Ophthalmic emergencies

Published on 14/03/2015 by admin

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Last modified 14/03/2015

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Chapter 36 Ophthalmic emergencies

USE OF THE SLIT LAMP

These remarks apply to the Haag Streit slit lamp, but the principles apply to all slit lamps. The patient and the examining doctor must both be comfortable. In particular, the patient should not be straining to keep the chin on the chin rest, and the patient’s forehead must rest comfortably against the forehead strap. The eye should be at the level of the black mark on the side of the two columns that hold the chin rest and forehead strap; this is achieved by adjusting the height of the chin rest. The slit lamp should then be adjusted so that it is in its mid position, allowing a full range of vertical and horizontal movement. This position is adjusted by rotating the joystick which controls the height of the slit lamp as well as the movement of the slit lamp in all directions, thereby controlling its focus.

After the patient is positioned correctly, the eye can be examined. On the bottom of the rotating light source column of the slit lamp is a knob that controls the width of the slit beam. Further up the column, immediately under the globe housing, is a control to adjust the intensity of the light; this same control also allows the insertion of a cobalt blue filter into the light, producing the characteristic blue light used to detect corneal ulcers with fluorescein dye. Near this control is another control that adjusts the height of the slit beam.

The slit lamp can be used in many ways. The easiest is simply to use it as a high-powered illumination source with magnification using the broad beam; this is particularly useful to detect corneal ulceration after instilling fluorescein dye and using the cobalt blue filter. To detect and assess iritis, a narrow slit beam can be shone through the anterior chamber; this will highlight any flare or cells. A slit beam can be shone directly through the pupil to retro-illuminate the iris using the red reflex; this is also a useful way of assessing the clarity of the media.

Intraocular pressures are measured using the application tonometer, which is either attached to the slit lamp on a swinging arm or is detached from the slit lamp and is placed on the platform immediately in front of the eye pieces.

TRAUMA

Blunt ocular trauma

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