Gonioscopy Techniques and Equipment Quiz

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Questions and Answers

Which lens is specifically designed for use with infants?

Barkan

Thorpe

Koeppe

Layden (correct)

What is a disadvantage of direct gonioscopy?

Requires a specific lens type

Allows for indentation gonioscopy

No panoramic view

Difficulty in mastering technique (correct)

What is a feature of the Swan Jacob lens?

Operative conditions focus (correct)

A prototype for indirect gonioscopy

Designed for infants

Used in adult patients primarily

Which option describes indirect gonioscopy?

Utilizes mirrors to combat total internal reflection Signup and view all the answers

Which lens is equipped with a mirror inclined at 62 degrees?

Goldmann Single Mirror Signup and view all the answers

What part of the trabecular meshwork is primarily involved in aqueous outflow?

Posterior segment Signup and view all the answers

What can be observed in the Schlemm’s canal when the trabecular meshwork is lightly pigmented?

A red band Signup and view all the answers

Which landmark is identified by a faint white line at the termination of Descemet’s membrane?

Schwalbe’s line Signup and view all the answers

At what stage does the trabecular meshwork begin to exhibit pigment deposition?

With aging Signup and view all the answers

What is the acronym used to remember angle structures?

I Can’t See This Stuff Signup and view all the answers

What types of gonioscopy are identified?

Direct and Indirect Signup and view all the answers

Which of the following is NOT a contraindication for performing gonioscopy?

Narrow anterior chamber angle Signup and view all the answers

What optical principle is utilized in gonioscopy?

Total internal reflection within anterior chamber Signup and view all the answers

What is a primary indication for gonioscopy?

Assessment of primary open angle glaucoma Signup and view all the answers

How does direct gonioscopy enhance visualization?

By permitting light to exit closer to the perpendicular at the lens-air interface Signup and view all the answers

Which grading system uses Scheie's gonioscopic grading?

Angle grading based on the width of the ciliary body band. Signup and view all the answers

Which gonioprism includes mirrors inclined at 59 degrees and 62 degrees?

Rich Trabeculoplasty lens. Signup and view all the answers

What appearance is indicative of hyperopes in relation to the angle's appearance?

The angle appears narrower. Signup and view all the answers

Which statement is true about the trabecular meshwork?

It is pigmented band located between Schwalbe's line and the anterior limit. Signup and view all the answers

What anatomical structures make up the anterior chamber angle (ACA)?

Iris, Ciliary Body, Scleral Spur, Trabecular Meshwork, Schwalbe’s Line Signup and view all the answers

Why is it important to evaluate the anterior chamber angle?

To assess the risk of angle closure prior to pupil dilation Signup and view all the answers

Which technique is considered the gold standard for visualizing the anterior chamber angle?

Gonioscopy Signup and view all the answers

What is a limitation of the Pen Torch method for evaluating the ACA?

Is influenced by the penlight position Signup and view all the answers

Which angle assessment technique can compare the size of an optic section to a gap between the section and iris reflection?

Van Herick’s Technique Signup and view all the answers

What is a limitation of Van Herick’s technique?

Unable to assess the superior angle, which is most likely to close Signup and view all the answers

In what situation is gonioscopy mandatory?

In all glaucoma patients and suspected cases Signup and view all the answers

What spares the ability to assess a portion of the anterior chamber angle in some techniques?

The slit lamp angle of illumination Signup and view all the answers

Study Notes

Gonioscopy

Gonioscopy is a technique used to visualize the anterior chamber angle.
It is considered the gold standard for examining the angle.
Gonioscopy is a fundamental part of a comprehensive eye exam.
It's essential for diagnosing glaucoma, especially in patients with suspected or confirmed angle closure.
Gonioscopy helps differentiate between angle closure and secondary glaucoma.
It allows visualization of the angle during procedures like laser trabeculoplasty and goniotomy.
Gonioscopy is divided into two types: direct and indirect.

Anterior Chamber Angle (ACA)

ACA is the anatomical angle formed by the root of the iris and the peripheral corneal vault.
It comprises several key structures: iris, ciliary body, scleral spur, trabecular meshwork, and Schwalbe's line.
The ciliary body is a longitudinal muscle of the eye.
The scleral spur is a protrusion of the sclera into the anterior chamber.
The trabecular meshwork drains aqueous humor to the anterior chamber.
Schwalbe's line marks the end of Descemet's membrane, appearing as a very fine glossy line.

Indications for Gonioscopy

Primary open-angle glaucoma and its risk factors.
Narrow anterior chamber angle—before pupil dilation.
Narrow-angle glaucoma for evaluation of peripheral anterior synechiae (PAS).
Secondary open-angle glaucoma and its risk factors.
Risk of angle neovascularization.
Risk of angle recession following trauma.
Evaluation of risk for foreign intraocular body.
Structural irregularities of the iris.
Post-laser peripheral iridotomy.

Contraindications for Gonioscopy

Hyphema or microhyphema caused by ocular trauma.
Recent intraocular surgery.
Lacerated or perforated globe.

Angle Evaluation Techniques

Pen torch method.
Smith's method.
Van Herick's technique.
Split limbal technique.
Gonioscopy.
Optical Coherence Tomography (OCT).

Pen Torch Method

Simplest technique, suitable for small children and situations where a biomicroscope isn't available.
The eye is illuminated with a pen torch at the temporal canthus.
The amount of eye illuminated by the pen torch allows grading of the angle.
Limitations exist; grading is subjective and not quantitative.

Van Herick's Technique

Quantitative method of assessing ACA size using a slit-lamp biomicroscope.
Compares the width of an optic section on the cornea to the gap between the section and the iris reflection.
Angle of 60° is consistently used for standardization of measurements.
Cannot assess the superior angle, which is often the area most prone to closure.

Gonioscopy Grading Systems

Several grading systems exist for evaluating the angle, including Shaffer's, Scheie's, and RP Centre grading systems.
Quantitative grading of the angle is important for the assessment of glaucoma risk.

Direct Gonioscopy Advantages and Disadvantages

Advantages:
- Height of observer can be changed.
- Suitable for sedated, comatose, and pediatric patients.
- Panoramic view.
- Less distortion.
- Useful for examining fundus with small pupils.
- Straight view.
- Simultaneous observation of both eyes.
- No coupling fluid required.
Disadvantages:
- Inconvenient.
- Special equipment required.
- Difficult to master.
- Does not stabilize the globe.
- Cannot perform indentation gonioscopy.

Indirect Gonioscopy Advantages and Disadvantages

Advantages:
- Quick and convenient.
- No special equipment required.
- Allows differentiation between appositional and synechial closure.
- Can create a corneal wedge.
Disadvantages:
- Inherent risk of inadvertent pressure on the cornea.
- Mirror image can be confusing.
- Coupling fluid is required.

Gonioscopic View

Includes structures like non-pigmented and pigmented trabecular meshwork, Schwalbe's line, scleral spur, and ciliary body band.
Observe visual markers like Schwalbe's line to aid in structural assessment.
Identifying anatomical structures in the gonioscopic field can help in differential diagnosis and procedural planning.

Optical Principles in Gonioscopy

Total internal reflection within the anterior chamber (ACA) prevents direct visualization of the angle.
Mirrors, prisms, and special lenses are used to overcome the problem of total internal reflection and improve visualization.

Types of Gonioscopy Lenses

Several lens types are available, including Koeppe, Richardson Shaffer, Layden, Barkan Thorpe, and Swan Jacob lenses, each tailored for different situations.

Gonioscopy Procedures

Procedure steps include checking and sterilizing the goniolens, correctly positioning and securing the gel, using your slit lamp, locating and positioning your thumb, and aligning the angle for visualization.

Clinical Considerations

Specific clinical situations determine the need for gonioscopy.
Knowledge of structures and potential abnormalities is important for diagnosis and care.

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Description

Test your knowledge on gonioscopy techniques, equipment, and the anatomy of the eye. This quiz covers lenses specifically designed for infants, types of gonioscopy, and key anatomical structures involved in aqueous outflow. Perfect for ophthalmology students and professionals looking to refresh their understanding.