Evaluation of Anterior, Posterior, and Total Corneal Astigmatism in Normal Subjects

Document Type : Original Article (s)

Authors

1 MSc Student, Department of Optometry, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran

2 Professor, Department of Optometry, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran

3 Associate Professor, Department of Ophthalmology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran

4 Instructor, Department of Epidemiology and Biostatistics, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran

5 Ophthalmic Research Center, Isfahan Parsian Clinic, Isfahan, Iran

Abstract

Background: The aim of this study was to evaluate the magnitude and axis orientation of anterior, posterior, and total corneal astigmatism (ACA, PCA, and TCA, respectively).Methods: In this retrospective study, pentacam topographical maps of 226 eyes (113 patients) with 1.0 to 6.0 diopters (D) of astigmatism were analyzed. Topographical anterior and posterior corneal surface astigmatism was determined. The magnitude and axis orientation of the anterior, posterior and total corneal astigmatism were compared.Findings: The mean age of the study population was 33.00 ± 6.74 years. The mean magnitude was 2.02 ± 0.99, 0.44 ± 0.20, and 1.98 ± 1.01 diopters for anterior, posterior, and total corneal astigmatism, respectively. Most eyes had with-the-rule (WTR) anterior astigmatism and against-the-rule (ATR) posterior astigmatism. With-the-rule astigmatism had a higher mean magnitude compared to against-the-rule and oblique astigmatism in anterior and posterior corneal astigmatism groups. Posterior corneal astigmatism magnitude exceeded 0.75 diopters in only 8% of the subjects. Anterior corneal astigmatism had a significant positive correlation with posterior and total corneal astigmatism (P < 0.001 for both, r = 0.83 and 0.98, respectively). Moreover, posterior corneal astigmatism had a significant positive correlation with total corneal astigmatism (P < 0.001, r = 0.78).Conclusion: The provided information of this study may be helpful in obtaining optimum results in astigmatism correction in refractive surgery or designing new intraocular lenses.

Keywords

References

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Journal of Isfahan Medical School
Volume 35, Issue 450 - Serial Number 450
September and October 2017
Pages 1382-1388

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History

  • Receive Date: 08 September 2017
  • Revise Date: 01 November 2024
  • Accept Date: 06 April 2022

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