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At least 1,189 records · Page 66Linked to original sources
PubMed1991

[On factors related to the width of anterior chamber angle--multivariate analysis of biometrically determined values].

Primary angle-closure glaucoma (PACG) is associated with certain biometric ocular features such as shallow anterior chamber, axial hyperopia, increased thickness of the lens and small corneal diameter. The vast majority of previous studies on PAGG has shown that females are affected more frequently than males. In an attempt to study the relationship between the angle width and ocular dimensions, we carried out gonioscopic examination and biometric measurements (corneal diameter, corneal radius, anterior chamber depth, lens thickness, relative lens position and axial length) in 1,169 eyes of 585 adult subjects who participated in the glaucoma screening in Gifu Prefecture. It was found that the angle width significantly correlated with each biometric value. The coefficient of determination calculated by multiple regression analysis was 0.41, suggesting that factors other than these are involved in determining the angle width. When the angle width of females was compared to that of males with identical refractive errors and biometric values, the angle width of females was significantly narrower than that of males. Hence, the difference in ocular dimensions does not adequately explain the higher incidence of narrow angle in females. Increased asymmetry of angle width between a pair of eyes with aging appeared to be related to asymmetry of lens thickness, anterior chamber depth and lens position.

Adult↗
PubMed1991

[Four cases of Cockayne syndrome].

The evaluation of four patients with Cockayne syndrome (CS) by computed tomography (CT) and magnetic resonance imaging (MRI) is reported. All patients had characteristic clinical manifestations of CS. In a special respect, we found hyperopia in two patients and previous habitual abortions in two maternal histories. Extrapyramidal signs were seen in one patient. Three patients are type 1 CS (case 1, 3, 4) and one patient (case 2) is type 2 CS (congenital form). The cranial CT in two patients (case 1, 2) revealed prominent calcifications in basal ganglia, dentate nucleus and hemispheric white matter. While CT showed vagal calcifications in basal ganglia in other two patients (case 3, 4), T2-weighted MRI revealed obvious low intensity area in putamen and caudate nucleus, and high intensity area in the white matter. Sagittal section revealed atrophic changes of cerebellar vermis and brain stem. Thus it seems that MRI may be useful diagnostic adjunct in CS patients.

Brain↗
PubMed1991

[Ocular changes in the Williams-Beuren syndrome].

One of the signs of Williams-Beuren syndrome are typical opthalmological findings. In a group of 13 patients with this disease, in 7 esotropia was detected, in 8 a star-shaped iris and in 9 hyperopia. Three children had yellowish opalescent spots in the stroma of the cornea and in one patient cataracta punctata was found. A tortuous course of the retinal vessels was found in three patients, incl. two with elevated arterial pressure. Detection of these ophthalmological changes can contribute to the correct diagnosis of Williams-Beuren's syndrome.

Abnormalities, Multiple↗
PubMed1991

[Incidence of refraction errors in Polish physicians].

An extensive inquiry sheet comprising between others questions on refraction had been sent by post to doctors chosen by chance. The incidence of myopia in the general population was estimated on 23.1-27.7 p.c. in men and 26.0-34.4 p.c. in women. The incidence of hyperopia--distinctly dependent on the age of the addressee--was 1/3 smaller; astigmatism showed to be the least frequent. No essential connection between the kind of error and the anthropometric characteristics, morbidity and the type of personality was found.

Adult↗
PubMed1990

[Epikeratophakia].

Since its introduction by Kaufman in 1979, epikeratophakia has been used successfully in several thousands of patients for the correction of refractive errors. With this technique the original curvature of the cornea is changed by suturing onto it a preshaped lenticule. Depending on the different types of refractive errors to be corrected, the tissue lens is a plus lens (aphakia, hyperopia), a minus lens (myopia), or a plano lens (keratoconus). Both prelated, lyophilized tissue lenses and freshly cut lenticules have been employed with good results. However, the simplicity of the surgical technique, as well as the possibility of rejection of fresh corneal tissue, has made use of the former type of epikeratophakia lenses much more common. The basic indication for epikeratophakia is the incapability of correcting refracting errors with conservative methods, such as glasses, contact lenses or, in cases of aphakia, intraocular lenses. The results obtained in a series of 71 patients who underwent epikeratophakia at our Institute compare favorably to those reported in the literature. Following are some of the factors we identified as being responsible for our improved results: (1) the performance of all surgical procedures by the same corneal surgeon; (2) a longer hospitalization period and thereby closer observation of all patients and possible detection of early complications; (3) long-term postoperative follow-up examinations of all patients by the operating surgeon. In summary, epikeratophakia has been shown to be a safe, effective and potentially reversible procedure for the correction of refractive errors.

Cornea↗
PubMed1990

Experimental myopia in tree shrews.

When deprived of form vision during postnatal development, tree shrews reliably develop an axial myopia characterized by elongation of the vitreous chamber, zonular dysplasia and a slight reduction in lens weight and thickness. Corneal flattening has been observed in animals visually deprived by eyelid suture but is absent in animals visually deprived with an opaque goggle. The sensitive period for myopia development starts about 15 days after the eyes open and sensitivity remains high for about 3-4 weeks thereafter. Recovery from experimental myopia can occur in tree shrews that are visually deprived using goggles for a short period. Blockade of action potentials from ganglion cells in deprived eyes by intravitreal injections of tetrodotoxin (TTX) does not prevent the development of myopia, suggesting that local retinoscleral mechanisms can contribute to experimental myopia in this species. Open eyes receiving intravitreal injections of either saline or TTX have shorter vitreous chambers than control eyes, suggesting that puncturing the globe reduces forces within the eye that contribute to its expansion. Animals treated intraperitoneally with lathyritic agents to block collagen cross-linking for three weeks during a 75-day period of monocular visual deprivation develop a very large myopia in the visually deprived eye that is accompanied by a large vitreous chamber elongation and marked thinning of the posterior sclera. The results from studies in tree shrews are consistent with the suggestion that an internally driven expansion acts in concert with ocular growth to increase the axial length of the eye, helping to move the eye from hyperopia toward emmetropia. The resistance of the sclera and/or choroid to this expansion may be affected by activity within the retina. Increased retinal activity associated with achieving a clear image on the retina may result in increased resistance to expansion, helping to hold the retina at the focal plane. Recovery may occur by a slowing of axial expansion while the optical surfaces proceed toward adult values.

Aminopropionitrile↗
PubMed1990

Bilateral macular holes in sporadic posterior microphthalmos.

The authors report an unusual sporadic case of bilateral posterior microphthalmos in an 8-year-old Chinese girl. Cycloplegic refraction showed hyperopia of 12.5 diopters in both eyes. Anterior segment examination showed normal corneal diameters, open angles, and normal lens thicknesses. Ultrasonography showed short vitreous compartments resulting in short axial lengths of 17.2 mm. Fundoscopy showed full-thickness macular holes associated with radiate retinal striae. This is the first report of bilateral macular hole formation in sporadic posterior microphthalmos. The literature is reviewed.

Child↗
PubMedDate not supplied

Corneal steepening in human eye bank eyes by combined hexagonal and transverse keratotomy.

An interrupted 5 mm diameter hexagonal keratotomy was modified to include six paracentral transverse incisions to augment the central corneal steepening. This combined modified-hexagonal and transverse (or hexagonal-transverse) keratotomy was performed on human eye bank eyes to an estimated 85% corneal depth yielding a mean of 7.50 +/- 1.69 diopter increase in central keratometric power (P less than .001); this finding was confirmed by keratography. These results encourage further studies of this procedure and its potential to surgically correct mild amounts of hyperopia.

Analog-Digital Conversion↗
PubMed1990

[The theoretical bases of refractogenesis].

Analysis of results after theoretic and experimental investigations of structural organization of vegetative nervous system, mechanisms of accommodation and its bioregulation allowed to make a conclusion that refractogenesis is formed under the influence of a double reciprocal principle of innervation and regulation (DRP) of effector apparatus of accommodation. According to the author's view, DRP ontogenesis, being genetically determined and characterized by individual character of development, has a decisive influence on the process of refraction formation. The latter is expressed in the fact that in prevailing activity of cholinergic component over adrenergic in their DRP, refraction is orientated towards myopia, and in prevailing activity of adrenergic component over cholinergic, on the contrary, towards hyperopia.

Accommodation, Ocular↗
PubMed1990

Prospective assessment of acuity and stereopsis in amblyopic infantile esotropes following early surgery.

Sensory and motor status were evaluated prospectively in a group of 84 infantile esotropes with fixation preference. Treatment consisted of part-time occlusion therapy, spectacles for bilateral hyperopia of 3.0 diopters or more and bimedial rectus recession. Successful occlusion therapy was associated with both a decrease in fixation preference and a "trade-off" in grating acuities of preferred and nonpreferred eyes. Three patients responded to occlusion therapy and spectacles alone; the remaining patients were treated surgically before their first birthday. Adequate alignment was achieved in over 75% of patients. During a mean follow-up of 28 months, 31 patients required further surgery to maintain horizontal and/or vertical alignment. Following occlusion therapy and surgery, acuity development proceeded normally. Postoperatively, approximately 35% of patients had at least gross stereopsis with random dot stereograms.

Amblyopia↗
PubMed1990

Rotational characteristics and stability of soft toric lenses.

Toric soft contact lenses of a double slab-off design were fitted to 72 patients (128 days) with varying refractive requirements. Rotational characteristics and lens stability were studied as related to sphere power, cylinder power, and axis orientation. The patients were followed over a 1-month period. Although rotation of all lenses was skewed nasally, the total number of all lenses showing no rotation or temporal was somewhat greater than those with nasal rotation. In addition lenses of oblique axis displayed the least amount of rotational instability. Finally this study suggests some differences when comparing the rotational characteristics between with-the-rule and against-the-rule astigmatism correction, low vs. high myopia, and myopia vs. hyperopia.

Adult↗
PubMed1990

[Clinical findings and trace metals (zinc & copper) in Leber's congenital amaurosis].

Sixteen (16) patients of Leber's congenital amaurosis diagnosed with ERG all had nystagmus since infancy; 9 cases showed the digito-ocular sign and 15 had axial hyperopia on cycloplegic refraction and/or A-scan ultrasonography. The common ophthalmoscopic findings were narrow vessels, grayish coloration and pigmentation in the retina. The average serum zinc level of 12 cases was significantly lower than that of the controls, while the copper level differed not much. The results suggest that it is advisable for the child patients to receive cycloplegic refraction and proper spectacle correction as early as possible, and zinc therapy.

Adolescent↗
PubMed1990

[X-chromosomal congenital retinoschisis. Clinical aspects and electrophysiology].

We evaluated retrospectively the clinical records and electrophysiological results of 52 patients suffering from X-linked congenital retinoschisis. Characteristic clinical findings were hyperopia (mean +2.3 +/- 3.1 D), reduced visual acuity (mean 0.24 +/- 0.2) and always macular pathology. Peripheral retinoschisis was present in 53% of the eyes. The natural course of the disease was normally stable. Complications were visual loss in 9.3%, vitreous hemorrhages in 4.7% and retinal detachments in 10.7% of the eyes. These complications generally occurred within the first decennium. Prophylactic laser coagulation was of no use because it was complicated by retinal detachment in 43% of our series. The electrooculogram was usually normal. In addition to the known electroretinographic findings of a low normal a-wave and reduced b-wave amplitudes, we found prolonged b-wave latencies and implicit times.

Adolescent↗
PubMed1990

Present status of radial keratotomy myopia surgery: aerospace considerations.

Radial keratotomy (RK) is one of several corneal surgery operations recently developed to change the refraction of the eye. RK consists of four to eight deep radial incisions extending from the corneal edge to a small central optical zone, which flattens when the corneal scars heal. This decreases the myopia, or excess corneal dioptric power by 2.00 to 6.00 diopters. The draw-backs of RK for aviators consists of the following problems and side effects: 1) several ocular surgical complications, which may cause loss of vision; 2) glare and dazzle inflight effects; 3) imprecise and unpredictable results; 4) diurnal change of refraction and vision; 5) residual regular and irregular astigmatism; 6) a decrease of best corrected vision; 7) late progressive hyperopia; and 8) greater susceptibility to aggravated ocular trauma. Radial keratotomy presently appears to be fraught with intrinsic hazards and is imprudent and inadvisable for pilots or aircrew, in whom long-term stable, non-fluctuating, asymptomatic, keen vision is required in both bright and dim light.

Aerospace Medicine↗
PubMed1985

Identical twins with subretinal neovascularization complicating senile macular degeneration.

This is the first report, to our knowledge, of proliferative macular degeneration developing in the same eye of identical twins. The concept of a familial predisposition in age related macular degeneration is consistent with other known risk factors including race, iris pigmentation, hyperopia and macular drusen which are known to be genetically determined. Monozygotic twins provide ophthalmology with an excellent opportunity to study the hereditary aspects of ocular disease.

Aged↗
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↗
PubMed1989

[Epikeratophakia surgery for refractive errors and keratoconus].

Epikeratophakia surgery is a relatively new surgical technique which involves suturing of prelathed corneal tissue on top of the recipient's cornea. The epikeratophakia lens is lathed according to the recipient's refractive needs and therefore can correct myopia and hyperopia; a plano lenticle can be used to correct keratoconus. In the past 3 years we operated on 25 patients (27 eyes). There were 11 cases of myopia, 7 of aphakia and 7 of keratoconus. The aphakic (hyperopic) group included patients with aphakia and traumatic aphakia in whom secondary implantation of an intraocular lens was contraindicated or who were contact-lens intolerant. In the myopic group, the average correction of 18.3 diopters improved to -1.9 diopters after surgery, and in the hyperopic-aphakic group from +10.9 diopters to +1.1 diopters. In the keratoconus group there was also marked improvement after surgery. There was no major complication during or after surgery. Epikeratophakia surgery is a reversible, extraocular procedure, which is fairly simple technically, does not cause immunological rejection, and gives fairly good results in certain refractive errors and in keratoconus.

Aphakia↗
PubMed1989

Optic disc photogrammetry: magnification factors for eye position, centration, and ametropias, refractive and axial; and their application in the diagnosis of optic nerve hypoplasia.

To determine if image magnification from ametropia or other factors required correction in the photogrammetric diagnosis of optic nerve hypoplasia, the following variables were studied using two standard 30 degrees field fundus cameras (Zeiss FF-3 and Kowa RC-2): (1) distance between the camera and the subject--variations in this distance do not change the image size; (2) decentration of the camera (i.e., decentration of the optic disc image within the field)--no effect was found using the Kowa camera, but in the Zeiss, a 2% (0.07 mm) increase in disc image size was found for each mm of optic disc decentration in the field; (3) ametropia, refractive experimental (induced in one subject with soft contact lenses, from +8.00 diopters (D) to -8.00D)--no significant change in image size was found (In addition, in 50 healthy adult eyes with various refractive errors, including ten with uncorrected aphakia, there was no significant difference found for the size of the optic nerve in different refractive ametropias. No correction factor was necessary for aphakia or for other refractive ametropias); and (4) ametropia, axial--axial myopia showed minor but significant magnification: a linear increase in the horizontal diameter of the optic disc image of 2% (0.07 mm) was found for each diopter of axial ametropia exceeding 3D. There was insufficient data for axial hyperopia. These magnification factors should be applied when measuring the optic disc on 35-mm transparencies to make a diagnosis of optic nerve hypoplasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Aphakia↗