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Optical and neural anisotropy in peripheral vision
摘要： Optical blur in the peripheral retina is known to be highly anisotropic due to nonrotationally symmetric wavefront aberrations such as astigmatism and coma. At the neural level, the visual system exhibits anisotropies in orientation sensitivity across the visual field. In the fovea, the visual system shows higher sensitivity for cardinal over diagonal orientations, which is referred to as the oblique effect. However, in the peripheral retina, the neural visual system becomes more sensitive to radially-oriented signals, a phenomenon known as the meridional effect. Here, we examined the relative contributions of optics and neural processing to the meridional effect in 10 participants at 08, 108, and 208 in the temporal retina. Optical anisotropy was quantified by measuring the eye’s habitual wavefront aberrations. Alternatively, neural anisotropy was evaluated by measuring contrast sensitivity (at 2 and 4 cyc/deg) while correcting the eye’s aberrations with an adaptive optics vision simulator, thus bypassing any optical factors. As eccentricity increased, optical and neural anisotropy increased in magnitude. The average ratio of horizontal to vertical optical MTF (at 2 and 4 cyc/deg) at 08, 108, and 208 was 0.96 6 0.14, 1.41 6 0.54 and 2.15 6 1.38, respectively. Similarly, the average ratio of horizontal to vertical contrast sensitivity with full optical correction at 08, 108, and 208 was 0.99 6 0.15, 1.28 6 0.28 and 1.75 6 0.80, respectively. These results indicate that the neural system’s orientation sensitivity coincides with habitual blur orientation. These findings support the neural origin of the meridional effect and raise important questions regarding the role of peripheral anisotropic optical quality in developing the meridional effect and emmetropization.
关键词： peripheral retina,anisotropy,wavefront aberrations,neural adaptation,adaptive optics
更新于2025-09-11 14:15:04
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Next Generation PERG Method: Expanding the Response Dynamic Range and Capturing Response Adaptation
摘要： Purpose: To compare a new method for steady-state pattern electroretinogram (PERGx) with a validated method (PERGLA) in normal controls and in patients with optic neuropathy. Methods: PERGx and PERGLA were recorded in a mixed population (n ? 33, 66 eyes) of younger controls (C1; n ? 10, age 38 6 8.3 years), older controls (C2; n ? 11, 57.9 6 8.09 years), patients with early manifest glaucoma (G; n ? 7, 65.7 611.6 years), and patients with nonarteritic ischemic optic neuropathy (N; n ? 5, mean age 59.4 6 8.6 years). The PERGx stimulus was a black-white horizontal grating generated on a 14 3 14 cm LED display (1.6 cycles/deg, 15.63 reversals/s, 98% contrast, 800 cd/m2 mean luminance, 258 field). PERGx signal and noise were averaged over 1024 epochs (~2 minutes) and Fourier analyzed to retrieve amplitude and phase. Partial averages (16 successive samples of 64 epochs each) were also analyzed to quantify progressive changes over recording time (adaptation). Results: PERGLA and PERGx amplitudes and latencies were correlated (Amplitude R2 ? 0.59, Latency R2 ? 0.39, both P , 0.0001) and were similarly altered in disease. Compared to PERGLA, however, PERGx had shorter (16 ms) latency, higher (1.393) lower (0.373) noise, and higher (4.23) signal-to-noise ratio. PERGx amplitude, displayed marked amplitude adaptation in C1 and C2 groups and no significant adaptation in G and N groups. Conclusions: The PERGx high signal-to-noise ratio may allow meaningful recording in advanced stages of optic nerve disorders. it quantifies response adaptation, which may be selectively altered in glaucoma and optic neuropathy.
关键词： signal-to-noise ratio,non-arteritic ischemic optic neuropathy,neural adaptation,glaucoma,pattern electroretinogram
更新于2025-09-04 15:30:14