Presentation on theme: "Ahmad Kheirkhah MD, Hasan Hashemi MD Rahman Nazari MD, Hamid Safi"— Presentation transcript:
1Evaluation of Corneal Changes following Pterygium Surgery Using Pentacam Ahmad Kheirkhah MD, Hasan Hashemi MD Rahman Nazari MD, Hamid SafiFarabi Eye Hospital, Tehran, IranThe authors have no financial interest in the subject matter of this poster.
2Introduction Pterygium Pterygium surgery Definition: Encroachment of a fibrovascular tissue from the bulbar conjunctiva onto the cornea.Causes regular or irregular astigmatism 1Produces significant alterations in corneal shape and curvaturePterygium surgeryImproves the visual acuityReduces the corneal astigmatism and irregularityChanges corneal topographic indices
3IntroductionCorneal topographical changes with decreased corneal astigmatism after pterygium surgery have been documented. 2,3But,Few studies have calculated the surgically-induced correction of the astigmatism. 4,5Corneal elevation changes after surgery has not been studied yet.No study has used Pentacam (Oculus, Wetzlar, Germany) for investigating the effects of pterygium and its excision on cornea.Purpose: To use Pentacam for evaluation of corneal changes in patients undergoing pterygium surgery.
4Materials & MethodsStudy population: 80 eyes of 80 consecutive patients with primary pterygium at Farabi Eye Hospital, Tehran, Iran from August 2008 to January 2009.Surgical technique: Excision of pterygium, mitomycin C application, free conjunctival autograft or amniotic membrane transplantation.Pentacam examination was performed preoperatively and at 1, 3, and 6 months after surgery.Measured corneal indices: mean keratometry, best fit sphere (BFS) and central corneal elevation(CCE).
5Materials & MethodsSurgically induced astigmatsm (SIA) was calculated from the topographical keratometric and astigmatic values by vectoral analysis using Holladay’s method.Statistical analysis was performed by SPSS software and statisical significance was tested using ANOVA and Paired t-test.
6RESULTs Value are expressed as mean ± standard deviation Preop 1 month 3 months6 monthsSIA3.723.603.57Keratometry(front)42.88 ± 1.9144.30 ± 1.7844.13 ± 1.7244.02 ± 1.67Keratomery (back)-6.35 ± 0.33-6.29 ± 0.28-6.30 ± 0.27-6.31 ± 0.29BFS (front)8.02 ± 0.327.76 ± 0.287.75 ± 0.487.77 ± 0.56BFS (back)6.44 ± 0.256.54 ± 0.256.54 ± 0.226.54 ± 0.26CCE (front)5.21 ± 4.554.70 ± 5.604.24 ± 4.044.93 ± 6.54CCE (back)4.66 ± 5.596.23 ± 4.635.24 ± 7.046.34 ± 5.72Value are expressed as mean ± standard deviationSIA: Surgically-induced astigmatismBFS: Best fit sphereCCE: Central corneal elevation
7ResultsSIA showed steepening of the cornea in the horizontal meridian.After surgery, the mean front keratometry increased (P<0.001) while mean back keratometry decreased (P=0.11).Decreases in front BFS and increases in back BFS were statistically significant (P<0.001).Decreases in front CCE and increase in back central elevation were not statistically significant.
8Discussion & Conclusion Pterygium surgery improves pterygium-induced with the rule astigmatism.Cornea becomes steeper after surgery.Pterygium surgery causes non-significant alteration in central corneal elevation.Further studies are needed to evaluate the factors influencing surgically-induced astigmatism.
9References1. Oldenburg JB, Garbus J, McDonnell JM, McDonnell PJ. Conjunctival pterygia. Mechanism of corneal topographic changes. Cornea Jul;9(3):200-4.2. Bahar I, Loya N, Weinberger D, Avisar R. Effect of pterygium surgery on corneal topography: a prospective study. Cornea Mar;23(2):113-7.3. Wu PL, Kuo CN, Hsu HL, Lai CH. Effect of pterygium surgery on refractive spherocylinder power and corneal topography. Ophthalmic Surg Lasers Imaging. 2009;40(1):32-7.4. Ozdemir M, Cinal A..Early and late effects of pterygium surgery on corneal topography. Ophthalmic Surg Lasers Imaging ;36(6):451-6.5. Fong KS, Balakrishnan V, Chee SP, Tan DT. Refractive change following pterygium surgery. CLAO J Apr;24(2):115-7.