Slit-Lamp Biomicroscopy

Slit-Lamp Biomicroscopy

Synonym/acronym: Slit-lamp examination.

Common use

To detect abnormalities in the external and anterior eye structures to assist in diagnosing disorders such as corneal injury, hemorrhage, ulcers, and abrasion.

Area of application





This noninvasive procedure is used to visualize the anterior portion of the eye and its parts, including the eyelids and eyelashes, sclera, conjunctiva, cornea, iris, lens, and anterior chamber, and to detect pathology of any of these areas of the eyes. The slit lamp has a binocular microscope and light source that can be adjusted to examine the fluid, tissues, and structures of the eyes. For example, slit lamp ophthalmoscopy can be performed using the microscope part of the slit lamp and a special lens placed close to the eye to examine the retina, optic disc, choroid, and blood vessels in the back or fundus of the eye. Ophthalmoscopy is helpful in the identification of retinal detachment, diseases such as glaucoma that affect the movement of eye fluid, or diseases that affect the blood vessels in the eyes such as hypertension and diabetes. Special attachments to the slit lamp are used for special studies and more detailed views of specific areas. Dilating drops or mydriatics may be used to enlarge the pupil in order to allow the examiner to see the eye in greater detail. Mydriatics work either by temporarily paralyzing the muscle that makes the pupil smaller or by stimulating the iris dilator muscle. Blue or hazel eyes dilate faster than brown eyes.

This procedure is contraindicated for

  • high alertPatients with narrow-angle glaucoma if pupil dilation is performed; dilation can initiate a severe and sight-threatening open-angle attack.
  • high alert Patients with allergies to mydriatics if pupil dilation using mydriatics is performed.


  • Detect conjunctival and corneal injuries by foreign bodies and determine if ocular penetration or anterior chamber hemorrhage is present
  • Detect corneal abrasions, ulcers, or abnormal curvatures (keratoconus)
  • Detect deficiency in tear formation indicative of lacrimal dysfunction causing dry eye disease that can lead to corneal erosions or infection
  • Detect lens opacities indicative of cataract formation
  • Determine the presence of blepharitis, conjunctivitis, hordeolum, entropion, ectropion, trachoma, scleritis, and iritis
  • Evaluate the fit of contact lenses

Potential diagnosis

Normal findings

  • Normal anterior tissues and structures of the eyes

Abnormal findings related to

  • Blepharitis
  • Conjunctivitis
  • Corneal abrasions
  • Corneal foreign bodies
  • Corneal ulcers
  • Diabetes
  • Ectropion
  • Entropion
  • Glaucoma
  • Hordeolum
  • Iritis
  • Keratoconus (abnormal curvatures)
  • Lens opacities
  • Scleritis
  • Trachoma

Critical findings


Interfering factors

  • Inability of the patient to cooperate and remain still during the procedure because of age, significant pain, or mental status may interfere with the test results.
  • Failure to follow medication restrictions before the procedure may cause the procedure to be canceled or repeated.

Nursing Implications and Procedure


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this procedure can assist in evaluating the structures of the eye.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially mydriatics if dilation is to be performed.
  • Obtain a history of the patient’s known or suspected vision loss, changes in visual acuity, including type and cause; use of glasses or contact lenses; eye conditions with treatment regimens; eye surgery; and other tests and procedures to assess and diagnose visual deficit.
  • Obtain a history of the patient’s symptoms and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Instruct the patient to remove contact lenses or glasses, as appropriate, unless the study is being done to check the fit and effectiveness of the contact lenses. Instruct the patient regarding the importance of keeping the eyes open for the test.
  • Review the procedure with the patient. Address concerns about pain and explain that mydriatics, if used, may cause blurred vision and sensitivity to light. There may also be a brief stinging sensation when the drop is put in the eye. Inform the patient that a health-care provider (HCP) performs the test in a quiet, darkened room, and that to evaluate both eyes, the test can take up 30 min (including time for the pupils to dilate before the test is actually performed).
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food or fluid restrictions unless by medical direction.
  • Instruct the patient to withhold eye medications (particularly miotic eye drops which may constrict the pupil preventing a clear view of the fundus and mydriatic eyedrops in order to avoid instigation of an acute open angle attack in patients with narrow angle glaucoma) for at least 1 day prior to the procedure.
  • Ensure that the patient understands that he or she must refrain from driving until the pupils return to normal (about 4 hr) after the test and has made arrangements to have someone else be responsible for transportation after the test.


  • Potential complications:
  • Dilation can initiate a severe and sight-threatening open-angle attack in patients with narrow-angle glaucoma.

  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient.
  • Ensure that the patient has complied with medication restrictions and pretesting preparations; assure that eye medications, especially mydriatics, have been restricted for at least 1 day prior to the procedure.
  • Instruct the patient to cooperate fully and to follow directions. Ask the patient to remain still during the procedure because movement produces unreliable results.
  • Seat the patient comfortably. If dilation is to be performed, administer the ordered mydriatic to each eye and repeat in 5 to 15 min. Drops are placed in the eye with the patient looking up and the solution directed at the six o’clock position of the sclera (white of the eye) near the limbus (gray, semitransparent area of the eyeball where the cornea and sclera meet). Neither dropper nor bottle should touch the eyelashes.
  • Ask the patient to place the chin in the chin rest and gently press the forehead against the support bar.
  • The HCP places the slit lamp in front of the patient’s eyes in line with the examiner’s eyes. The external structures of the eyes are inspected with the special bright light and microscope of the slit lamp. The light is then directed into the patient’s eyes to inspect the anterior fluids and structures and is adjusted for shape, intensity, and depth needed to visualize these areas. Magnification of the microscope is also adjusted to optimize visualization of the eye structures.
  • Special attachments and procedures can also be used to obtain further diagnostic information about the eyes. These may include, for example, a camera to photograph specific parts, gonioscopy to determine anterior chamber closure, and a cobalt-blue filter to detect minute corneal scratches, breaks, and abrasions with corneal staining.


  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Instruct the patient to resume usual medications, as directed by the HCP.
  • Recognize anxiety related to test results, and encourage the family to recognize and be supportive of impaired activity related to vision loss, anticipated loss of driving privileges, or the possibility of requiring corrective lenses (self-image). Discuss the implications of the abnormal test results on the patient’s lifestyle. Provide contact information, if desired, for a general patient education Web site on the topic of eye care (e.g.,
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Inform the patient that visual acuity and responses to light may change. Suggest that the patient wear dark glasses after the test until the pupils return to normal size. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include color perception test, fluorescein angiography, gonioscopy, intraocular muscle function, intraocular pressure, nerve fiber analysis, refraction, Schirmer tear test, and visual field testing.
  • Refer to the Ocular System table at the end of the book for related tests by body system.
Handbook of Laboratory and Diagnostic Tests, © 2013 Farlex and Partners
References in periodicals archive ?
Slit-lamp biomicroscopy revealed bilateral 2-3+ cells in the anterior chamber, posterior synechia, and pigment precipitates on the lens, all of which were more severe in the right eye.
Traditional methods for evaluating DR, including slit-lamp biomicroscopy and stereo fundus photography, are relatively insensitive to small pathological changes in the retina.
Secondary to backward light scattering, the developed corneal haze following CXL can be detected clinically and graded subjectively on slit-lamp biomicroscopy and evaluated quantitatively using Scheimpflug densitometry [7].
Ophthalmic examinations included slit-lamp biomicroscopy, fundus exam, Schirmer tear test, conjunctival bacterial culture and isolation, corneal touch threshold, tonometry, and corneal diameter measurement.
Diabetic macular oedema is diagnosed stereoscopically as retinal thickening in the macula using slit-lamp biomicroscopy. The ETDRS defined DME as retinal thickening or presence of hard exudates within 1 DD of the centre of the macula.
The observation and examination of the anterior segment of the eye by using slit-lamp biomicroscopy is subjective.
The depth of anterior chamber was normal according to slit-lamp biomicroscopy; we assumed that it might be because of the fact that the lens cortex has not been prolapsed out in these four cases; however the exact anterior chamber depth should be determined by ultrasound pachymetry, Pentacam, or IOL master to confirm whether the anterior chamber depth was normal in the future.
Implanted donor grafts were clearly visible a few hours after surgery, and correct orientation was verified by slit-lamp biomicroscopy (Figure 2(b)).
Baseline examination included VA, BCVA, IOP, slit-lamp biomicroscopy pre- and post-mydriasis, gonioscopy, funduscopic examination, and automated Humphrey SITA-standard 30-2 VFA.
The slit-lamp biomicroscopy results showed that 70.83% of the eyes had medial corner entropion; 42% exhibited hair in the medial caruncle; 33% had distichiasis; 27% had mild paracentral corneal macula; and 13%, corneal melanosis.
Slit-lamp biomicroscopy is an easy, rapid and inexpensive method for estimating the optic disc size and changes in POAG.The aim of this study is to enlist the morphological changes of the optic nerve head in our local population diagnosed as having POAG.