OBJECTIVE: To evaluate the relationship between retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and the degree of myopia.
METHODS: A total of 28 eyes of 14 healthy subjects with myopia, 9 eyes with low myopia (spherical equivalent [SE] between -0.75 D and -3.00 D) and 19 eyes with moderate to high myopia (SE >-3.0 D), were included. Total average
and mean quadrant RNFL thicknesses were measured by Stratus OCT. Associations between RNFL measurements and spherical equivalent refraction were evaluated by linear regression analysis.
RESULTS: Twenty two out of 28 eyes were classified as below normal limits with reference to the normative database of the RNFL thickness. There was a significant correlation between refraction and average RNFL thickness (p=0.04), indicating that for every decrease of 1.00 D in refraction (more myopic), there was a 2.86 µm decrease in the average RNFL thickness. The most frequently abnormal sector was at the nasal quadrant, where 78% of myopic eyes were below normal limits. A significant correlation was seen between refraction and nasal RNFL thickness (p=0.02), showing a decrease of 3.37 µm in the nasal RNFL thickness for every 1.00 D decrease. There was also a significant correlation between refraction and inferior RNFL thickness (p=0.007). For every decrease of 1.00 D in refraction, there was a decrease of 6.27 µm in the inferior RNFL thickness. There were no significant correlations between the refraction and the superior and temporal RNFL thickness (p = 0.12 and 0.64, respectively).
CONCLUSION: There was a decrease in the average RNFL thickness as the refractive error became more myopic, suggesting the need for the Stratus OCT RNFL normative database to have corrective factors for refractive error among myopic patients. Although both the nasal and inferior quadrants positively correlated with myopia, majority of the nasal quadrant showed below normal thickness based on the Stratus OCT normative database. A careful interpretation of RNFL measurements, especially the nasal quadrant, should be done among myopic subjects to avoid mislabeling them as glaucoma suspects.

Human ; Male ; Female ; Adult ; Myopia 9 ; Tomography, Optical Coherence ; Healthy Volunteers ; Myopia 3 ; Myopia ; Eye ; Refractive Errors ; Nerve Fibers ; Glaucoma

The authors examined the specificity of the dopamine-2 receptor for eyeball growth of the experimental myopic chicken eyes. Two day-old white Leghorn chickens were monocularly deprived of vision by lid suture of the right eyes. We measured the axial lengths of chicken's eyes by ultrasonography at the 2nd day and the 4th weeks. The right eyes of the first group were instillated with 0.04cc of tris buffer solution, those of the second and third group were instillated with 0.04cc of 0.02% SKF38393 hydrochloride solution and 0.02% bromocriptine solution individually. All solutions were instillated into the right eyes two times per day during 4 weeks. At the 2nd day of the age, the axial lengths of the first group's eyeballs were 7.83 +/- 0.14mm in the right, 7.87 +/- 0.15mm in the left eyes, 7.78 +/- 0.16mm in the right eyes, 7.77 +/- 0.11mm in the left eyes of the second group and 7.89 +/- 0.12mm in the right eyes, 7.87 +/- 0.12mm in the left eyes of the third group. Each group was not statistically different (p>0.05). But at the four weeks of the age, the axial lengths of the lid sutured right chicken eyeball were 11.39 +/- 0.27mm in the first group, 11.40 +/- 0.40mm in the second group and 11.20 +/- 0.40mm in the third group, The third group was statistically different from the first or 2nd group (p<0.05). The growth of the axial lengths of the right chicken eyeballs from the 2nd day to the 4th week of the age was 3.50 +/- 0.35mm in the first, 3.63 +/- 0.42mm in the second and 3.21 +/- 0.29mm in the third group. The right eyes of the third group were found significantly less growth than those of other groups. These results suggest that dopamine-2 receptor playa role in eyeball growth.
2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine ; Bromocriptine ; Chickens* ; Myopia* ; Sensitivity and Specificity* ; Sutures ; Tromethamine ; Ultrasonography