Peripapillary retinal nerve fiber layer thickness variations with myopia.

PURPOSE: To determine the relationship between peripapillary retinal nerve fiber layer (RNFL) thickness and myopia using optical coherence tomography (OCT). DESIGN: Prospective observational case series. METHODS: One hundred thirty-two young males with myopia (spherical equivalent [SE], -0.50 to -14.25 diopters) underwent ophthalmic examination of one randomly selected eye. Optical coherence tomography (OCT-1, version 4.1) was performed by a single operator using circular scans concentric with the optic disc with scan diameters of 3.40 mm, 4.50 mm, and 1.75 x vertical disc diameter (VDD). For each scan diameter, mean peripapillary RNFL thickness was calculated. Statistical analysis comprised repeated-measurements analysis and Pearson correlation. RESULTS: Mean peripapillary RNFL thickness did not correlate with SE for the 3.40-mm (r = -0.11, P = 0.22), 4.50-mm (r = -0.103, P = 0.24), or 1.75xVDD (r = -0.08, P = 0.36) OCT scan diameters. Neither did mean peripapillary RNFL thickness correlate with axial length for the 3.40-mm (r = -0.04, P = 0.62), 4.50-mm (r = 0.03, P=0.75), or 1.75xVDD (r = -0.02, P = 0.78) scan diameters. Mean peripapillary RNFL thicknesses for the 3.40-mm, 4.50-mm, and 1.75xVDD scans were 101.1+/-8.2 microm (95% confidence interval [CI], 99.4-102.8), 78.9+/-8.2 microm (95% CI, 77.5-80.3), and 97.5+/-10.9 microm (95% CI, 95.6-99.4), respectively. CONCLUSIONS: Mean peripapillary RNFL thickness did not vary with myopic SE or axial length for any OCT scan diameter investigated. Retinal NFL thickness measurements may be a useful parameter to assess and monitor glaucoma damage in myopic subjects.

Optic disk ovality as an index of tilt and its relationship to myopia and perimetry.

PURPOSE: To examine the association of optic disk ovality with myopic refractive error, axial length, and the visual field. DESIGN: Prospective observational case series. METHODS: The study included 150 randomly recruited male subjects with myopia. In all cases, one eye was randomly selected, and subjective refraction, slit-lamp examination, applanation tonometry, gonioscopy, A-scan ultrasonography, funduscopy, and color optic disk stereo photography were performed. Disk ovality was assessed using the ratio of minimum to maximum disk diameter (index of tilt). A ratio of < or = 0.8 was considered as significant disk tilt. Visual fields were tested using static automated threshold perimetry with two methods of optical correction: trial lenses and contact lenses. RESULTS: Of the total sample, 137 subjects completed the study. Mean age was 21.2 +/- 1.1 year, and mean spherical equivalent was -6.36 +/- 3.56 diopters. Mean ovality ratio was 0.83 +/- 0.09; 55 subjects (40.2%) had significant tilted optic disks. Greater optic disk ovality (tilt) correlated with greater myopia (P = .009) and longer axial length (P = .009); 95.6% of subjects had normal visual fields with both methods of optical correction. Using multiple linear regression analysis, greater tilt was independently related to a higher mean defect on testing with trial lenses (P < .01). CONCLUSIONS: Increased optic disk tilt was associated with higher myopia and reduced sensitivity on field testing. These factors are important in the assessment of glaucoma in patients with myopia.

Use of optical coherence tomography to assess variations in macular retinal thickness in myopia.

PURPOSE: To investigate the variation in macular retinal thickness in otherwise normal young Asian myopic subjects by using optical coherence tomography (OCT). METHODS: One hundred thirty ophthalmically normal men 19 to 24 years of age with myopia (spherical equivalent, -0.25 to -14.25 D) underwent examination of one randomly selected eye. Visual acuity, refraction, slit lamp examination, applanation tonometry, gonioscopy, A-scan ultrasound, fundus examination, visual field testing, and optic disc photography were performed. Exclusion criteria were visual acuity worse than 20/30, previous intraocular surgery, intraocular pressure >21 mm Hg, or other ocular diseases. Three horizontal transfixation and three vertical transfixation OCT scans (ver.4.1; Carl Zeiss Meditec, Dublin, CA) of 6 mm each were conducted on each eye by a single operator. Neurosensory retinal thicknesses at 100 points along each scan were measured, and the overall average, maximum, and minimum retinal thicknesses were analyzed by simple linear regression and analysis of variance. RESULTS: The average macular retinal thickness (overall) was 230.9 +/- 10.5 microm and was not significantly related to the degree of myopia. The mean maximum retinal thickness (at the parafovea) was 278.4 +/- 13.0 microm, and correlated negatively with axial length (P = 0.03). The mean minimum retinal thickness (at the foveola) was 141.1 +/- 19.1 microm, and this was positively correlated with axial length (P = 0.015) and spherical equivalent (P = 0.0002). The retina was thicker at the superior and nasal parafovea compared to the inferior or temporal parafovea. CONCLUSIONS: Average retinal thickness of the macula does not vary with myopia. However, the parafovea was thinner and the fovea thicker with myopia.

Prevalence, incidence, and progression of myopia of school children in Hong Kong.

PURPOSE: To determine the prevalence, incidence, and progression of myopia of Chinese children in Hong Kong. METHODS: A cross-sectional survey was initially conducted. A longitudinal follow-up study was then conducted 12 months later. RESULTS: A total of 7560 children of mean age 9.33 (95% confidence interval [CI] = 9.11-9.45; range, 5-16) participated in the study. Mean spherical equivalent refraction (SER) was -0.33 D (SD = 11.56; range, -13.13 to +14.25 D). Myopia (SER

Localization of cortical cataract in subjects of diverse races and latitude.

PURPOSE: To compare the characteristics of early cortical cataract localization in three groups in cataract epidemiologic surveys performed in Reykjavík, Melbourne, and Singapore. METHODS: Individuals who had right eyes with an area of cortical opacity less than 20% of the pupil when dilated 7 mm or more were selected as subjects. This included 197 subjects from the Reykjavík Eye Study, 231 from the Vitamin E, Cataract, and Age-Related Maculopathy (VECAT) study in Melbourne, and 92 from the Singapore-Japan Cooperative Cataract Study, all showing early-stage cataract in pupils dilated to 7 mm or more. Scheimpflug and retroilluminated photographs were used to locate opacities. Localization of cortical cataract was determined by dividing the retroillumination image into seven concentric circles with diameters of 1 through 7 mm, and eight sections of 45 degrees radial octants. The positive rate of opacification was then calculated for each quadrant. RESULTS: The highest positive rate of opacification was observed in the lower nasal quadrant in all groups. The relative risk of the prevalence of cortical opacity in the lower nasal oblique hemisphere to the upper temporal oblique hemisphere was the highest in the Singaporean subjects followed by those of Melbourne and then of Reykjavík. CONCLUSIONS: The prevalence of cortical cataract was higher in the lower nasal quadrant than in the other quadrants for all subjects of diverse race in three climatically different locations. This higher prevalence was most pronounced in subjects living at low latitude. These results support the view that solar UV exposure is a possible risk factor for development of human cortical cataract.

A randomized trial of rigid gas permeable contact lenses to reduce progression of children's myopia.

PURPOSE: To test whether rigid gas permeable (RGP) contact lens wear can reduced the rate of myopia progression in school age children. DESIGN: Randomized clinical trial. SETTING: Single clinical center. STUDY POPULATION: Both eyes of 428 Singaporean children. INCLUSION CRITERIA: 6 through 12 years of age with myopia between -1 and -4 diopters, astigmatism

Prevalence of primary cornea guttata and morphology of corneal endothelium in aging Japanese and Singaporean subjects.

The purpose of the present study was to examine, in the aging people, racial and gender differences in the morphology of corneal endothelium as well as the incidence of cornea guttata in two Asian subject groups, one in Singapore and the other in Japan. Four hundred and sixty-five Chinese Singaporeans and 299 Japanese subjects (residents of Monzen-machi, Ishikawa Prefecture) aged 50 years and older were recruited for the study. Corneal endothelial abnormalities were diagnosed with slit-lamp biomicroscopy and specular microscopy. Primary cornea guttata appeared as beaten metal appearance in slit-lamp images and dark regions in specular images. In addition to cornea guttata, corneal endothelial morphology was also analysed with specular microscopy. The mean cell density was 2,808/mm(2) in the Japanese subjects which was significantly higher than the 2,718/mm(2) seen in the Singaporeans (p < 0.001). The incidence of cornea guttata was significantly higher in the Singaporeans than in the Japanese individuals and also higher in women than in men of both racial groups. These differences support not only a racial and a gender factor but also a possible environmental influence.