Does Retinal Ganglion Cell Loss Precede Visual Field Loss in Glaucoma?

Area of Science:

• Ophthalmology
• Neuroscience
• Vision Science

Background:

• A widely held belief in glaucoma research is that substantial retinal ganglion cell (RGC) loss precedes detection of glaucomatous damage by standard automated perimetry (SAP).
• This belief is often supported by citations of four key historical articles.
• Recent reviews have questioned the evidence presented in these foundational articles.

Purpose of the Study:

• To critically evaluate the accuracy of citations referencing four key articles on RGC loss and SAP detection thresholds.
• To determine if the evidence in the key articles truly supports the prevailing notion of RGC loss preceding detectable visual field defects.

Main Methods:

• A systematic review of publications from the first six months of 2019 that cited one or more of the four key articles was conducted.
• The accuracy of quotes and the interpretation of evidence within these 2019 publications were assessed against the original data and conclusions of the key articles.

Main Results:

• Quotes from 2019 publications were found to be inadequately supported by the data and conclusions in the cited key articles.
• In several instances, the evidence within the key articles appears to support the opposite conclusion.
• The data suggest that visual field sensitivity loss on SAP may be detectable before significant RGC loss occurs.

Conclusions:

• The common assertion that substantial RGC loss precedes SAP detection in glaucoma may be based on misinterpretations and inaccurate citations of key literature.
• Evidence suggests that functional changes detectable by SAP may occur earlier in the glaucomatous process than previously assumed.
• Re-evaluation of the foundational evidence is necessary to accurately understand the sequence of events in glaucoma progression.