ISSN: 1300-0365
Dil: Türkçe
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Analysis Of The Correlation Between Pterygium Size Andinduced Astigmatism
S. Samet ERMİŞ*, Ümit İNAN*, Faruk ÖZTÜRK**
* Yrd.Doç.Dr., Afyon Kocatepe Üniversitesi Ahmet Necdet Sezer Uygulama ve Araştırma Hastanesi Göz Hastalıkları AD,** Doç.Dr., Afyon Kocatepe Üniversitesi Ahmet Necdet Sezer Uygulama ve Araştırma Hastanesi Göz Hastalıkları AD, AFYON
Purpose: Before invasion of the visual axis, pterygia typically induce with the rule astigmatism. Our study investigates the relation between horizontal length, vertical width of the pterygium and induced corneal astigmatism.
Institution: Afyon Kocatepe University, Ahmet Necdet Sezer Hospital Eye Clinic.
Method: Forty eyes of 36 patients with primary pterygia and 40 eyes of 40 normal control subjects were examined with keratometry and corneal topography. Pterygium horizontal length, vertical width and horizontal cornea diameter were measured with milimetric scale of biomicroscope. Percentage extension of the pterygium onto the cornea was calculated by dividing pterygium horizontal length with horizontal cornea diameter. The relation between percentage extension of the pterygium and induced astigmatism was investigated by regression analysis method.
Results: Mean keratometric astigmatism was 1.76±1.13 diopter (D) in pterygium cases, 1.30±0.76 D in control cases. Mean topographic astigmatism was 2.31±1.87 D in pterygium cases and 1.02±0.65
D in control cases. While there was no statistically significant difference between keratometric values of the cases (p=0.33), topographic values were significantly different between two groups of cases (p<0.001). Pterygia 3.0 mm wide or more had significantly higher astigmatism than the other pterygia (p<0.001). There was nearly perfect correlation between pterygia who had percentage extension more than 20% and induced astigmatism (Pearson's correlation coefficient, r=0.931).
Conclusion: Topographic astigmatism was significantly higher in cases with pterygium than control subjects. Pterygia appear to have minimal effect on corneal refractive power until they exceed 20% of the horizontal corneal diameter, once this size is reached increasing degrees of with the rule astigmatism are induced. Pterygium vertical width is also important in inducing corneal astigmatism.Keywords: Pterygium, Astigmatism, Corneal topography,Turkiye Klinikleri J Ophthalmol 2001, 10:171-174
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