Luke Long-Kuang Lin

Long-term Evaluation of Refractive Status and Optical Components in Eyes of Children Born Prematurely

PURPOSEnTo evaluate the refractive status and optical components in school age children born prematurely and to examine the risk factors associated with refractive errors.nnnMETHODSnThe participants were a cohort of children aged 7 to 9 years with gestational age less than 35 weeks or birth weight less than 1500 g. The participants neonatal histories were reviewed; their refractive status and optical components were measured. The study results were compared with the results of age-matched children from a national survey.nnnRESULTSnOf the 108 children studied, 48 (44%) had retinopathy of prematurity (ROP); 29 (27%) had ROP ≥ stage 3. Compared with the control subjects, the study cases showed higher prevalence of myopia (48% vs. 29%), hyperopia (23% vs. 15%), and astigmatism (73% vs. 41%). Common ocular features included shallow anterior chamber depth (ACD), thick lenses, and steep corneal curvature. The hyperopic cases had the shortest axial length (AL), whereas the myopia cases had significantly shallower ACD and greater LT. Those with a history of ROP had more prominent changes in the anterior segment. Generalized estimating equations showed that refractive errors could be predicted by a combination of optical components.nnnCONCLUSIONSnIn children born prematurely, the development of myopia is mainly influenced by anterior segment components, whereas hyperopia is mainly attributable to short AL. Astigmatism is primarily cornea-related. A combination of various optical components results in complicated refractive outcomes. The presence of ROP may be associated with significantly shorter ACD, thicker lens, and higher myopia and astigmatism. (ClinicalTrials.gov number, NCT01045616.).

Visual outcomes for high myopic patients with or without myopic maculopathy: a 10 year follow up study

Aim: To evaluate the visual outcomes for high myopic patients aged 40 years and older with or without myopic maculopathy. Methods: 552 high myopic (spherical equivalent ⩽−6.0D or axial length ⩾26.5 mm) patients were enrolled in the study, 230 cases with myopic maculopathy (at least lacquer cracks were identified) and 322 cases without maculopathy. The initial and final visual acuity (VA) (after 10 years) was compared between two groups. Additionally, the relation between sex, age, refraction, and axial length was analysed to find out the possible risk factors associated with visual outcome in myopic maculopathy. Results: In 92% of patients aged 40–49, final VA was better than 20/40 after 10 years of follow up. However, it was less than 40% in those older than 60 years. For more than 50% of patients older than 40 years of age with maculopathy, their vision had decreased more than two lines in Snellen VA after 10 years of follow up, compared to only 4.3% of analogues without myopic maculopathy. Patchy atrophy and choroidal neovascularisation in myopic macular degeneration groups showed poorer visual outcome than lacquer cracks in the macular lesion group. Other prognostic factors of visual outcomes were myopic refraction, axial length, and ageing. Conclusions: Clearly, prognosis for patients with maculopathy is poorer than for those without maculopathy. Refractive status, axial length, and ageing are the main factors involved in determining the visual outcomes. The macular grading also affects the visual outcome for high myopic patients.

Changes of the ocular refraction among freshmen in National Taiwan University between 1988 and 2005

PurposeThe prevalence of myopia in Taiwan has been reported to be increasing in the sequential nationwide survey. The purpose of this study is to compare the change of ocular refraction among freshmen in 1988 and 2005 in National Taiwan University.MethodsThe refractive status of freshmen in National Taiwan University in 2005 was examined. The refractive status and corneal radius of each student were measured with autorefractometer. The data was compared with the data obtained in 1988. All the refractions of the right eye were chosen and myopia was defined as a mean spherical equivalent of −0.25u2009D or more.ResultsThe mean refractive status of total 4686 freshmen was −4.25±2.74u2009D in 1988 (−4.12±2.72u2009D for males and −4.41±2.75u2009D for females). The prevalence of myopia was 91.3% (90.1% for males and 92.8% for females). The prevalence of high myopia (over −6.0u2009D) was 23.5% (22.2% for males and 25.1% for females). In 2005, the mean refractive status of total 3709 freshmen was −4.93±2.82u2009D (−4.93±2.83u2009D for males and −4.93±2.80u2009D for females). The prevalence of myopia was 95.9% (95.9% for males and 95.9% for females). The prevalence of high myopia was 38.4% (38.1% for males and 38.8% for females).ConclusionsThe prevalence and severity of myopia in freshmen of National Taiwan University increased significantly in 2005 compared to 1988. The distribution of refractive status in different college changed also. These findings may be explained by the early onset of myopia.

The genetic effect on refractive error and anterior corneal aberration: twin eye study.

PURPOSEnTo investigate the role of heredity in determining refractive variables, anterior corneal curvature, and anterior corneal aberrations.nnnMETHODSnThirty-three monozygotic and 10 dizygotic twin pairs were enrolled in this study. Corneal curvature, corneal astigmatism, and corneal topography were obtained from computerized videokeratoscope. The CTView program was used to compute anterior corneal aberrations from corneal height data of the videokeratoscope. Correlation analysis was performed to investigate the symmetry of the refractive error, corneal curvature, corneal astigmatism, and anterior corneal aberrations between right and left eyes of each twin pair. Heritability (h2) of these parameters was also calculated.nnnRESULTSnPositive correlations were noted between right and left eyes for spherical power, total astigmatism, mean corneal curvature, and corneal astigmatism. In monozygotic twins, vertical coma, secondary vertical coma, spherical aberration, and secondary spherical aberration were moderately correlated. In dizygotic twins, vertical coma, secondary horizontal coma, and spherical aberration were moderately correlated. In unrelated controls, secondary vertical coma, secondary horizontal coma, and secondary spherical aberration were moderately correlated. Root-mean-square (RMS) of higher order aberrations (3rd to 6th orders), RMS of spherical aberration, and RMS of coma were moderately correlated between right and left eyes in all three groups. Heritability of spherical aberration, RMS of spherical aberration, and corneal astigmatism (h2 = 0.56, 0.44, and 0.46) were greater than those of refractive power, corneal curvature, and other higher order aberrations.nnnCONCLUSIONSnThese results suggest that corneal astigmatism and spherical aberration possess a greater genetic predisposition than those of other refractive errors and higher order aberrations.

Prevalence of Anisometropia in Taiwanese Schoolchildren

BACKGROUND AND PURPOSEnThis study investigated the prevalence and distribution of anisometropia in Taiwanese schoolchildren using nationwide data from refractive surveys performed in 1995 and 2000.nnnMETHODSnComplete survey data was obtained for 11,175 students in 1995 and 10,878 students in 2000. The refractive status of each student was measured using an autorefractometer under cycloplegia and rechecked with retinoscopy. The difference in refractive status between each participants eyes was determined. Chi-squared statistic was used to assess the difference between the 2 surveys. Multiple linear regression was used to determine the trend and effects of covariates.nnnRESULTSnMost of the schoolchildren (77.6% in 1995, 71.9% in 2000) were not anisometropic. Most of the anisometropic differences were in the range 0.5 to 1.0 D (14.1% in 1995 vs 17.9% in 2000). About 6% of schoolchildren in 1995 and 7.0% in 2000 had anisometropic differences in the range from -1.0 to -2.0 D. Fewer than 4% of students had a level of anisometropia greater than 2.0 D (2.7% vs 3.2%, respectively). The prevalence of anisometropia and the extent of anisometropic difference both increased with age and with maximal myopic refraction (both p < 0.0001). Both the prevalence and extent of anisometropia showed significant differences between the 2 surveys (both p < 0.0001).nnnCONCLUSIONSnMost of the Taiwanese schoolchildren surveyed were non-anisometropic. The prevalence and amount of anisometropia were significantly increased from 1995 to 2000. The mechanisms responsible for these increases have not been determined, but may be related to increase of myopic refraction.

Long-term visual prognosis of infantile-onset high myopia

PurposeTo investigate the clinical course and changes of refractive status in infantile-onset myopic children who received fully corrected glasses and to determine their visual prognosis.MethodsIn all, 57 children with infantile-onset high myopia (spherical equivalent over −5.0u2009D prior to the age of 5 years) were included in this study. All children received initial full-correction glasses at the mean age of 3.52 years. The cycloplegic refraction, axial length, and the best-corrected visual acuity were collected every 6 months. The mean follow-up time was 9.36 years.ResultsWe noted that the tendency toward progression or regression of myopia appeared to be related to the degree of refractive error. Lower grades of high myopia (−5.0 to −7.75u2009D) showed a greater tendency to progress than those of the highest initial myopic refraction level (≤−11.0u2009D). While the latter group exhibited a more-substantial regression rate than those cases of the lower initial refraction level. About 80% of infantile-onset high myopes demonstrated a final best-corrected vision of greater than 20/40, with 37% of children revealing a best-corrected vision level even better than 20/25.ConclusionClinical course of infantile high myopia is different to school myopia. Usually, higher degree of high myopia showed a stable state of myopia, or even possible regression, whereas the lower grades of high myopia revealed a strong tendency to progress.

The effect of green classroom on the prevention of myopia progression

Three classrooms from one primary school and one junior high school, respectively, were randomly chosen to be painted green. Another three classrooms from each school were chosen to serve as the control. The refractive status of the students from the classrooms under study were examined and recorded in the beginning of the study. The changes in refraction were compared between the experimental and the control group at the end of the study, after a follow-up period of 1 l / 2 year.

Prevalence and Patterns of Myopic Progression Among Schoolchildren: Eight-Year Longitudinal Study

The patterns of myopic progression and the degree of myopia were studied after an 8-year follow-up of schoolchildren. A longitudinal study was conducted in Taiwan from 1984 to 1991, with 593 children originally enrolled. Altogether 278 children were followed completely from the ages of 7 to 15 years. The cycloplegic refraction, corneal radius, and biometric axial length were measured each year. The results showed that the mean myopic shift was -0.11 D per year before myopia, whereas there was -0.64 D per year myopic progression after myopia development. During emmetropization 73% of subjects had a myopic shift of less than -0.25 D per year; in 50% of myopic students the myopic progression was -0.5 to -1.0 D per year and in 19% more than -1.0 D per year. Analyzing the patterns of myopic shift, we found that the rate of myopic shift was more rapid while myopization occurred. The pattern of myopic progression remains the same for myopic children with different age of onset. Axial elongation of the eyeball is the main ocular component that changes during myopic progression.