ophthalmodynamometer

oph·thal·mo·dy·na·mom·e·ter (f-thlm-dn-mm-tr, p-)

n.

1. An instrument for determining the near point of convergence of the eyes.

2. An instrument that measures the blood pressure in the retinal vessels.

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oph·thalmo·dyna·mome·try n.

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ophthalmodynamometer

[-din′əmom′ətər]

Etymology: Gk, ophthalmos, eye, dynamis, force, metron, measure

an instrument for measuring pressure on the sclera while the fundus is studied with an ophthalmoscope. It may be used to measure blood pressures in the ophthalmic artery.

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ophthalmodynamometer (ODM) 

1. Instrument for measuring the near point of convergence of the eyes.

2. Instrument for measuring the blood pressure of the central retinal artery. There are two types: the compression type (e.g. Bailliart's ophthalmodynamometer) in which the pressure is raised by pressing on the eye, the force being produced by a spring-loaded plunger resting on the temporal bulbar conjunctiva of the anaesthetized eye, while the examiner observes the optic nerve through an ophthalmoscope. The other type is by suction in which negative pressure is applied to the eye using a scleral vacuum cup near the limbus (e.g. Doppler's ophthalmodynamometer). The diastolic pressure is read from the gauge provided with the instrument when the central retinal artery is seen to pulsate on the optic disc and the systolic pressure is read when all arterial pulsations just cease (the instrument should be removed immediately afterwards). A low systolic pressure is indicative of an occlusive disease of the carotid artery (a comparison between the two eyes is also very informative) as such disorders are responsible for a significant percentage of ocular symptoms and strokes. See amaurosis fugax; Hollenhorst's plaques.