Are All Retinal Nerve Fiber Layer Defects on Optic Coherence Tomography Glaucomatous?

Area of Science:

• Ophthalmology
• Medical Imaging
• Neurology

Background:

• Optic coherence tomography (OCT) is widely used for detecting retinal nerve fiber layer (RNFL) defects.
• Prediagnosis of glaucoma is often based on RNFL thinning identified via OCT.
• Non-glaucomatous causes of RNFL defects can mimic glaucoma findings.

Purpose of the Study:

• To investigate patients with suspected glaucoma based on OCT RNFL defects.
• To identify the prevalence and causes of non-glaucomatous RNFL defects.
• To evaluate the diagnostic accuracy of OCT in differentiating glaucoma from other optic neuropathies.

Main Methods:

• Retrospective analysis of 357 patients referred with suspected glaucoma.
• Review of ophthalmic examination notes, OCT, Heidelberg Retinal Tomography (HRT) II, and fundus photographs.
• Detailed medical history, systemic, and neurological examinations for patients with unexplained RNFL defects.

Main Results:

• Of 357 patients, 60.5% had open-angle glaucoma, 9.2% low-tension glaucoma, and 10.9% pre-perimetric glaucoma.
• 10.9% of patients had normal ophthalmic examinations with no RNFL defects on OCT.
• Diagnoses for non-glaucomatous RNFL defects included ischemic optic neuropathy (2.8%), optic neuritis (0.6%), optic disc drusen (0.6%), pseudotumor cerebri (0.3%), and cerebral palsy (0.3%).

Conclusions:

• OCT RNFL assessment alone can be misleading for glaucoma diagnosis.
• Diagnosis requires integrating OCT findings with clinical examination, patient history, and other imaging modalities like HRT.
• A comprehensive approach is essential to differentiate glaucoma from other conditions causing RNFL defects.