Abstract
Purpose: :
To study a correlation of a change in retinal nerve fiber layer (RNFL) thickness with visual field defect after optic papillitis.
Methods: :
In prospective study, 20 patients with optic papillitis and 20 healthy subjects were studied. RNFL thickness was measured using optic coherence tomography (OCT 3000, Humphrey-Zeiss). The patients underwent steroid treatment. The pattern of thickness measurements from OCT in the 32 sectors around the optic disc was analyzed to obtain the Fourier coefficients (i.e., the amplitude and phase of each sinusoid). The unaffected eyes were used instead of the affected eyes before optic papillitis to study the change of RNFL thickness distribution. The difference of Fourier component phase and amplitude of both eyes in the patients was studied and compared with healthy subjects.
Results: :
Mean best-corrected visual acuity and mean deviation of visual field testing was 0.041 and -19.38±9.57 dB before treatment and 0.810 and -7.17±3.49 at 6 months after treatment. OCT showed a marked increase of the total RNFL thickness with a double-hump pattern before treatment. After treatment, OCT scan revealed a gradual decrease of the thickness corresponding to the resolution of disc swelling. At 6 months, OCT showed the total thickness reduction with a double-hump pattern. Mean total RNFL thickness was 312±62 µm, 121±19 µm and 65±10 µm before treatment and 1 month and 6 months after treatment, respectively. No significant difference was found in the absolute difference of both eyes in any Fourier component phase between the patients and healthy subjects. Mean absolute difference of F2 component phase of both eyes was 0.152±0.142 in the patients and 0.156±0.137 in healthy subjects, and was similar to each other. In the DC and Fourier 1 to 14 components, the ratio of the amplitude of the affected eye/that of the unaffected eye was 0.594 to 0.780, and there was no significant difference between any two of them. Mean deviation of visual field testing was significantly correlated with mean RNEL thickness (r=0.837, P<0.0001), and the ratio of DC amplitude of affected eye/ that of unaffected eye (r= 0.857, P<0.0001) and the ratio of F2 component amplitude of affected eye/ that of unaffected eye (r = 0.955, P<0.0001).
Conclusions: :
The pattern of RNFL thickness distribution at 6 months after treatment may be a compressed form moving downward of that before optic papillitis. A change of visual field at 6 months may be associated with the impairment of RFNL by optic papillitis.
Keywords: neuro-ophthalmology: optic nerve • visual impairment: neuro-ophthalmological disease • imaging/image analysis: clinical