What are the diagnosis and treatment options for micro retinal neural atrophy?

Diagnosis and Treatment of Retinal Neural Atrophy

Diagnostic Approach

A multimodal imaging protocol is essential for diagnosing retinal neural atrophy, with optical coherence tomography (OCT), fundus autofluorescence (FAF), and color fundus photography forming the core diagnostic triad. 1

Primary Imaging Modalities

• Optical Coherence Tomography (OCT) is the gold standard for documenting retinal nerve fiber layer (RNFL) thickness and quantifying ganglion cell loss, with thinning confirming neural atrophy 2
• Fundus Autofluorescence (FAF) provides high contrast imaging with regulatory acceptance for detecting and quantifying atrophic areas, showing strongly decreased signal that correlates with loss of function 1
• Color Fundus Photography (CFP) documents baseline appearance for future comparison and visualizes a broad range of fundus abnormalities including areas of depigmentation with sharply demarcated borders 1
• Near-Infrared Reflectance (NIR) imaging is resistant to media opacities and enables detection of atrophy, serving as an auxiliary tool for foveal assessment 1

Advanced Imaging When Indicated

• Fluorescein Angiography (FA) should be performed at baseline to exclude concurrent neovascularization and when incident neovascularization is suspected during follow-up 1
• Indocyanine Green Angiography (ICG-A) may be optionally performed if doubts remain about the cause of atrophy for differential diagnosis, particularly to distinguish AMD from conditions like Stargardt disease 1
• Brain and orbital MRI with contrast is mandatory for all patients with unexplained optic atrophy to exclude compressive lesions, demyelination, or structural abnormalities 2

Functional Assessment

• Automated visual field testing (Humphrey 24-2 and 30-2) documents the pattern and extent of field defects, with central scotomas suggesting optic neuropathy 2
• Visual acuity testing using ETDRS charts in LogMAR scale establishes baseline function and monitors progression 3
• Microperimetry captures the relationship between anatomic progression and visual function decline, assessing retinal sensitivity and fixation stability 4, 3

Etiological Investigation

• Laboratory screening including ESR/CRP if age >50 years to investigate giant cell arteritis, and thyroid function tests if thyroid eye disease is suspected 2
• Pupillary examination for relative afferent pupillary defect indicates asymmetric optic nerve dysfunction 2
• Color vision assessment using Ishihara plates or Panel D-15, as deficits are characteristic of optic neuropathies 2

Treatment Approach

For Geographic Atrophy (Dry AMD)

The AREDS2 formulation (vitamin C, vitamin E, zinc 25mg, copper, lutein 10mg, zeaxanthin 2mg) is the only proven intervention to slow progression of geographic atrophy, reducing risk by up to 36% over 10 years. 5

• Prescribe AREDS2 supplements to all patients with intermediate or advanced dry AMD in at least one eye 5
• Mandatory smoking cessation as cigarette smoking increases AMD progression risk proportional to pack-years smoked 5
• Avoid beta-carotene formulations in current or former smokers due to 18% increased cumulative incidence of lung cancer 5
• Use 25mg zinc dose rather than 80mg, as it shows equivalent efficacy with reduced genitourinary hospitalizations 5
• Coordinate with primary care physicians before initiating long-term supplementation due to potential adverse effects 5

For Neovascular AMD with Atrophy

Initiate intravitreal anti-VEGF therapy immediately with three loading doses at 4-week intervals using aflibercept, ranibizumab, or bevacizumab. 5

• Administer three loading doses at exactly 4-week intervals 5
• Maintenance regimens include aflibercept every 8 weeks, treat-and-extend, PRN, or monthly injections based on treatment response 5
• Continue AREDS2 supplementation in combination with anti-VEGF therapy 5
• Monitor with OCT at each visit to assess for subretinal or intraretinal fluid 5

For Optic Atrophy

• Treat the underlying cause when identified: surgical decompression for compressive lesions, immunosuppression for inflammatory causes 2
• Mandatory smoking cessation as tobacco interferes with mitochondrial metabolism and worsens hereditary optic neuropathies 2
• Avoid alcohol consumption in hereditary optic neuropathies as it exacerbates mitochondrial dysfunction 2

Visual Rehabilitation

Refer all patients with reduced visual function to vision rehabilitation services immediately, as visual training improves fixation stability, reading speed, and visual acuity. 2, 3

• Optical/electronic magnifying devices and bright lights help patients read more effectively 2, 5
• Microperimetry-based visual rehabilitation improves fixation stability (P1 values from 45% to 51%), reading speed (from 47 to 69 words per minute), and visual acuity (0.7 to 0.6 LogMAR) within one week of training 3
• Low vision aids including electronic reading aids optimize existing visual function 2

Monitoring Protocol

• Serial visual field testing every 6-12 months to monitor for progression 2
• OCT monitoring of RNFL thickness to document structural changes over time 2
• Regular comprehensive eye examinations for early detection, as early symptoms may be subtle 5
• Fellow eye monitoring every 6-12 months even without symptoms in patients with unilateral disease, as the fellow eye remains at exceptionally high risk 5

Critical Clinical Considerations

• Geographic atrophy progression rates range from 0.53 to 2.6 mm²/year (median ~1.78 mm²/year), with faster expansion in patients under age 75 6, 4
• Rate of significant visual loss from 20/50 or better to 20/100 or worse is 8% of eyes per year 6
• Central vision loss is common but total blindness is extremely rare, as peripheral vision is typically preserved 5
• Subretinal neovascularization develops in approximately 20% of eyes with geographic atrophy over time 6
• No FDA-approved therapies currently exist to significantly slow geographic atrophy progression, though complement inhibition therapies are under investigation 7