Primary Indications for Optical Coherence Tomography (OCT)
The primary indication for Optical Coherence Tomography (OCT) is the detection, evaluation, and management of macular diseases, particularly macular edema associated with retinal vein occlusions, diabetic retinopathy, and other macular pathologies. 1
Key Clinical Applications of OCT
Retinal Disease Applications
OCT serves as a critical diagnostic tool for retinal conditions:
Macular Edema Assessment:
- Provides high-resolution imaging of the macula to detect and quantify macular edema
- Guides treatment decisions for anti-VEGF injections, corticosteroids, or laser therapy 1
- Enables objective measurement of retinal thickness changes over time
Retinal Vein Occlusions:
- Detects macular edema, vitreoretinal interface changes, and subretinal fluid
- Quantifies retinal thickness to monitor treatment response
- Helps distinguish RVO from other macular diseases 1
Diabetic Retinopathy:
- Evaluates macular edema and monitors response to treatment
- Identifies microstructural changes secondary to ischemia
- Demonstrates loss of inner retinal layers at the fovea in diabetic macular ischemia 1
Glaucoma Management
OCT provides essential structural information for glaucoma diagnosis and monitoring:
Retinal Nerve Fiber Layer (RNFL) Assessment:
- Measures RNFL thickness at standardized locations around the optic nerve head
- Detects structural alterations before functional changes occur 1
- Provides quantitative data to supplement clinical examination
Optic Nerve Head Evaluation:
- Documents optic nerve damage and progression
- Distinguishes glaucomatous from non-glaucomatous optic neuropathy 1
Anterior Segment Applications
OCT is valuable for anterior segment assessment:
Angle Evaluation:
- Evaluates angle configuration in primary angle-closure disease
- Provides quantitative measurements of angle structures
- Useful when gonioscopy is precluded by corneal disease or poor patient cooperation 1
Corneal Assessment:
- Evaluates corneal contour and astigmatism
- Assists in toric IOL selection and astigmatism management 1
Clinical Decision Making with OCT
When to Order OCT
For macular disease evaluation:
- When visual acuity is disproportionate to cataract or other media opacity
- To identify retinal disease that may impact postoperative visual prognosis 1
- To detect epiretinal membranes that increase risk of cystoid macular edema
For glaucoma assessment:
- To establish baseline optic nerve and RNFL status
- To detect early glaucomatous damage before visual field changes
- To monitor progression of optic nerve damage 1
For vitreomacular interface disorders:
- To diagnose and characterize vitreomacular adhesion and traction
- To identify epiretinal membranes and associated retinal changes 1
Limitations and Pitfalls
Image Quality Issues:
- Media opacities can degrade image quality
- Operator technique affects reliability of measurements
- Results should be interpreted in context of clinical examination 1
Normative Database Limitations:
- Some individual findings may not fall within normative databases
- Caution needed when interpreting statistically abnormal results 1
Technical Considerations:
- Different OCT devices may produce slightly different measurements
- Consistency in using the same device for longitudinal monitoring is important
Advanced OCT Applications
OCT Angiography (OCTA):
- Non-invasive detection of capillary nonperfusion and vascular abnormalities
- May potentially replace fluorescein angiography for some applications 1
- Currently limited by image artifacts and field of view
Enhanced Depth Imaging and Swept-Source OCT:
- Improved visualization of choroidal structures
- Better assessment of posterior segment pathologies 2
OCT has revolutionized ophthalmic practice by providing non-invasive, high-resolution cross-sectional imaging of ocular structures, enabling earlier diagnosis, more precise monitoring, and better-informed treatment decisions across multiple ophthalmic conditions.