Refractive Status Of Cornea After Penetrating Keratoplasty

With the modern micro-operation in ophthalmology continuously perfect and the clinical application of anti-immunity medicine , the success rate of keratoplasty is increased consumedly and the occasions of immuno-rejection descend . Grafts after transplant is guaranteed to be transparent.Because the corneal transplant itself goes forward on the pathological cornea, the tailoring of corneal bed and slice , diameter of corneal bed and slice match, the turning force of suture around the cut and the cornea status of donor-receipt etc. all make error of refraction usually after corneal transplantation .Particularly the high astigmatism,irregular astigmatism and anisometropia make some patients misty ,tears film abnormality and eye tired after keratolpasty though the slice keeping transparent and unsatisfied with these symptoms .Therefore the research of the penetrating corneal transplantation get great significant to increasing sight after the PK ,attaining satisfied curative effect. In this paper 25 patients that had partial penetrating keratoplasty ( 29 eyes ) are selected among those had had it between November of 2001 and 2004 July .The refractive status are analyzed. All patients removed sutures within 5～10 months after PK. Check the cornea refractions after removing stures 3 months. The time of callbacking is different ,the longest 32 months and the shortest 6 months. With Topcon KR7100 type keratometer measuring cornea refractive power in two main meridians , curvatures radius and axis .With the phoropter examining whole eye refraction status ,according results subjective refraction is done to measure the corrected sight. In all cases the planting slices are transparent. All sutures are removed in 5 ～10 months after planting and the corneal refractions are checked after removing-suture 3 months. The refractive power in FK of 29 eyes measured with keratometer is 43.73+/-3.85D and curvature radius is7.81+/-0.56 mm .The refractive power in SK is 46.35+/-1.49 D and curvature radius is 7.27+/-0.26 mm. The mean corneal refractive power is 44.69+/-3.64 D. The astigmatism of all cases is myopic and the average power is -3.66+/-2.40 .Among them astigmatism with the rule are 16 eyes (54.5%), astigmatism against the rule are 5 eyes(18.2%) and oblique astigmatism are 8 eye(27.3%). The proportion of astigmatism with the rules is the largest. The uncorrected visual acuity post-keratoplasty below 0.3 are 17 eye(58.6%). Among them the below 0.1 are 3 eyes(10.3%). With frame glasses correcting, the corrected visual acuity below 0.3 are 6 eye(20.7%) and no eye is below 0.1. The uncorrected visual acuity up 0.8 are 2 eyes(6.9%) and corrected visual acuity up 0.8 are 8 eyes(27.6%). The corneal refractive status post-transplantation is concern with various factors. 1. Whether the edge of grafts is vertical ,it determines the corneal astigmatism post-transplantation .the data had shown that the edge angle with ordinary trephine is 18°.To decrease this kind of error , Hessburg –Barron vacuum trephine is adopted .On the one hand it guarantees to aim at the corneal optical center, on the other hand the vacuum attraction do away with the layers shifting .In these patients average astigmatism post-keratoplasty is 3.66+/-2.40D. Comparing with the 1.02D(0.25～2.00D) applying the Barron vacuum trephine system provided by native Li Qun etc. the number is higher. 2. The match of diameter of the bed and graft: The adoption of larger graft can lowered the cornea curvature, enlarge refractive power , deepen the anterior chamber and make eye axis long. If graft is larger than bed , the positive spherical glasses will reduce 0.67D . The different match of diameter of the bed and graft has no significance statistically . 3. Suture: 3.1 The controlling result of astigmatism with different suture methods has difference. The double running suture can counteract the turn power of single running sutureand is a kind of more stable, dependable way which controls astigmatism better. 3.2 Adjusting the suture during the operation: Adjusting the suture during the operation with the guiding of keratometer can make tension distribute afresh, get more control of astigmatism from operation ,and be beneficial to the best uncorrected visual acuity in the earlier period 。3.3 Selective removal interrupted suture post keratoplasty: With the examination of refraction and cornea geography diagram, the suture on steep the meridian is removed. The tension will distribute afresh under the intro-ocular pressure and astigmatism will relieve immediately. If the time of removal sutures is more earlier, the curvature will vary more larger. The earlier incompletion cut causes large variety of corneal flexibility and curvature after removal suture 4. Status of bed :...