Diagnosing endophthalmitis can be challenging in patients with advanced microbial keratitis, and the visual outcomes are often poor. With this in mind, a study in Cornea reports clinicians should be suspicious if a patient presents with vision of light perception or worse, a history of cataract extraction or a full-thickness ulcer or perforation.

“While clinicians should have a high index of suspicion for endophthalmitis in any patient with severe microbial keratitis, we found that pseudophakic patients and those whose vision has dropped to light perception or no light perception are at particularly high risk of this devastating complication,” says researcher Karen Christopher, MD, of the University of Colorado School of Medicine’s Department of Ophthalmology.  

Her team’s investigation enrolled 81 eyes with severe microbial keratitis that underwent ocular ultrasonography for possible endophthalmitis. Out of the 81 eyes, 15 were diagnosed with endophthalmitis based on clinical findings and evidence of vitritis on ultrasound.

Compared with the keratitis-only group, patients with endophthalmitis more often had light perception or no light perception (73.3% vs. 31.8%,), nearly double the rate of a history of cataract surgery (80.0% vs. 45.5%,) and more than three times the rate of full-thickness ulcer or perforation (33.3% vs. 9.1%). Additionally, gram-positive organisms were more common in the endophthalmitis group (60% vs. 30.3%).

Choroidal thickening or retinal detachment may also be red flags for endophthalmitis. Ultrasound findings showed choroidal thickening and retinal detachment were much more common in the endophthalmitis group (26.7% vs. 3.4% and 13.3% vs. 8.4%, respectively) in addition to an expected greater prevalence of membranous and dispersed vitreous opacities, the researchers noted.

 Final visual acuity was also worse in the endophthalmitis group (2.3 vs. 3.5 LogMAR).

Although microbial keratitis-associated endophthalmitis is relatively rare, earlier diagnosis and treatment may have a positive impact on typically poor final outcomes, the researchers noted in their paper.  Additionally, they cautioned that ultrasound should be performed on all eyes with ulcers that limit view to the posterior segment to evaluate for vitritis.

Christopher KL, Hood CT, Mian SI. Endophthalmitis in advanced microbial keratitis: Risk factors and examination findings. Cornea. May 29, 2020 [Epub ahead of print].