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PubMedDate not supplied

One-year results of custom laser epithelial keratomileusis with the Nidek system.

PURPOSE: To evaluate long-term results of custom laser epithelial keratomileusis (LASEK) for correction of myopia and hyperopia using the Custom Ablation Transition Zone (CATz) software and hyaluronic acid masking fluid (Laservis) for final corneal smoothing. METHODS: We conducted a prospective study of 297 eyes of 167 patients. All eyes had LASEK for correction of myopia or hyperopia. The Nidek EC-5000 excimer laser, FinalFit software, and CATz ablation profile was used in all eyes. Laservis was used as masking fluid to remove corneal micro-irregularities during the final phase of the treatment. RESULTS: Mean preoperative spherical equivalent refraction was -5.46 +/- 2.57 D (range -14.13 to +3.50 D). At 1 year after LASEK, mean spherical equivalent refraction was -0.15 +/- 0.50 D (range -4.00 D to +1.00 D). CONCLUSIONS: LASEK with the Nidek EC-5000 excimer laser, FinalFit and Custom Ablation Transition Zone (CATz) software, with corneal smoothing, was safe and effective at 1 year after surgery.

Adult↗
PubMedDate not supplied

Hyperopic laser in situ keratomileusis with 5.5-, 6.5-, and 7.0-mm optical zones.

PURPOSE: To evaluate the results of laser in situ keratomileusis (LASIK) for the correction of hyperopia and hyperopic astigmatism using a large 7.0-mm optical zone and to compare them with treatments using a 5.5- and 6.5-mm optical zone. METHODS: One hundred sixty-one eyes of 89 patients with a mean preoperative spherical equivalent refraction of +2.44 +/- 1.32 diopters (D) (range: +0.00 to +5.62 D, cylinder 5.25 to 0.00 D) were treated for hyperopia and hyperopic astigmatism using a 7.0-mm optical zone and were analyzed retrospectively. Postoperatively, patients were examined after 1 day, 1 week, 1 month, 3 months, and 1 year. Eyes treated previously at the same center by the same surgeons with 5.5- and 6.5-mm optical zone applications were used as controls. All treatments were performed with the Nidek EC 5000 CXII excimer laser system (Nidek, Gamagori, Japan). A nasal hinged flap was created using the Nidek MK 2000 microkeratome in all cases. RESULTS: The mean postoperative spherical equivalent refraction after 1 month (n=89) was +0.12 +/- 0.72 D (range: -1.75 to +2.75 D), +0.13 +/- 0.74 D (range: -1.88 to +1.62 D) at 3 months (n=70), and +0.20 +/- 0.69 D (range: -1.62 to +1.12 D) at 1 year (n=33). Regression between 1 month and 1 year was 0.08 D in the 7.0-mm optical zone group. Regression was 0.25 D in the 5.5-mm group and 0.02 D in the 6.5-mm optical zone group between 1 month and 1 year. In both the 5.5- and 6.5-mm optical zone groups, 13% of eyes lost one line in visual acuity (2% in the 7.0-mm optical zone group). The gain of one or more lines in visual acuity was 19% in the 5.5-mm group, 17% in the 6.5-mm group, and 27% in the 7.0-mm optical zone group. All data represent primary cases without retreatment. CONCLUSIONS: Increasing the optical zone size from 5.5 mm to 6.5 mm and to 7.0 mm seems to improve refractive results, stability, and safety of hyperopic and hyperopic-astigmatic LASIK treatments. Although some hyperopic and astigmatic eyes are endangered by loss of lines in best spectacle-corrected visual acuity, more eyes gain one or more lines.

Adult↗
PubMedDate not supplied

Five techniques for improving outcomes of hyperopic LASIK.

PURPOSE: To determine whether five changes to our hyperopic LASIK protocol produced better outcomes. METHODS: Five changes, both technical and surgical, were instituted for the treatment of hyperopia. These five changes were nomogram refinements accounting for accommodation, use of a 7.0-mm optical zone and a 9.5-mm transition zone, a targeted mean flap diameter of 10.5 mm, sequential interruption of the laser ablation, and cleaning of the interface. The study comprised 43 eyes undergoing LASIK for hyperopia or hyperopic astigmatism with a mean preoperative spherical equivalent refraction of +2.28 diopters (D), a mean sphere of +1.93 D (range: +4.25 to +0.25 D), and mean cylinder of +1.10 D (range: +4.50 to +0.25 D). The NIDEK CXII excimer laser was used for all treatments. RESULTS: From 1 day to 3 months postoperatively, the mean hyperopic shift was <0.50 D. Postoperatively, the number of patients achieving a distance best spectacle-corrected visual acuity (BSCVA) of 20/20 gradually increased to 93% by 3 months. The number of eyes that achieved 20/15 increased by 11.7% compared to preoperatively. Eighty-eight percent of eyes maintained or gained lines of BSCVA. Four patients lost 1 line of BSCVA. One patient lost >1 line of vision due to visually significant microstriae. CONCLUSIONS: The outcomes support the observation that five surgical and technical modifications to the hyperopic LASIK procedure result in excellent visual quality and refractive outcomes and a low rate of regression.

Adult↗
PubMed2000

Vision-dependent changes in the choroidal thickness of macaque monkeys.

PURPOSE: To determine whether changes in the eye's effective refractive state produce changes in the thickness of the choroid in infant monkeys. METHODS: Normal developmental changes in choroidal thickness were studied in 10 normal rhesus monkeys. Hyperopia or myopia was induced by rearing 26 infant monkeys with either spectacle or diffuser lenses secured in front of one or both eyes. The treatment lenses were worn continuously beginning at approximately 3 weeks of age for an average of 120 days. Refractive status and ocular axial dimensions, including choroidal thickness, were measured by retinoscopy and high-frequency A-scan ultrasonography, respectively. RESULTS: Three lines of evidence indicate that the normal increase in choroidal thickness that occurs during early maturation can be altered by the eye's refractive state. First, in monkeys experiencing form deprivation or those in the process of compensating for imposed optical errors, choroidal thickness and refractive error were significantly correlated with eyes developing myopia having thinner choroids than those developing hyperopia. Second, the choroids in eyes recovering from binocularly induced myopia increased in thickness at a faster rate than the choroids in recovering hyperopic eyes. Third, monkeys recovering from induced anisometropias showed interocular alterations in choroidal thickness that were always in the appropriate direction to compensate for the anisometropia. These changes in choroidal thickness, which were on the order of 50 microm, occurred quickly and preceded significant changes in overall eye size. CONCLUSIONS: Changes in the eye's effective refractive state produce rapid compensating changes in choroidal thickness. Although these choroidal changes are small relative to the eye's refractive error, they may play an important role in the visual regulation of axial growth associated with emmetropization.

Animals↗
PubMed2001

Genes and environment in refractive error: the twin eye study.

PURPOSE: A classical twin study was performed to examine the relative importance of genes and environment in refractive error. METHODS: Refractive error was examined in 226 monozygotic (MZ) and 280 dizygotic (DZ) twin pairs aged 49 to 79 years (mean age, 62.4 years). Using a Humphrey-670 automatic refractor, continuous measures of spherical equivalent, total astigmatism, and corneal astigmatism were recorded. Univariate and bivariate maximum likelihood model fitting was used to estimate genetic and environmental variance components using information from both eyes. RESULTS: For the continuous spectrum of myopia/hyperopia, a model specifying additive genetic and unique environmental factors showed the best fit to the data, yielding a heritability of 84% to 86% (95% confidence interval [CI], 81%-89%). If myopia and hyperopia (< or = -0.5 D and > or = 0.5 D, respectively) were treated as binary traits, the heritability was 90% (95% CI, 81%-95%) for myopia and 89% (95% CI, 81%-94%) for hyperopia. For total and corneal astigmatism, modeling showed dominant genetic effects are important; dominant genetic effects accounted for 47% to 49% of the variance of total astigmatism (95% CI, 37%-55%) and 42% to 61% of corneal astigmatism variance (95% CI, 8%-71%), with additive genetic factors accounting for 1% to 4% and 4% to 18%, respectively (95% CIs, 0%-13% and 0%-60%, respectively). CONCLUSIONS: Genetic effects are of major importance in myopia/hyperopia; astigmatism appears to be dominantly inherited.

Aged↗
PubMed2001

Repeat cycloplegic examinations at the Naval Operational Medicine Institute.

BACKGROUND: Cycloplegic examination is required for applicants who desire entry into Naval Aviation training. Before this study, all cycloplegic examinations performed at any site were repeated at the Naval Operational Medicine Institute (NOMI), Pensacola, FL, on all student naval aviator (SNA) candidates to assess for latent hyperopia which exceeded established limits for entry into training. HYPOTHESIS: Repeat cycloplegic examination does not vary sufficiently to change student status regarding physical qualification for training. METHODS: Data analysis of cycloplegic examinations repeated at the NOMI, for which the first and second examination were recorded in the Aviation Medical Data Retrieval System (AMDRS), over 10 yr. RESULTS: There were 3919 SNA applicants who had cycloplegic examinations repeated at NOMI. Of them, 3903 (99.59%) were within standards on the repeat examination. There were 16 candidates who were sent to NOMI with a previously disqualifying cycloplegic examination. On second cycloplegic examination, 15 were within standards for SNA. Only 15 of the SNAs with a first cycloplegic examination within standards were outside SNA standards on repeat examination. Of these 15, 12 were also outside SNA standards in distant visual acuity and/or in manifest refraction. The remaining 3 were found to have excessive myopia, not latent hyperopia, on the second cycloplegic examination. The standard deviation between the first and the second cycloplegic examination was computed to be less than 0.50 diopters in any meridian. CONCLUSION: The cycloplegic examination of SNA candidates need only be repeated if the first cycloplegic examination is outside the SNA limit or within two standard deviations of the SNA limit.

Adult↗
PubMed1991

A nation-wide study of myopia prevalence in Israel. Findings in a population of 312,149 young adults.

We conducted a nation-wide survey of the Prevalences of Myopia and other refractive errors in Israel, from data of medical examinations of an unselected population of 312,149 subjects ages 17 to 19 years. 80.47% of the population were emmetropic in both eyes. Myopia in both eyes was found in 16.27% of the population. The prevalence of monocular myopia was 1.69%. Manifest hyperopia in both eyes was found in 0.93% and astigmatism at least in one eye was found in 7.13%. The various errors of refraction (myopia, hyperopia and astigmatism) were more common among females.

Adolescent↗
PubMed2005

[The evaluation of visual disorders in preschool children].

OBJECTIVE: The purpose of this study was to investigate the visual disorders and their causes in preschool children. MATERIALS AND METHODS: We have examined 839 children of 2-6 years. They were divided into two age groups: of 2-3 years (I gr.) and of 4-6 years old (II gr.). We estimated the visual acuity at 3m distance, binocular vision, refractive status by cycloplegic skiascopy (sol. cyclogyli 1% x 2). RESULTS: Impaired vision was found in 14.94% of children, but it was significant in the second group (p<0.05); binocular vision was absent in 4.2% of the children. The evaluation of refraction showed that the cause of visual disorders was hyperopia of various degree (43.26%), hyperopic astigmatism (23.08%), spasm of accommodation (14.42%). The second group had significantly more cases of astigmatism and spasm of accommodation (27.38% and 16.67%, respectively), less common--strabismus (1.19%); it was significantly different from the first group (p<0.05). CONCLUSIONS: Visual disorders were diagnosed in 14.94% of 2-6 years children. Impaired vision of preschool children was caused by the ocular ametropias (hyperopia of various degrees, astigmatism) and disorders of accommodation.

Age Factors↗
PubMed2004

Refractive errors among students occupying rooms lighted with incandescent or fluorescent lamps.

The purpose of the study was to determine whether the development of refractive errors could be associated with exposure to light emitted by incandescent or fluorescent lamps. 3636 students were examined (1638 boys and 1998 girls, aged 6-18 years, mean age 12.1, SD 3.4). The examination included retinoscopy with cycloplegia. Myopia was defined as refractive error < or = -0.5 D, hyperopia as refractive error > or = +1.5 D, astigmatism as refractive error > 0.5 DC. Anisometropia was diagnosed when the difference in the refraction of both eyes was > 1.0 D. The children and their parents completed a questionnaire on exposure to light at home. Data were analyzed statistically with the chi2 test. P values of less than 0.05 were considered statistically significant. It was found that the use of fluorescent lamps was associated with an increase in the occurrence of hyperopia (P < 0.01). There was no association between sleeping with the light turned on and prevalence of refractive errors.

Adolescent↗
PubMed2005

[Prevalence of refractive errors in 7 and 8 year-old children in the province of Western Pomerania].

PURPOSE: To determine the prevalence of refractive errors in 7 and 8 year-old schoolchildren in the province of Western Pomerania. MATERIAL AND METHODS: 140 pupils of elementary schools were examined. Measurements of visual acuity and retinoscopy after cycloplegia were carried out. RESULTS: Prevalence of hyperopia, myopia, and astigmatism was 76.1%, 3.3% and 5.1%, respectively. No statistically significant differences between 7 and 8 year-old children were found. CONCLUSIONS: 1. There is a relatively high prevalence of refractive errors, with hyperopia prevailing, among 7 and 8 year-old schoolchildren. 2. Myopia in young children is a cause for concern an further studies. 3. High prevalence of refractive errors in children calls for systematic examination and focused interviewing by medical professionals of the school health care system.

Child↗
PubMed2005

Guidelines for prescribing optical correction in children.

As the eye grows, the axial length increases while the cornea and lens flatten. High refractive errors which are common in the neonatal period, reduce rapidly during the first year of life through the process called emmetropization. The possibility that long-term full- time glasses wear may impede emmetropization must be considered. Hyperopia greater than 5.00 diopters (D) in young children is associated with an increased risk of amblyopia and strabismus, therefore optical correction should be prescribed. When hyperopia is associated with esotropia, full correction of the cycloplegic refractive error should be prescribed. Myopia greater than 8.00 D and astigmatism greater than 2.50 D are common causes of isometropic amblyopia. Patients with hyperopic anisometropia with as little as l D difference between the eyes may develop amblyopia while the difference should reach 3-4 D for myopic anisometropia to develop amblyopia. Full cycloplegic refractive difference between two eyes should be given to the anisometropic child in spite of age, strabismus and degree of anisometropia. Myopia control is the attempt to slow the rate of progression of myopia such as cycloplegic agents, plus lenses at near, and rigid contact lenses.

Adolescent↗
PubMed1991

[The measurement of visual refraction of pupils].

The ocular refraction was measured by applying 1% atropine eye-drops for 3 days in 5,458 eyes (male 2,944, female 2,514) of the pupils aged 7-17 in rural areas. The results were as follows: the majority of the pupils had hyperopia (male 84.71%, female 80.55%); the frequency of the measurements was not in normal distribution; the degree of far-sight began to recede and gradually become converted to myopias with advancing age but varying greatly between age-groups. The myopias began to appear at the age of 9 and increased rapidly at the age of 14 for girls and 15 for boys. From then on the rate of conversion continued to increase with schoolgirls more than schoolboys and, as a result, formed "the dangerous stage of myopia", the values of physiological visual refraction were shown as follows: pupils aged 7-9 + 2.00 D- + 2.50 D, aged 10-13 + 1.50 D- + 1.75 D, aged 14-17 + 1.00 D- + 1.25 D. The possibility of pathological hyperopia was greater if the pupils aged 7-9 and the value of visual refraction over +3.75 D, aged 10-13 had the value over +3.00 D and aged 14-17 had the value +2.50 D. The possibility of developing myopia was great in those pupils aged 7-9 whose value was under +1.00 D and in those aged 10-17 whose value was under +0.50 D. The deprived vision of the pupils should be routinely corrected by skiascopy.

Adolescent↗
PubMed1990

Refractive error in a Puerto Rican rural population.

The distribution of refractive error in migrant workers and their families living in Patillas, Puerto Rico was studied. A total of 1,109 patients with an age range of 5-81 years and above was screened using the modified clinical technique. The refractive distribution of the total screened indicated that 10.2 percent had myopia, 17.7 percent had hyperopia and the rest had a combination of other refractive error (astigmatism, anisometropia and emmetropia). Myopia was most frequent in the age group 11-20 years (16.7 percent) and 21-30 years (16.8 percent) and decreased in the younger and older age groups. Frequency of hyperopia increased from age 31-70 years and then decreased thereafter. Hyperopic astigmatism was more common than myopic astigmatism across all age groups.

Adolescent↗
PubMed1989

Risk factors associated with branch vs. central retinal vein occlusion.

Records of 145 consecutive central and 214 branch retinal vein occlusion (CRVO and BRVO) patients were reviewed retrospectively to determine the differences in risk factors associated with these two diseases. Mean ages and sex ratios of both groups did not differ significantly. Hypertension and hyperopia were significantly more prevalent in BRVO than in CRVO, and elevated intraocular pressure, elevated erythrocyte sedimentation rate (ESR), and a positive tuberculin skin test were significantly more prevalent in CRVO. We conclude that the causes of the ESR elevation are more significant risk factors for CRVO, and systemic hypertension and hyperopia continue to be the main risk factors for BRVO.

Age Factors↗
PubMed1988

The relationship between refractive errors and retinal detachment--analysis of 1,166 retinal detachment cases.

We compared 1,166 eyes with retinal detachment to 11,671 eyes of patients without retinal detachment in order to clarify the distribution of refraction ranges and the relative frequency in incidence of retinal detachment for each range. In the retinal detachment group, hyperopia was detected in 8.58%, emmetropia in 9.26% and myopia in 82.16%, and the corresponding ratios in the control group were 24.29%, 41.30% and 34.41%, respectively. The retinal detachment group thus exhibited a high frequency of myopia, as has been known. The relative frequency of retinal detachment for each range of refraction was 0.35 for hyperopia, 0.22 for emmetropia and 0.83 for myopia in the range -0.75 to -2.75 D. The relative frequency increased with an increase of severity in myopia up to the range of higher than -15.0 D, where the frequency was 68.6 times higher than for the hyperopic range.

Adolescent↗
PubMed1981

The eyes of young chickens grow toward emmetropia.

The distribution of refractive errors was followed in chicks from hatching to 8 weeks of age. A dramatic progressive decrease in the variability of refractions was observed over this period. In addition, there appeared to be a parallel decline in hyperopia, even when the artifactual hyperopia of retinoscopy was taken into account. These results are evidence for a postnatal development regulatory mechanisms, most likely dependent on vision, which directs growth of the eye toward emmetropia.

Animals↗
PubMed1994

[A CT study of the relation between ocular axial biometry and refraction].

Ocular biometry in 255 eyes (131 subjects) with CT scan revealed that the length of the antero-posterior axis was 23.63 +/- 0.92 mm in hyperopia, 24.62 +/- 0.38 mm in emmetropia and 26.68 +/- 0.75 mm in myopia, and the length of the horizontal transverse axis was correspondingly 24.61 +/- 0.53 mm, 24.91 +/- 0.37 mm and 25.12 +/- 0.73 mm. There were significant differences among groups of different refractions, and the axial length increased with the severity of myopia. It was evident that refractive errors were chiefly caused by the varying axial lengths. The authors propose the parameter of the ocular diametrical ratio which is the ratio of the anteroposterior axis to the horizontal transverse axis, and accordingly hyperopia has a ratio under 1, myopia a ratio over 1 and an emmetropic eye is apparently spherical with the ratio in the vicinity of 1. The authors point out that the refractive state is determined by the ocular diametrical ratio.

Adult↗
PubMed1993

[Stereoacuity and ametropia].

The stereoacuity threshold (ST) was measured in 124 cases of correctable ametropia, comprising 100 cases of myopia (-0.75 to -13.00D) and 24 cases of hyperopia (+0.87 to +5.00D). The mean ST in myopia without and with correction was 97.73" and 8.25" respectively and in hyperopia without and with correction was 21.37" and 9.74" respectively, both differing significantly from the value of 5.15" in normal eyes. The results indicated that the ametropia could have affected ST through reduced visual acuity and possibly other factors.

Adolescent↗