Abstract
Purpose :
The use of anesthetics is subject of discussion in ocular surface microbiome research. One publication showed a significant lower alpha diversity when using an anesthetic(1). However, the diluting effect of the anesthetic drop itself was not accounted for. On the other hand, using anesthetics will enable patients to tolerate sampling better and this might allow better sampling. Furthermore, as vertical stratification of bacteria on the ocular surface is expected, with the presence of transient species in the more superficial layers and a more resident commensal microbiota in the deeper layers, more pressure will alter the microbial composition of the samples.
(1)Shin H et al. Changes in the Eye Microbiota Associated with Contact Lens Wearing. MBio. 2016;7(2):e00198.
Methods :
To analyze the effect of anesthetic drops on the composition of the ocular surface microbiome, we sampled volunteers undergoing strabismus and ORL surgery. Per subject, the left and the right eye were sampled when patients were under general anesthesia. Before sampling, a drop of artificial tears or a drop of topical oxybuprocaine was applied in a randomized way. By using artificial tears as a control, we aimed at accounting for the diluting effect of the anesthetic. By using volunteers under general anesthesia, we wanted to assure similar pressure with or without topical anesthesia since the executer was not influenced by the patient’s reaction. By comparing both eyes of one person, the immunological and genetic background was the same. The effect of lifestyle factors, such as sleeping side preference, was minimalized by randomization. Subjects filled in a small questionnaire to take into account the most obvious confounding factors. Bacterial DNA of the samples was quantified with Qubit and will be used for 16S amplicon sequencing on the Illumina MiSeq platform.
Results :
We analyzed 48 eyes. The median DNA yield (Q1-Q3) per sample was 2.86 (0,08-8,79) ng/ml. The amount of DNA was higher when no anesthetic was used (artificial tears group) (p= 0.015). The sampling order had no influence on the DNA yield (p= 0.20).
Conclusions :
With our research, we aim to distinguish the anesthetic effect versus the diluting effect of an anesthetic drop on ocular surface microbiome research. The sequencing results are currently pending and will be presented on ARVO 2020.
This is a 2020 ARVO Annual Meeting abstract.