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PubMed1994

Histopathological findings in failed human epikeratophakia lenticules.

Six human epikeratophakia lenticules were removed 1 to 23 months after refractive keratoplasty for aphakia (n = 2) and myopia (n = 4). The myopic group included one epi-lenticule treated with ArF-excimer laser for hyperopia. Reasons for removal were epithelial defect (n = 4), edema of host cornea (n = 1), and overcorrection (n = 1). The epi-lenticule stroma showed centrally a regular fibrillar structure with a low keratocyte density. Electron microscopy (n = 1) revealed preserved cytoplasmic organelles and nuclear appearance. Mononuclear cells were absent. Polysaccharide was demonstrated in the stroma. Bowman's layer was normal without breaks. The epithelium had variable thickness. In the peripheral wound region stromal and epithelial irregularities were evident.

Adult↗
PubMed2006

Defining myopia using refractive error and uncorrected logMAR visual acuity >0.3 from 1334 Singapore school children ages 7-9 years.

AIM: To determine the association of spherical equivalent (SE) with low uncorrected visual acuity (VA) along with a proposed definition for myopia using logMAR VA >0.3 as the criteria. METHODS: 1334 Chinese schoolchildren (mean age 7.8; range 7-9 years) were enrolled in the study after those who had hyperopia > or =+2.00 dioptres (D) and astigmatism > = -2.00 D were excluded. Uncorrected logMAR VA was measured for both eyes. Cycloplegia autorefraction was achieved by the instillation of three drops of 1% cyclopentolate 5 minutes apart. The average of five successful consecutive refraction and keratometry readings were obtained with calibrated Canon RK5 autokeratorefractometers by well trained optometry students, at least 30 minutes after the instillation of the third drop of cyclopentolate. SE cut-off points (-0.25 D, -0.5D, -0.75 D, -1.0 D) were evaluated. RESULTS: Using different SE cut-off points, the myopia prevalence rates of this sample of schoolchildren varied from 45.8% (SE at least -0.25 D) to 30.7% (SE at least -1.0 D). The cut-off point of > or =-0.75 D had a sensitivity and specificity of 91.8% (95% CI, 89.2 to 94.4) and 93.7% (95% CI, 92.1 to 95.3), respectively, to predict low vision defined as uncorrected logMAR VA > 0.3 (either eye). The next best cut-off point of -0.5D had a higher sensitivity (93.3%), but lower specificity (87.9%). CONCLUSIONS: The cut-off points of -0.75D and -0.5D in SE refraction are appropriate for the prediction of uncorrected logMAR VA worse than 0.3, which is the criterion for the US common state adult driver licensing standard.

Child↗
PubMed2006

Refractive outcomes after cataract surgery with primary lens implantation in infants.

AIMS: To show the refractive outcomes, accuracy of intraocular lens power selection, and visual outcomes and complications in infants undergoing cataract surgery. METHODS: The refraction (spherical equivalent) of 14 operated eyes in 8 children aged <1 year was plotted over time. Preoperative and final recorded visual acuities were assessed. RESULTS: The median follow-up was 37.25 months. The median initial postoperative refraction was (+)6.75 dioptres. CONCLUSIONS: Refractive outcomes for each eye were not entirely predictable and were variable between infants. However, there was a consistent pattern in each infant who underwent bilateral surgery, with both eyes following a similar pattern of refractive change with time: a decreasing myopic shift was seen in 8 eyes, possibly demonstrating emmetropisation. The two unilateral cases appeared to show a linear myopic shift. 4 eyes in 2 patients did not follow a myopic shift curve and one of these patients showed an early trend towards increased hyperopia. Definite causes for this erratic refractive change were not identified. A postoperative refraction >4.5 dioptres avoided early onset myopia. The range of difference between postoperative and predicted refraction using SRK-T was (-)2.85 to 2.97 dioptres. Most of the visual results are encouraging compared with historical data in older children.

Cataract↗
PubMed2006

Prevalence and causes of visual impairment and blindness in Sistan-va-Baluchestan Province, Iran: Zahedan Eye Study.

AIM: To determine the prevalence and causes of visual impairment and blindness in the Sistan-va-Baluchestan Province of Iran. METHODS: A population-based cross-sectional study with a multistage cluster sampling technique was used to identify the study subjects. Visual acuity (VA) was defined for all participants aged >or=10 years. Participants with a VA of <20/60 were examined by an ophthalmologist to determine the causes of low vision or blindness. RESULTS: 5446 (84.0%) of the invited people were examined. The prevalence of visual impairment (VA <20/60) was 6.81% (95% CI 5.91% to 7.71%) and of bilateral blindness (VA <3/60) was 0.79% (95% CI 0.50% to 1.08%). Visual impairment increased with age and illiteracy. Bilateral blindness doubled in women aged >40 years. The causes of visual impairment and blindness were cataract (37.7%), corneal opacity (15.0%), amblyopia (15.0%), glaucoma (5.7%) and hyperopia (5.0%). 39.5% of the visual impairment cases were potentially curable. CONCLUSION: The estimated magnitude of visual impairment and blindness was much higher than our expectations. Further investigation of the pattern of vision loss in women and children, particularly as a result of trachoma and amblyopia, is warranted. Implementation of measures to treat curable cases of the study population can improve the situation in the region dramatically.

Adolescent↗
PubMed1980

Photogrammetry experiments with a model eye.

Digital photogrammetry was performed on stereophotographs of the optic nerve head of a modified Zeiss model eye in which optic cups of varying depths could be simulated. Experiments were undertaken to determine the impact of both photographic and ocular variables on the photogrammetric measurements of cup depth. The photogrammetric procedure tolerates refocusing, repositioning, and realignment as well as small variations in the geometric position of the camera. Progressive underestimation of cup depth was observed with increasing myopia, while progressive overestimation was noted with increasing hyperopia. High cylindrical errors at axis 90 degrees led to significant errors in cup depth estimates, while high cylindrical errors at axis 180 degrees did not materially affect the accuracy of the analysis. Finally, cup depths were seriously underestimated when the pupil diameter was less than 5.0 mm.

Astigmatism↗
PubMed1996

Role of epithelial hyperplasia in regression following photorefractive keratectomy.

AIM: To determine the relation between epithelial hyperplasia and regression of effect after photorefractive keratectomy (PRK). METHODS: Seventy unilaterally treated patients with PRK were examined. All eyes had been treated with the Summit excimer laser 27 (SD 7) months previously with zone diameters of 4.1 to 5.0 mm. The untreated fellow eyes served as controls. Epithelial thickness was measured centrally with a thin slit optical pachometer and manifest subjective refraction was performed. RESULTS: The epithelium was 21% thicker in the treated eye (p < 0.0001). The relation between refractive regression and epithelial hyperplasia was significant (r = 0.41; p < 0.001). CONCLUSIONS: Epithelial hyperplasia after PRK correlated with the myopic shift (including hyperopia reduction) after treatment with the Summit laser. A model is proposed suggesting that both subepithelial and epithelial layers contribute to regression in the Summit treated eyes with 18 microns of epithelial hyperplasia contributing each dioptre of regression.

Adult↗
PubMed2001

Ophthalmic manifestations of tuberous sclerosis: a population based study.

BACKGROUND/AIMS: Tuberous sclerosis complex (TSC) has retinal and non-retinal ophthalmic manifestations. This study was designed to determine the prevalence of the ophthalmic manifestations and of refractive errors in a population of patients with TSC. METHODS: 179 patients identified were in a prevalence study of TSC in the south of England and 107 of these agreed to full ophthalmic examination which was successful in 100. Ophthalmic examination included examination of the eyelids, cover test, examination of the irides, dilation funduscopy using both direct and indirect ophthalmoscopy, and refraction using retinoscopy. Myopia was defined as a spherical equivalent <-0.5D and hyperopia as a spherical equivalent >+0.5D. RESULTS: Retinal hamartomas were seen in 44 of the 100 patients. The commonest morphological type of hamartoma seen was the flat, translucent lesion in 31 of the 44 patients (70%). The multinodular "mulberry" lesion was seen in 24 of the 44 patients (55%) and the transitional type lesion was seen in four of the 44 patients (9%). Punched out areas of retinal depigmentation were seen in 39 of the 100 patients but only six of 100 controls. 27% of eyes were myopic, 22% were hyperopic, and 27% had astigmatism >0.75D. Of the non-retinal findings, 39 patients had angiofibromas of the eyelids, five had non-paralytic strabismus, and three had colobomas. CONCLUSION: Apart from the higher prevalence of flat retinal hamartomas, the findings of this study compare closely with previous large clinic based series of TSC patients. Refractive findings were similar to previous studies of a similarly aged non-TSC population. This is the first series to document the statistically significant association of punched out chorioretinal depigmentation with TSC and the authors believe that it should be looked for as an aid to diagnosis.

Adolescent↗
PubMed2002

Emmetropisation following preterm birth.

BACKGROUND/AIMS: Even in the absence of retinopathy of prematurity (ROP), premature birth signals increased risk for abnormal refractive development. The present study examined the relation between clinical risk factors and refractive development among preterm infants without ROP. METHODS: Cycloplegic refraction was measured at birth, term, 6, 12, and 48 months corrected age in a cohort of 59 preterm infants. Detailed perinatal history and cranial ultrasound data were collected. 40 full term (plus or minus 2 weeks) subjects were tested at birth, 6, and 12 months old. RESULTS: Myopia and anisometropia were associated with prematurity (p<0.05). More variation in astigmatic axis was found among preterm infants (p<0.05) and a trend for more astigmatism (p<0.1). Emmetropisation occurred in the preterm infants so that at term age they did not differ from the fullterm group in astigmatism or anisometropia. However, preterm infants remained more myopic (less hyperopic) than the fullterm group at term (p<0.05) and those infants born <1500 g remained more anisometropic than their peers until 6 months (p<0.05). Infants with abnormal cranial ultrasound were at risk for higher hyperopia (p<0.05). Other clinical risk factors were not associated with differences in refractive development. At 4 years of age 19% of the preterm group had clinically significant refractive errors. CONCLUSION: Preterm infants without ROP had high rates of refractive error. The early emmetropisation process differed from that of the fullterm group but neither clinical risk factors nor measures of early refractive error were predictive of refractive outcome at 4 years.

Anisometropia↗
PubMed2002

Factors associated with undercorrected refractive errors in an older population: the Blue Mountains Eye Study.

AIMS: To identify characteristics of people with clinically relevant undercorrected refractive errors. METHODS: The Blue Mountains Eye Study was a population based survey of 3654 Australians aged 49-97 years. Examinations included a standardised refraction and measurement of presenting and best corrected visual acuity. Clinically relevant undercorrected refractive error was defined as improvement of >/=10 letters (2+ lines on the logMAR chart) in subjects with presenting acuity 6/9 or worse. Associations with a range of demographic and ocular variables were explored, adjusting for age and sex, presented as odds ratios (OR) with 95% confidence intervals (CI). RESULTS: Undercorrected refractive error was present in 814/3654 subjects (10.2%). Older age (p <0.001), hyperopia (OR 1.45, CI 1.15 to 1.83), longer interval from last eye examination (p <0.001), past occupation as tradesperson (OR 1.64, 1.13 to 3.29) or labourer (OR 2.00, CI 1.39 to 2.89), receipt of government pension (OR 1.47, CI 1.12 to 1.94), and living alone (OR 1.34, CI 1.05 to 1.72) were all associated with undercorrected refractive error. Past or current use of distance glasses (OR 0.25, CI 0.20 to 0.32) and driving (OR 0.67, CI 0.52 to 0.86) were associated with a lower prevalence. CONCLUSIONS: Increasing age and measures of socioeconomic disadvantage and isolation were found to predict undercorrected refractive error. Given the documented impacts from correctable visual impairment, these findings suggest a need to target education and eye care services.

Age Factors↗
PubMed2002

Risk factors for nuclear lens opacification: the Reykjavik Eye Study.

PURPOSE: The purpose of this study is to examine risk factors for nuclear lens opacification in citizens of Reykjavik. METHODS: 1,045 persons, 583 females and 462 males aged 50 years and older, were randomly sampled and underwent a detailed eye examination and answered a questionnaire. In all Scheimpflug photography of the anterior eye segment was done including the lens as well as retroilluminated photography of the lens. These photographs were used for the diagnosis of lens opacification. The data was analyzed using a logistic regression model. RESULTS: An increased risk for all grades of nuclear opacifications was found with ageing (OR = 1.228, 95% CI = 1.192-1.264, p = 0.000), cigarette smoking for more than 20 pack/years (OR = 2.521, 95% CI = 1.521-4.125, p = 0.000) and pipe or cigar smoking (OR = 2.478, 95% CI = 1.200-5.116, p = 0.014). Outdoor exposure, cortical lens opacification grade II and III and computer usage were not found to be linked to higher risk of nuclear opacification. No correlation was found between nuclear opacification and the consumption of vitamins, herring, sardines and shrimps, cod-liver oil or plant oil, nor were iris color, hyperopia, systemic steroid use, cardiovascular disease, diabetes, glaucoma and pseudoexfoliation found to have a significant effect. CONCLUSIONS: Ageing is a major risk factor for nuclear lens opacification, and smoking is a major modifiable risk factor. Cortical and nuclear lens opacifications do not share the same modifiable risk factors.

Aged↗
PubMedDate not supplied

A retrospective analysis of five intra-ocular lenses and the predictive value of six different intra-ocular lens power calculation formulas.

PURPOSE: To evaluate the refractive and visual outcome after implantation of five different lenses and to evaluate the accuracy of six different intra-ocular lens (IOL) power formulas. SETTING: Department of Ophthalmology, University Medical Centre Rotterdam, The Netherlands. METHODS: In total, 288 eyes had cataract surgery with implantation of a polymethylmethacrylate lens (Centra55B) or a foldable silicone lens (AMO SI40, Staar AA, Silens 5, Pliolens). The pre- and postoperative refraction and visual outcome were analysed for all lenses under study. Six different IOL power formulas have been used to compare the accuracy of the predictive refractive outcome. RESULTS: The Staar Plate Haptic lens was found to have the best uncorrected visual acuity (UCVA) compared to the Centra55B, AMO SI40 and the Pliolens. Based on the A constant given by the company, the Pliolens revealed a significant overcorrection and the Staar Plate Haptic lens an undercorrection. The achieved postoperative refraction minus the intended postoperative refraction caused significant myopia with the Pliolens and hyperopia with the Staar Plate Haptic lens. The SRK-T and the Holladay formulas give the best predictive lens calculations in relation to the axial length. CONCLUSION: The A constant of all lenses has to be adjusted for our institute. Especially the AMO SI40, the Staar AA lens and the Silens 5 showed a remarkable difference compared to the A constant given by the company. All foldable lenses were comparable in their visual outcome. The significantly better UCVA of the Staar Plate Haptic lens can be explained by the emmetropic outcome of the postoperative refraction.

Aged↗
PubMed1977

An ectodermal dysplasia syndrome of alopecia, onychodysplasia, hypohidrosis, hyperkeratosis, deafness and other manifestations.

A girl is reported with a hitherto apparently undescribed ectodermal dysplasia syndrome. The main findings include: alopecia, onychodysplasia, hypohidrosis, sensorineural deafness, skin with a tan color and hyperkeratosis (involving also plams and soles), unusual facies (with slight auricle and nose abnormalities), pectus excavatum, severe hyperopia, EEG abnormalities, and retarded bone age. The patient also presents mongoloid palpebral slanting, narrow palpebral fissures, bilateral esotropia, photophobia and dermatoglyphics with extensive ridge dissociation. The etiology is unknown but presumed to be genetic, possibly due to the homozygous state of an autosomal recessive mutation.

Alopecia↗
PubMed1985

Clinical observations concerning choroidal folds.

This paper deals with 6 patients who suffer from choroidal folds. Special emphasis will be laid on several aspects of differential diagnostics. In our 6 cases discussed here, we found a retrobulbar tumor in 3 patients, hypotony in 1, and a marked hyperopia in another as causes. In the 6th patient no pathological condition was found, and, therefore, we characterized the choroidal folds in this case as idiopathic.

Aged↗
PubMed2003

Identification of infants with significant refractive error and strabismus in a population screening program using noncycloplegic videorefraction and orthoptic examination.

PURPOSE: The second Cambridge Infant Vision Screening Program examined whether screening for accommodative errors by using videorefraction without cycloplegia could effectively serve as a first stage of screening for refractive errors, measured by standard cycloplegic retinoscopy. The screening also included an orthoptic examination for detection of strabismus. METHODS: All infants born in the Cambridge (UK) Health District, over a 2-year period, were invited for screening. Of those 5142 (76%) with mean age 8.1 +/- 0.8 months (SD) attended and received noncycloplegic videorefraction and an orthoptic examination. All those with a focusing error or orthoptic problem, as well as a randomly selected sample of visually normal control subjects, were invited to follow-up a month later for cycloplegic retinoscopy, repeat noncycloplegic videorefraction and orthoptic examination. RESULTS: Of the 5142 screened, 514 had a focusing error or orthoptic problem (positives). Four hundred thirty-nine of these and 284 visually normal control subjects (negatives) attended follow-up. A refractive or orthoptic condition was confirmed in 59.0% of the positive cases, whereas infants in 96.8% of the negative cases were confirmed normal. Adjusting for the proportions of the population represented by those infants seen at follow-up, sensitivity for the screening procedure was calculated at 0.67 and specificity at 0.96. Detailed results are presented in terms of the different conditions detected at screening (far, near, and anisometropic focus and orthoptic error), distribution of greatest axes at screening, and a comparison of initial videorefraction with repeat videorefraction and cycloplegic retinoscopy. CONCLUSIONS: A noncycloplegic screening procedure, simpler to perform than cycloplegic screening, succeeded in detecting a large proportion of infants with significant ametropia, particularly those with significant hyperopia, which is considered to be a strabismogenic and amblyogenic risk factor.

Accommodation, Ocular↗
PubMed2003

Ocular measurements throughout the adult life span of rhesus monkeys.

PURPOSE: To examine the relationship of ocular components to refraction throughout the adult life span of the rhesus monkey (Macaca mulatta). METHODS: Cycloplegic retinoscopy, A-scan ultrasonography, slit lamp examination, indirect ophthalmoscopy, and keratometry were performed in a cross-sectional study of 111 monkeys, aged 5 to 31 years. Lens thickness and anterior and vitreous chamber depths were measured from the echograms. The intercorrelations of these variables were analyzed, as well as their association with age and sex. RESULTS: In monkeys aged 5 to 15 years, the mean refractive value of +1.5 D with an SD of 1.7 D was maintained near the previously established developmental asymptote of +2 D. In monkeys older than 15 years, there was greater interindividual variation (SD = 4.5 D), including extreme myopia and hyperopia. The cornea became steeper with age. The axial length of the eyes increased up to 12 years of age and began to shorten after 20 years. Changes also occurred in the other individual components that constitute eye length. These age-related changes were decreased vitreous chamber depth, decreased anterior chamber depth, and increased lens thickness. In general, males had longer eyes than females. The eyes of old monkeys were more likely to exhibit cataract and drusen, but age-related changes in focal atrophy of the retinal pigment epithelium did not achieve statistical significance. CONCLUSIONS: The components of the monkey eye change with age in a pattern similar to that reported in humans. Age-related changes in individual ocular components that could be detrimental to refraction appear to be compensated for by changes in other components.

Aging↗
PubMed2005

Support for polygenic influences on ocular refractive error.

PURPOSE: Refractive errors, myopia, and hyperopia are common conditions requiring corrective lenses. The familial clustering of myopia has been well established. Several chromosomal regions have been linked to high myopia (12q, 17q, and 18q), to quantitative refraction among twins (3q, 4q, 8p, and 11p), and to families with moderate myopia (22q). This study examined the familial aggregation and pattern of inheritance of ocular refraction in an adult population, by using data from the Beaver Dam Eye Study. METHODS: Familial correlations were examined and segregation analysis was performed on the average refractive error measurements in the right and left eyes after adjustment for age, sex, and education. Analyses were based on 2138 individuals in 620 extended pedigrees with complete data on age, sex, education, and spherical equivalent. RESULTS: Substantial positive correlation was found between siblings (0.33), parents and offspring (0.17), and cousins (0.10) and lower correlation among avuncular pairs (0.08) after adjustment for age, sex, and years of education. The results of this segregation analysis do not support the involvement of a single major locus throughout the entire range of refractive error. However, models allowing for familial correlation, attributable in part to polygenic effects, provided a better fit to the observed data than models without a polygenic component, suggesting that several genes of modest effect may influence refractive error, possibly in conjunction with environmental factors. CONCLUSIONS: These results support the involvement of genetic factors in the etiology of refractive error and are consistent with reports of linkage to multiple regions of the genome.

Family Health↗
PubMed2005

Axial growth and changes in lenticular and corneal power during emmetropization in infants.

PURPOSE: To evaluate the contribution made by the ocular components to the emmetropization of spherical equivalent refractive error in human infants between 3 and 9 months of age. METHODS: Keratophakometry in two meridians was performed on 222 normal-birthweight infant subjects at 3 and 9 months of age. The spherical equivalent refractive error was measured by cycloplegic retinoscopy (cyclopentolate 1%). Anterior chamber depth, lens thickness, and vitreous chamber depth were measured by A-scan ultrasonography over the closed eyelid. RESULTS: Both the mean and SD for spherical equivalent refractive error decreased between 3 and 9 months of age (+2.16 +/- 1.30 D at 3 months; +1.36 +/- 1.06 D at 9 months; P < 0.0001, for the change in both mean and SD). Average ocular component change was characterized by increases in axial length, thinning, and flattening of the crystalline lens, increases in lens equivalent refractive index, and decreases in lens and corneal power. Initial refractive error was associated in a nonlinear manner with the change in refractive error (R(2) = 0.41; P < 0.0001) and with axial growth (R(2) = 0.082; P = 0.0005). Reduction in hyperopia correlated significantly with increases in axial length (R(2) = 0.16; P < 0.0001), but not with changes in corneal and lenticular power. Decreases in lenticular and corneal power were associated with axial elongation (R(2) = 0.40, R(2) = 0.12, respectively; both P < 0.0001). CONCLUSIONS: Modulation in the amount of axial growth in relation to initial refractive error appeared to be the most influential factor in emmetropization of spherical equivalent refractive error. The associations between initial refractive error, subsequent axial growth, and change in refractive error were consistent with a visual basis for emmetropization. The cornea and crystalline lens lost substantial amounts of dioptric power in this phase of growth, but neither appeared to play a significant role in emmetropization.

Accommodation, Ocular↗
PubMed2005

Refractive error, ocular biometry, and lens opalescence in an adult population: the Los Angeles Latino Eye Study.

PURPOSE: To characterize age- and gender-related differences in refractive error, ocular biometry, and lens opalescence (NOP) in a population-based sample of adult Latinos. Also assessed were the determinants of age-related refractive differences. METHODS: Participants in the Los Angeles Latino Eye Study (LALES), a population-based study of Latinos aged 40 years and more, underwent an ophthalmic examination, including ultrasonic measurements of axial length (AL), vitreous chamber depth (VCD), anterior chamber depth (ACD), lens thickness (LT), and noncycloplegic automated and subjective refraction. Corneal curvature/power (CP) was measured using an autorefractor. NOP was graded at the slit lamp by an ophthalmologist using the Lens Opacity Classification System II. Age- and gender-related differences were calculated. Multiple regression models were used to identify the determinants of age-related refractive differences. RESULTS: Of the 6357 LALES participants, 5588 phakic individuals with biometric data were included in this analysis. Older individuals had shallower ACDs, thicker lenses, more NOP, and more hyperopia compared to younger individuals (P < 0.001). There was no age-related difference in AL (P > or = 0.05). Women had significantly shorter AL, shallower ACD and VCD, than did men (P < or = 0.01). The strongest determinants of refractive error were AL (primarily VCD) and CP. NOP was a small but significant determinant of refractive error in older individuals. CONCLUSIONS: Age- and gender-related differences in ocular biometric, refractive error, and NOP measurements are present in adult Latinos. While the relative contribution of NOP in determining refractive error is small, it is greater in older persons compared to younger individuals.

Adult↗