Ellipsoid Zone Recovery and Outer Nuclear Layer Changes Following IV Penicillin Treatment for Syphilitic Retinitis.

Abstract

Purpose : Spectral-domain optical coherence tomography (SD-OCT) reveals significant ellipsoid zone (EZ) loss in syphilitic retinitis. Gradual EZ reconstitution occurs after initiation of IV penicillin treatment. We aim to quantify the recovery of the EZ after completion of two-week penicillin treatment and to characterize relative changes in the outer nuclear layer (ONL).

Methods : A retrospective chart review of 16 patients diagnosed with syphilitic retinitis was performed. Patients received at least a 14-day course of IV penicillin and had one SD-OCT scan before and after treatment initiation. Each SD-OCT was analyzed using a custom retinal layer segmentation software and manually corrected. EZ and ONL metrics were then extracted from each SD-OCT along with EZ-RPE thickness maps. For ONL metrics, patients with positive (20 eyes) and negative (5 eyes) syphilis lumbar punctures (LP) were compared. Wilcoxon signed rank and Wilcoxon ranked sum tests were used to determine statistical significance.

Results : Images from 28 eyes (16 patients) with syphilitic retinitis were analyzed. There was a 146.8% (SD: 218.8%; p<0.0001) increase in overall EZ volume after completion of treatment and the EZ central subfield volume increased by 174.7% (SD: 239.6%; p<0.0001). The area of complete EZ loss (0 µm EZ) decreased by 72.0% (SD: 33.6%; p<0.0001). The ILM to Outer plexiform layer (OPL) volume decreased by 7.9% (SD: 6.1%; p<0.0001) and the central subfield volume decreased by 12.5% (SD: 14.5%; p<0.0001). The ONL-RPE volume increased by 2.4% (SD: 12.4%; p=0.255) and the central subfield volume increased by 8.7% (SD: 23.0%; p=0.005). Lastly, ONL-EZ volume decreased by 4.7% (SD: 13.4%; p=0.011) and the central subfield volume decreased by 5.0% (SD: 30.6%; p=0.594). There was no significant difference in ONL metrics between LP positive and negative patients. Despite overall improvement, no eyes had complete EZ recovery after finishing treatment course.

Conclusions : Our study shows that there is EZ volume recovery after initiation of penicillin treatment. This recovery may be at the expense of the ONL as ONL-EZ is overall decreasing after starting treatment. In addition, there was no significant difference in ONL volume changes between LP positive and negative eyes, suggesting that central nervous system involvement beyond the retina may not affect the rate of ONL changes.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.