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PubMed2006

The 10th Bielschowsky Lecture. Changes in strabismus over time: the roles of vergence tonus and muscle length adaptation.

Patients with long-standing unilateral strabismus, such as "sensory" exotropia in the absence of fusion, or esotropia with unilateral amblyopia, typically show bilateral deviations under anesthesia, often symmetric. Forced ductions usually show symmetric muscle tightness. Changes in extraocular muscle lengths thus appear to occur primarily bilaterally, whether fusion is present or not. With skeletal muscles responding to changes in stimulation by the gain or loss of sarcomeres, it is likely that abnormal or unguided vergence tonus, which changes the lengths of the extraocular muscles bilaterally, is largely responsible for changes in the angle of strabismus over time. This mechanism helps explain the development of [1] increasing "basic" deviations in accommodative esotropia; [2] torsional deviations with apparent oblique muscle "overaction/underaction" and A and V patterns; [3] recurrent esotropia with early presbyopia; [4] occasional divergence insufficiency in presbyopes; and [5] basic cyclovertical deviations that mimic superior oblique muscle paresis.

Adaptation, Ocular↗

PubMed2006

[Refractive surgery: a solution for elimination of glasses?].

Refractive surgery corresponds to all surgical methods designed for correction of refractive errors called ametropia (myopia, hyperopia, astigmatism and presbyopia). This area in ophthalmology, recently opened, is in continuous progress concerning techniques of treatment and also of diagnosis. These innovations allowed spectacular performances making possible the corrections of all refractive defaults. Two main categories can be distinguished depending on the corneal or intraocular location of the surgery. The first group includes incisions, excimer photoablation, laser thermokeratoplasty and intrastromal segments. The second group represents implantation of intraocular lens in front of natural lens (phakic IOL) or taking the place of the lens after its removal (pseudophakic IOLs).

Algorithms↗

PubMed2006

[Extent of visual impairment in a population attending an ophthalmology center in Africa. Findings in 828 cases at the Tropical Ophthalmology Institute of Africa in Bamako, Mali].

The purpose of this prospective observational study was to evaluate the extent of visual impairment in a socially and professionally active population attending the Tropical Ophthalmology Institute of Africa (IOTA). Thanks to high recruitment rate at the IOTA, which is the third reference eye centre, a total of 828 patients ranging from 18 and 50 years of age and consulting for the first time were included between February 1 and May 4, 2003. Each patient underwent a thorough ocular examination. Data were recorded using a dedicated study form. Most patients (40%) consulted for reduced visual acuity. Diagnosis determined organic disease in 75.6% of cases (626 patients) and ametropia (including presbyopia) in 18.5% (153 patients). In the remaining 6% of cases (49 patients), ophthalmic examination was normal. Bilateral blindness was observed in 5.8% of cases (48 patients). The main cause of bilateral blindness was cataract (19.2%). The third most common cause (14.6%) was ocular manifestations of HIV infection, confirming that the epidemiology of blindness is changing and that HIV/AIDS should be taken into account. Unilateral blindness accounted for 11.5% of cases (95 patients). The main causes of unilateral blindness were trauma (50.5%), infection (26%) and degenerative disease (18%). Low vision accounted for 8.5% of cases (70 patients). The main cause of low vision was ametropia. This is one of the few hospital-based studies on causes of blindness in West Africa. The major finding is the high prevalence of blinding ocular complications of HIV infection. Another important finding is the high incidence of low vision that is often disregarded in West Africa.

Adolescent↗

PubMed1991

Lens optical quality is a direct function of lens sutural architecture.

We analyzed the structural and functional relationship between lens sutures and lens optical quality (focal length variability) by correlative scanning electron microscopy (SEM) and laser scan analysis. Twenty-two rabbit lenses (8 pigmented and 14 albino) were used in this study. Lenses were initially scanned by a low-power helium-neon laser beam that was passed either at an acute angle to a lens suture or along a lens suture. The results of laser scan analysis with the incident beam passed at an acute angle to a lens suture showed that generally, rabbit lenses were well corrected for spherical aberration. Subsequent SEM analysis showed that areas of lenses scanned that produced the least amount of focal variability were characterized by uniform fiber cells arranged in parallel, radial cell columns. In contrast, the results of laser scan analysis with the incident beam passed along a lens suture showed that there was significant focal length variability, i.e., spherical aberration at the lens sutures. Subsequent SEM analysis showed that the areas of lenses scanned that produced the greatest amounts of focal variability (lens sutures) were characterized by nonuniform fiber cell ends arranged as erratic suture branches in single growth shells and collectively as erratic suture planes formed between growth shells extending from the embryonic nucleus to the lens periphery. Furthermore, the amount of focal variability was directly proportional to the degree of structural disorder at the lens sutures. This is the first study to unequivocally show that the relationship between lens optical quality and specific parameters of lens morphology (lens sutures) can be quantified. These findings may help to elucidate the pathologic changes that lead to presbyopia and cortical cataractogenesis because these lenses are characterized by asymmetrical suture patterns and planes.

Animals↗

PubMed1990

[Ophthalmologic examination of the mentally retarded at a central institution].

In 1985-86 an ophthalmologist screened 221 patients, ranging in age from six to 81, at Naerlandheimen central institution for mentally handicapped. The screening showed an alarming incidence of eye disease in this group, regardless of the etiology of the mental handicap or the patient's age. Only 44 patients had completely normal eye status without errors of refraction. 40 patients had errors of refraction only and eight had presbyopia only, but otherwise normal findings. 129 had one or more eye anomalies or diseases. There was a large incidence of cataract (52 cases), keratoconus (21 cases), strabismus (59 cases) and conjunctivitis or blepharitis (17 cases). The result emphasizes the importance of close and frequent examination of the status of the eyes of mentally retarded people throughout their lifespan.

Adolescent↗

PubMed1989

Do active substances of the thymus influence the processes of aging? I. Effects of treatment with embryonal and early fetal thymic calf extracts (ETCE) on some organs of grown-up young mice.

Our previous investigations indicated that embryonal and early fetal thymic calf extracts (ETCE), unlike those obtained from adult thymus, cause lymphopenia and hypogammaglobulinemia, counteract anaphylactic shocks and prolong the survival of allografts and xenografts in adult rodents. This paper presents the level of unsaturated fatty acid peroxides and the morphology of some organs in adult mice treated parenterally with ETCE. ETCE treatment resulted in the fall in the level of cerebral and splenic unsaturated fatty acid peroxides. Histology of thymus, liver and spleen in mice injected with ETCE remained similar to that of corresponding neonatal mouse organs. Experimental results, supplemented by such previous observations as longevity of some animals treated with ETCE, disappearance of presbyopia and climacteric symptoms in people treated with embryonal thymus per os, suggest that active substances produced by embryonal and early fetal thymus not only affect the immunological system but also interfere with the processes of organ differentiation and aging.

Aging↗

PubMed1989

[Asthenopia and objective ophthalmological findings in a population of 2058 VDT operators in Lombardy].

A large population of 2058 VDT operators from all compartments in Lombardia of a large national company was studied. An "ergophthalmological" questionnaire was administered to all subjects, followed by an ophthalmological-orthoptic examination. Ametropias showed a prevalence of 51.9%; the most common refractive defect was myopia followed by astigmatism and hyperopia. Heterophorias with bad or mediocre compensation had a prevalence of 4.1 and 11% respectively. The study of symptoms showed a frequency of 23.5% of intense asthenopic complaints and 21.1% of less severe and less frequent symptomatology. Asthenopia was significantly correlated (chi square) with sex, VDT exposure, refraction, presbyopia, and decompensated heterophorias.

Adult↗

PubMed1988

[Amplitude of accommodation in Zairian subjects].

The authors studied the amplitude of accommodation in Zairian patients who consulted the Ophthalmic Clinic of University of Kinshasa from February 24 to July 31, 1986. During this period, of 1326 Zairians seen, 159 (318 eyes) were included in this study. Patients with monocular visual acuities less than 10/10, or with ocular pathology, astigmatisms and anisometropias exceeding one diopter were excluded from the study. The mean age +/- SD was 32 years +/- 12 with a range of 10 to 58 years. There were 101 males and 58 females. The measurements were performed, once for each patient, with Osterberg Bino-Oculus apparatus according to the "push-up" method and the plus spherical method. The amplitude of accommodation decreased with the age. This decrease was more notable between 30 and 40 years. The age of onset of presbyopia calculated from the amplitude of accommodation according to the "push-up" method was 39 years. The values of the amplitude of accommodation obtained by the both methods could be superposed (p greater than 0.05). They were similar to those of black patients and were also inferior to the white patients obtained by other authors.

Accommodation, Ocular↗

PubMed1987

Eye diseases in northern Nigeria: prevalence, age and sex differences.

This study presents the prevalence, age, and sex differences of eye diseases in northern Nigeria using the records of 1677 eye hospital patients. The most common eye disease are cataract, refractive error and presbyopia, and diseases of the conjunctiva and sclera. There are no significant age and sex differences in the prevalence of most eye conditions.

Adolescent↗

PubMed1986

High degrees of astigmatism: are hydrogels the answer?

A bilateral compound hyperopic astigmat, with-the-rule, with incipient presbyopia and refractive amblyopia fitted with toric (custom) soft lenses in a monofit mode is described. Shortly after wearing the hydrogel toric lenses the patient developed a severe allergic reaction from a thimerosal based saline, which eventually resolved.

Adult↗

PubMed1979

Cataractogenous effect of hair dyes: a clinical and experimental study.

Observations based on a clinical and experimental study of the effect of hair dye (paraphenylenediamine) on the lens are reported. Two hundred individuals of either sex using hair dye were examined in detail and lenticular changes were found in 89% while only 23% in controls. The lenticular changes were related to duration, amount, and individual sensitivity to dye. Various types of lenticular opacities encountered are mentioned. In addition some individuals (7%) were found to develop early presbyopia. Experimental study which was conducted in rats and rabbits confirmed the cataractogenic effect of hair dye beyond doubt. It is concluded that hair dye is potentially toxic to the human lens.

Adult↗

PubMed1977

[Unrecognized paralyses of accommodation and their importance in diagnostics and expertise (author's transl)].

Paralyses of accommodation are safely diagnosticizable even in patients over 45 years of age provided there is no complete presbyopia. The identification can be a key to diagnosing the entire disease pattern. In one case a suspected Adie's syndrome with amblyopia and without any connection with internment and damage due to malnutrition was identified as ophthalmoplegia interna with partial atrophy of the n. opticus, most probably caused by malnutrition encephalopathy or encephalitis. In another patient, a bilateral isolated accommodation paralysis indicated damage of the accommodation center during concussion of the brain (possibly only a functional damage).

Accommodation, Ocular↗

PubMed1983

[Age and photopic and mesopic visual acuity].

Visual acuity at high luminance (100 cdm2) and at low luminance (0.8 cdm2) was measured in normal subjects aged between 20 and 50 years. A decrease of visual acuity at Low luminance was noted with increasing age whereas high luminance acuity remained unchanged (20/20). At thirty years of age, low luminance visual acuity was an average of 20/30 decreasing at 40 years to 20/40. Results were confirmed by statistical analysis. A short study with interference fringes, formed by a coherent light (neon-helium laser) produced directly on the retina and thus by-passing optical effects on the eye, suggested that the retina-brain system was responsible for decreased mesopic visual acuity, night myopia or right presbyopia not playing any part in this decrease as suggested by some authors. Consequences of these findings, concerning particularly workers at low luminance such as pilots or drivers, are discussed.

Adult↗

PubMed1983

[Visual fatigue during work associated with increased visual loading].

Visual perception is an important factor of human activity. The quality of production activity of the worker depends on its accuracy and speed. Representative groups of workers with various occupational activities, associated with considerable loading of visual system, were systematically examined by clinical and functional methods in the course of several years. A total of 765 subjects were examined, aged from 20 to 55 and a length of service from I to 25 years. The results reveal considerable alterations in visual system within one working day. The most general features of those alterations are as follows: elevation of the threshold of electric sensitivity towards the end of the working day, reduction of light-distinguishing and colour distinguishing sensitivity, the closest point of clear vision is removed father, unproper ergogram with an ascending course, reduction of fusion ability towards the end of the working day, etc. A great part of the subjects over the age of 40, were established to have uncorrected presbyopia, leading to high strain of accommodation and convergation, followed by visual fatigue. The adaptation of visual system to labour conditions is the best at the age range 25-35. The alterations in the visual function are far better manifested in the age group over 40. The determination of fatigue degree and the time of developing of the first alterations is of particular significance for the introduction of additional rest for rehabilitation.

Adult↗

PubMed1978

[Several functions of the visual analyzer in chronic alcoholic patients].

The authors examined 615 patients with chronic alcoholism. The study demonstrated an increased number of individuals with myopia, presbyopia, amblyopia, angiomas and angiosclerosis among them as compared to that of the general population. The frequency of optical nerve atrophies in the patients was not high (0.32%). In 205 cases the function of colour sensory and darkness adaptation was determined. The highest frequency of colour sensory was in the group of patients with the withdrawal syndrome. Eventually this function had a tendency towards restitution. The velocity of darkness adaptation was drastically changed in patients with chronic alcoholism but it was also reversible.

Adolescent↗

PubMed1995

[Occupational ophthalmopathy].

The authors describe a syndrome diagnosed in workers who perform tasks requiring visual strain. The syndrome comprises worse visual control, discomfort in orbital area and characteristic changes of refraction and accommodation. The young people having emmetropia and myopia demonstrate temporary and later consistent increase of refraction, and the elderly ones--decreased refraction and early development of presbyopia. In both cases marked fall of accommodation was shown. The article suggests also a possible scheme describing pathogenesis of the syndrome.

Adolescent↗

PubMed1995

Correcting lens system for perimetry.

A lens system to correct for both refractive error and perimeter test distance is frequently needed for accurate perimetry. Patients often lack appropriate near vision corrections and full aperture trial case lenses, when they are available, barely cover the central 30 degrees and hence frequently produce lens rim artefacts. A special system of correction lenses has been developed for perimetry which overcomes these problems. This system is head mounted, being based upon the Essilor presbyopia demonstration set, and is suitable for use with most perimeters.

Equipment Design↗

PubMed1994

Age-related vision changes: a primary care guide.

Visual impairment becomes more prevalent with age. A person has "low vision" when legally blind or partially sighted. In addition, many older patients have functional visual impairment that affects their ability to read, even with corrective lenses. Normal visual changes that occur with aging include presbyopia, decreased contrast sensitivity, decreased dark/light adaptation, and delayed glare recovery. The four most prevalent age-related ocular diseases are macular degeneration, open-angle glaucoma, cataract, and diabetic retinopathy. The primary care practitioner can identify patients with visual problems with a careful history and in-office tests of visual acuity. Patients with visual impairments should be referred to an eye care practitioner for a more comprehensive ocular evaluation.

Age Factors↗