Monitoring VEGF levels with low-volume sampling in major vision-threatening diseases: age-related macular degeneration and diabetic retinopathy

Abstract

The purpose of this article is to demonstrate the capacity of paper-based ELISA (P-ELISA) to monitor VEGF in patients requiring treatment for vision-threatening diseases. The most commonly encountered vision-threatening diseases are age-related macular degeneration (AMD) and diabetic retinopathy (DR), both of which may require short-term or life-long anti-VEGF injection treatment therapy. Accurate measurement of VEGF concentration in aqueous humor can provide significant and timely information to diagnose the disease state. Adequate and precise therapy may consequently be provided. At odds with conventional diagnostic approaches is the fact that a maximum of only 200 microliters of aqueous humor can be safely removed from the eye for testing. Fortunately, new diagnostic platforms, such as P-ELISA, require only minute volumes, i.e., approximately 2 microliters per test "well" and approximately 40 microliters total to quantify VEGF levels, and the testing process takes less than an hour. Thus, point-of-care (POC) diagnostics, such as P-ELISA, should be examined and improved upon as needed in order to develop an efficient tool for outpatient clinics and others to obtain semi-quantitative results that might facilitate accurate dosing of anti-VEGF treatment and delay or prevent the progression of AMD and DR.

Paper-Based ELISA: A Novel Diagnostic Approach for Monitoring Aqueous Humour VEGF Level in Ocular Diseases

“…For those patients with poor response to anti-VEGF therapies, early detection of elevated VEGF via ultrasensitive p-ELISA can alert a clinical ophthalmologist to increase treatment frequency or change the therapeutic approach. Because elevations in VEGF level appear earlier than morphological changes or visual acuity changes, monitoring VEGF levels can provide helpful early detection of disease and further prevent undesirable vision loss in those afflicted [39] (Figure 3). In addition to being ultrasensitive, p-ELISA for VEGF level detection takes only a short time (<1 h) compared to conventional ELISA (4-5 h).…”

“…The correlation between elevated VEGF, structural change, and vision impairment in patients receiving anti-VEGF therapy[39]. The Y coordinates represent VEGF levels, the structural changes, and vision impairment.The X coordinates represent the time sequence after the injection of anti-VEGF agent.…”

“…The 3 different outpatient clinic scenarios for the follow-up examination of the patients receiving anti-VEGF treatment[39]. (a) Optical imaging modalities: the patient receives the optical imaging test only to determine whether to receive anti-VEGF treatment or observation.…”

Sensitive tear screening of diabetic retinopathy with dual biomarkers enabled using a rapid electrokinetic patterning platform

“…[8][9][10][11][12] Among proteomic diagnostics, the paperbased enzyme-linked immunosorbent assay (P-ELISA) is a promising tool for the rapid screening of some diseases. 13 Hsu et al 14,15 reported an inexpensive and highly sensitive detection technique for proliferative DR (PDR), retinal vein occlusion, and age-related macular degeneration based on the P-ELISA diagnostic approach. They prepared 2 μL of aqueous humor from patients and mixed it with bevacizumab to react with horseradish peroxidase.…”

Ultrasensitive enzyme-free fluorescent detection of VEGF165 based on target-triggered hybridization chain reaction amplification

“…To date, various VEGF 165 detection techniques have been reported, including ELISA assays, [14][15][16] immunohistochemistry, optical methods, 17 and radioimmunoassay. However, these methods are mainly time-consuming, labor-intensive, and complex and involve expensive reagents.…”