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Heritability of Corneal Curvature and Pentacam Topometric Indices

A Population-Based Study

Heydarian, Samira Ph.D.; Hashemi, Hassan M.D.; Yekta, Abbasali Ph.D.; Ostadimoghaddam, Hadi Ph.D.; Derakhshan, Akbar M.D.; Aghamirsalim, Mohammadreza M.D.; Khabazkhoob, Mehdi Ph.D.

doi: 10.1097/ICL.0000000000000589
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Purpose: To investigate familial aggregation of anterior and posterior corneal curvature, corneal astigmatism, and some corneal topometric indices using the Pentacam.

Methods: Of 3,851 eligible individuals who resided in the selected areas, 2,779 met the conditions for analysis. However, analysis was limited to families whose Pentacam measures were available for at least 2 family members (father or mother and a child), resulting in 1,383 individuals in 382 families. All selected subjects underwent a set of examinations, including refraction, uncorrected and corrected visual acuity measurement, slitlamp biomicroscopy, and Pentacam imaging. Heritability estimation was used to calculate familial aggregation.

Results: The results of our study showed a fairly high corneal curvature heritability. The heritability of K2 and K1 in the anterior surface was 58.61% (95% confidence interval [CI], 54.99–62.23) and 55.82% (95% CI, 52.66–58.98), respectively. The heritability of posterior corneal curvature was slightly higher than that of the anterior corneal curvature. The heritability of K2 and K1 in the posterior surface was 63.42% (95% CI, 60.07–66.77) and 59.67% (95% CI, 55.85–63.49), respectively. Investigation of the quantitative topographic corneal indices showed that index of surface variance (ISV), central keratoconus index, and index of vertical asymmetry (IVA) had the highest levels of heritability (81.2% [95% CI, 73.64–88.76], 75.21% [95% CI, 67.19–82.28], and 66.46% [95% CI, 61.99–70.93], respectively). However, keratometric power deviation and index of height asymmetry had the lowest heritability levels (7.48% 95% CI, [4.94–10.02] and 18.31% [95% CI, 16.07–20.55], respectively).

Conclusion: The familial aggregation and relatively high heritability of the corneal curvature and some keratoconus-related indices, such as ISV and IVA, confirm a high correlation between these phenotypes and genetic factors and warrant further investigation of the genetic mechanisms in keratoconus.

Department of Rehabilitation Sciences (S.H.), School of Allied Medical Sciences, Mazandaran University of Medical Sciences, Sari, Iran; Noor Research Center for Ophthalmic Epidemiology (H.H.), Noor Eye Hospital, Tehran, Iran; Refractive Errors Research Center (A.Y., H.O.), Mashhad University of Medical Sciences, Mashhad, Iran; Khatam-al-Anbia Hospital (A.D.), Mashhad University of Medical Sciences, Mashhad, Iran; Eye Research Center (M.A.), Tehran University of Medical Sciences, Tehran, Iran; and Department of Medical Surgical Nursing (M.K.), School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

Address correspondence to Abbasali Yekta, Ph.D., Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad 9183896858, Iran; e-mail: yektaa@mums.ac.ir

The authors have no funding or conflicts of interest to disclose.

Supported by the Mashhad University of Medical Sciences.

Accepted January 12, 2019

© 2019 Contact Lens Association of Ophthalmologists, Inc.