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Peripapillary RNFL significantly thicker in higher hyperopic eyes
Anisometropia affects the development of the anterior and posterior segments of the eye, regardless of the presence of amblyopia, according to researchers in a clinical prospective study.
Their study included hyperopic anisometropic patients with and without amblyopia, between 6 years and 40 years of age.
Researchers included 220 eyes of 110 patients, of which 80 patients had hyperopic anisometropic amblyopia and the remaining 30 patients had hyperopic anisometropia without amblyopia.
Male patients made up 62.7% (n = 69), and females accounted for 37.3% (n = 41) of the study participants. Mean patient age was 16.36 years.
Seventy-four had anisometropia in the left eye, and 36 had anisometropia in the right eye.
Researchers obtained the refractive error and the values of keratometry, axial length (AL), central corneal thickness (CCT), peripapillary retinal nerve fiber layer (RNFL) thickness and central macular thickness (CMT) using the RK-F1 autorefractor (Canon), LenStar LS-900 (Haag-Streit) and Spectralis OCT (Heidelberg Engineering) to compare between the higher hyperopic and fellow eyes.
The macular thickness protocol consisted of macular scans of six radial lines, 30° apart and a diameter of 6 mm, centered on the fovea.
Researchers found a higher degree of hyperopia in all groups in the left eye. Right eye dominance was more common than left eye dominance in all patients.
The mean interocular differences in spherical equivalent between the higher hyperopic and fellow eyes were 3.61 D in the amblyopic group and 2.59 D in the non-amblyopic group, according to researchers. They found a significant difference for the mean interocular difference in spherical equivalent between the groups.
There were also significant differences between the higher hyperopic and fellow eyes in terms of mean best corrected visual acuity, spherical equivalent refraction, CCT, mean keratometry, AL, CMT and peripapillary RNFL thickness in all patients.
In the amblyopic group, the interocular difference in spherical equivalent was moderately correlated with the difference in peripapillary RNFL thickness. In the non-amblyopic group, researchers found this correlation weak and not significant
There were no significant correlations between interocular difference in spherical equivalent and the difference in CMT in the amblyopic and non-amblyopic groups.
In addition, in the amblyopic group, the interocular difference in AL was moderately correlated with the difference in the peripapillary RNFL thickness.
“The amblyopic process may affect the various levels of visual pathway,” according to researchers.
“The authors think that if amblyopia affects the process of emmetropization including postnatal reduction of ganglion cells ... the under-development is more severe so that differences in AL and spherical equivalent seem to be correlated with the differences in peripapillary RNFL thickness in patients with hyperopic amblyopia,” researchers wrote. – by Abigail Sutton