Evaluation of visual function and OCT parameters in ethambutol-induced optic neuropathy: a longitudinal study.
Sachdeva Gaurav, Dhiman Rebika, Raj Dharam, Lavanya Gandepalli, Mohan Anant, Pujari Amar, Phuljhele Swati, Saxena Rohit
AI Summary
This study found that ethambutol-induced optic neuropathy causes progressive structural damage despite some visual improvement, highlighting the irreversible nature and the predictive value of OCT parameters for visual recovery.
Abstract
Aims
To evaluate structural and visual functional parameters in ethambutol-related toxic optic neuropathy (EON).
Methods
In this prospective study, we recruited 95 adults with EON presenting within 1 month of onset and 100 age-matched healthy controls. Best-corrected visual acuity (Early Treatment Diabetic Retinopathy Study chart), colour vision (Ishihara pseudoisochromatic plates), contrast sensitivity (Pelli-Robson chart), Humphrey visual field analysis (HVF 30-2 Swedish Interactive Threshold Algorithm-FAST), visual evoked response and spectral domain optical coherence tomography for macular ganglion cell-inner plexiform layer (mGC-IPL), retinal nerve fibre layer (RNFL) and papillomacular bundle (PMB) analyses were done at baseline, 3 months and 6 months.
Results
Almost 52% eyes showed significant visual improvement of ≥ 2 Snellen lines after stopping the drug. RNFL (cases-100.84±21.87 µm vs controls-98.05±7.21 µm; p=0.37) and PMB thickness (cases-51.10±17.26 µm vs controls-53.45±6.42 µm; p=0.19) in cases were comparable with controls at baseline, but showed significant thinning at 6 months follow-up (RNFL -83.77±21.06 µm; PMB-30.96±11.02 µm; p<0.0001 for both). Average GC-IPL thickness (cases-29.66±6.86 µm; controls-39.68±2.59 µm) and ganglion cell-inner plexiform layer (GCL) volume (cases-0.85±0.17 mm 3 ; controls-1.08±0.069 mm 3 ) was significantly less as compared with controls (p<0.0001 for all) at baseline and showed significant further deterioration on follow-up (p<0.001 for all). The average GC-IPL thickness (p value :<0.0001, r:-0.31), GCL volume (p value :<0.000, r:-0.29) and PMB thickness (p value :0.043, r:-0.14) showed a significant negative correlation with final vision at 6 months.
Conclusion
Progressive structural damage despite visual improvement raises concern about the irreversible nature of EON. PMB, GC-IPL thickness and GCL volume are better predictors of visual recovery in EON.
MeSH Terms
Shields Classification
Key Concepts6
In a prospective study of 95 adults with ethambutol-related toxic optic neuropathy (EON) and 100 age-matched healthy controls, almost 52% of eyes with EON showed significant visual improvement of ≥ 2 Snellen lines after stopping the ethambutol drug.
In a prospective study of 95 adults with ethambutol-related toxic optic neuropathy (EON) and 100 age-matched healthy controls, retinal nerve fibre layer (RNFL) thickness in cases (100.84±21.87 µm) and papillomacular bundle (PMB) thickness in cases (51.10±17.26 µm) were comparable with controls (RNFL: 98.05±7.21 µm, p=0.37; PMB: 53.45±6.42 µm, p=0.19) at baseline, but showed significant thinning at 6 months follow-up (RNFL: 83.77±21.06 µm; PMB: 30.96±11.02 µm; p<0.0001 for both).
In a prospective study of 95 adults with ethambutol-related toxic optic neuropathy (EON) and 100 age-matched healthy controls, average macular ganglion cell-inner plexiform layer (GC-IPL) thickness (cases: 29.66±6.86 µm; controls: 39.68±2.59 µm) and ganglion cell-inner plexiform layer (GCL) volume (cases: 0.85±0.17 mm³; controls: 1.08±0.069 mm³) were significantly less as compared with controls (p<0.0001 for all) at baseline and showed significant further deterioration on follow-up (p<0.001 for all).
In a prospective study of 95 adults with ethambutol-related toxic optic neuropathy (EON) and 100 age-matched healthy controls, average macular ganglion cell-inner plexiform layer (GC-IPL) thickness (p-value: <0.0001, r: -0.31), ganglion cell-inner plexiform layer (GCL) volume (p-value: <0.000, r: -0.29) and papillomacular bundle (PMB) thickness (p-value: 0.043, r: -0.14) showed a significant negative correlation with final vision at 6 months.
Progressive structural damage, despite visual improvement, in ethambutol-related toxic optic neuropathy (EON) raises concern about the irreversible nature of EON.
A prospective study recruited 95 adults with ethambutol-related toxic optic neuropathy (EON) presenting within 1 month of onset and 100 age-matched healthy controls to evaluate structural and visual functional parameters at baseline, 3 months, and 6 months.
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