Effect of disagreement between refractive, keratometric, and topographic determination of astigmatic axis on suture removal after penetrating keratoplasty

Abstract

Background/aims-Post-keratoplasty astigmatism can be managed by selective suture removal in the steep axis. Corneal topography, keratometry, and refraction are used to determine the steep axis for suture removal. However, often there is a disagreement between the topographically determined steep axis and sutures to be removed and that determined by keratometry and refraction. The purpose of this study was to evaluate any diVerence in the eVect of suture removal, on visual acuity and astigmatism, in patients where such a disagreement existed. Methods-37 cases (from 37 patients) of selective suture removal after penetrating keratoplasty, were included. In the first group "the disagreement group" (n=15) there was disagreement between corneal topography, keratometry, and refraction regarding the axis of astigmatism and sutures to be removed. In the second group "the agreement group" (n=22) there was agreement between corneal topography, keratometry, and refraction in the determination of the astigmatic axis and sutures to be removed. Sutures were removed according to the corneal topography, at least 5 months postoperatively. Vector analysis for change in astigmatism and visual acuity after suture removal was compared between groups. Results-In the disagreement group, the amount of vector corrected change in refractive, keratometric, and topographic astigmatism after suture removal was 3.45 (SD 2.34), 3.57 (1.63), and 2.83 (1.68) dioptres, respectively. In the agreement group, the amount of vector corrected change in refractive, keratometric, and topographic astigmatism was 5.95 (3.52), 5.37 (3.29), and 4.71 (2.69) dioptres respectively. This diVerence in the vector corrected change in astigmatism between groups was statistically significant, p values of 0.02, 0.03, and 0.03 respectively. Visual acuity changes were more favourable in the agreement group. Improvement or no change in visual acuity occurred in 90.9% in the agreement group compared with 73.3% of the disagreement group. Conclusions-Agreement between refraction, keratometry, and topography was associated with greater change in vector corrected astigmatism and was an indicator of good prognosis. Disagreement between refraction, keratometry, and topography was associated with less vector corrected change in astigmatism, a greater probability of decrease in visual acuity, and a relatively poor outcome following suture removal. However, patients in the disagreement group still have a greater chance of improvement than worsening, following suture removal. (Br J Ophthalmol 2000;84:837-841)

Rapid suture management of post-keratoplasty astigmatism

“…This study showed that corneal topography performed between 30 and 40 min of suture removal can identify the next set of sutures requiring removal. As has been previously conclusively shown, 7,13 selective suture removal in our study also reduced post-keratoplasty astigmatism and improved visual acuity. The reason for leaving the patient for 30-40 min after suture removal is to allow the cornea to take its new configuration after removal of the tight sutures.…”

“…Topography enables determination of steep semi-meridians corresponding to tight sutures. 13,14 Burk et al 2 evaluated the removal of multiple sutures at the same visit to control post-keratoplasty astigmatism. They reported an average change of astigmatism of 2-3 D, but this average was associated with a large range (0-12 D).…”

Effectiveness of Corneal Topography Guided Suture Removal of the Patients with Penetrating Keratoplasty in Astigmatism Treatment

“…2,4 Buna rağmen postkeratoplasti astigmatizma bu hastalarda tatmin edici görme rehabilitasyonu elde etmede hala en büyük engeldir. 5 Birçok faktör postkeratoplasti astigmatizmanın tahmin edilemeyen ve değişken doğasına katkıda bulunmaktadır. Bunlar alıcı korneanın biyomekaniğini, donör göz ve alıcı yatağının trepanizasyonunu, sütür tekniğini ve postoperatif tedaviyi içermektedir.…”

“…Bunlar alıcı korneanın biyomekaniğini, donör göz ve alıcı yatağının trepanizasyonunu, sütür tekniğini ve postoperatif tedaviyi içermektedir. 3,5 Literatürde 20 D kadar yüksek astigmatizma vakaları bildirilmiştir. 6,7 Yapılan çeşitli araştırmalarda keratoplasti girişimi sonrası olgularda ortalama 4-6 D astigmatizma bulunmuş; göz-lük ve kontakt lensi tolere edemeyen, refraktif cerrahi girişim gerektiren yüksek astigmatizma insidansı en az %10 olarak saptanmıştır.…”

“…5 , yüksek postoperatif astigmatizmanın düşürülmesi için girişimlerin, özellikle de bir kombine sütür tekniği kullanılmış ise erken postoperatif dönemde (5-6 ay) yapılmasını önermi-şlerdir. Bazı separe sütürlerin erken alınmasının da eğer kontinü sütür hala yerinde ise daha az yara yerinde sızıntı ya da açılma riski ile birlikte olabileceğini ve sonuçta rahat gözlük kullanımının sağladığı erken görsel iyileşmenin elde edilebileceğini bildirmişlerdir.…”