(n.) A defect of the eye or of a lens, in consequence of which the rays derived from one point are not brought to a single focal point, thus causing imperfect images or indistinctness of vision.
Example Sentences:
(1) The authors have presented in two previous articles the graphic solutions resembling Tscherning ellipses, for spherical as well as for aspherical ophthalmic lenses free of astigmatism or power error.
(2) The high incidence of infant astigmatism has implications for critical periods in human visual development and for infant acuity.
(3) The most frequently occurring signs were: tilting of the disc (89%), oblique direction of the vessels (89%) and myopic astigmatism (96%).
(4) There was no evidence of glaucoma in any of the patients although two patients exhibited keratoconus and another one manifested moderate to high astigmatism.
(5) Of 809 eyes that underwent the Kelman phacoemulsification and aspiration (KPE) procedure, we report on 4 patients (0.49%) who developed sudden against-the-rule (AR) astigmatism after intraocular lens implantation.
(6) The two last methods are used for correction of astigmatism.
(7) The eyes were compared to 105 control eyes in which no astigmatic incisions were performed to assess the estimated effect of the TAK incisions.
(8) The choice of the method depends on the kind and degree of astigmatism and the degree of the spherical ametropia of the operated eye.
(9) The change in refractive astigmatism was as high as 1.50DC (diopter cylinder).
(10) The endpoint for the procedure is corneal astigmatism that will allow either spectacle or contact lens correction, depending on the patient's visual needs.
(11) A total of 527 astigmatic patients were examined for their axial distribution.
(12) Astigmatism greater than +1.25 diopters (as high as +5.50 diopters) was most commonly associated with dacryoceles (eight of 12 eyes) and with hemangiomas (14 of 17 eyes).
(13) In terms of the various keratometry values compared, mean K (corneal refractive power), flattest K, steepest K, astigmatism and the axis of astigmatism, 65% to 75% of the cases on automated keratometry were within 0.26 dioptres or 11 degrees of manually determined values; the difference was statistically significant (p < 0.001).
(14) Young adulthood myopia progression also appeared to be accompanied by a slight tendency toward a with-the-rule astigmatic shift.
(15) Forty-nine cases of primary keratophakia and 13 cases of secondary keratophakia were analyzed for postoperative astigmatism.
(16) A numerical example reveals some lesser known properties of the circle of least confusion of astigmatic pencils.
(17) Group II includes 10 patients with astigmatism due to circumscribed peripheral limbal corneal dystrophy.
(18) Amblyopia was due to anisometropia in 24 cases (50%), strabismus in 9 cases (18.7%), high astigmatism (meridional) in 7 cases (14.5%) and other causes or a combination of factors in 8 cases (16.7%).
(19) The differences between the 2 eyes were not statistically significant so far as the amount of astigmatism, final visual acuity, and peripheral anterior synechiae were concerned.
(20) Results showed that the wearing of spherical soft contact lenses, such as those used in this study, cannot be expected to predictably mask astigmatism.
Retina
Definition:
(n.) The delicate membrane by which the back part of the globe of the eye is lined, and in which the fibers of the optic nerve terminate. See Eye.
Example Sentences:
(1) The distribution of gelsolin, a calcium-dependent actin-severing and capping protein, in the retina of the developing and adult rabbit was studied.
(2) At day 7 MD occupy about 14% area of posterior retina in transverse sections in Campbell rats versus 7% in normal animals.
(3) Chromatolysis and swelling of the cell bodies of cut axons are more prolonged than after optic nerve section and resolve in more central regions of retina first.
(4) Reverse transcription of retina mRNA followed by DNA amplification using D4-specific nucleotides demonstrates the presence of D4 mRNA in retina.
(5) Electroretinographic (ERG), morphometric and biochemical studies on retinas from monkeys or rats reveal that moderate level developmental lead (Pb) exposure produces long-term selective rod deficits and degeneration.
(6) Cultured cells from fourth to ninth passage showed positive labelling for S 100 protein, carbonic anydrase (CAA), glutamine synthetase (GS), alpha cristallin (alpha C) and polyclonal glial fibrillary acidic protein (GFAP) antibody, but were negative for both monoclonal GFAP antibody and also for Muller cells in the retina.
(7) This study examines the morphology of sporadic congenital microphthalmia in 1-day-old chicks, with particular emphasis on the neural retina.
(8) We based our approach on the anteroposterior location of the incarceration site and the amount of retina incarcerated into the wound.
(9) The posterior retina remained uninvolved, and no further treatment was needed.
(10) On histopathologic examination there were microabscesses in the inner choroid and subretinal space, disrupting the outer retina but sparing the inner retina.
(11) Although the Ca2+-independent mechanism accounts for about two thirds of the total acetylcholine release in the dark, the amount of acetylcholine released in this way is small compared with the release of acetylcholine triggered by stimulation of the retina with light.
(12) These results are consistent with the idea that RPE pigment dispersion is triggered by a substance that diffuses from the retina at light onset.
(13) A specific vitamin A-dependent fluorophore was isolated from these retinas using thin-layer chromatography (TLC).
(14) Premature infants possessed 35-50% higher levels of retinal vitamin C than those found in mature retinas.
(15) The relationship of these observations to the genesis of positional markers in the regenerating retina is discussed.
(16) One may speculate whether clinical conditions exist--apart from hereditary retinal dystrophies--in which the retina becomes more sensitive to light from strong artificial or natural sources, which are otherwise innoxious.
(17) We also used an optical device to stabilize images of the real world upon the retina.
(18) The three-dimensional view obtained with scanning electron microscopy provides another perspective on the pathogenetic changes of the RCS retina.
(19) Although the chicks were behaviorally and electrophysiologically blind at the time of hatching, their retinas appeared morphologically comparable to normal chicks at this stage.
(20) These observations suggest that IDDM patients have reduced fibrinolytic activity in their retinas, which might predispose them to thromboembolic disease.