Fungal keratitis can result in serious visual impairment and mainly concentrated in tropical and subtropical regions in developing countries, such as India and Brazil, as it accounts for 40% to 50% of all isolated keratitis cases. Currently, there are more than 70 pathogens that can cause fungal keratitis, but the clinical isolates of these pathogens are mainly concentrated in a few genera. The fungal isolates vary from country to country due to climate and environmental impacts. Fusarium and Candida are the most common pathogens in developed countries (such as the United States and the United Kingdom). Rare pathogens, such as Rhizopus, Sarocladium, Colletotrichum, Exserohilum, Bipolaris, Curvularia crescentulum, Purpureocillium lilacinum, and Pythium insidiosum have been reported in dozens of cases among both white and black populations. Because fungal species have different growth patterns, so do their clinical manifestations, pathogenic invasiveness, and microbial characteristics. The clinical diagnosis of infectious keratitis based on slit lamp examination poses a challenge, and microbial detection remains the gold standard. However, early empirical treatment based on lesion manifestations is also required. Many studies have shown that Fusarium keratitis has feathery edges due to horizontal growth, whereas Aspergillus keratitis has immune rings and hypopyon due to vertical growth. Pythium insidiosum is a fungal-like organism that appears as branching, sparsely septate or aseptate filaments. Its host animals are mammals, but ocular infections are uncommon in China. Water exposure, contact lens wear, and trauma are the main predisposing factors. Despite the fact that this study focused on fungi, the microbial species of Pythium insidiosum still has to be explored more. Endothelial plaque, hypopyon, and peripheral reticular infiltration are the most common clinical symptoms, indicating that the genus produces considerable enzymatic hydrolysis in the surrounding and deep tissues. Because of the lack of ergosterol drug targets in the cytoplasmic membrane, antifungal medications are ineffective and illnesses are difficult to manage. Submit manuscript at www.walshmedicalmedia.com/submissions/eye-diseases-disorders.html or send as an e-mail attachment toeyedisorders[at]emedsci[dot]com