Dilated Fundoscopic Examination: Indications and Technique
When to Perform Dilated Fundoscopy
Dilated fundoscopic examination should be performed whenever optimal visualization of the optic nerve, macula, and peripheral retina is required, as examination through an undilated pupil provides inadequate assessment of these critical structures. 1
Mandatory Indications for Dilated Examination
- Comprehensive eye evaluations: All patients undergoing complete ophthalmologic assessment require dilation for adequate fundus examination 1
- Diabetic patients: All patients with diabetes mellitus require dilated ophthalmoscopy to detect and grade diabetic retinopathy and macular edema 1
- Advanced HIV disease: Patients with CD4 counts <50 cells/mm³ require dilated examination by an ophthalmologist to screen for CMV retinitis 1
- Retinal vein occlusions: Dilated examination is essential to assess macular edema, ischemia, neovascularization, and peripheral retinal complications 1
- Glaucoma suspects: Dilated examination is preferred for optimal optic nerve head evaluation, though not absolutely required for initial assessment 1
- Hypertensive emergencies: Patients with suspected hypertensive emergency (SBP ≥180 or DBP ≥120 mmHg) should undergo funduscopy, as 14% of examined patients show grade III/IV retinopathy 2
Specific Clinical Scenarios Requiring Dilation
- Visual symptoms: Patients with photopsias or floaters (10.2% have retinal detachment) 3
- Head trauma: To detect intravitreous hemorrhage and Berlin edema 3
- Suspected papilledema: To evaluate optic disc edema in patients with headache or neurologic symptoms 3, 4
- Focal neurologic deficits: May assist with triage of suspected transient ischemic attack 4
How to Perform Dilated Fundoscopy
Preparation and Dilation
- Pupillary dilation is required for optimal examination of structures posterior to the iris 1
- Dilation enables adequate visualization of the optic nerve, macula, and peripheral retina 1
- Contraindication: Contact tonometry and dilation may be deferred in suspected ocular infection or corneal trauma 1
Examination Technique
The preferred technique involves magnified stereoscopic visualization using slit-lamp biomicroscopy through a dilated pupil 1
Step-by-Step Approach:
Slit-lamp biomicroscopy with appropriate lenses: Recommended for evaluating the posterior pole and midperipheral retina 1
Indirect ophthalmoscopy: Best method for examining the far peripheral retina 1
- Provides optimal examination of the optic nerve, macula, and peripheral retina 1
Direct ophthalmoscopy: Complements stereoscopic visualization by providing greater magnification for optic nerve detail 1
Red-free illumination: May aid in evaluating the retinal nerve fiber layer 1
Key Structures to Assess
- Optic nerve head: Evaluate for edema, pallor, hemorrhages, cup-to-disc ratio, and neovascularization 1
- Macula: Assess for edema, exudates, hemorrhages, and structural abnormalities 1
- Retinal vasculature: Examine for caliber changes, hemorrhages, cotton wool spots, microaneurysms, and neovascularization 1
- Peripheral retina: Screen for tears, detachment, and peripheral vascular abnormalities 1
- Vitreous: Evaluate for hemorrhage and posterior vitreous detachment 1
Common Pitfalls to Avoid
- Attempting fundoscopy without dilation: Undilated examination provides inadequate visualization of critical structures and misses significant pathology 1
- Relying solely on non-mydriatic photography: While useful for screening diabetic retinopathy, it cannot replace comprehensive dilated examination for complete assessment 5
- Skipping fundoscopy in hypertensive emergencies: Retinopathy can occur even with SBP <200 mmHg and DBP <120 mmHg, and no clinical signs reliably predict its presence 2
- Assuming visual symptoms predict retinal findings: Patients with significant retinopathy may be asymptomatic, and those without visual disturbances can still have severe disease 2