Impairment of retinal adaptive circuitry in the myopic eye

• Published in: Vision research (Oxford) Vol. 51; no. 3; pp. 367 - 375
• Main Authors: Ho, Wing-cheung, Ng, Yiu-fai, Chu, Patrick Ho-wai, Fong, Ying-ying, Yip, Kwun-sum, Kee, Chea-su, Chan, Henry Ho-lung
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 09.02.2011; Elsevier
• Subjects: Adaptation; Adaptation, Physiological - physiology; Adult; Biological and medical sciences; Contrast; Contrast Sensitivity - physiology; Electroretinography - methods; Eye and associated structures. Visual pathways and centers. Vision; Female; Fundamental and applied biological sciences. Psychology; Humans; Inner retina; Luminescence; Male; Medical sciences; Multifocal electroretinogram (mfERG); Myopia; Myopia - physiopathology; Ophthalmology; Refractive Errors - physiopathology; Retina - pathology; Retina - physiology; Vertebrates: nervous system and sense organs; Vision disorders; Young Adult; Inner retina; Contrast; Myopia; Multifocal electroretinogram (mfERG); Adaptation; Electroretinography; Vision disorder; Electrophysiology; Retina; Eye; Visual system; Eye disease; Refractive error
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/j.visres.2010.12.001

► The paracentral mfERG response, reflecting inner retina, was reduced in myopic eye. ► The central retinal function appeared normal in adult myopic eye. ► Compared to outer retina, inner retina was more prone to be affected in myopic eye. Previous studies have proposed that the inner retina is affected in myopes. This study aimed to investigate the changes in adaptive circuitry of the inner retina in myopia, using the global flash multifocal electroretinogram (global flash mfERG) with different levels of contrast (luminance modulation). Fifty-four myopes had global flash mfERG recorded with different contrasts. The direct component (DC) and the induced component (IC) of the mfERG response were pooled into six regions for analysis. The response amplitudes and implicit times at different contrasts were also analysed. Results showed that myopes had significant reduction in the paracentral DC amplitude for the 29% and 49% contrasts and in the paracentral IC amplitude at all contrasts measured. The peripheral IC amplitude for the 49% contrast was also reduced. No significant change was found in implicit time for either DC or IC response. Refractive error explained about 14% of the variance in DC and 16% of the variance in IC amplitude respectively; axial length could not account for additional variance in either paracentral DC or IC amplitudes in the hierarchical regression models used. We concluded that the paracentral retinal region in myopes showed signs of impaired retinal adaptation, suggesting a functional loss at the inner retinal layer. In addition, functions attributed to the outer retinal layer showed only small changes due to myopia.