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Anisometropia of ocular refractive and biometric measures among 66‐ to 79‐year‐old female twins
Author(s) -
Pärssinen Olavi,
Kauppinen Markku,
Kaprio Jaakko,
Rantanen Taina
Publication year - 2016
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/aos.13125
Subject(s) - anisometropia , refraction , subjective refraction , astigmatism , ophthalmology , medicine , optometry , refractive error , visual acuity , optics , physics
Purpose To examine the prevalence of anisometropia of spherical refraction (Aniso SR ), astigmatism (Aniso AST ) and spherical equivalent (Aniso SE ) and their associations with spherical refraction ( SR ), refractive astigmatism ( AST ), spherical equivalent ( SE ) and interocular differences of ocular biometric parameters among elderly female twins. Methods Refraction of 117 monozygotic ( MZ ) and 116 dizygotic ( DZ ) female twin subjects aged 66–79 years was assessed with an auto‐refractor (Topcon AT ) and controlled by subjective refraction. Corneal refraction, anterior chamber depth and axial length were measured with a Zeiss IOL Master. Participants with eyes operated for cataract or glaucoma were excluded, but the grade of nuclear opacity was not recorded. The associations between the absolute values of Aniso SR , Aniso AST and Aniso SE with SR , AST , SE , corneal refractive power ( CR ), corneal astigmatism ( CAST ), anterior chamber depth ( ACD ) and axial length ( AL ) and with their interocular differences were calculated. When calculating the interdependencies of the differences, the real and absolute differences between the right and left eye were used. Results Means ± standard deviations for Aniso SR , Aniso AST and Aniso SE were 0.67 ± 0.92 D, 0.42 ± 0.41 D and 0.65 ± 0.71 D, respectively. Aniso SR , Aniso AST and Aniso SE >1.0 D were present in 14.7%, 4.2% and 17.7% of cases, respectively. Anisometropia of spherical refraction (AnisoSR), Aniso AST and Aniso SE were higher the more negative the values of SR or SE . Hyperopic ametropia did not increase these anisometropia values. The correlations of Aniso SR and Aniso SE with the absolute values of interocular differences in CR and AL were non‐significant. Using the real values of the interocular differences, the respective correlations were significant. The correlation between the real interocular differences in CR and AL was negative ( r = −0.258, p < 0.001). Thus, the combined effect of the real interocular differences in CR and AL was a decrease in Aniso SR and Aniso SE (emmetropization). Conclusion Higher Aniso SR and Aniso SE were associated with more myopic refraction and longer AL . Higher Aniso AST was associated with more negative SR and higher AST and CAST . The negative correlation between real interocular differences in CR and AL indicated their influence of emmetropization in Aniso SR and Aniso SE .