Role of Radiation Therapy in PTERYGIUM by Doctor DAAHIMA

1. PTERYGIUM:ROLE OF RADIOTHERAPY

2. Take a look over anatomy of eye
 The ocular adnexa consist of structures including the
eyelids, cilia, lacrimal glands, lacrimal drainage
apparatus, and conjuctiva.

3.  The eyeball is a spherical organ composed of three
tunicae.
 The outer coat consists of the clear cornea on the front
and the sclera, a fibrous hypocellular layer that
occupies 90% of the posterior aspect of the globe.
 The uvea, or middle coat, is formed by the chroid,
ciliary body and iris, all of which contain a high
concentration of melaocytes as well as vessels.
 The innermost and sensory layer is the retina and its
analogs. This coat extends from the oraserrata retinae
anteriorly to the optic nerve posteriorly.

4.  The vascular supply to the posterior half of the retina
derives from the central retinal artery, which enters
the globe through the optic nerve.
 The choroid is split into anterior ciliary and posterior
ciliary arteries.
 The lens is suspended from the ciliary body and is
located posterior to the iris..

5.  The orbit is composed of seven bones: Frontal,
Maxilla, Lacrimal, Palatine, Ethmoid, Sphenoid and
Zygomatic.
 The bony orbit encloses the ocular globe, vessels,
nerves, orbital fat, lacrimal gland, and ocular muscles:
superior, inferior, medial, and lateral recti as well as
superior and inferior oblique muscles that are inserted
on the sclera

6. Benign Ocular Disease
 Radiation therapy is most commonly used for the
treatment of malignant tumors, however since long
time it has been applied to the eye globe or the orbit
with the purpose of achieving control of selective
benign processes.

7. PTERYGIUM
 Pterygium is a benign ocular growth of fibrovascular
tissue on conjuctiva.
 Pterygium can cause irritation, erythema of the
cornea, ma obstruct vision and become of cosmetic
concer for a patient.
 Age 20-50 yrs
 Dry, Dusty and hot conditions: which can cause trauma to the
corneal stem cells and cause slow decay of these cells, thich in turn
allows overgrowth of thickened fibrovascular tissue at the limbus and
onto the cornea.

8.  The loss of corneal stem cells is most apparent at the
horizontal limbal region where exposure to the
environment is greatest.
 It is also theorized that ultraviolet light exposure may
increase the risk of development of pterygium.
 Most frequently Medial/Nasal aspect of conjuctiva.

9.  Primary treatment: SURGERY
 Complete surgical excision and replacement of loss
stem cells by autograft is the surgery of choice.
 Recurrence rate after surgery alone are in range of 20%
to 68%.
 Adjuvant treatment for pterygium can involve
radiation therapy or topical chemotherapeutic agents
to minimize regrowth of fibrovascular tissue.

10.  In a prospective randomized study, 96 eyes with
pterygium were operated on and received β-radiation
with a Strontium-90 (90Sr) eye applicator, or sham
radiation within 24 hours of surgery.
 control rates were approximately 93.2% for the β-
radiation group verses 33.3% for the sham radiation
group.

11.  Single dose β-radiation after surgery proved to be a
simple, safe and effective treatment to reduce the risk
of pterygium recurrence.
 Current surgical techniques have made the use of
irradiation for pterygium sporadic and is only
employed in selected cases.