Signal strength is a parameter introduced in analysis software version 4.0.1, of the OCT stratus, that combines SNR and uniformity of the signal within a scan The scale of signal strength ranges from 1 to 10, with 1 representing poor image quality and 10 representing excellent image quality It has been showed that signal strength has a better image quality discriminating ability than SNR The operation manual recommends a minimum signal strength of 5 for macular thickness measurement There is no consensus on the level of signal strength above which should be considered to be good quality The inclusion Criteria for acceptable signal strength varies widely in the literature the purpose of our study is to examine the relationship between signal strength and macular thickness measured by stratus OCT

Inclusion Criteria:

• healthy subjects in this study other than refractive error, all included eyes had no concurrent ocular pathologic features BCVA of at least 20/30, and had spherical refractive error within the range of
• 4.00 D to 4.00 D

Exclusion Criteria:

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healthy