Slit Lamp Examination Techniques

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Questions and Answers

Which of the following is NOT an advantage of direct ophthalmoscopy?

Provides a relatively higher level of magnification ~15X

Easier to conduct than other methods of posterior segment evaluation

Can be performed on large or small pupils

Provides a stereoscopic view of the posterior segment (correct)

What is the purpose of the red-free filter on a direct ophthalmoscope?

To assess corneal scar and abrasion

To differentiate retinal and choroidal lesions (correct)

To detect media opacities

To enhance the view of the optic nerve head

What is the function of the rheostat on a direct ophthalmoscope?

To switch between the red-free filter and the fixation cross

To control the illumination (correct)

To change the lens power

To adjust the aperture size

Which of the following is a disadvantage of direct ophthalmoscopy?

It provides a limited field of view (C) Signup and view all the answers

What is the function of the cobalt blue filter on a direct ophthalmoscope?

To assess corneal scar and abrasion (B) Signup and view all the answers

What is the purpose of Specular Reflection?

To observe irregularities, deposits, or excavations in a smooth surface. (A) Signup and view all the answers

When using Specular Reflection, which of the following is true?

The angle of incidence is always equal to the angle of reflection. (A) Signup and view all the answers

What is the purpose of using a 'Red-free' filter in Filtered Illumination?

To make blood vessels and rose bengal stain appear black to enhance contrast. (B) Signup and view all the answers

During the Van Herick Technique, where should the slit lamp be focused?

At the limbus. (C) Signup and view all the answers

What does a widening of the slit beam during the Van Herick Technique indicate?

The slit beam is bridging the corneo-scleral transition area. (B) Signup and view all the answers

What is the purpose of the Cobalt Blue filter in Filtered Illumination?

To visualize corneal staining with fluorescein dye. (D) Signup and view all the answers

What is the role of a barrier filter, such as Yellow Wratten, when used with fluorescein?

To block out certain wavelengths of light, making the fluorescein stain more visible. (B) Signup and view all the answers

During the Van Herick Technique, what is the angle between the arms of the slit lamp?

60 degrees (A) Signup and view all the answers

What is the first step in properly setting up for an examination?

Wash hands (C) Signup and view all the answers

Which structure is examined last in an efficient assessment of the anterior segment?

Lens (A) Signup and view all the answers

What describes the appearance of the fundus in individuals with high pigment density?

Tessellated or tigroid appearance (D) Signup and view all the answers

Where is the optic nerve head (ONH) positioned relative to the macula?

Nasally (A) Signup and view all the answers

What is a significant characteristic of the outer margins of the optic nerve head?

They should be clear and defined (D) Signup and view all the answers

Which part of the anterior segment is evaluated by eversion of the eyelids?

Superior tarsal conjunctiva (A) Signup and view all the answers

What appearance does the fundus typically have in individuals with sparse pigmentation?

More red due to visible vessels (A) Signup and view all the answers

What should be done before starting the examination of the right eye?

Prepare instrument and set up illumination (A) Signup and view all the answers

What is the recommended position for the patient during the BIO procedure?

Supine position (C) Signup and view all the answers

Why should the macula be examined last during the BIO procedure?

The bright light may reduce patient cooperation. (C) Signup and view all the answers

How should the examiner position themselves during the BIO procedure?

Beside the patient, leaning over. (C) Signup and view all the answers

What is a key step to take when documenting findings from a BIO?

Invert and reverse the image in your mind or use a specific fundus diagram method. (C) Signup and view all the answers

What is the initial gaze direction of the patient during the BIO procedure?

Directly up. (C) Signup and view all the answers

When using a handheld lens during BIO, what is the ideal distance from the patient's eye?

2 inches (D) Signup and view all the answers

What technique can the examiner use to view different parts of the retina?

Tilting their head and moving around the patient. (B) Signup and view all the answers

What should the examiner instruct the patient to do during the BIO exam?

Look at various extremes of their vision. (B) Signup and view all the answers

What should be done if a media opacity appears to move in the same direction as the movement of the eye?

The opacity lies in the anterior capsule. (B) Signup and view all the answers

Why is it important to provide the patient with adequate instructions before the examination?

To inform them of the purpose of the test, the use of bright light and the potential for close proximity to their eye or face. (D) Signup and view all the answers

Why is it advised to perform this technique in a dimly lit room?

To allow for maximal pupil dilation, which can be helpful for visualization. (A) Signup and view all the answers

What is the principle that is used to assess media opacities?

Motion of parallax plus nodal point. (A) Signup and view all the answers

How is the power of the correcting lens determined during the examination?

The power of the correcting lens must be the algebraic sum of the ametropias of the practitioner and the patient, minus the dioptric amount of their accommodation. (B) Signup and view all the answers

What is the purpose of using a +10.00DS lens at the beginning of the examination?

To enhance the visibility of the anterior media structures, such as the cornea and lens. (A) Signup and view all the answers

What is the red-reflex and what does it indicate?

The red-reflex is a reflection of light off the retina, indicating a clear media. (B) Signup and view all the answers

How does the practitioner determine the location of a media opacity?

By observing the direction of the opacity's movement relative to the eye's movement. (D) Signup and view all the answers

What is the purpose of using a 'V' shape formed by blood vessels during fundus examination?

To locate the optic nerve head (ONH) (C) Signup and view all the answers

What is the correct formula for calculating the correcting lens power?

Examiner’s Ametropia + Patient’s Ametropia - accommodation (D) Signup and view all the answers

What type of image is formed by the condensing lens in a binocular indirect ophthalmoscope (BIO)?

Real, aerial, inverted, and reversed (C) Signup and view all the answers

Which of the following is NOT a feature that is examined during optic nerve head evaluation?

Presence of a foveal-reflex (D) Signup and view all the answers

When examining the macula, what observation is NOT typically made?

Presence of a 'V' shape formed by blood vessels (D) Signup and view all the answers

During fundus examination, how are the four quadrants of the retina typically assessed?

The patient moves their gaze to different quadrants while the examiner remains stationary (C) Signup and view all the answers

What is the primary advantage of using a binocular indirect ophthalmoscope (BIO) for fundus examination?

It provides a panoramic and stereoscopic view of the entire fundus (A) Signup and view all the answers

What is the purpose of the light source in a BIO?

To illuminate the retina (A) Signup and view all the answers

Study Notes

Slit Lamp Examination (SLE)

Used for binocular examination of the eye, from anterior to posterior segment
Used for examining the tear film, anterior vitreous, posterior segment using auxiliary lenses, intraocular pressure (Goldmann tonometry), anterior chamber depth, contact lens fittings, gonioscopy, and minor surgical procedures
Utilizes a laser delivery system

Instrumentation

Biomicroscopes vary in features and types
Composed of two basic parts on a common pivoting base
Observation system (microscope): binocular eyepieces, magnification control
Illumination system: adjustable light beam (variable height, width, angle), filters (red-free, cobalt blue, diffuser)

Methods of Illumination

Diffuse Illumination: Wide, unfocused beam of light, directed obliquely toward the eye, used for general view of the eye and adnexa (lids, lashes, conjunctiva, sclera, cornea, iris)
Optic Section: Thin slit beam (minimum 0.25 mm), optically slices tissue, examines tissue layers and depth, used for assessing the depth of anomalies or bodies in tissue
Parallelepiped (3-Dimensional View): 1-2 mm slit beam, illuminates a rectangular area allowing a layered, 3-dimensional view of tissue layers, useful for tear film, cornea, lens
Conical Beam: Small, spot or square of light, used for evaluating clarity of the anterior chamber, assessing debris in the anterior chamber

Methods of Observation

Direct: Observation and illumination systems are focused coincidentally, area under observation is illuminated directly, used for general examination purposes
Indirect/Proximal: Observation and illumination systems are not focused coincidentally, incident light falls on area adjacent to object/area of interest, used for evaluating structures and fine details, useful for viewing iris, fine vascularization, pigment spots, corneal edema

Retro-Illumination

Object under observation is illuminated using light that's reflected from a deeper structure within or behind the structure
Usually 30-45 degree angle between observation and illumination systems
Useful for viewing structures and fine details obscured by direct light or for viewing deeper structures, for example, retina

Sclerotic Scatter

Bright parallelepiped focused on the light transmission within the cornea which transmits within the cornea
Useful for viewing subtle corneal changes (edema, scars, striae, foreign bodies)

Specular Reflection

Parallelepiped beam
Bright specular reflection is seen from the cornea, gradually increase magnification, tear film on the anterior surface, endothelium on the posterior surface
Useful for observing irregularities, deposits, or excavations in smooth surfaces, corneal endothelium, and tear film evaluation

Filtered Illumination

Various filters used to enhance the assessment of certain structures and abnormalities (e.g., cobalt blue, yellow wratten, red-free, neutral density)
Cobalt blue: used with fluorescein dye to visualize corneal staining
Yellow wratten: used with fluorescein to visualize corneal staining
Red-free: used to visualize blood vessels
Neutral density: uniformly decreases illumination intensity

Van Herick Technique

Used to assess the anterior chamber depth
Use low to medium magnification, 60-degree angle between arms of the slit lamp with observation system perpendicular to the eye
Establish the ratio between the thickness of the anterior chamber (DAC) to the thickness of the cornea (CT) to determine the grading

Slit Lamp Routine Assessment

Steps for properly conducting a slit lamp examination: explanation of the procedure, appropriate test setup (washing hands, headrests, etc.), proper examination sequence using efficient and logical order, assessment, and recording

Funduscopy

Color of the fundus varies among individuals, from reddish-orange to more red or tessellated/tigroid appearance
Optic nerve head (ONH) lies nasal to macula; its dimensions, margins, and cup-to-disc ratio are assessed for indications of specific pathology
Retinal vessels (arteries and veins) have different thicknesses. The ratio (A/V) is generally 2:3
Macula, the central area of the fundus with cone photoreceptors, is darker and thicker than other sections

Direct Ophthalmoscopy

Provides a view of the posterior pole, macular region, optic nerve, and vascular arcades
Less demanding to perform compared to other methods
Magnification ranges up to about 15x

Binocular Indirect Ophthalmoscopy (BIO)

Head-borne device using an illumination system and oculars
Used to examine all the areas of the fundus with a panoramic and stereoscopic view
Advantages: provides stereoscopic view, wider field of view, high contrast, excellent depth of focus, independent of refractive errors, variety of lens options, relatively short examination time
Disadvantages: inverted and reversed image, low magnification, dilation required, more difficult to perform

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Description

Explore the essential techniques and instrumentation used in Slit Lamp Examination (SLE) for ocular health. This quiz covers methods of illumination, examination areas, and the components of biomicroscopes. Test your knowledge on the critical aspects of SLE and enhance your understanding of ocular diagnostics.