الفهرس 
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Abstract
eratoplasty is a long process that entails a huge team behind, Starting from the donor, eye-bank staff and finally the surgeon, Post-keratoplasty astigmatism can be a major frustration for the patient and the surgeon due to its impact on the visual acuity. Astigmatic correction after keratoplasty can be a challenge to manage, lots of measures been used for its management, ranging from contact lenses; spectacles; suture removal/adjustment; wedge resection; Excimer laser and arcuate incisions (Zirm 1989)(Dursun et al. 2003).
1.1 Penetrating and Lamellar Keratoplasty
Penetrating keratoplasty (PKP) is a relatively safe surgery for managing patients with dense corneal opacities and surface irregularities; it achieves great graft clarity. (Javadi et al. 2005).
However, PKP jeopardize the intraocular anatomy and immunological integrity of the eye. Hence, it increases the risk of rejection and intraocular inflammation. As regards the endothelial cell loss, DALK has insignificant T
o properly assess the success of any surgery that aims at treating astigmatism, it is best to analyze the power and the axis of astigmatism. Alpins described a novel method for analysis of astigmatic treatment (Alpins 1993). The following methods are used for analysis of astigmatism treatment:
1.2 Simple Subtraction Analysis
The simplest method for analysis of astigmatism is subtracting the postoperative from preoperative astigmatism without reference to the axis. The result would be either an increase (a positive value) or a decrease (a negative value) in pre-existing astigmatism a this study, we will compare the topographic and refractive effects from the arcuate relaxing incision in keratoplasty astigmatism treatment in DALK versus PKP fter surgery (Alpins 2001)
ostoperative keratoplasty astigmatism is considered one of the limiting factors in visual quality after keratoplasty.
high postoperative astigmatism can compromise the patient’s return to normal binocular vision. Anisometropia may result in a headache, photophobia, burning, tearing, diplopia, and blurred vision. Which carries an impact on the quality of patients’ life and a major economic burden, “especially due to the high cost of the keratoplasty”.
Arcuate relaxing incision is considered an effective, simple method of reducing astigmatism after keratoplasty, however the difference in biomechanics between DALK and PKP due to tightness of the graft in DALK being pushed by the host Descemet’s membrane might affect the outcome of the incision.
Our main aim of this study was to compare the impact of the arcuate incision using the diamond knife on corneal astigmatism among DALK and PKP group, we compared the visual acuity, refractive astigmatism, spherical equivalent, topographic astigmatism using oculus Pentacam, besides vector analysis using VECTrAK software. To our knowledge, this is the second study to compare the arcuate incision in DALK vs. PKP after (Kubaloglu et al. 2011) we will compare our results with theirs.