Iraqi Postgraduate Medical Journal

Current Issue

By Issue

By Author

By Subject

Author Index

Keyword Index

About Journal

Aims and Scope

Editorial Board

Publication Ethics

Indexing and Abstracting

Related Links

FAQ

Peer Review Process

Journal Metrics

News

The Effect of Posterior Corneal Astigmatism on Ocular Residual Astigmatism in Virgin Eyes

,

Document Type : Research Paper

Abstract

 
BACKGROUND:
Ocular astigmatism is the sum of corneal astigmatism and internal astigmatism. The component of ocular astigmatism that cannot be a attributed to the anterior corneal surface is referred to as ocular residual astigmatism.
OBJECTIVE:
To evaluate the difference between ocular residual astigmatism and total ocular residual astigmatism in normal virgin eyes with refractive errors.
PATIENTS AND METHODS:
Eighty four patients ( 135 virgin eyes) with refractive errors were enrolled consecutively in this study at the Lasik clinic in Ibn Al- Haitham Teaching Eye Hospital. Measurement of astigmatism was done by
manifest refraction and corneal topography using Oculus Pentacam, and these measurements were used for calculating ocular residual astigmatism and total ocular residual astigmatism with comparison between them.
RESULTS:
The study showed a significant difference between the means of ocular residual astigmatism (-0.7416 ± 0.4341 ) and the total ocular residual astigmatism (-0.6223 ± 0.401) in with the rule astigmatism (P value < 0.001), and the means of ocular residual astigmatism (-0.8113 ± 0.38517) versus the means
of total ocular residual astigmatism (-0.6658 ± 0.3844) in against the rule astigmatism (P value <0.001).
CONCLUSION:
The ocular residual astigmatism based on the total corneal topographic astigmatism corresponds better with manifest refractive cylinder than the ocular residual astigmatism based solely on anterior corneal
topographic astigmatism .
KEY WORDS: Ocular residual astigmatism, Posterior corneal astigmatism.
 
ABSTRACT:
BACKGROUND:
Ocular astigmatism is the sum of corneal astigmatism and internal astigmatism. The component of ocular astigmatism that cannot be a attributed to the anterior corneal surface is referred to as ocular residual astigmatism.
OBJECTIVE:
To evaluate the difference between ocular residual astigmatism and total ocular residual astigmatism in normal virgin eyes with refractive errors.
PATIENTS AND METHODS:
Eighty four patients ( 135 virgin eyes) with refractive errors were enrolled consecutively in this study at the Lasik clinic in Ibn Al- Haitham Teaching Eye Hospital. Measurement of astigmatism was done by
manifest refraction and corneal topography using Oculus Pentacam, and these measurements were used for calculating ocular residual astigmatism and total ocular residual astigmatism with comparison between them.
RESULTS:
The study showed a significant difference between the means of ocular residual astigmatism (-0.7416 ± 0.4341 ) and the total ocular residual astigmatism (-0.6223 ± 0.401) in with the rule astigmatism (P value < 0.001), and the means of ocular residual astigmatism (-0.8113 ± 0.38517) versus the means
of total ocular residual astigmatism (-0.6658 ± 0.3844) in against the rule astigmatism (P value <0.001).
CONCLUSION:
The ocular residual astigmatism based on the total corneal topographic astigmatism corresponds better with manifest refractive cylinder than the ocular residual astigmatism based solely on anterior corneal
topographic astigmatism .
 

Keywords

References
  1. Alpins N, Stamatelatos G. Corneal topographic astigmatism measurement. Highlight of ophth. 2014; 42:11-2.
  2. Alpins N. The basics of astigmatism and how to deal with it. In: Kapoor S, Pallikaris IG, Rao SK (Eds). Tips and tricks lasik surgery. New Delhi : Jaypee Brothers Medical Publishers ; 2007: 142- 52.
  3. Rosenfield M. Refractive status of the eye. In: Benjamin WJ (Eds). Borish’s clinical refraction. 2nd  ed. Missouri: Butterworth Heinemann Elsevier; 2006:11-4.
  4. Klijn S, Reus  NJ, van der Sommen CM, Sicam VA. Accuracy of  total corneal astigmatism measurements with a scheimpflug imager and a color light-emitting diode corneal topographer. Am J Ophthalmol.2016; 167: 72-8.
  5. Ventura BV, Wang L, Weikert MP, Robinson SB, Koch DD. Surgical management of astigmatism with toric intraocular lenses. Arq Bras Oftalmologia. 2014; 77:125-31.
  6. Patsoura E. Posterior corneal astigmatism and it’s importance in selection of toric intraocular lens.EC Ophthalmology. 2017; 4.5: 608-12.
  7. Alpins NA, Tabin GC, Adams LM, Aldred GF, Kent DG, Taylor HR. Refractive versus corneal changes after photorefractive keratectomy for astigmatism. J Refract Surg. 1998;14:386-96.
  8. GmbH O. Interpretation Guide [Internet]. Pentacam.com. 2018 [cited 5 March 2018]. Availablefrom: https://www.pentacam.com/int/ophthalmologist-with-pentacam/service/interpretation-guide.html.
  9. Ho JD, Tsai CY, Liou SW. Accuracy of corneal astigmatism estimation by neglecting the posterior corneal surface measurement. Am J Ophthalmol.2009; 147:788-95.

10. ASSORT Vector Calculator | Planning outcomes with ASSORT [Internet]. Assort.com. 2018 [cited 5 March 2018]. Available from: http://www.assort.com/assort-vector-calculator-0.

11. Alpins N, Ong JKY, Stamatelatos G. Corneal topographic astigmatism (CorT) to quantify total corneal astigmatism. J Refract Surg . 2015;31: 182-86.

12. Holladay JT, Moran JR, Kezirian GM. Analysis of aggregate surgically induced refractive change, prediction error, and intraocular astigmatism. J Cataract Refract Surg. 2001; 27: 61-79.

13. Kock DD, Ali SF, Weikert MP, Shirayama M, Jenkis R, Wang L. Contribution of posterior corneal astigmatism to total corneal astigmatism. J Cataract Refract Surg. 2012 ;38: 2080-87.

 

Iraqi Postgraduate Medical Journal
Volume 20, Issue 3
July 2021
Page 255-261
Files
Share
Export Citation
Statistics