[Astigmatism in corneal graft. Prevention and treatment].
The tremendous development of the photokeratoscope and corneal topography analysis explains the development of corneal astigmatism study in corneal graft. Our study consists in a review of the bibliography. The prevention of the astigmatism needs the following: before the trephination, the astigmatism has to be treated (correction of against the rule astigmatism which is usual in the aphake people); during the trephination, to minimize the deformation of the eye ball, to choose a good diameter for the keratoconus case, to use a pneumatic trephine in order to have a perpendicular cut (the use of the laser Excimer seams promising); The suture of the corneal graft can be done with a double running suture 10/0 and 11/0. The 10/0 is removed at the third month, the visual recovery is faster but the average astigmatism is not as good as with the interrupted 10/0 sutures and running suture 11/0. This technique is good for an old patient or a one eyed people specially interested in a faster recovery of visual acuity. The second possibility is to use 16 interrupted sutures with and 11/0 running suture. With this technique, the sutures are removed selectively depending on the keratometry and the photokeratoscopy. The visual recovery is longer but the astigmatism at the end is very low. When all the sutures have been removed, the residual astigmatism can be treated when there is not any misalignement between the cornea and the graft. The keratometry, photokeratoscopy allows to find the meridian which is abnormal and to find out if the astigmatism is symmetrical or asymmetrical. The astigmatism is symmetrical if the deformation is the same at either side of the meridian. When the abnormal meridian is the steepest, the only thing to do is a relaxing incision (one or two if is asymmetric, two if the astigmatism is symmetric). The size of the relaxing incision is determined by the photokeratoscopy and the deepness by the effect obtained during surgery looking at a qualitative keratometer. On the table, the effect must be about 50% of over correction. When, the abnormal meridian is the flattest, the only thing to do is a wedge resection (if the astigmatism is asymmetric) or two wedge resections (if the astigmatism is symmetric). The size of the cuneiform resection is choosen with photokeratoscopy. The study of the literature about the Ruiz incision adapted to corneal graft cannot nowadays conclude to the accuracy and safety of this technique.(ABSTRACT TRUNCATED AT 400 WORDS)
Riss
I
I
Clinique ophthalmologique, Hôpital Pellegrin, Bordeaux.
D001251:Astigmatism / Q000209:etiology* / Q000517:prevention & control / Q000628:therapy; D016039:Corneal Transplantation / Q000009:adverse effects*; D006801:Humans
Astigmatisme dans les greffes de la cornée. Prévention et traitement.