The Correlation of Differences in the Ocular Component Values with the Degree of Myopic Anisometropia

PURPOSE: To determine the relationship between the differences in the ocular component values with the degree of anisomyopia. METHODS: Refraction, corneal power (CP), and biometry were examined in 50 myopic adults with refractive differences (RD) over 1.50 diopters (D). Ocular components were measured by ultrasound biometry and keratometry. The correlation between the differences in the ocular component values with the degree of anisomyopia was analyzed by linear regression analysis. RESULTS: Among 50 adults with anisomyopia, 5 had RD from 1.50 to 2.99 D, 11 had RD from 3.00 to 3.99 D, 9 had RD from 4.00 to 5.99 D, 12 had RD from 6.00 to 7.99 D, 7 had RD from 8.00 to 11.99 D, and 6 had > or =12.00 D. There was no significant correlation between the ocular components (CP, crystalline lens thickness [LT], and anterior chamber depth [ACD], and the length from the cornea to the posterior surface of the lens [ACD + LT]) and the RD (p > 0.05). The RD showed a significantly positive correlation with vitreous chamber depth (VCD), and axial length (r = 0.963, p < 0.0001). CONCLUSIONS: The severity of anisomyopia was not correlated with the between-eye differences in the anterior chamber values of the eye (CP, ACD, LT, ACD + LT). The severity of anisomyopia was significantly correlated with the between-eye differences in VCD.

Change in Ocular Dimensions with Age in Patients with Emmetropia

PURPOSE: We evaluated changes in ocular dimensions according to age in patients with emmetropia. METHODS: We examined the refraction, corneal curvature, and biometry in 150 subjects from 5 to 75 years old with spherical equivalent refractions under +/-0.75 diopter (D). Ocular dimensions were measured by A-scan ultrasonography and keratometry. We analysed the distribution and change of ocular dimensions according to age (1: 0~19-year-old group, 2: 20~39-year-old group, 3: 40~59-year-old group, 4: 60~79-year-old group). RESULTS: The values for corneal radius (CR), vitreous chamber depth (VCD) and axial length (AL) were highest in group 2. Lens thickness (LT) increased with increasing age, whereas anterior chamber depth (ACD)decreased with increasing age (P<0.05). CR, VCD, AL (P<0.05) and ACD (P=0.10) seem to have higher values in males, while LT seems to have a higher value in females (P=0.06). CONCLUSIONS: Axial length increases with increasing age in subjects aged 0 to 39 years in emmetropia. In subjects aged 40 years or older, axial length becomes smaller with age. In each age group compensational changes to achieve emmetropia according to AL change are shown in ocular dimensions like CR, VCD, ACD, LT.

Change of Corneal Astigmatism with Aging in Koreans with Normal Visual Acuity

PURPOSE: To evaluate the distribution and change of corneal astigmatism with aging in persons with normal visual acuity. METHODS: We classified 504 subjects (504 eyes) showing good naked vision at least 1.0 from 3 to 83 years into 15 groups with 5 year interval and analyzed corneal astigmatism using refraction and keratometry. RESULTS: With-the-rule astigmatism (WTR) was shown in 98.5% between 3 and 25 years and progressively decreased with aging. In 61 to 65 years' group WTR was 34.1% and against-the-rule astigmatism (ATR) was 36.4%. After then ATR was more predominant. Mean corneal astigmatism was about 1 diopter under 20 years and progressively decreased to 0.5 D at 60 years with aging. CONCLUSIONS: 84.7% of persons with normal visual acuity have corneal astigmatism. WTR was predominant in the youth but progressively decreased with aging to equal balance with ATR in the mid sixties. After then corneal astigmatism would be inclined to against-the-rule. The amount of corneal astigmatism was decreased from about an 1 diopter in twenties to 0.5 diopter in sixties.