CNS / Brain · Organ at risk

Globes (Eyes)

Educational Summary

Dose constraints

High-Grade Glioma

ScheduleConstraintSource
60 Gy / 30 fx
Standard course
Mean <35 Gy, max <50 GyeviQ 409

Quoted from eviQ 409, checked 2026-09-25. Full table with references →

Stereotactic Radiosurgery (SRS)

ScheduleConstraintSource
1 fx
15–24 Gy
D0.1 cc ≤8 Gy (ideal)UK SABR consensus 2022
3 fx
24–30 Gy
D0.035 cc ≤15 Gy (ideal), ≤20 Gy (acceptable)eviQ 3253
5 fx
25–35 Gy
D0.035 cc ≤22.5 Gy (ideal), ≤25 Gy (acceptable)eviQ 3253

Listed as the orbits in the source.

Quoted from eviQ 3253, checked 2026-09-25. Full table with references →

Anatomy

The eyeballs, each sitting in its bony orbit, with the lens and cornea at the front and the retina lining the back.

Function in the body

The eyes focus light onto the retina at the back of the eye, which turns it into nerve signals for the brain.

Why it matters

High dose to the back of the eye can damage the retina and cause vision loss; dose to the front can cause dry eye, corneal injury and cataract. The globes matter when the target reaches the nasal cavity, sinuses, orbit or skull base — mainly nasopharynx and sinonasal cancers. In brain radiosurgery and glioma treatment they matter for targets near the orbit and the frontal lobe.

How to contour

Brouwer 2015 splits each eyeball into two structures rather than one whole globe:

  • Anterior segment: everything in front of the vitreous — the cornea, iris, ciliary body and lens.
  • Posterior segment: everything behind the lens — the vitreous, retina and choroid. It includes the whole retina but excludes the optic nerve.

The EPTN 2018 atlas instead contours the cornea and the retina as thin separate structures (drawn with a 2–3 mm brush). Many protocols evaluate the whole globe, so check which structure your limit refers to. The lens is contoured as its own structure.

Further reading

  • RTOG 0615 — RTOG 0615 protocol — A Phase II Study of Concurrent Chemoradiotherapy Using Three-Dimensional Conformal Radiotherapy (3D-CRT) or Intensity-Modulated Radiation Therapy (IMRT) + Bevacizumab (BV) for Locally or Regionally Advanced Nasopharyngeal Cancer Source
  • DAHANCA 2025 — Danish Head and Neck Cancer Group (DAHANCA) Radiotherapy Quality Assurance Guidelines 2025 Source

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