Slit Lamp Examination

The slit lamp examination uses a specialized microscope called a slit lamp (or biomicroscope) to examine the eye in great detail. The instrument provides a magnified, three-dimensional view of eye structures using an adjustable beam of light.

What Is a Slit Lamp?

The slit lamp combines:

• Microscope for magnification (6x to 40x)
• Adjustable light source that can be narrowed to a "slit"
• Chin rest to stabilize patient's head

The "slit" of light allows the doctor to see thin cross-sections of eye structures, similar to how a flashlight beam shows dust particles in the air.

Structures Examined

Front of the Eye (Anterior Segment)

Eyelids and lashes

• Inflammation, infections
• Abnormal growths
• Lash problems

Conjunctiva

• Redness, inflammation
• Growths or lesions
• Dryness

Cornea

• Clarity and shape
• Abrasions, ulcers
• Dystrophies
• Infections

Anterior chamber

• Inflammation (cells, flare)
• Bleeding
• Depth

Iris

• Shape and color
• Inflammation
• Pupil abnormalities
• Argyll Robertson pupils

Lens

• Cataracts
• Position
• Clarity

Back of the Eye (With Additional Lenses)

With special lenses, the slit lamp can also examine:

• Vitreous
• Retina
• Optic nerve
• Macula

Common Uses

Routine Eye Examination

• Part of comprehensive eye exam
• Checking eye health

Specific Conditions

• Dry eye evaluation
• Contact lens fitting
• Infection diagnosis
• Inflammation (uveitis) assessment
• Cataract evaluation
• Glaucoma assessment (with gonioscopy)

After Eye Procedures

• Post-surgical monitoring
• Laser treatment follow-up

The Procedure

Preparation

• Usually no special preparation
• Remove contact lenses
• May have dilating drops placed

During the Exam

• Sit at the instrument with chin on rest
• Forehead against the bar
• Keep both eyes open
• Look straight ahead or as directed
• Bright light will be shone into eye
• Exam takes a few minutes

What You'll Experience

• Bright light (may be uncomfortable but not painful)
• Doctor looking closely at your eye
• May feel air puff if pressure measured (tonometry)
• May have dye drops (fluorescein) placed

Special Techniques

Fluorescein Staining

• Orange dye drops placed on eye
• Shows corneal damage, dry areas
• Used for contact lens fitting

Gonioscopy

• Special lens placed on eye
• Views drainage angle for glaucoma
• Numbing drops used first

Fundus Examination

• High-magnification lens used
• Detailed view of optic nerve and retina
• Better detail than ophthalmoscope alone

In Neuro-Ophthalmology

Slit lamp exam helps evaluate:

• Pupil abnormalities
• Uveitis causing light sensitivity
• Optic nerve appearance (with lens)
• Argyll Robertson pupils
• Eye movement abnormalities

After the Exam

• No restrictions usually
• If dilated, temporary light sensitivity
• If fluorescein used, may have orange tears briefly
• Can usually drive unless dilated

What the Doctor Is Looking For

Finding	May Indicate
Corneal infiltrates	Infection, inflammation
Cells in anterior chamber	Uveitis
Irregular pupil	Prior inflammation, trauma
Lens opacity	Cataract
Disc swelling	Papilledema, optic neuritis
Pale disc	Optic atrophy