Abstract
PURPOSE:
To provide the first description of posterior corneal astigmatism as measured by the IOLMaster 700 (Carl Zeiss Meditec, Jena, Germany) and assess how its characteristics compare to previous measurements from other devices.
METHODS:
A total of 1,098 routine IOLMaster 700 biometric measurements were analyzed to provide magnitudes and orientation of steep and flat axes of anterior and posterior corneal astigmatism. Subgroup analysis was conducted to assess correlation of posterior corneal astigmatism characteristics to anterior corneal astigmatism and describe the distribution of posterior corneal astigmatism with age.
RESULTS:
Mean posterior corneal astigmatism was 0.24 ± 0.15 diopters (D). The steep axis of posterior corneal astigmatism was vertically oriented in 73.32% of measurements. Correlation between the magnitude of anterior and posterior corneal astigmatism was greatest when the steep axis of the anterior corneal astigmatism was oriented vertically (r = 0.68, P < .0001). Vertical orientation of the steep axis of anterior corneal astigmatism became less common as age increased, whereas for posterior corneal astigmatism it remained by far the most common orientation.
CONCLUSIONS:
This first description of posterior corneal astigmatism measurement by the IOLMaster 700 found the average magnitude of posterior corneal astigmatism and proportion of vertical orientation of steep axis was lower than previous estimates. The IOLMaster 700 appears capable of providing enhanced biometric measurement for individualized surgical planning.
[J Refract Surg. 2018;34(5):331–336.]
- 1.Akman A, Asena L, Güngör SG. Evaluation and comparison of the new swept source OCT-based IOLMaster 700 with the IOL-Master 500. Br J Ophthalmol. 2016; 100:1201–1205.
10.1136/bjophthalmol-2015-307779 Crossref Medline, Google Scholar - 2.Jhanji V, Yang B, Yu M, Ye C, Leung CK. Corneal thickness and elevation measurements using swept-source optical coherence tomography and slit scanning topography in normal and keratoconic eyes. Clin Exp Ophthalmol. 2013; 41:735–745.
10.1111/ceo.12113 Crossref Medline, Google Scholar - 3.Royston J, Dunne M, Barnes D. Measurement of posterior corneal surface toricity. Optom Vis Sci. 1990; 67:757–763.
10.1097/00006324-199010000-00002 Crossref Medline, Google Scholar - 4.Dunne MC, Royston JM, Barnes DA. Posterior corneal surface toricity and total corneal astigmatism. Optom Vis Sci. 1991; 68:708–710.
10.1097/00006324-199109000-00006 Crossref Medline, Google Scholar - 5.Dunne M, Royston JM, Barnes DA. Normal variations of the posterior corneal surface. Acta Ophthalmol (Copenh). 1992; 70:255–261.
10.1111/j.1755-3768.1992.tb04133.x Crossref Medline, Google Scholar - 6.Dubbelman M, Weeber HA, Van Der Heijde RG, Völker-Dieben HJ. Radius and asphericity of the posterior corneal surface determined by corrected Scheimpflug photography. Acta Ophthalmol Scand. 2002; 80:379–383.
10.1034/j.1600-0420.2002.800406.x Crossref Medline, Google Scholar - 7.Patel S, Marshall J, Fitzke F. Shape and radius of posterior corneal surface. J Refract Surg. 1993; 9:173–181. Link, Google Scholar
- 8.Edmund C. Posterior corneal curvature and its influence on corneal dioptric power. Acta Ophthalmol. 1994; 72:715–720.
10.1111/j.1755-3768.1994.tb04687.x Crossref, Google Scholar - 9.Dubbelman M, Sicam V, Van der Heijde G. The shape of the anterior and posterior surface of the aging human cornea. Vis Res. 2006; 46:993–1001.
10.1016/j.visres.2005.09.021 Crossref Medline, Google Scholar - 10.Prisant O, Hoang-Xuan T, Proano C, Hernandez E, Awad S, Azar DT. Vector summation of anterior and posterior corneal topographical astigmatism. J Cataract Refract Surg. 2002; 28:1636–1643.
10.1016/S0886-3350(01)01258-5 Crossref Medline, Google Scholar - 11.Módis L, Langenbucher A, Seitz B. Evaluation of normal corneas using the scanning-slit topography/pachymetry system. Cornea. 2004; 23:689–694.
10.1097/01.ico.0000126315.05519.0b Crossref Medline, Google Scholar - 12.Ho J-D, Tsai C-Y, Liou S-W. Accuracy of corneal astigmatism estimation by neglecting the posterior corneal surface measurement. Am J Ophthalmol. 2009; 147:788–795.
10.1016/j.ajo.2008.12.020 Crossref Medline, Google Scholar - 13.Chen D, Lam AK. Intrasession and intersession repeatability of the Pentacam system on posterior corneal assessment in the normal human eye. J Cataract Refract Surg. 2007; 33:448–454.
10.1016/j.jcrs.2006.11.008 Crossref Medline, Google Scholar - 14.Koch DD, Ali SF, Weikert MP, Shirayama M, Jenkins R, Wang L. Contribution of posterior corneal astigmatism to total corneal astigmatism. J Cataract Refract Surg. 2012; 38:2080–2087.
10.1016/j.jcrs.2012.08.036 Crossref Medline, Google Scholar - 15.Miyake T, Shimizu K, Kamiya K. Distribution of posterior corneal astigmatism according to axis orientation of anterior corneal astigmatism. PLoS One. 2015; 10:e0117194.
10.1371/journal.pone.0117194 Crossref Medline, Google Scholar - 16.Gudmundsdottir E, Jonasson F, Jonsson V, Stefánsson E, Sasaki H, Sasaki K. “With the rule” astigmatism is not the rule in the elderly. Acta Ophthalmol. 2000; 78:642–646.
10.1034/j.1600-0420.2000.078006642.x Crossref, Google Scholar - 17.Shajari M, Friderich S, Sadeghian MP, Schmack I, Kohnen T. Characteristics of corneal astigmatism of anterior and posterior surface in a normal control group and patients with keratoconus. Cornea. 2017; 36:457–462.
10.1097/ICO.0000000000001143 Crossref Medline, Google Scholar - 18.Klijn S, Reus NJ, van der Sommen CM, Sicam VAD. Accuracy of total corneal astigmatism measurements with a Scheimpflug imager and a color light-emitting diode corneal topographer. Am J Ophthalmol. 2016; 167:72–78.
10.1016/j.ajo.2016.04.011 Crossref Medline, Google Scholar - 19.Goggin M, Zamora-Alejo K, Esterman A, van Zyl L. Adjustment of anterior corneal astigmatism values to incorporate the likely effect of posterior corneal curvature for toric intraocular lens calculation. J Refract Surg. 2015; 31:98–102.
10.3928/1081597X-20150122-04 Link, Google Scholar - 20.Koch DD, Jenkins RB, Weikert MP, Yeu E, Wang L. Correcting astigmatism with toric intraocular lenses: effect of posterior corneal astigmatism. J Cataract Refract Surg. 2013; 39:1803–1809.
10.1016/j.jcrs.2013.06.027 Crossref Medline, Google Scholar - 21.Abulafia A, Koch DD, Wang L, New regression formula for toric intraocular lens calculations. J Cataract Refract Surg. 2016; 42:663–671.
10.1016/j.jcrs.2016.02.038 Crossref Medline, Google Scholar - 22.Ferreira TB, Ribeiro P, Ribeiro FJ, O'Neill JG. Comparison of astigmatic prediction errors associated with new calculation methods for toric intraocular lenses. J Cataract Refract Surg. 2017; 43:340–347.
10.1016/j.jcrs.2016.12.031 Crossref Medline, Google Scholar - 23.Goggin M, van Zyl L, Caputo S, Esterman A. Outcome of adjustment for posterior corneal curvature in toric intraocular lens calculation and selection. J Cataract Refract Surg. 2016; 42:1441–1448.
10.1016/j.jcrs.2016.10.004 Crossref Medline, Google Scholar - 24.de Jong T, Sheehan MT, Koopmans SA, Jansonius NM. Posterior corneal shape: comparison of height data from 3 corneal topographers. J Cataract Refract Surg. 2017; 43:518–524.
10.1016/j.jcrs.2017.03.021 Crossref Medline, Google Scholar - 25.An Y, Kim H, Joo C-K. Comparison of anterior segment measurements between dual and single Scheimpflug camera. Journal of the Korean Ophthalmological Society. 2016; 57:1056–1062.
10.3341/jkos.2016.57.7.1056 Crossref, Google Scholar
