Ocular Surface Squamous Neoplasia (OSSN) – a cancer of the eye
Raghubeer*, 52; a driver by profession; had a pricking sensation in his left eye for over a month. He experienced occasional redness and irritation but kept brushing this aside. Gradually the redness and pricking increased in intensity and soon his left eye started watering. He took a closer look at his eye in the mirror – he noticed a small whitish-pink spot over the white part of his eye, the conjunctiva. He ignored this small spot, but soon the foreign body sensation in his eye increased. He visited an eye doctor who performed an eye surgery to remove this mass that he doctor called a ‘pterygium’. But in 2 months time, Raghubeer noticed this mass developing again at exactly the same spot. Finally he came to our institute to seek an opinion, 6 months after he first noticed this tiny white spot, which had grown in size.
This condition was diagnosed as an Ocular Surface Squamous Neoplasia (OSSN). This lesion is a tumour or cancer of the conjunctiva. The conjunctiva is a thin, almost transparent covering that covers the white part of the eye (Sclera). OSSN is a tumour that arises from the squamous epithelium of the conjunctiva.
But what had caused this tumour in Raghubeer?
There are various risk factors for OSSN such as prolonged sunlight exposure, vitamin A deficiency and infections among others. Prolonged sunlight exposure increased the damage due the harmful ultraviolet (UV) radiation and this can lead to the development of OSSN.
Human immunodeficiency virus (HIV) infection and HPV (Human papilloma virus) are also implicated as risk factors in OSSN. Exposure to chemicals such as arsenicals, petroleum products, beryllium and cigarette smoke are also risk factors..
The White Mass on the Conjunctiva
Raghubeer underwent an eye surgery called as excision surgery. The tumour was excised along with a 4 mm margin of healthy conjunctiva and the involved cornea was also scraped off (alcohol assisted kerato-epitheliectomy). The base of the tumour was treated with cryotherapy and finally covered with an amniotic membrane graft which serves as a scaffolding over which the healthy new conjunctival epithelium can grow.
Depending on the size and the location of an OSSN, the treatment options vary. Excision with clear margins is considered the treatment of choice. Any corneal extension can be dealt with by performing an eye surgery called alcohol assisted kerato-eptheliectomy. However, in those cases with widespread involvement of the conjunctiva and sclera, a lamellar sclerectomy may have to be performed. After tumor excision, double freeze-thaw cryotherapy is applied to the healthy conjunctival margins. The defect may be closed with absorbable sutures or in large defects, an amniotic membrane may be placed. The surgical technique is the ‘no-touch’ technique.
Take Home Message:
A pterygium is a benign (non cancerous) growth of the conjunctiva, whereas an OSSN or a squamous neoplasia is a cancerous or malignant tumour. Raghubeer’s ordeal underscores the importance of an ocular oncologist. Ocular oncology, or cancers of the eye is a specialized branch of ophthalmology with trained specialists.