Back in 2013, Sarraf et al. were the first to describe the presence of multiple or isolated band-shaped, focal or diffuse hyper-reflective lesions visible at the level of the internal nuclear layer in patients who present with an acute onset of negative scotoma, and called it Paracentral Acute Medial Maculopathy (PAMM). PAMM is a spectral domain OCT (SD-OCT) finding interpreted as a possible more superficial variant of Acute Macular Neuroretinopathy [5].
Its etiology is unknown, although the most supported hypothesis is based on a vascular origin. A localized retinal capillary ischemia at the level of the intermediate plexus has been proposed as the underlying mechanism for the development of these lesions.
As Chen et al. describes, retinal vascular associations leading to retinal vasculopathy and PAMM include eye compression injuries causing global ocular ischemia, sickle cell crisis, Purtscher's retinopathy, inflammatory occlusive retinal vasculitis, post-H1N1 vac- cine, hypertensive retinopathy, migraine disorder, and post-upper respiratory infection [6].
Early clinical evidence suggests that cases of COVID-19 are frequently characterized by hyperinflammation, renin-angiotensin-aldosterone system imbalance, and a particular form of vasculopathy, thrombotic microangiopathy, and intravascular coagulopathy. In pauci-symptomatic or poorly clinical cases there are no conclusive studies [7].
To date, there is very limited evidence of the correlation between COVID-19 and the appearance of retinal lesions, presumably because there is a wide clinical variation in the presentation and severity of the disease, that may induce the appearance of different mor- phological patterns of retinal involvement. Marinho et al [3], for instance, describe the presence of hyper-reflective lesions at the level of ganglion cell and inner plexiform layers more prominently at the papillomacular bundle, but we must be extremely careful with these findings because, as Vavvas DG et al [8] point out, OCT hyper-reflective bands in the inner retina and/or ganglion cell layer can confuse us with normal inner retinal vessels. Recently, Landecho [4] described a cotton wool spots in the examination of the eye fundus of the retina and, as corresponds in the B-scan optical coherence tomography, inflammation of the nerve fiber layer of the retina appears, in 6 of 24 asymptomatic subjects fourteen days after hospital discharge for bilateral COVID-19 pneumonia. For this reason, we consider the study with multimodal imaging to be important, agreeing with these authors that we must check at least the near infrared reflectance record to confirm that the hyper-reflective bands do not represent normal vessels (Figure 1 and 2).
Exclusively from an ophthalmological point of view and given the potential implica- tions, COVID-19 infection should be excluded using all means available in cases showing these hyper-reflective lesions at the level of ganglion cell and inner plexiform layers in OCT imaging, to facilitate a timely diagnosis and intervention. Vascular occlusions described in COVID-19 cases might as well be the cause for these retinal findings [7] or could possibly be associated with the neurological manifestations described in animal studies and in COVID-19 neurological events [9,10,11].
This case, and the papers presented by other authors [3,4,8] support a probable hypothesis that these retinal OCT findings should be considered another sign of COVID-19 disease and the importance of retinal imaging study in these patients. Furthermore, as far as we know, our case is the first case of COVID-19 diagnosed through an imaging study of the retina.