HYPODENSE HOLES & MICROCYSTIC MACULAR EDEMA

 

Apart from retinoschisis and PIRDs, discussed in previous posts, some other unusual features seen on OCT images in glaucoma patients are “hypodense holes” and “microcystic macular edema”.

In 2011, Xin et al., described “holes” within the RNFL of glaucomatous eyes on circumpapillary OCT scans. These holes appear as small round or oval regions of very low or absent (‘‘hypodense’’) reflectance, conspicuous in contrast to the normally strong reflectance produced by axons within the RNFL. The holes tended to occur immediately adjacent to a vessel. In Xin’s study, 33(16%) of glaucomatous eyes showed these holes but none were present in healthy controls.

Hypodense holes

Glaucomatous eyes can also have microcystic macular edema (or microcystic macular degeneration). These lesions are pseudo-cysts (lacunae or vacuolar inclusions) seen in the inner nuclear layer (INL) in the form of a perifoveal ring on OCT scans.

Microcystic macular edema

Two recent OCT studies have estimated the frequency of ‘‘microcystic macular edema’’ (i.e., finding pseudo-cysts within the INL) in glaucoma and documented the clinical characteristics of those cases. Brazerol and colleagues studied 218 glaucoma patients and observed INL microcysts in eight eyes (2.8%) of eight patients (3.7%).

Hasegawa and colleagues have also described microcystic lesions of the INL in glaucomatous eyes using OCT. They reported microcystic INL lesions in 6.0% (13 of 217) eyes with primary open angle glaucoma.

Among Hasegawa’s patients, a larger proportion of advanced glaucoma was seen associated with microcystic edema (P=0.013). There was also a significantly worse deviation in the VF mean deviation slope in eyes with microcysts (P=0.027).

REFERENCES:

Xin D, Talamini CL, Raza AS, de Moraes CG, Greenstein VC, Liebmann JM, Ritch R, Hood DC. Hypodense regions (holes) in the retinal nerve fiber layer in frequency-domain OCT scans of glaucoma patients and suspects. Invest Ophthalmol Vis Sci. 2011 Sep 9;52(10):7180-6. doi: 10.1167/iovs.11-7716. PMID: 21791587; PMCID: PMC3207719.

Brazerol J, Iliev ME, Höhn R, Fränkl S, Grabe H, Abegg M. Retrograde Maculopathy in Patients With Glaucoma. J Glaucoma. 2017 May;26(5):423-429. doi: 10.1097/IJG.0000000000000633. PMID: 28169924.

Hasegawa T, Akagi T, Yoshikawa M, Suda K, Yamada H, Kimura Y, Nakanishi H, Miyake M, Unoki N, Ikeda HO, Yoshimura N. Microcystic Inner Nuclear Layer Changes and Retinal Nerve Fiber Layer Defects in Eyes with Glaucoma. PLoS One. 2015 Jun 12;10(6):e0130175. doi: 10.1371/journal.pone.0130175. PMID: 26066021; PMCID: PMC4467090.