Importance of RNFL Analysis

Glaucoma Diagnosis:

• Detects early glaucomatous damage before functional vision loss occurs.
• Helps differentiate between normal-tension glaucoma and other optic neuropathies.

Glaucoma Progression Monitoring:

• Tracks changes in RNFL thickness over time to evaluate disease progression.

Neuro-Ophthalmic Conditions:

• Identifies optic nerve atrophy or swelling in conditions like optic neuritis, ischemic optic neuropathy, or papilledema.

Screening High-Risk Patients:

• Useful in patients with a family history of glaucoma or ocular hypertension.

Technology Used in RNFL Analysis

RNFL analysis is performed using Optical Coherence Tomography (OCT), a non-invasive imaging technology.

• Spectral-Domain OCT (SD-OCT):
  • High resolution (3–7 microns), allowing detailed imaging of the RNFL.
• Swept-Source OCT (SS-OCT):
  • Faster scanning and better penetration into deeper structures.

Procedure

Patient Preparation:

• The patient is seated, and their chin and forehead are stabilized on the OCT device.
• The patient is instructed to fixate on a target light to ensure alignment.

Scanning:

• The OCT device captures cross-sectional images of the retina, focusing on the optic nerve head.
• Scans are analyzed to create a thickness map of the RNFL.

Data Analysis:

• RNFL thickness is measured in a circular area around the optic disc.
• Results are compared to a normative database to identify abnormalities.

Key Parameters in RNFL Analysis

Global RNFL Thickness:

• Average thickness of the RNFL across the entire scan circle.

Sectoral RNFL Thickness:

• Thickness in specific quadrants:
  • Superior: Commonly affected early in glaucoma.
  • Inferior: Also vulnerable in glaucomatous damage.
  • Nasal: Less commonly affected.
  • Temporal: Includes the papillomacular bundle, often spared in early glaucoma.

Deviation Maps:

• Highlight regions where the RNFL thickness deviates from normal values.

Trend Analysis:

• Longitudinal measurements to monitor progression.