Subclinical Keratoconus Detection in Identical Twins
Isaac Ramos, Gustavo Guerra, Vitor Buchmuller de Oliveira, Ivan Ferreira
Citation Information :
Ramos I, Guerra G, Oliveira VB, Ferreira I. Subclinical Keratoconus Detection in Identical Twins. Int J Kerat Ect Cor Dis 2016; 5 (1):35-39.
To report clinical keratoconus in only one eye of two identical female twins, along with subclinical disease in the fellow eyes, elaborating on the two-hit hypothesis of ectasia development, which relates to the combination of genetics and the impact of environment.
Methods
Case report and literature review.
Results
Two identical 48-year-old female twins were presented for clinical evaluation. Mild keratoconus was detected in the right eye of twin 1, characterized by classic slit-lamp findings (exacerbated corneal nerves and incomplete Fleisher's ring) and front surface curvature abnormalities, including asymmetry of the inferior–superior curvature at 6 mm (I–S value) of 2.78 D and a grade 1 Topographic Keratoconus Classification pattern. Topographic Keratoconus Classification was possible in the fellow eye of twin 1 (I–S value = 1.22 D) and negative in both eyes of twin 2 (I–S value = −0.46 OD and −0.13 OS). Ambrósio's Relational Thickness for the maximal progression meridian was 209 and 354 in twin 1 and 360 and 392 in twin 2 in the right and left eyes respectively. The final deviation value of the Belin–Ambrósio Enhanced Ectasia Display was 4.54 and 1.47 in twin 1 and 1.7 and 1.35 in twin 2.
Conclusion
Corneal tomography data provide a better representation of corneal genotype in detecting mild, subclinical, or forme fruste keratoconus in the fellow eyes with normal topography of these twins. These cases present high risk or susceptibility for ectasia progression if environmental factors are associated (second hit).
How to cite this article
Guerra G, de Oliveira VB, Ferreira I, Ramos I, Belin MW, Ambrósio R Jr. Subclinical Keratoconus Detection in Identical Twins. Int J Kerat Ect Cor Dis 2016;5(1):35-39.
Keratoconus and corneal ectasia after LASIK. J Refract Surg 2005;21:749-752.
Screening for ectasia risk: what are we screening for and how should we screen for it? J Refract Surg 2013 Apr;29(4):230-232.
Post-LASIK keratectasia triggered by eye rubbing and treated with topography-guided ablation and collagen cross-linking – a case report. Cornea 2012 May;31(5):575-580.
Topographic and tomographic properties of forme fruste keratoconus corneas. Invest Ophthalmol Vis Sci 2010 Nov;51(11):5546-5555.
[The “forme fruste” of keratoconus]. Wiener klinische Wochenschrift 1961 Dec;73:842-843.
Topography-guided surface ablation for forme fruste keratoconus. Ophthalmology 2006 Dec;113(12):2198-2202.
Chasing the suspect: keratoconus. Br J Ophthalmol 2009 Jul;93(7):845-847.
Global consensus on keratoconus and ectatic diseases. Cornea 2015 Apr;34(4):359-369.
High heritability of posterior corneal tomography, as measured by Scheimpflug imaging, in a twin study. Invest Ophthalmol Vis Sci 2014 Nov 25;55(12):8359-8364.
Corneal ectasia after LASIK despite low preoperative risk: tomographic and biomechanical findings in the unoperated, stable, fellow eye. J Refract Surg 2010 Nov;26(11):906-911.
Preoperative topographic characteristics of eyes that developed postoperative LASIK keratectasia. J Refract Surg 2013 Aug;29(8):540-549.
Optical coherence tomography combined with videokeratography to differentiate mild keratoconus subtypes. J Refract Surg 2014 Feb;30(2):80-87.
Longterm stability of ectasia in a young patient with asymmetric keratoconus. Int J Kerat Ect Cor Dis 2015;4(2):66-68.