Medical Dictionary

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iridocystectomy (ir′i-do-sis-tek′to-me)
An operation for making an artificial pupil when posterior synechiae follow extracapsular extraction of cataract; the border of the iris and a portion of the capsule of the lens are drawn out through an incision in the cornea and cut off. [irido- + G. kystis, bladder (capsule), + ektome, excision]

iridodiagnosis (ir′i-do-di-ag-no′sis)
Diagnosis of systemic diseases by observation of changes in form and color of the iris.

iridodialysis (ir′i-do-di-al′i-sis)
A colobomatous defect of the iris caused by its separation from the scleral spur. [irido- + G. dialysis, loosening]

iridodilator (ir′i-do-di-la′ter)
Causing dilation of the pupil; applied to the musculus dilator pupillae.

iridodonesis (ir′i-do-do-ne′sis)
Agitated motion of the iris. SYN: tremulous iris. [irido- + G. doneo, to shake to and fro]

iridokinetic (ir′i-do-ki-net′ik)
Relating to the movements of the iris.

iridology (ir-i-dol′o-je)
A hypothetical non–evidence-based system of medicine based on an examination of the iris, using a chart on which certain areas of the iris are presumed diagnostically specific for particular organs, systems, and structures. [irido- + G. logos, study]

iridomalacia (ir′i-do-ma-la′she-a)
Degenerative softening of the iris. [irido- + G. malakia, softness]

iridomesodialysis (ir′i-do-mes′o-di-al′i-sis)
Separation of adhesions around the inner margin of the iris. [irido- + G. mesos, middle, + dialysis, loosening]

iridomotor (ir′i-do-mo′tor)
SYN: pupillomotor.

iridoparalysis (ir′i-do-pa-ral′i-sis)
SYN: iridoplegia.

iridopathy (ir-i-dop′a-the)
Pathologic lesions in the iris.

iridoplegia (ir′i-do-ple′je-a)
Paralysis of the musculus sphincter iridis. SYN: iridoparalysis. [irido- + G. plege, stroke] complete i. paralysis of both the dilator and sphincter muscles of the iris. reflex i. absence of the pupillary light reflex, as in the Argyll Robertson pupil. sympathetic i. i. due to the paralysis of the sympathetically innervated dilator pupillae muscle.

iridoptosis (ir′i-dop-to′sis)
Prolapse of the iris. [irido- + G. ptosis, a falling]

iridorrhexis (ir′i-do-rek′sis)
Deliberate, surgical tearing of the iris from the scleral spur in order to increase the breadth of a coloboma. [irido- + G. rhexis, rupture]

iridoschisis (ir-i-dos′ki-sis)
Separation of the anterior layer of the iris from the posterior layer; ruptured anterior fibers float in the aqueous humor. [irido- + G. schisma, cleft]

iridosclerotomy (ir′i-do-skle-rot′o-me)
An incision involving both sclera and iris. [irido- + sclera, + G. tome, incision]

iridotomy (ir-i-dot′o-me)
Transverse division of some of the fibers of the iris, forming an artificial pupil. [irido- + G. tome, incision] laser i. peripheral iridectomy as performed by laser.

Iridoviridae (ir′i-do-vir′i-de)
A family of viruses including iridescent viruses of insects (Iridovirus) and viruses that infect frogs and fish. These viruses are large, icosahedral (120–170 nm in diameter), and contain lipid. The genome is a single molecule of double-stranded DNA with molecular weight of 130–160 × 106.

Iridovirus (ir′i-do-vi′rus)
A genus of viruses (family Iridoviridae) comprised of the iridescent insect viruses of which the type species is the tipula iridescent virus.

irigenin (i-ri-jen′in)
A trihydroxy trimethoxy isoflavone component of iridin.

iris, pl .irides (i′ris, ir′i-dez) [TA]
The anterior division of the vascular tunic of the eye, a diaphragm, perforated in the center (the pupil), attached peripherally to the scleral spur; it is composed of stroma and a double layer of pigmented retinal epithelium from which are derived the sphincter and dilator muscles of the pupil. SYN: orris. [G. rainbow, the i. of the eye] i. bicolor a variegated or two-colored i.. SYN: monocular heterochromia. i. bombé a condition occurring in posterior annular synechia, in which an increase of fluid in the posterior chamber causes a forward bulging of the peripheral i.. plateau i. in angle-closure glaucoma, a flat appearance of the i. rather than a forward convexity. tremulous i. SYN: iridodonesis.

iris frill
SYN: collarette.

irisin (i′ri-sin)
SYN: iridin (2) .

iritic (i-rit′ik)
Relating to iritis.

iritis (i-ri′tis)
Inflammation of the iris. SEE ALSO: iridocyclitis, uveitis. fibrinous i. acute inflammation of the iris, with profuse exudate; occurs in uveitis of tertiary syphilis. follicular i. rarely used term for chronic i. with glassy nodules situated deep down between the anterior and posterior layers of the iris. i. glaucomatosa an outpouring of exudate and cells after control of angle-closure glaucoma. hemorrhagic i. i. with such severe hyperemia that hyphema occurs. nodular i. i. with aggregations of round cells in the iris. plastic i. i. with a fibrinous exudation. quiet i. i. without inflammatory signs such as redness or edema of the cornea. serous i. inflammation of the iris, with a serous exudate in the anterior chamber. sympathetic i. i. consecutive to a similar condition in the other eye.

iron (Fe) (i′ern, i′run)
A metallic element, atomic no. 26, atomic wt. 55.847, that occurs in the heme of hemoglobin, myoglobin, transferrin, ferritin, and i.-containing porphyrins, and is an essential component of enzymes such as catalase, peroxidase, and the various cytochromes; its salts are used medicinally. For individual salts not listed below, see ferric and ferrous entries. [A.S. iren] albuminized i., i. albuminate a compound of i. oxide and albumin; rendered soluble by the presence of sodium citrate; occurs as reddish brown, lustrous granules, odorless or nearly so; used in anemia. i. alum SYN: ferric ammonium sulfate. i. filings small packets of Paragonimus spp. eggs that can be seen in the sputum; the egg clumps tend to be yellow-brown. i. protoporphyrin a protoporphyrin to which an i. atom is complexed; e.g., heme. i. pyrites native sulfide of i..

iron-52 (52Fe)
A radioactive iron isotope; a cyclotron-produced positron emitter with a half-life of 8.28 h, used to study iron metabolism.

iron-55 (55Fe)
An iron isotope; a positron emitter with a half-life of 2.73 years; used (less often than 59Fe) as a tracer in study of iron metabolism and in blood perfusion studies.

iron-59 (59Fe)
An iron isotope; a gamma and beta emitter with a half-life of 44.51 days; used as tracer in the study of iron metabolism, determination of blood volume, and in blood transfusion studies.

irradiate (i-ra′de-at)
To apply radiation from a source to a structure or organism. [see irradiation]

irradiation (i-ra-de-a′shun)
1. The subjective enlargement of a bright object seen against a dark background. 2. Exposure to the action of electromagnetic radiation ( e.g., heat, light, x-rays). 3. The spreading of nervous impulses from one area in the brain or cord, or from a tract, to another tract. SEE ALSO: radiation. [L. ir-radio, (in-r), pp. -radi-atus, to beam forth]

irrational (i-rash′un-al)
Not rational; unreasonable (contrary to reason) or unreasoning (not exercising reason). [L. irrationalis, without reason]

irreducible (ir-re-doo′si-bl, i-re-)
1. Not reducible; incapable of being made smaller. 2. In chemistry, incapable of being made simpler, or of being replaced, hydrogenated, or reduced in positive charge.

irrespirable (ir-re-spir′a-bl)
1. Incapable of being inhaled because of irritation to the airway, resulting in breath-holding. 2. Denoting a gas or vapor either poisonous or containing insufficient oxygen. 3. Denoting an aerosol composed of particles with aerodynamic size larger than 10 μ.

irresponsibility (ir′re-spons-i-bil′i-te)
The state of not acting in a manner that is responsible, for conscious or unconscious reasons. criminal i. the state, usually attributed to mental defect or disease, that renders a person not responsible for criminal conduct.

irresuscitable (ir′re-sus′i-ta-bl)
Incapable of being revived.

irreversible (ir-re-ver′si-bl)
Incapable of being reversed; permanent. [L. in- (ir-) neg. + re-verto, pp. -versus, to turn back]

irrigate (ir′i-gat)
To perform irrigation. [L. ir-rigo, pp. -atus, to i., fr. in, on, + rigo, to water]

irrigation (ir-i-ga′shun)
The washing out of a body cavity, space, or wound with a fluid. [see irrigate]

irrigator (ir′i-ga-ter)
An appliance used in irrigation.

irritability (ir′i-ta-bil′i-te)
The property inherent in protoplasm of reacting to a stimulus. [L. irritabilitas, fr. irrito, pp. -atus, to excite] electric i. the response of a nerve or muscle to the passage of a current of electricity; in cases of degeneration in nerve or muscle this i. is altered or lost. See modal alteration, qualitative alteration, quantitative alteration. myotatic i. the ability of a muscle to contract in response to the stimulus produced by a sudden stretching.

irritable (ir′i-ta-bl)
1. Capable of reacting to a stimulus. 2. Tending to react immoderately to a stimulus. Cf.:excitable.

irritant (ir′i-tant)
1. Irritating; causing irritation. 2. Any agent with this action. primary i. a substance that causes inflammation and other evidence of irritation, particularly of the skin, on first contact or exposure, or as a reaction to cumulative contacts, not dependent on a mechanism of sensitization.

irritation (ir-i-ta′shun)
1. Extreme incipient inflammatory reaction of the tissues to an injury. 2. The normal response of nerve or muscle to a stimulus. 3. The evocation of a normal or exaggerated reaction in the tissues by the application of a stimulus. [L. irritatio]

irritative (ir-i-ta′tiv)
Causing irritation.

irrumation (ir′oo-ma′shun)
SYN: fellatio. [L. irrumo, pp. -atus, to give suck]

irruption (i-rup′shun)
Act or process of breaking through to a surface. [L. irruptio, fr. irrumpo, to break in]

irruptive (i-rup′tiv)
Relating to or characterized by irruption.

IRS-1
Abbreviation for insulin receptor substrate-1.

IRV
Abbreviation for inspiratory reserve volume.

Irvine
A. Ray, Jr., U.S. ophthalmologist, *1917. See I.-Gass syndrome.

ISA
Abbreviation for intrinsic sympathomimetic activity.

Isamine blue (is′a-men, i′sa-)
SYN: pyrrol blue.

isauxesis (i-sawk-ze′sis)
Growth of parts at the same rate as growth of the whole. [G. isos, even, + auxesis, increase]

ischemia (is-ke′me-a)
Local anemia due to mechanical obstruction (mainly arterial narrowing or disruption) of the blood supply. [G. ischo, to keep back, + haima, blood] myocardial i. inadequate circulation of blood to the myocardium, usually as a result of coronary artery disease. SEE ALSO: angina pectoris, myocardial infarction. postural i. the reduced blood pressure and flow induced in a part, e.g., the leg or foot, by raising it above the heart level; used to reduce bleeding during surgical operations on the extremities. i. retinae diminished blood supply in the retina due to failure of the arterial circulation; it may occur as a result of arterial embolism or spasm; poisoning, as by quinine; or exsanguination from recurring profuse hemorrhages; bilateral transitory or permanent blindness may result. silent i. myocardial i. without accompanying signs or symptoms of angina pectoris; can be detected by ECG and other lab techniques. SEE ALSO: silent myocardial infarction.

ischemic (is-ke′mik)
Relating to or affected by ischemia.

ischesis (is-ke′sis)
Suppression of any discharge, especially of a normal one. [G. ischo, to hold back]

ischia (is′ke-a)
Plural of ischium.

ischiadic (is-ke-ad′ik)
SYN: sciatic (1) .

ischiadicus (is-ke-ad′i-kus)
SYN: sciatic. [L.]

ischial (is′ke-al)
SYN: sciatic (1) .

ischialgia (is-ke-al′je-a)
1. Obsolete term for pain in the hip; specifically, the ischium. SYN: ischiodynia. 2. Obsolete term for sciatica. [G. ischion, hip, + algos, pain]

ischiatic (is-ke-at′ik)
SYN: sciatic (1) .

ischio-
The ischium. [G. ischion, hip joint, haunch (ischium)]

ischioanal (is-ke-o-a′nal)
Relating to the ischium and the anus.

ischiobulbar (is-ke-o-bul′bar)
Relating to the ischium and the bulb of the penis.

ischiocapsular (is-ke-o-kap′soo-lar)
Relating to the ischium and the capsule of the hip joint; denoting that part of the capsule which is attached to the ischium.

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