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O.J. Lehmann, P. Dumais, C. Backhouse, P.J. Gage, M. Asai–Coakwell; Reduced Human and Murine Corneal Thickness in an Axenfeld–Rieger Syndrome Subtype . Invest. Ophthalmol. Vis. Sci. 2006;47(13):188.
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© ARVO (1962-2015); The Authors (2016-present)
Axenfeld–Rieger Syndrome is a genetically heterogeneous disorder with mutations (PITX2 and FOXC1) identified in up to 50% of cases. In light of the changes in corneal thickness observed in some developmental glaucomas, we investigated whether cases of Axenfeld–Rieger due to PITX2 mutation exhibited distinctive features.
Central corneal thickness (CCT) was measured in patients and mice with PITX2/Pitx2 mutations. CCT measurements in affected and unaffected individuals from a single PITX2 mutation pedigree were recorded with ultrasonic pachymetry [DGH Technology] whilst murine CCT was measured with optical coherence tomography (OCT) [Zeiss]. The OCT was first calibrated with plastic films whose thickness had been accurately determined with scanning electron microscopy (SEM). Subsequently it was used to measure CCT in ex vivo eyes from Pitx2+/– and wild type murine littermates.
CCT in individuals with PITX2 mutation was significantly lower than in unaffected first–degree relatives [PITX2: mean 477µm (range 425–517), control: mean 582µm (550–590), P = 0.0004, t–test]. The OCT correlated with the reference SEM measurements, and OCT measurement demonstrated significantly reduced CCT in Pitx2+/– compared to wild type mice [Pitx2+/–: mean 72µm, wt: mean 88µm, P = 0.035].
These data provide the first example of reduced CCT in a genetic subtype of glaucoma and the similar CCT reduction (∼20%) in patients and mice with comparable mutations emphasises the utility of this murine model. These results offer potential for guiding molecular genetic testing in patients with Axenfeld–Rieger and may provide one explanation for the greater disease severity observed with PITX2 mutation. The ability to optically measure murine CCT provides scope for serially imaging the developing anterior segment, in vivo.
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