Gonioscopy in Eye Care

Gonioscopy is a crucial diagnostic procedure in optometric and ophthalmological care, essential for evaluating the anatomy and function of the anterior chamber angle. This specialized technique uses a gonioscopy lens to overcome the total internal reflection at the cornea-air interface, enabling visualization of structures typically hidden during routine slit-lamp examinations. Proper gonioscopy aids in assessing glaucoma risk and informs precise clinical decisions aimed at protecting patients' ocular health.

Effective gonioscopy begins with selecting the appropriate lens type. The two primary lenses used in clinical practice include:

• Three-Mirror Gonioscopy Lens: Offers detailed views of both the anterior chamber angle and peripheral retina, requiring coupling gel for clarity and stability.
• Four-Mirror Gonioscopy Lens: Designed for quick, efficient evaluation of the anterior chamber angle without the need for coupling gel, providing ease of use and minimal patient discomfort.

The clinician carefully places the chosen lens on the anesthetized cornea, skillfully coordinating lens manipulation and slit-lamp examination to obtain accurate, detailed views of critical anatomical structures for diagnosing angle abnormalities.

Accurate gonioscopy requires recognizing specific anatomical landmarks within the anterior chamber angle, including:

• Schwalbe's Line: A thin reflective boundary marking the transition from corneal endothelium to trabecular meshwork.
• Trabecular Meshwork: A granular or pigmented band responsible for aqueous humor drainage.
• Scleral Spur: A distinct white band posterior to the trabecular meshwork, serving as a reference point for other structures.
• Ciliary Body Band: A darker, pigmented area posterior to the scleral spur, indicating an open angle.

Employing grading systems such as Shaffer or Spaeth allows clinicians to objectively assess angle openness and determine glaucoma risk. Mastery of these landmarks enhances diagnostic precision and improves patient outcomes.

Gonioscopy plays a vital role in diagnosing and managing conditions including:

• Angle-Closure Glaucoma: Early detection of narrowed or blocked angles to prevent acute episodes.
• Open-Angle Glaucoma and Ocular Hypertension: Identification of trabecular meshwork irregularities affecting aqueous drainage.
• Pigment Dispersion and Pseudoexfoliation Syndromes: Detection of pigment and exfoliative debris in the trabecular meshwork, contributing to increased intraocular pressure.
• Neovascular Glaucoma: Recognition of abnormal blood vessel formation within the angle, enabling prompt therapeutic intervention.

Routine gonioscopy in high-risk individuals, such as older adults, hyperopes, or patients with a glaucoma family history, ensures timely detection and targeted treatments including laser iridotomy, selective laser trabeculoplasty (SLT), or appropriate pharmacological therapies.