean axis of 126°±19° SD; at day 1, mean KP = 0.036 D ± 1.2 with a mean corneal thickness of 1.12 mm ± 0.19; at day 7, mean KP = 0.26 D ± 0.49 and mean corneal thickness = 0.99 mm ± 0.12; at 1 month, mean KP = 1 D ± 0.4 and mean corneal thickness = 0.77 mm ± 0.027. Visante OCT confirms the progressive regression of postoperative oedema of the incision (Rs = -0.10, p = .45). At the same time, KP shows first a decrease at day 1, then a progressive increase after day 7 with a final measure at day 30 close to the preoperative value but without statistically significative difference (p = .32) and no linear correlation found (Rs = - 0.21, p = .37).
Conclusions: :
this study suggest a correlation link between local corneal induced astigmatism and regression of the oedema of incision after phacoemulsification. Biomechanical properties of the cornea are discussed.
Keywords: cornea: clinical science • imaging/image analysis: clinical • astigmatism