Background: high myopia is a global burden that attracted researchers to its consequences. Although, there is few data regarding what high myopia causes to the normally appearing eyes. Effect of high myopia on retinal function can be detected by the multifocal electroretinography, which is capable of measuring and mapping retinal functions. Purpose: to measure changes in retinal functions in response to elongation of the axial length (AL). Patients and Methods: this is a descriptive study in which 15 patients aging 18-40 years with spherical equivalent (SE) of ≤-5 were included. A thorough ocular examination, including but not limited to visual acuity; best corrected visual acuity; anterior segment examination and fundus examination, was done and standard multifocal electroretinogram (mfERG) was performed. The measurements were taken in concentric rings and in quadrants, and then analyzed and statistically compared to normal readings of the matching age group. Results: a total of 30 eyes those were completely normal except for long AL with normal or tessellated fundi. The mfERG showed varying reductions in amplitudes (amp.) as well as elongations of implicit times (Imp.T), of both P1 and N1 components, at almost all rings and quadrants. Conclusion: retinal functions at different layers were significantly affected by extension of the AL, and that increases as the axial length increases. Recommendations: future studies should consider high myopia in normally appearing eye as well as in Egyptians to detect any special pattern of retinal function affection for that ethnicity.