The retinal foveal avascular zone as a systemic biomarker to evaluate inflammatory bowel disease control

Abstract

Background Inflammatory bowel disease (IBD) is a systemic inflammatory disease and is classified as Crohn’s disease (CD) or ulcerative colitis (UC) depending on the extent of gastrointestinal tract involvement. IBD can be associated with extraintestinal findings, such as fever, weight loss, arthralgia, and mucocutaneous lesions, as well as hepatic, renal and ophthalmological involvement. Clinical parameters and colonoscopy are used to establish the criteria for controlled or non-controlled disease and subsequent definition of treatment. Our objective in the present study was to compare the area of the foveal avascular zone (FAZ) in patients with a diagnosis of IBD during remission and active disease. Methods 144 eyes of 72 patients with IBD were evaluated via a complete ophthalmological exam. Fundus photography and optical coherence tomography/angiography (OCT/OCTA) were performed with a Topcon Triton. The macula and posterior pole were evaluated by binocular indirect ophthalmoscopy and fundus biomicroscopy. The area of the FAZ was determined via manual delimitation of superficial retinal vascular layers from OCTA with image6.net software. To establish disease activity, we considered the Mayo Score, fecal calprotectin levels, colonoscopy results and clinical parameters. All retinal parameters were evaluated in a blinded manner. Means were compared between groups using the Mann–Whitney test. Results The participants had a mean age of 42.26 years and included 28 males (38.88%) and 44 females (61.11%). Among the participants, 37 had a diagnosis of CD (51.38%), and 35 had a diagnosis of UC (48.61%). Twenty-five patients (34.72%) had active disease, and 47 (65.27%) were in remission. The area of the FAZ did not differ significantly between the CD and UC groups ( p = 0.91 for the right eye and p = 0.76 for the left eye) but did differ significantly between the remission and active disease groups ( p = 0.01 for the right eye and p = 0.02 for the left eye). Discussion Our study is the first to evaluate the area of the FAZ in patients with IBD via swept-source OCTA. The area of the FAZ did not differ significantly in either eye between the CD and UC groups. However, patients classified as having active disease according to clinical parameters and colonoscopy presented a significant decrease in the area of the FAZ compared with patients in remission. The area of the FAZ is an ophthalmological parameter that can be obtained non-invasively and is increased in ischemic diseases such as diabetic retinopathy. The FAZ may decrease due to vascular engorgement or increased systemic inflammation. This parameter can be used to help determine whether a patient is in remission or active IBD, thus potentially reducing the need for invasive exams during disease follow-up.

Retinal microvascular abnormalities in patients after COVID-19 depending on disease severity

“…If this is just a local finding or similar changes could be found in other organs remains an unsolved question. Other studies have suggested VD in central retina as a possible vascular biomarker and examined its relationship with systemic conditions: diabetes, 23 chronic kidney disease, 24 inflammatory bowel disease, 25 amyloidosis 26 or Alzheimer, 26 so could VD be considered a biomarker for microvascular abnormalities after the infection of SARS-CoV-2? Longitudinal studies over time will be necessary to assess vascular outcomes in COVID-19.…”

Retinal blood flow in critical illness and systemic disease: a review

“…The retina and brain share similar microvascular anatomy, and while direct visualisation of CBF is difficult, retinal imaging is comparatively convenient [14]. Retinal structural and blood flow changes associated with systemic and central nervous system illness are increasingly reported [15][16][17] with the use of ocular imaging to assess systemic disease termed "oculomics" [18]. Retinal changes may, therefore, associate with CBF in critically ill patients, offering a novel biomarker to monitor in realtime and reduce cerebral hypoperfusion.…”

“…There was no association between a diagnosis of Crohn’s disease or ulcerative colitis and retinal blood flow, but when either group of patients had active disease, FAZ area was reduced compared to patients in remission, suggesting altered retinal blood flow autoregulation by systemic inflammatory status [ 16 ]. Systemic sclerosis has involvement of the microvasculature as one of the earliest features.…”

“…There is a need for improved monitoring of cerebral perfusion in a critical care environment to allow perfusion-directed resuscitation, improve patient outcomes, and possibly reduce long-term cognitive impairment. These retinal imaging studies demonstrate that retinal vessel density and retinal perfusion are affected by systemic haemodynamic changes [ 116 ], and the systemic inflammatory response [ 16 , 118 ], but also that it does not simply provide a mirror to systemic haemodynamic status, being resistant to change in some models [ 124 ] and providing additional information in others (Table 2 ) [ 117 , 120 , 125 ].…”

“…These retinal imaging studies demonstrate that retinal vessel density and retinal perfusion are affected by systemic haemodynamic changes [ 116 ], and the systemic inflammatory response [ 16 , 118 ], but also that it does not simply provide a mirror to systemic haemodynamic status, being resistant to change in some models [ 124 ] and providing additional information in others (Table 2 ) [ 117 , 120 , 125 ].…”