Depending on the cause, the clinical presentation may somewhat vary:

• Postoperative - Cataract surgery, secondary intraocular lens (IOL) implantation, penetrating keratoplasty, glaucoma drainage device implantation, trabeculectomy and vitreous procedures (vitrectomies or intravitreal injections) have all been associated with an increased risk for postoperative endophthalmitis [1] [2]. Symptoms can develop within the first six weeks (acute-onset) or after six weeks (delayed- onset) [1] [3]. Decreased visual acuity, eye pain, eyelid edema, ocular discharge, inability to visualize the fundus and hypopyon are typical signs, while the loss of red fundus reflex, light perception, and papillitis are seen in more severe cases [3] [4]. An insidious and prolonged clinical course is common for delayed-onset endophthalmitis [3] [4].
• Posttraumatic - Approximately 25% of endophthalmitis occurs in the setting of ocular trauma [3], with decreased vision, swelling of the eyelid, severe eye pain, uveitis, vitritis, hypopyon and presence of corneal ring ulcers being the most important symptoms [3].
• Endogenous - Symptoms of endophthalmitis as a result of hematogenous spread of bacterial or fungal organisms may be similar to exogenous forms, the most important signs being reduced visual acuity, eyelid edema, eye pain, and hypopyon [5]. Additionally, photophobia and the presence of floaters can also be reported in the majority of patients [5]. An absence of the red fundus reflex along with corneal edema and impaired visualization of the fundus, like in other forms, is frequently observed [5].

A thorough patient history is the first step in workup, as it can reveal vital clues regarding risk factors and pathogenesis of eye-related problems. Many authors suggest that typical signs and symptoms encountered in endophthalmitis are sufficient to make a diagnosis [1] [4] [5], but fundoscopy and a slit-lamp examination to support these findings must be performed. Vitritis, corneal infection, hypopyon, and clumps of thick material in the anterior chamber are some of the most common findings [4]. Imaging studies, such as magnetic resonance imaging (MRI) or computed tomography (CT scan) must be performed in the post-traumatic eye injury to exclude the presence of foreign bodies in other sites [1]. To confirm the underlying cause and determine optimal therapy, microbiological studies are necessary. A sampling of the vitreous humor, either by performing a vitrectomy or needle aspiration, is needed in order to obtain a viable sample for the investigation [4] [5]. Identification of bacterial or fungal pathogens are performed by culturing the samples in specific media, and vitrectomy carries a significantly higher rate of positive results compared to needle sample aspiration [4]. Detection of microorganisms by molecular techniques - polymerase chain reaction (PCR) and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has recently emerged as a novel method with superior results compared to cultivation and other laboratory tests (eg. serology), but their introduction in regular practice is yet to occur [1] [2] [5].

1. Vaziri K, Schwartz SG, Kishor K, Flynn HW Jr. Endophthalmitis: state of the art. Clin Ophthalmol. 2015;9:95-108
2. Safneck JR. Endophthalmitis: A review of recent trends. Saudi J Ophthalmol. 2012;26(2):181-189.
3. Kernt M, Kampik A. Endophthalmitis: Pathogenesis, clinical presentation, management, and perspectives. Clin Ophthalmol. 2010;4:121-135.
4. Durand ML. Endophthalmitis. Clin Microbiol Infect. 2013;19(3):227-234.
5. Sadiq MA, Hassan M, Agarwal A, et al. Endogenous endophthalmitis: diagnosis, management, and prognosis. J Ophthalmic Inflamm Infect. 2015;5:32.