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PubMed2003

Blindness and vision impairment in a rural south Indian population: the Aravind Comprehensive Eye Survey.

OBJECTIVE: To determine the prevalence of blindness and vision impairment in a rural population of southern India. DESIGN: A population-based cross-sectional study. PARTICIPANTS: A total of 17200 subjects aged 6 years or older, including 5150 subjects aged 40 years or older from 50 clusters representative of three southern districts of Tamil Nadu in southern India. METHODS: All participants had preliminary screenings consisting of vision using a LogMAR illiterate E chart and anterior segment hand light examinations at the village level. Subjects aged 40 years or older were offered comprehensive eye examinations at the base hospital, including visual acuity using LogMAR illiterate E charts and refraction, slit-lamp biomicroscopy, gonioscopy, applanation tonometry, dilated fundus examinations, and automated Humphrey central 24-2 full threshold perimetry; subjects younger than 40 years of age who had any signs or symptoms of ocular disease were also offered comparable examinations at the base hospital. MAIN OUTCOME MEASURES: Visual impairment was defined as best-corrected visual acuity <6/18, and blindness was defined using both Indian (<6/60) and World Health Organization (<3/60) definitions. RESULTS: Comprehensive examinations at the base hospital were performed on 5150 (96.5%) of 5337 persons 40 years of age or older. Among those 40 years of age and older, presenting visual acuity at the <3/60 level was present in 4.3% (95% confidence interval [CI]: 3.8, 4.9) and 11.4% (95% CI: 10.6, 12.3) at the <6/60 level. After best correction, the corresponding figures were 1.0% (95% CI: 0.79, 1.2) and 2.1% (95% CI: 1.7, 2.5). Over 70% of subjects improved their vision by at least one line, and nearly a third by three lines after refraction. Age-related cataract was the most common potentially reversible blinding disorder (72.0%) among eyes presenting with blindness. CONCLUSIONS: Blindness and vision impairment remain major public health problems in India that need to be addressed. Cataracts and refractive errors remain the major reversible causes for the burden of vision impairment in this rural population.

Adolescent↗
PubMed2006

Switchable electro-optic diffractive lens with high efficiency for ophthalmic applications.

Presbyopia is an age-related loss of accommodation of the human eye that manifests itself as inability to shift focus from distant to near objects. Assuming no refractive error, presbyopes have clear vision of distant objects; they require reading glasses for viewing near objects. Area-divided bifocal lenses are one example of a treatment for this problem. However, the field of view is limited in such eyeglasses, requiring the user to gaze down to accomplish near-vision tasks and in some cases causing dizziness and discomfort. Here, we report on previously undescribed switchable, flat, liquid-crystal diffractive lenses that can adaptively change their focusing power. The operation of these spectacle lenses is based on electrical control of the refractive index of a 5-mum-thick layer of nematic liquid crystal using a circular array of photolithographically defined transparent electrodes. It operates with high transmission, low voltage (<2 Vrms), fast response (<1 sec), diffraction efficiency > 90%, small aberrations, and a power-failure-safe configuration. These results represent significant advance in state-of-the-art liquid-crystal diffractive lenses for vision care and other applications. They have the potential of revolutionizing the field of presbyopia correction when combined with automatic adjustable focusing power.

Accommodation, Ocular↗
PubMed2004

[Correction of myopia by PRK method with the use of MEL 80 excimer laser--initial report].

PURPOSE: The aim of this study was to evaluate the effectiveness of PRK procedure by estimation: changes of visual acuity, refractive errors, IOP, pachymetry, high order aberrations before and after surgery. MATERIAL AND METHODS: In the First Department and Clinic of Ophthalmology Medical School 22 patients went through ophthalmological examination for PRK procedure. In this study we used MEL 80 excimer laser. There were 13 women (15 eyes) and 5 men (7 eyes). The myopia was corrected from -1.75D till -6.5D. The patients were from 22 to 41 years of age. RESULTS: The correction for myopia by PRK method with MEL 80 excimer laser is effective and safe laser procedure. Stabilization of the refraction post photorefractive keratectomy was after 2 months and there was no increase of intraocular pressure in all cases. The procedure increased the high order aberrations.

Adult↗
PubMed1992

Vision defects in albinism.

We have examined the possible presence of color vision anomalies in 9 individuals (17 eyes, 1 blind) with fundus findings suggesting ocular albinism using the Ishihara plates, the 28-hue Roth test, and the Davico anomaloscope. Results indicate that four of these individuals show no sign of the anomalies expected in an albino in either of the two eyes. Of the remaining cases, two are simple deuteranomals in both eyes, according to Pickford's classification criteria. The rest have protanomaly; however, in these the deviation toward red appears in both eyes in only one subject, whereas in the other two subjects it appears in only one eye, their binocular color vision being basically normal. Our study shows that a large proportion of these albinos have photophobia, pendular nystagmus, strabismus, noticeable refractive errors (astigmatism and high myopia), and poor visual acuity [usually less than 6/30 (20/100) with correction]. The measurement of contrast sensitivity function (CSF) indicates that the frequency of 12 cpd cannot be perceived, even in binocular vision.

Adolescent↗
PubMed1990

Variable expressivity in X-linked congenital stationary night blindness.

X-linked congenital stationary night blindness (CSNB) is a well-documented disorder in which the most striking clinical features are impaired night vision, nystagmus and myopia. Recent reports have highlighted differing features between families, and it has been suggested that these discrepancies may be the result of two loci on the X chromosome or of two mutant alleles. We outline the clinical and visual function findings in 42 affected members from 10 families and 1 adopted person. There was a relative unawareness of the disorder in clinical practice. At least one of the main features of CSNB was absent in 75% of the patients. The visual function values varied widely, both between and within families (visual acuity 20/30 to 20/400, refractive error +1.50 to -22.50 and rod segment elevation 1.5 to 3.0 log units). The findings are consistent with a single allele exhibiting a wide variation in clinical expression.

Adolescent↗
PubMed2006

Ocular abnormalities in Apert syndrome: genotype/phenotype correlations with fibroblast growth factor receptor type 2 mutations.

BACKGROUND/PURPOSE: Apert syndrome, a disorder of craniosynostosis, syndactyly, and other craniofacial malformations, is caused by point mutations (Ser252Trp or Pro253Arg) in the fibroblast growth factor receptor 2 gene. This study's goal was to determine ophthalmic phenotype/genotype correlations in patients with either mutation. METHODS: A retrospective chart review of demographic and ophthalmologic data was performed for 18 children carrying either the S252W (11) or the P253R (7) mutation. Fisher exact tests were performed to determine significance of variable phenotypes between the two mutation groups. RESULTS: In the P253R group, 85% had strabismus (14% required surgery), 71% had ptosis, 43% had amblyopia, 14% had nasolacrimal duct obstruction, 14% had myopia, 14% had hyperopia, and 14% had astigmatism. In the S252W group, 91% had strabismus (64% required surgery), 73% had ptosis, 73% had amblyopia, 100% had nasolacrimal duct obstruction, 36% had myopia, 9% had hyperopia, and 82% had astigmatism. Overall, S252W and P253R groups showed significantly different numbers of patients with strabismus requiring surgery (p = 0.039), superior rectus muscle underaction (p = 0.024), nasolacrimal duct obstruction (p = 0.0002), and astigmatism (p = 0.005). CONCLUSIONS: Compared with patients with the P253R mutation, Apert syndrome patients with the S252W mutation may have more severe ocular phenotypes with a higher likelihood of developing strabismus, especially vertical deviation. They also are more likely to develop astigmatic refractive errors and tearing secondary to nasolacrimal system anomalies.

Acrocephalosyndactylia↗
PubMed1991

Ocular dimensions and schematic eyes of freshwater and sea turtles.

Measurements were made of the ocular dimensions from living and frozen eyes of one species of freshwater turtle, Pseudemys scripta elegans, and of three species of marine turtles, Chelonia mydas, Dermochelys cariacea, and Eretmochelys imbricata. Estimates of refractive error by retinoscopy were also obtained with eyes in air and under water. The results suggest that unaccommodated eyes of all four species are approximately emmetropic in air but strongly hyperopic in water. Schematic eyes were calculated for each species in both air and water.

Adaptation, Physiological↗
PubMed2003

The autonomic control of accommodation and implications for human myopia development: a review.

Prolonged nearwork has long been associated with myopia development, however, there is no well described linking mechanism. One theory suggests that if accommodation accuracy during nearwork is not maintained, the defocused retinal image leads to myopia development. Here we review the findings of research aimed at determining whether the autonomic inputs to the ciliary smooth muscle are involved in this type of environmental myopia. We examine whether an autonomic imbalance could be a precursor to axial elongation and the resulting myopia. Accommodation responses, such as tonic accommodation and nearwork-induced accommodative adaptation, as a function of refractive error, are described in relation to an autonomic imbalance model. The collective results of this research point to anomalous accommodation responses, possibly as a result of underlying anomalous autonomic input to the ciliary muscle, being involved in myopia development and progression.

Accommodation, Ocular↗
PubMed1983

Ocular findings among mentally retarded children in Finland.

The distribution of refractive errors, astigmatism, anisometropia, visual acuity and organic ophthalmic diseases were determined among 149 Finnish mentally retarded (IQ less than 70) children, aged 9-10 years. The case group was classified in 3 categories according to the degree of mental retardation. The control group (n = 100) was selected by random sampling.

Adolescent↗
PubMed2001

The interoccasion repeatability of intraocular pressure measurement using the Tono-Pen in a sample of school-aged children.

PURPOSE: The purpose of this study was to assess the interoccasion repeatability of the Tono-Pen XL portable applanation tonometer in school-aged children. METHODS: Thirty-one normal children were recruited from The Ohio State College of Optometry Pediatric Clinic. They ranged in age from 6 to 14 years. Intraocular pressure was measured using the Tono-Pen XL in both eyes of all subjects on two different occasions within a median of 9 days. Refractive error was measured by noncycloplegic autorefraction. Data from right eyes only are presented. RESULTS: There was no average difference in the intraocular pressure between occasions. The 95% limits of agreement between occasions were -5.58 to 4.87 mm Hg. CONCLUSIONS: The Tono-Pen XL gives reasonably repeatable readings between occasions in school-aged children.

Adolescent↗
PubMed2000

Comitant strabismus.

A review of the literature on comitant strabismus of the period from April 1999 until April 2000 is presented. A rather new and increasingly important issue is the psychosocial aspect of strabismus. Two studies have demonstrated that strabismus creates a significant negative social prejudice on the patients and that it can significantly reduce an applicant's ability to obtain employment. Subsequently, strabismus surgery can no longer be called "cosmetic". Concerning the timing of surgery in congenital esotropia, it was reported that early surgery does not ensure continued alignment, but frequently requires additional operations. The increased risk of early-onset strabismus in prematurely born children was confirmed by several studies, and the importance of regular ophthalmologic controls of all preterm infants screened for retinopathy of prematurity was stressed. It was reported that risk factors are cicatricial retinopathy of prematurity, refractive error, family history of strabismus, and poor neurodevelopmental outcome, rather than low gestational age and regressed acute retinopathy of prematurity. A number of other aspects of interest concerning exotropia, esotropia, and dissociated vertical deviation are presented in this review.

Anti-Dyskinesia Agents↗
PubMed1991

Permanent grounding and flying restrictions in Canadian Forces pilots: a 10-year review.

The medical files were reviewed of all Canadian Forces pilots in whom a permanent change in flying category was recommended during the period 1 January 1978 through 31 December 1987. In an average pilot population of 2,697 pilots, 60 permanent groundings (2.2 per thousand) and 209 permanent operational flying restrictions (7.7 per thousand) were assigned among 258 pilots. Coronary heart disease was the most common cause for permanent grounding (25% of total), followed by neurologic disorders including migraine (22% of total), other cardiovascular disorders, including mitral valve prolapse and arrhythmias (17%), and psychiatric problems (12%). Refractive errors were the most common basis for an operational flying restriction (25%), followed by orthopedic disorders (17%), mainly low back pain. The relevance of these observations is discussed in terms of medical selection and surveillance procedures.

Adult↗
PubMed1986

Reported satisfaction, fluctuation of vision, and glare among patients one year after surgery in the Prospective Evaluation of Radial Keratotomy (PERK) Study.

We studied satisfaction with the results of radial keratotomy one year after surgery on one eye as reported by 354 patients in the Prospective Evaluation of Radial Keratotomy (PERK) Study. We measured satisfaction using an index based on ten questions that were part of a longer psychometric questionnaire. Patients were generally satisfied with the results of radial keratotomy-48% were very satisfied, 42% were moderately satisfied, and 10% were dissatisfied. A lot of trouble with fluctuating vision was reported by 12% of patients before surgery and by 34% one year after surgery; 17% reported a lot of trouble with glare both before surgery and one year after surgery. The three major factors that influenced satisfaction were uncorrected visual acuity, residual refractive error, and subjective daily fluctuation in vision. A multiple regression equation that incorporated these three variables, glare, and patient sex was able to predict only 46% of the variance in patient satisfaction.

Adult↗
PubMed1976

Vision analysis and refractive status of youths in a juvenile detention home population.

Clinical optometric findings of 633 juvenile dentention youths were statistically evaluated and compared to data from the general population. The youths had a higher referral rate of refractive errors, organic problems, and muscle in balances than the general population. Female youths exhibited a higher incidence and greater severity of myopia than males at all ages. Referral rate for astigmatism among the youths was higher than the general population although the dioptric power was in agreement with previous studies.

Adolescent↗
PubMed1982

Pattern-reversal electroretinograms in squint amblyopia, artificial anisometropia and simulated eccentric fixation.

Pattern-reversal electroretinograms were recorded in 10 normals and 10 adult patients with squint amblyopia (visual acuity 0.3 or less). The effects of artificial anisometropia and simulated eccentric fixation were tested in normals. The pattern-reversal ERG amplitude was reduced linearly with increased defocusing (0 to + 3 D). A significant amplitude reduction was observed when defocusing amounted to + 1 D. The amplitudes were not reduced below the range of normal variability at 4 degrees of simulated eccentric fixation. In the amblyopia patients, refractive errors were corrected. None had eccentric fixation of more than 4 degrees. Yet, the pattern-reversal ERGs were lower in the amblyopic eyes compared with the opposite normal eyes. The difference in amplitude means was statistically significant. The finding supports the view that retinal function is impaired in human squint amblyopia.

Adolescent↗
PubMedDate not supplied

Blindness and low vision in adults in Ozoro, a rural community in Delta State, Nigeria.

BACKGROUND: The objective of this article is to determine the prevalence and causes of blindness and low vision in Ozoro, a rural town of Delta State in Nigeria, in order to provide baseline information for planning a prevention of blindness programme. METHODS: A cross sectional study using a stratified random sampling method was used to select the compounds. The five communities in the town formed the different sub-groups or strata. Visual acuity were recorded for all adults 40 years and older. Persons who had visual acuity less than 6/18 were further examined to determine the cause of low vision or blindness. The WHO definition of visual impairment according to visual acuity was used as criteria for classification. RESULTS: A total of 815 persons (coverage of 51.7%) were examined using a modified WHO PBL record of blindness form. The prevalence of blindness (VA < 3/60 in the better eye) for people of 40 years and above was 6.3% (95% CI, 4.6% to 8%) and low vision VA 6/24 to 3/60 in the better eye was 25.2%. The estimated prevalence of bilateral blindness for all ages was 1.3% and low vision was 5%. The rate of blindness and low vision increased with age being highest in subjects who were 60 years and above. The main causes of blindness and low vision were cataract, accounting for 60% of all bilateral blindness and 51.7% of all low vision. Other causes of blindness include, posterior segment diseases (11.7%). Glaucoma was presumed to be cause of blindness in 9.8% of cases; others were uncorrected aphakia 5.9%, and globe abnormalities 5.9%. Refractive error was the second major cause of low vision accounting for 22% of bilateral low vision. CONCLUSION: The magnitude of blindness and low vision in this oil rich Ozoro community in Delta State is high and majority are avoidable causes of blindness.

Adult↗
PubMed2005

The relationship between anisometropia, patient age, and the development of amblyopia.

PURPOSE: Anisometropia is a common cause of amblyopia. The relationship between anisometropia, patient age, and the development of amblyopia is unknown. Photoscreening identifies children with anisometropia in a manner that is not biased by visual acuity and allows a unique opportunity to evaluate how patient age influences the prevalence and depth of anisometropic amblyopia. METHODS: A statewide preschool photoscreening program screened 120,000 children and identified 792 with anisometropia greater than 1.0 diopter. Age was correlated with visual acuity and amblyopia depth. Data were compared with those from 562 strabismic children similarly identified. RESULTS: Only 14% (6/44) of anisometropic children aged 1 year or less had amblyopia. Prevalence was 40% (32/80) for 2-year-olds, 65% (119/182) for 3-year-olds, and peaked at 76% (age 5). Amblyopia depth also increased with age. Moderate amblyopia prevalence was 2% (ages 0 to 1), 17% (age 2), and rose steadily to 45% (ages 6 to 7). Severe amblyopia was rare prior to age 4, 9% at age 4, 14% at age 5, and 9% at ages 6 to 7. In contrast, children with strabismus had a stable prevalence of amblyopia (30% at ages 0 to 2, 42% at ages 3 to 4, 44% at ages 5 to 7). CONCLUSIONS: Younger children with anisometropic refractive error have a lower prevalence and depth of amblyopia than do older children. By age 4, when most children undergo traditional screening, amblyopia has usually already developed. New vision screening technologies that allow early detection of anisometropia provide ophthalmologists an opportunity to intervene early, perhaps retarding, or even preventing, the development of amblyopia.

Age Factors↗
PubMed2003

Refractive abnormalities in childhood.

The knowledgeable pediatrician can make a significant contribution to the management of refractive errors by aiding in the early recognition of abnormalities, making appropriate referrals, and reinforcing the ophthalmologist's recommendations to the family. If this article has focused the reader's attention and caused a few rays of light to fall on an important subject, it has achieved its purpose.

Accommodation, Ocular↗