https://www.selleckchem.com/products/guanidine-thiocyanate.html Visual disturbance or visual failure due to toxicity of an ingested substance or a severe nutritional deficiency can present significant challenges for diagnosis and management, for instance, where an adverse reaction to a prescribed medicine is suspected. Objective assessment of visual function is important, particularly where structural changes in the retina or optic nerve have not yet occurred, as there may be a window of opportunity to mitigate or reverse visual loss. This paper reviews a number of clinical presentations where visual electrophysiological assessment has an important role in early diagnosis or management alongside clinical assessment and ocular imaging modalities. We highlight the importance of vitamin A deficiency as an easily detected marker for severe combined micronutrient deficiency. Retinopathy of prematurity (ROP) is a potentially blinding disease of immature retinal vasculature. ROP regresses in majority of the cases and very few go on to develop ROP needing treatment. Fundus fluorescein angiography (FFA) is the gold standard technique to study retinal vasculature. The present study was undertaken with the objective to identify the FFA findings associated with the progression of ROP. Prospective single centre study in a tertiary care hospital of 99 eyes of 50 preterm babies. Fundus fluorescein angiography (FFA) was performed in all babies using RetCam 3 at the first detection of ROP. The babies were followed up for the progression of ROP. The FFA predictors for the progression of ROP were evaluated using the Mann-Whitney U test and Fisher's test. Thirty-eight eyes were Type 1 ROP at initial presentation and were lasered. Amongst the rest, 24 eyes showed features of stage 3 ROP with intense leakage on FFA and were designated as FFA-treatable ROP and were also lasered. Amongst the rest of the 37 eyes, the disease progression was seen in 13 eyes and the disease regression was see