Optic Disc Vascularity Changes Observed in Patients Receiving Radiation Therapy

Radiation therapy (RT) significantly affects retinal density parameters in patients with nasopharyngeal cancer (NPC), according to a study published in Photodiagnosis and Photodynamic Therapy. 

Researchers enrolled 30 participants in a retrospective, single center study consisting of 14 patients treated with RT (mean age 36.19±14.48 years) and 16 age-matched healthy control individuals (mean age 41.31±9.91 years). The primary objective was to assess the significance of RT on perifoveal and parafoveal vascular parameters. Patients in the treatment group were administered concurrent chemotherapy every 3 weeks. Researchers excluded patients with media opacities that could potentially affect imaging quality, ocular disease, systemic diseases affecting the optic nerve or retina, and those who had previous ocular surgery from the analysis. 

The team performed ophthalmic examinations on all participants including intraocular pressure measurements, slit lamp analysis, fundoscopy, and optical coherence tomography angiography (OCTA).

They obtained measurements of optic disc density, retinal nerve fiber layer (RNFL) thickness, area of the foveal avascular zone (FAZ), superficial capillary plexus vascular density (sCVD), and deep capillary plexus vascular density (dCVD) in the foveal, parafoveal, and perifoveal zones.

Investigators reported that hemi disc vessel densities were significantly lower in patients who underwent RT compared with controls (51.11±3.45 vs 53.01±3.51; P =.042). They also noted significantly lower parafovea and perifovea superficial/deep vessel densities (P <.001) among patients with RT. The team found negative correlations between the maximum optical density (Dmax) of the optic tract and superficial and deep vessel densities (P =.013 and P =.006, respectively). They also noted a negative correlation between the mean density (Dmean) of glob and vessel densities. Investigators determined that there were no significant differences between the groups in mean foveal parameters, but noted a significant expansion of the FAZ with higher radiation doses.

“Although none of the patients in our study had marked vision loss and retinal abnormalities with the examination, OCTA findings showed that there was a significant decrease in the optic disc inferior half vascular density, and both superficial and deep capillary plexus vessel density in the parafoveal and perifoveal regions of the retina in the RT group,” according to the researchers.

Study limitations include a small sample size and the absence of baseline assessments prior to treatment.

Reference

Dağdelen M, Şerikoğlu Akbaş Z, Barlas C, Can G, Arıcı C, Uzel Ö. Evaluation of retinal and optic disc vascular changes and retinal nerve fiber layer thickness in patients with nasopharyngeal carcinoma following image guided intensity- modulated radiation therapy using optical coherence tomography angiography. Photodiagnosis and Photodynamic Therapy. Published online April 28, 2022. doi:10.1016/j.pdpdt.2022.102887