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At least 901 records · Page 50Linked to original sources
PubMed1990

Atypical nerve fiber layer defects in high myopes with high-tension glaucoma.

The incidence of atypical optic nerve head and retinal nerve fiber layer defects was studied in 61 high myopic eyes (greater than or equal to -5 diopters) and 91 emmetropic or hyperopic eyes (0 to +3 diopters) of 152 patients with chronic high-tension glaucoma, and in 45 control myopic eyes (greater than or equal to -5 diopters). Horizontal ovalness or cyclotorsion, oblique insertion of the optic disc, and bean pot disc were more common in the high myopes. In the eyes with high myopia with glaucoma, inferior dominant nerve fiber layer defects, ectopic fiber defects, and multiple nerve fiber layer defects were common. The incidence of superior nerve fiber layer defects or superior-inferior equal nerve fiber layer defects was high in round or vertically oval discs and low in cyclotorted or horizontal oval discs. The oblique insertion of the discs correlated positively with a higher incidence of ectopic defects in high myopic eyes with glaucoma. The incidence of focal type nerve defects is higher in older patients and high myopes with oblique insertion of the optic disc. Atypical shape of the optic disc correlates positively with atypical retinal nerve fiber layer defects in eyes with high-tension glaucoma.

Adolescent↗
PubMed1976

[Contribution on the infraocular optics (author's transl)].

Experience indicates that a person will have a comfortable vision only if the sizes of the image in both eyes are approximately equal; a tolerance of approximately 5% is acceptable for this. In other words both optical systems, consisting of a spectacle lens, a contact lens, and the eye must have approximately the same focal length. Patients who have one phacic and one aphacic eye will usually possess quite different focal lengths with conventional contact lens correction. However, with the addition of spectacles and of appropriate contact lenses on one or both eyes, the ophthalmologist has at his disposal a new variable. The given formulas and rules of thumb enable him to choose the strength of spectacles-contact lens combinations so that the patient will also have sharp vision in both eyes and regain a comfortable binocular sight. The method is illustrated by examples.

Contact Lenses↗
PubMed1976

[The astigmatism bioblique. II. Mathematical description (author's transl)].

Optical surface showing an astigmatism bioblique could only approximately be described by mathematical formulas. The best approximation is that one which shows a close relation between regular and bioblique astigmatism. It allows the calculation of the best correcting cylinder, which brings the anavoidable residual astigmatism to a minimum.

Astigmatism↗
PubMed1993

Negative implant. A retrospective study.

Implantation of a negative power intraocular lens is one of the options for surgical correction of high myopia. We studied 36 eyes with a Fechner Worst Claw Lens, implanted in Groningen between March 1987 and November 1991. The preoperative myopia ranged from -7.00 to -30.00 diopters. Twenty one eyes had a follow up period of more than 12 months. The IOL power was calculated with the van der Heyde method. Correction within 1 diopters of emmetropia has been achieved in 55.5% of the cases. Deviation of more than 2 diopters occurred in 25%. In 24 eyes the best corrected postoperative visual acuity improved. Due to the IOL the retinal image increases in size as compared to spectacle correction. In none of the cases complications were encountered during surgery. In the postoperative period one IOL had to be replaced because of an error made in the calculation of the lens power. In one case endothelial decompensation occurred, probably due to a combination of compulsive eye rubbing and a preexisting cornea guttata. The rim of the IOL optic is the part which is the closet to the endothelium. Our recommendation is that one should avoid indentation of the cornea. No other serious complications occurred in this study.

Adult↗
PubMedDate not supplied

Contemporary optics and ocular pathology.

A significant advantage of Fourier optics over classical optics is that it permits a differentiation between optical and retinal-neural causes of visual impairment. The basic methods of Fourier optics are introduced in a nonmathematical manner, as are their relationship to current clinical methods of measuring visual performance. Potential ophthalmic applications for Fourier optics in both clinical diagnosis and pre-operative ocular evaluation are discussed, and the importance of clinical measurement of visual performance at intermediate contrast states is emphasized.

Cataract↗
PubMedDate not supplied

Improved lensometry with a programmed calculator-lensometer combination.

The arithmetic associated with prescription calculation seems to be the major source of error and inefficiency in the performance of traditional lensometry. We have found that a programmed calculator used in combination with a lensometer achieves greater accuracy in less time than does the lensometer alone. This approach may be a useful alternative to the physician who does not wish to make a substantial investment in a fully automatic device.

Computers↗
PubMedDate not supplied

Ocular involvement in the fetal alcohol syndrome.

Maternal alcohol abuse during pregnancy causes malformations of the eyes with serious consequences to the vision of the affected children. A high percentage (up to 90%) of children suffering from the fetal alcohol syndrome have eye abnormalities, including malformation in the outer eye region, disorders of motility, and defects of different intraocular structures. Two kinds of malformations stand out as most typical--hypoplasia of the optic nervehead (up to 48%) and increased tortuosity of the retinal vessels, especially of the arteries (up to 49%). Visual acuity is often moderately or severely reduced. Considering the developmental timing of different tissues of the eye, one can presume that there is a risk for deleterious effects of alcohol on eye structures at any point of time from early gestation until development is completed.

Adolescent↗