Take a look at the deviation maps when assessing structural change in glaucoma

The structural analysis of the thickness of peripapillary retinal nerve fiber layer (pRNFL) and the inner layers of the posterior pole with optical coherence tomography (OCT), either alone or combined, have a very high diagnostic accuracy (1). However, glaucomatous damage and structural progression can be overlooked if we only rely on color-coded sectors evaluation and/or global thickness summary statistical analyses (2).

Most of the currently available OCT devices offer reports with topographic deviation maps that may help with glaucoma diagnosis and monitoring. - Combined pRNFL and ganglion cell-inner plexiform layer (GCIPL) wide-field deviation/probability maps can help to detect progression in early glaucomatous eyes (3). - Topographic analysis may also help distinguish glaucomatous from healthy myopic eyes (4). - Finally, in advanced glaucoma, where RNFL thickness evaluation cannot detect further progression due to the floor effect, progressive changes in the deviation maps together with GCIPL thickness loss rates may help to identify structural worsening (5).
Contributor: Nestor Ventura-Abreu, Institut Clinic d’Oftlamologia, Hospital Clinic Barcelona, Spain

References

1. Mwanza J-C, Warren JL, Budenz DL. Utility of combining spectral domain optical coherence tomography structural parameters for the diagnosis of early Glaucoma: a mini-review. Eye Vis (London, England). 2018;5(13):9.
2. Hood DC, Melchior B, Tsamis E, Liebmann JM, De Moraes CG. Did the OCT Show Progression since the Last Visit? J Glaucoma. 2021;30(4):E134-E145.
3. Lee WJ, Kim TJ, Kim YK, Jeoung JW, Park KH. Serial Combined Wide-Field Optical Coherence Tomography Maps for Detection of Early Glaucomatous Structural Progression. JAMA Ophthalmol. 2018;136(10):1121-1127.
4. Baek SU, Kim KE, Kim YK, Park KH, Jeoung JW. Development of Topographic Scoring System for Identifying Glaucoma in Myopic Eyes: A Spectral-Domain OCT Study. Ophthalmology. 2018;125(11):1710-1719.
5. Shin JW, Sung KR, Lee GC, Durbin MK, Cheng D. Ganglion Cell–Inner Plexiform Layer Change Detected by Optical Coherence Tomography Indicates Progression in Advanced Glaucoma. Ophthalmology. 2017;124(10):1466-1474.

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