(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.
Cornea
Definition:
(n.) The transparent part of the coat of the eyeball which covers the iris and pupil and admits light to the interior. See Eye.
Example Sentences:
(1) Displacement of the surface of the cornea of bovine eyes after disruption of intact structures was investigated by means of holographic interferometry.
(2) The patient, a 12 year-old boy, showed a soft white yellowish mycotic excrescence with clear borders which had followed the introduction of a small piece of straw into the cornea.
(3) Increased amounts of laminin in the basal epithelium of the cornea and of collagen type III in the stroma and subepithelial components of the stroma were observed.
(4) We report on a membrane inflation method of wound spreading in intact human corneas using the Baribeau Micronscope.
(5) When 5 corneas with quiescent HSK were cultured in vitro, 3 again became HSV antigen positive.
(6) Corneas of bullfrog (Rana catesbeiana) were mounted between lucite chambers.
(7) The eye is of the closed vesicle type and is composed of retina, cornea, vitreous body, lens and optic nerve.
(8) The steps in the model are the drug elimination rate in the precornea and anterior chamber, the rate of drug dissolution, the rate of drug penetration into the cornea, and the rate of drug transport into the aqueous humor.
(9) Gas trapping and corneal edema were not observed in uncovered corneas or corneas covered with membrane lenses.
(10) Since lymphocytic cells in intimate contact with degenerating keratocytes have previously been identified in the cornea, these observations provide a basis for the view that cell-mediated immunopathogenesis is involved in the etiology of herpetic stromal keratitis.
(11) Lactate dehydrogenase (LDH) levels and subunit isozyme patterns in cornea were monitored in 36 albino rabbits wearing thick, rigid, gas-permeable contact lenses for periods of 24 h, 2 and 7 days, and 1 and 3 months.
(12) Calculations of energies of activation, taken from Arrhenius plots, indicate that the diffusion of drug across the cornea may be by two different mechanisms that depend on the physical-chemical characteristics of the perfusant.
(13) The mean in the newborn-to-6-month-old group was 47.59 D; in the 12-18-month-old group it had decreased to 45.56 D. The cornea appears to stabilize at about 54 months, with an average reading of 42.69 D. Evaluation of 11 eyes diagnosed as having persistent hyperplastic primary vitreous revealed that eyes with this diagnosis generally have steeper corneas than normal eyes at any given age.
(14) There was no significant difference in the wound-healing rate, but at 36 hours there was a reduction in wound-healing rate of the excimer ablated corneas.
(15) More importantly, this study reports the first detection of LAT in RNA extracted from 9% of corneas from latently infected rabbits (n = 22) by the polymerase chain reaction.
(16) Cat corneas were stored at refrigerator temperatures in M-K medium (TC-199, 5% dextran), modified M-K medium (TC-199, 1% chondroitin sulfate), or on the intact globe in moist chambers for intervals of one to nine days.
(17) Pterygia, triangular sheets of fibrovascular tissue that invade the cornea, have recurrence rates of 30% to 50% with currently available surgical procedures.
(18) Rabbit corneas grown in organ culture (24 well plate) were inoculated topically with 50 microliters (5 x 10(5) pfu) of different ocular adenoviral serotypes (ATCC and clinical isolates).
(19) A recipient cornea gradually developed wrinkling and opacification in Bowman's layer following an uneventful myopic epikeratoplasty.
(20) In neurological diseases the hyposensitivity could include the cornea, conjunctiva and lid margin.