Slit Lamp & Checking Angles

Slit Lamp Basics

A slit lamp is essentially a large microscope that we use to look at a patient's eye
It is mainly for looking at the front of the eye, but with special lenses (90D / 20D), you can look into the back of the eye as well
Doing a preliminary slit lamp exam is vital to the way we operate at HEA in getting our patients prepped to see our providers
That being said, it is important to know how it works!

There are 2 main types of slit lamps we have at HEA (Haag Streit and Topcon)
Both types work almost identically, but there are a couple slight differences between them
Be able to know what each knob and dial does, and also how to fix an issue that you see. For example, if the slit beam is too bright or it is very short in height, how do you adjust these issues?

Tips

Be sure that the patient is comfortable (ask them)
Make sure their forehead is firmly on the headrest at all times! Often you will have the eye clear in the optics, and then without touching anything, it will become blurry (this is likely due to he patient moving their forehead away). This is especially important when checking IOP
Older towers have the table lock as a foot pedal on the tower itself, but vast majority have it beneath the arm of the slit lamp
When looking at OD, tell them to look at your right ear to keep their eyes straight ahead
When looking at OS, have them look at your left ear
For large movements, push the base
For small movements, use the joystick
Focusing on the eye requires you to move the joystick closer or farther away from it

Clinical Pearls

Explain what angles are are!!!
Myopic patients likely have a very open angle!
Hyperopic patients likely have a very narrow/shallow angle!
Patients with more advanced cataracts can also have a narrow angle because when a cataract matures, it also swells and pushes the iris forward

You can dilate under the following conditions (still check angles though as things can change):

1) They have had cataract surgery in the eye

2) They have a narrow angle but have had a YLPI

3) We dilate them on a regular basis

Angle closure attack in OS!!
Symptoms of an angle closure attack can occur many hours after dilation as it sometimes takes a while for the pressure to build up! Sometimes patients go home after an eye exam, and then develop pain and redness later in the day
Patients can have pain and redness in the AM because their eyes dilate while they are asleep and wake up with high IOP, but then it decreases as the pupil constricts

1) Have the candidate walk you through all parts of the slit lamp and what they do

Table arm locking lever (or foot pedal)
Bring the SL to the patient, situate their head comfortably on it, and line their eyes up properly
Power switch
Chinrest height adjuster
Headrest eye mark
Slit beam size adjuster (slit & fully open)
Filter lever (Haag Streit vs. Topcon)
Light intensity knob (various locations)
Slit beam measurement scale
Slit beam height adjustment knob
Slit beam angle adjuster (at 90 degrees to be vertical)
Joystick (move slit lamp up / down / left / right)

Locking Screws

Optics

2) Mess up all dial and switches on the slit lamp and see if candidate can fix the issues

In anatomical terms, where exactly is the angle?
Why are we concerned with angles?
True of False: For small movement with the slit lamp, we push the base around
If my glasses Rx is -.25 - 4.50 X 120, would you be particularly concerned about dilating my eyes? Why or why not?
If my glasses Rx is -7.25- .25 X 56, would you be concerned about dilating my eyes? Why or why not?
True or False: The signs and symptoms of an angle closure attack always happen immediately after dilation

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