What is Pterygium? causes, types, symptoms, signs, complications and treatment

Medico Feeds November 05, 2020


Pterygium:

Pterygium (pterygion-a wing) is a triangular encroachment of the conjunctiva onto the cornea,usually on the nasal side.


Etiology:

Exact etiology of Pterygium is not definitely known. But it is more common in people living in hot climates.

It also occurs with prolonged exposure to sun, ultra violet rays,dry heat,high wind and dust.

Pathology:

It is due to the elastic degeneration followed by vascularized granulation of the subconjunctival tissue, which encroaches the cornea.

Clinical features:

It usually occurs in old age and it is more common in males than females.

Symptoms:

- foreign body sensation
- irritation
- defective vision 
- cosmetic intolerance
- diplopia

Signs:

It present as a triangular fold of conjunctiva intrude on the cornea, mostly on the nasal side.

Sometimes,it occurs on temporal side or even on both sides.

Parts of Pterygium:

1. Head - apical part on the cornea
2. Neck - present in limbal area
3. Body - extending between limbus and the canthus
4. Cap - whitish infiltrate infront of the head.

Types:

1. Progressive type
     It is a thick,fleshy and vascular with Fuch's spot (whitish infiltrate infront of the head of the pterygium).

2. Regressive type
     It is thin, atrophic and with less vascularity. There is no cap, but deposition of iron (Stocker's line) is seen. It becomes membraneous but never disappear.


Complications:

- cystic degenerations and infections
- neoplastic changes.

Differential diagnosis:

Pterygium should be differentiated from pseudopterygium. It occurs after chemical burns of the eye.

Treatment:

Surgical excision is the only satisfactory treatment.

Recurrence of pterygium after surgery is the main problem (30-50%). It can be reduced by,

- Conjunctival limbal auto graft ( CLAU)
- Amniotic membrane graft and mitomycin C
- Lamellar keratectomy
- Lamellar keratoplasty.

Surgical technique of excision:

1. After topical anaesthesia,eye is draped and exposed.

2. Head of the pterygium is lifted and dissected off from cornea.

3. Main mass of pterygium is then separated from the sclera.

4. The tissue is excised taking care not to damage the underlying medial rectus muscle.

5. Haemostasis is achieved and the episcleral tissue exposed is cauterised thoroughly.

6. Conjunctival limbal auto graft ( CLAU) transplant to cover the defect after excision.

7. Use of fibrin glue to stick the autograft in place reduces discomfort with the sutures.

Pterygium is more common condition. One should protect eye from various external sources.