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PALANISWAMY KRISHNAMURTHY, Rengaraj Venkatesh, Pradeep Ramulu, Srinivasan Kavitha, David Friedman, Harry Quigley, Robert Wojciechowski, Fiona Seager; Conserved anatomic features in sibling pairs concordant for angle closure. Invest. Ophthalmol. Vis. Sci. 2013;54(15):6245. doi: https://doi.org/.
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To compare the inter-sibling differences in ocular parameters for sibling pairs who are concordant or discordant for angle closure.
Two hundred and one patients with angle closure (PACS, PAC, or PACG) were recruited from the Aravind Eye Hospital in Pondicherry. All patients and one similarly-aged sibling underwent the following testing: (1) subjective refraction to determine spherical error, (2) pachymetry to determine central corneal thickness (CCT), (3) A-scan to determine anterior chamber depth (ACD), lens thickness and axial length, and (4) anterior segment OCT to determine anterior chamber width, anterior chamber volume, and lens vault. The presence/absence of angle closure was characterized in siblings through a gonioscopic exam conducted by a masked physician, and used to characterize sibling pairs as concordant or discordant with regards to angle closure. Differences in proband/sibling ocular parameters in concordant and discordant sibling pairs were assessed through correlation analyses and through comparison of absolute proband-sib differences in the measured parameters.
133 sibling pairs (66%) were concordant for angle closure, while 68 (34%) were discordant. Greater inter-sibling correlation was observed for concordant sib pairs as compared to discordant sib pairs with regards to axial length (r=0.47 vs. 0.33), anterior chamber depth (r=0.20 vs. -0.16), CCT (r=0.55 vs. 0.37), and lens vault (r=0.25 vs. 0.20). All other parameters showed similar correlations for concordant and discordant sib pairs (r values within 0.05 of each other). Larger proband-sibling differences were noted in discordant sibling pairs as compared to concordant sibling pairs for axial length (Δ=0.66 vs 0.16 mm, p<0.001), anterior chamber depth (Δ=0.51 vs. 0.07 mm, p<0.001), anterior chamber volume (Δ=30 vs. 12 mm3, p<0.001), lens vault (Δ=0.33 vs. 0.11 mm, p<0.001), and anterior chamber width (Δ=0.25 vs. 0.08 mm, p=0.02), but not for central corneal thickness, lens thickness, or spherical error.
Axial length, anterior chamber depth and volume, and lens vault are more highly preserved in sibling pairs concordant for angle closure as compared to sibling pairs discordant for angle closure. This finding suggests that preservation of these features across family members plays an important role in the heritability of angle closure.
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