II. Indications
III. Physiology
-
Aqueous Humor
- Ciliary body produces Aqueous Humor
- Aqueous Humor flows through pupil and into anterior chamber
- Trabecular meshwork drains Aqueous Humor into the venous system
- Intraocular Pressure
- Intraocular Pressure is a balance between Aqueous Humor production (ciliary body) and drainage (trabecular mesh)
- Intraocular Pressure may normally vary with Blood Pressure and respiration
- Introcular pressure typically decreases at night
IV. Techniques: Applanation Tonometry - Intraocular Pressure measurement
- Background
- Applanation devices measure the amount of pressure needed to flatten a small portion of the Cornea
- Apply Topical Eye Anesthetic to Cornea before testing
- Goldmann Tonometer
- Slit-lamp based device that offers most accurate Intraocular Pressure measurement
- Portable electronic Applanation Tonometers (e.g. Tono-Pen, Accupen)
- Accurate Tonometry alternative to the Goldmann Tonometer
- Non-contact Tonometers (air-puff)
- Least accurate Tonometry method, but no Topical Anesthetic needed
- Schiotz (older, manual method, rarely used in U.S.)
- Requires a skilled, practiced clinician to use accurately
- Scale <3.5 (5.5g plunger) recheck with 7.5g plunger
- Scale <6.0 (7.5g plunger) recheck with 10g plunger
- Scale <8.5 (10g plunger) recheck with 15g plunger
- Scale <11.0 (15g plunger)
V. Interpretation
- Normal Intraocular Pressure
- Intraocular Pressure 8 to 21 mmHg
- Elevated Intraocular Pressure (Glaucoma)
- Intraocular Pressure > 21 mmHg
-
Decreased Intraocular Pressure (Ocular Hypotony)
- Intraocular Pressure <5 mmHg
VI. Exam: Less accurate methods to estimate Intraocular Pressure
- Eye pressure applied through upper Eyelid
- Firmer eye suggests a higher Intraocular Pressure
- Anterior Chamber Depth
- Penlight illumination of anterior chamber
- Normal
- Illumination from lateral side lights entire iris
- Abnormal (increased pressure)
- Iris is bowed forward and nasal side is in shadow
- Nasal iris is not illuminated
VII. References
- Trobe (2012) Physician's Guide to Eye Care, AAO, p. 28
Images: Related links to external sites (from Bing)
Related Studies
| Definition (MSH) | The pressure of the fluids in the eye. |
| Definition (CSP) | pressure of the fluids of the eye against the tunics; produced by continual renewal of the fluids within the interior of the eye. |
| Concepts | Organ or Tissue Function (T042) |
| MSH | D007429 |
| SnomedCT | 363938006, 251737001, 41633001 |
| LNC | LP96294-1, MTHU034775 |
| English | Intraocular Pressure, Intraocular Pressures, Ocular Tension, Ocular Tensions, Pressure, Intraocular, Pressures, Intraocular, Tensions, Ocular, Tension, Ocular, intraocular pressure, Ocular tension, Physiologic Intraocular Pressure, ocular tension, pressure in eye, intraocular pressures, Ocular tension (observable entity), Intraocular pressure, IOP - Intraocular pressure, Intraocular pressure (observable entity), Intraocular pressure, NOS, Intraocular pressure (observable)-RETIRED |
| Swedish | Ögontryck |
| Czech | nitrooční tlak |
| Finnish | Silmänpaine |
| Russian | VNUTRIGLAZNOE DAVLENIE, GLAZNOE DAVLENIE, ВНУТРИГЛАЗНОЕ ДАВЛЕНИЕ, ГЛАЗНОЕ ДАВЛЕНИЕ |
| Japanese | 眼圧, 眼内圧 |
| Italian | Tensione oculare, Pressione intraoculare |
| Croatian | INTRAOKULARNI TLAK |
| Polish | Ciśnienie śródoczne, Ciśnienie śródgałkowe, Ciśnienie wewnątrzgałkowe |
| Portuguese | Pressão Intraocular, Tensão Ocular |
| Norwegian | Øyetrykk, Intraokulært trykk |
| Spanish | presión intraocular (entidad observable), presión intraocular, Tensión Ocular, Presión Intraocular |
| French | Ophtalmotonus, Pression intra-oculaire, Tension oculaire, Tonus oculaire |
| German | Augendruck, Intraokularer Druck |
| Dutch | Druk, intraoculaire, Intraoculaire druk, Oogdruk |
Ontology: Tonometry (C0040420)
| Definition (MSH) | Measurement of the pressure or tension of liquids or gases with a tonometer. It has been developed to measure pressure in the EYE; the BLOOD VESSELS; and the STOMACH. |
| Concepts | Diagnostic Procedure (T060) |
| MSH | D008365 |
| ICD9 | 89.11 |
| ICD10 | 92016-00 |
| SnomedCT | 164732007, 141903009, 164729009 |
| LNC | LP32273-2, LP76227-5 |
| English | Tonometry NOS, tonometry (procedure), tonometry, Tonometry NOS (procedure), Tonometry (procedure), Tonometry |
| Portuguese | Tonometria |
| Spanish | Tonometría, tonometría, SAI, tonometría, SAI (procedimiento), tonometría (procedimiento), tonometría |
| German | Tonometrie, Augeninnendruck-Messung |
| French | Tonométrie |
| Czech | tonometrie |
| Italian | Tonometria |
| Norwegian | Tonometri, Måling av øyetrykket, Øyetrykksmåling |
| Dutch | Tonometrie |
Ontology: Tonometer (C0183969)
| Definition (UMD) | Measuring instruments designed to determine intraocular pressure. These instruments may use several different techniques: applanation, indentation, and noncontact (air puff) tonometry. Tonometers can be attached to a slit lamp, and portable and handheld devices are also available. Ophthalmic tonometers are mainly intended for assessing ocular hypertension (intraocular pressure between 10 and 24 mm Hg is considered normal), usually to screen patients for glaucoma. |
| Definition (NCI) | A handheld instrument that provides a measurement of intraocular pressure. |
| Concepts | Medical Device (T074) |
| SnomedCT | 391932009 |
| English | Ophthalmodynamometers, Tonometers, Ophthalmic, Tonometers, Ophthalmic Tonometers, Ophthalmotonometers, tonometer, tonometered, tonometers, Tonometer, Ophthalmotonometer (physical object), Ophthalmotonometer |
| Spanish | oftalmotonómetro (objeto físico), oftalmotonómetro |
Ontology: Depth of anterior chamber of eye (C0429492)
| Concepts | Finding (T033) |
| SnomedCT | 251690005, 363948008 |
| English | AC - Anterior chamber depth, Anterior chamber depth, depth of anterior chamber of eye (physical finding), anterior chamber depth, depth of anterior chamber of eye, Depth of anterior chamber of eye, of anterior chamber depth, ACD - Anterior chamber depth, Anterior chamber depth (observable entity), Depth of anterior chamber (observable entity), Depth of anterior chamber |
| Spanish | Depth of anterior chamber, Depth of anterior chamber (observable entity), profundidad - cámara anterior, profundidad - cámara anterior (entidad observable), Anterior chamber depth, ACD - Anterior chamber depth, Anterior chamber depth (observable entity), profundidad de la cámara anterior (entidad observable), profundidad de la cámara anterior |
Ontology: Applanation tonometry (C0430862)
| Concepts | Diagnostic Procedure (T060) |
| SnomedCT | 252803002 |
| English | AT- Applanation tonometry, applanation tonometry, Applanation tonometry, Applanation tonometry (procedure) |
| Dutch | applanatietonometrie |
| German | Applanationstonometrie |
| Italian | Tonometria da applanazione |
| Portuguese | Tonometria de achatamento |
| Spanish | Tonometría de aplanamiento, tonometría por aplanamiento (procedimiento), tonometría por aplanamiento |
| Japanese | 圧平眼圧測定, ｱｯﾍﾟｲｶﾞﾝｱﾂｿｸﾃｲ |
| French | Tonométrie d'applanation |
| Czech | Aplanační tonometrie |
| Hungarian | Ellaposítás tonometria |
Ontology: Digital tonometry (C0430865)
| Concepts | Diagnostic Procedure (T060) |
| SnomedCT | 252805009 |
| English | Digital tonometry, Digital tonometry (procedure), Portable electronic applanation tonometry |
| Spanish | tonometría digital (procedimiento), tonometría digital |
Ontology: Schiotz tonometry (C0848285)
| Concepts | Diagnostic Procedure (T060) |
| SnomedCT | 389149000 |
| English | Schiotz tonometry, Schiotz tonometry (procedure) |
| Spanish | tonometría de Schiotz (procedimiento), tonometría de Schiotz |
Ontology: Applanation tonometer (C1271524)
| Definition (UMD) | Ophthalmic tonometers designed to determine intraocular pressure by measuring the force required to flatten the cornea apex by a fixed amount. These instruments are typically small and reusable instruments and are attached to a slit lamp; the tonometer includes a tip to be applied to the cornea and a manually controlled spring that applies a variable force on the cornea through the tip. The application of the tonometer tip flattens the cornea, producing a thin circular outline that is split into two green semicircles when viewed through the slit lamp oculars; then the force applied is adjusted until both semicircles just overlap and the force value is shown in the instrument scale as pressure (typically in mm Hg). Handheld (electronic penlike devices) and pneumatic applanation tonometers (i.e., pneumatotonomers) are also available. Applanation ophthalmic tonometers (e.g., Goldman and Barraquer types) can measure the amount of force applied; they are intended mainly for assessing ocular hypertension (intraocular pressure between 10 and 24 mm Hg is considered normal), usually to screen patients for glaucoma. |
| Concepts | Medical Device (T074) |
| SnomedCT | 391933004 |
| English | Ophthalmic Tonometers, Applanation, Applanation Tonometers, Applanometers, Applanation tonometer (physical object), Applanation tonometer |
| Spanish | tonómetro de aplanamiento (objeto físico), tonómetro de aplanamiento |
Ontology: Non-contact tonometry (C1300249)
| Concepts | Diagnostic Procedure (T060) |
| SnomedCT | 389150000 |
| LNC | LP32275-7 |
| English | Tonometry.non contact, Air-puff tonometry, Non-contact tonometry (procedure), Non-contact tonometry, Noncontact tonometry |
| Spanish | tonometría sin contacto (procedimiento), tonometría sin contacto |
Ontology: Goldmann applanation tonometry (C1300251)
| Concepts | Diagnostic Procedure (T060) |
| SnomedCT | 389152008 |
| English | Goldmann applanation tonometry (procedure), Goldmann applanation tonometry |
| Spanish | tonometría por aplanamiento de Goldmann (procedimiento), tonometría por aplanamiento de Goldmann |
