How to Use a Cornea Drill Rust Ring

An alger brush is the most common type of corneal drill. It is used to remove a rust ring after a metallic foreign body is removed from the corneal epithelium. The cornea is the thick, transparent outer protective covering of the anterior portion of the eye. It is very common for metallic particles to become embedded in the cornea even when safety glasses are worn. The alger brush is the best corneal drill because it uses centrifugal force. This helps to minimize risk of corneal penetration because the drill self-stops when it reaches the basement membrane of the cornea.

Things You'll Need

• Alger brush (Corneal Drill)
• Corneal Anesthetic (Proparacaine, Alcaine, Tetracaine)
• Slit Lamp or Loupe
• Corneal Spud or fine gauge hypodermic needle
• Sodium Flourescein

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Instructions

• 1

  Anesthetize the cornea using Proparacaine, Lidocaine or Tetracaine. One drop of anesthetic is sufficient. The cornea will be anesthetized almost immediately.

• 2

  Instruct the patient to find a target to look at and to keep his eyes open wide. Make sure the direction in which he is looking allows you the best access to the foreign body.

• 3

  Remove the metallic foreign body. This is best done with a corneal spud (a small surgical instrument that looks like a spatula) or a fine gauge hypodermic needle. Approach the cornea tangentially with the instrument instead of perpendicularly. Position the instrument under the edge of the metallic particle and gently lift, flicking it off the cornea. Removing the foreign body is the easy part.

• 4

  Remove the metallic foreign body. This is best done with a corneal spud (a small surgical instrument that looks like a spatula) or a fine gauge hypodermic needle. Approach the cornea tangentially with the instrument instead of perpendicularly. Position the instrument under the edge of the metallic particle and gently lift, flicking it off the cornea. Removing the foreign body is the easy part.

• 5

  Try to remove the rust ring with the spud or needle. You have more control than you will with the alger brush and you will damage less of the epithelium. Although the alger brush is very quiet, it does make a soft whirring sound. This can be very disconcerting to an already apprehensive patient.

• 6

  Remove the residual rust with the alger brush. Turn the instrument on by spinning the top of the instrument. There is an arrow that shows you which way to spin it to turn it on. Hold the instrument so that you have the most control over it. Brace your hand against the slit lamp or brace your elbow against the slit lamp table to ensure that your hand is steady.

• 7

  Reposition the patient, making sure she is still and keeping her eyes open wide. If the patient cannot hold her eyes open, you will need to have an assistant maintain the patient's upper eye lid with a swab.

• 8

  Apply the alger brush tangentially to the cornea. Move the tip of the brush over the rust colored, oxidized portion of the cornea. This removes the damaged epithelium. Keep the area you are debriding as small as possible. But don't be afraid to press firmly into the cornea, remember the instrument will stop itself if you are pressing too deep. Keep moving the tip across the rust ring until all of the discolored epithelium is gone.

• 9

  Instill one drop of sodium flourescein to check the extent of the wound. Treat the wound topically like a corneal abrasion depending on the extent. Typically, prescribe one drop of a broad spectrum antibiotic four times a day for four days.