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Multifocal ERG and Microperimetry Changes in Response to Ranibizumab Treatment of Neovascular AMD: Randomized Phase 2
Masumi G Asahi1, Josh Wallsh1, Spencer M Onishi1
1Clinical Research Department, Retina Macula Institute, Torrance, CA, USA.
Purpose:
To compare monthly versus pro re nata (PRN) ranibizumab injections in the treatment of exudative macular degeneration (AMD) while assessing the utility of microperimetry (MP) and multifocal electroretinography (mfERG) testing when monitoring response to treatment.
Methods:
A randomized exploratory trial comparing the efficacy of monthly versus PRN dosing of ranibizumab (0.5 mg or 2.0 mg) for patients with exudative AMD over 12 months. High-resolution optical coherence tomography (HR-OCT) studies were used to guide PRN treatment and any cystic spaces or subretinal fluid prompted retreatment. Macular function was assessed using mean sensitivity on MP and N1-P1 response density on mfERG. Best-corrected visual acuity (BCVA) was measured with Early Treatment Diabetic Retinopathy Study (ETDRS) letters and anatomic response assessed with central foveal thickness (CFT) using HR-OCT studies.
Results:
The 12-month study was completed by 43 patients in the PRN cohort and 33 patients in the monthly cohort. Mean BCVA improved by 6.0 ± 1.3 ETDRS letters in the PRN cohort compared to 7.3 ± 2.8 ETDRS letters in the monthly cohort (p=0.68). A reduction in mean CFT of 64.5 ± 13.3 and 96.3 ± 22.0 µm occurred in the PRN and monthly cohorts, respectively (p=0.22). Macular function assessed with mfERG decreased comparably in both the PRN and monthly cohorts (p=0.33). For all patients, average mean sensitivity significantly improved by 1.7 ± 0.5 dB (p<0.05) and N1-P1 response density significantly decreased by 0.52 ± 0.21 nV/deg2 (p<0.05).
Conclusion:
Both PRN and monthly treatment of exudative AMD with ranibizumab improve visual function as assessed by BCVA and MP. Macular thickening also improved as demonstrated by HR-OCT findings. However, the decreased retinal function noted by mfERG suggests that some loss of retinal function still occurs despite effective treatment. These measures of visual function may be useful in assessing retinal health and response to treatment in future clinical trials.
Insights
Both monthly and pro re nata (PRN) ranibizumab injections effectively treat exudative age-related macular degeneration (AMD), improving visual acuity and reducing macular thickening. However, multifocal electroretinography (mfERG) indicates some retinal function loss persists with either treatment regimen.
Area of Science:
- Ophthalmology
- Retinal Diseases
- Pharmacology
Background:
- Exudative age-related macular degeneration (AMD) is a leading cause of vision loss.
- Ranibizumab is an anti-vascular endothelial growth factor (anti-VEGF) therapy used to treat wet AMD.
- Treatment strategies include monthly injections or pro re nata (PRN) dosing based on disease activity.
Observation:
- A randomized trial compared monthly versus PRN ranibizumab injections in patients with exudative AMD over 12 months.
- High-resolution optical coherence tomography (HR-OCT) guided PRN retreatment based on fluid presence.
- Macular function was evaluated using microperimetry (MP) and multifocal electroretinography (mfERG).
Findings:
- Both monthly and PRN ranibizumab cohorts showed improvements in best-corrected visual acuity (BCVA) and reductions in central foveal thickness (CFT).
- Mean BCVA gains were comparable between groups (PRN: 6.0 ETDRS letters, Monthly: 7.3 ETDRS letters; p=0.68).
- While MP showed significant improvement in mean sensitivity (1.7 dB; p<0.05), mfERG revealed a comparable decrease in N1-P1 response density in both cohorts (p=0.33), suggesting persistent retinal function decline.
Implications:
- Both dosing regimens of ranibizumab are effective in improving visual acuity and retinal anatomy in exudative AMD.
- The study highlights the utility of MP and mfERG in assessing treatment response and retinal health.
- Despite treatment, mfERG findings suggest ongoing retinal function loss, underscoring the need for continued monitoring and potential therapeutic advancements.
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