Browsing by Author "Topuz, H"

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Age-Related Differences in Normal Corneal Topography
(Slack inc, 2004) Topuz, H; Ozdemir, M; Cinal, A; Gumusalan, Y
BACKGROUND AND OBJECTIVE: The aim of this study was to compare age-related differences in the corneal topography of a normal population using a computerized corneal topography system. PATIENTS AND METHODS: The randomized comparative study included 240 eyes of 120 subjects with normal corneas. Subjects were divided into six age groups: 5 to 10 years (group 1), 11 to 20 years (group 2), 21 to 30 years (group 3), 31 to 40 years (group 4), 41 to 50 years (group 5), and 51 years or older (group 6). Average corneal power and corneal astigmatism were examined. An average corneal topography map was constructed and the astigmatism pattern was determined in each age group. RESULTS: Average corneal power values were 41.64 +/- 0.85 diopters (D), 42.35 +/- 0.90 D, 42.63 +/- 0.99 D, 42.94 +/- 0.93 D, 43.38 +/- 0.77 D, and 43.53 +/- 0.88 D in groups 1 to 6, respectively (P <.001). Mean astigmatism values were similar in all age groups (P = .225). Younger subjects had with-the-rule astigmatism, but older subjects showed a shift to oblique or against-the-rule astigmatism. The averaged maps of groups 1 to 3 showed a vertical bow-tie pattern, but the central steep area gradually extended horizontally and it became a round configuration in groups 4 to 6. CONCLUSION: This study suggests that the normal cornea becomes steeper in the horizontal line and superior vertical quadrant and shifts from with-the-rule to against-the-rule astigmatism, but the amount of physiological corneal astigmatism does not change with age.
The Effect of Pterygium Surgery on Corneal Topography
(Slack inc, 2001) Cinal, A; Yasar, T; Demirok, A; Topuz, H
OBJECTIVE: The aim of this prospective randomized clinical study was to evaluate the effect of pterygium surgery on the corneal topography using a computerized corneal topography system. PATIENTS AND METHODS: Computerized corneal topography was performed on 27 patients with primary pterygium before and after pterygium excision surgery. The topographical changes that occurred following surgery were evaluated using paired and unpaired two-tailed t-test and Pearson coefficient of correlation analyses. Simulated keratometric astigmatism at the central 3 mm and the total mean refractive powers of the whole cornea were measured before and after surgery. Following surgery, fattened or steepened corneal areas were determined. RESULTS: Simulated keratometric astigmatism at 3 mm was found to be 2.30 +/- 2.08 D (0.2 - 7.63) preoperatively and 0.82 +/- 0.74 D (0.06 - 2.79) postoperatively. The difference between these two values was statistically significant (t = -3.46, P = 0.002). Total mean refractive power of the whole cornea was found to be 42.26 +/- 0.63 (40.80 - 43.64) preoperatively and 43.69 +/- 0.88 (41.50 - 44.90) postoperatively and the difference was 1.42 +/- 0.87. There was a statistically significant high difference (t = 28.36, P < 0.001). When preoperative and postoperative corneal topographies were compared, the whole cornea was found steeper at the postoperative period except a little region in the superior nasal quadrant. CONCLUSION: We believe that corneal topographical changes caused by the pterygium are almost reversible after surgical treatment, and postoperatively the cornea becomes steeper.