Ocular Surface Squamous Neoplasia (OSSN)
What is Ocular Surface Squamous Neoplasia?
Ocular surface squamous neoplasia (OSSN) is a broad term, which denotes a spectrum of malignancy arising from the surface layer of the eye (conjunctiva and cornea). It can be thought of as a “skin cancer” of the eye.
Who are at risk of developing cancer of the ocular surface?
Ocular surface squamous neoplasia is seen more commonly in older patients who have an extensive history of sun exposure, for examples outdoor workers, surfers or sunbathers. Also, patients who have defective immune systems are more likely to develop OSSN.
How is OSSN diagnosed?
- In general, the diagnosis is made by an optometrist or ophthalmologist.
- In some cases, the patients or their family members may identify a suspicious lump in their eyes.
- The appearance of Ocular Surface Squamous Neoplasia may look just like a Pterygium, and it may require a tissue sample to confirm the diagnosis.
What is the best treatment for OSSN?
The gold standard treatment of Ocular surface squamous neoplasia is complete surgical excision with freezing of the surrounding areas (Cryotherapy).
The procedure is performed under local anaesthesia and the aim of the treatment is to remove all the cancerous tissues and destroy any residual tumour cells.
For larger tumours, topical chemotherapy in the form of an eye drop can be given for several weeks in order to reduce the size of the tumour before surgical excision.
Furthermore, some patients may be required to use these eye drops for several months after surgery when the tumour margins are not clear. These eye drops are generally well tolerated with minimal side effects.
Patients who had successful surgery should have lifelong follow-up by an ophthalmologist as there is a small chance of recurrence of the tumour from seeding of the tumour.