PTERYGIUM

Defination: it means wing of butterfly. It is subepithelial fibrovascular proliferation of conjunctiva over cornea invading the Bowman's membrane.

Pathogensis: it is a degenerative condition common in dry sunny envrionment. Exposure to ultraviolet rays is implicated as risk factor.

Pseudopterygium:  Band of conjunctiva adherent to cornea at its apex. It is caused by corneal ulcer,  chemical burn, truama and cicatrizing conjunctivitis

Laterality: Nasal side is affected more

Stocker's line: An iron line in front of apex of pterygium

Parts: Apex is triangular part over cornea, neck is narrow part at limbus and body is remaining fleshy part

fuchs islets are small flecks present at advancing edge representing pterygial epithlial cells

Differential diagnosis: Psuedopterygium. 

Probe test is done in which a probe is passed under the neck in pseudopterygium. The probe cannot be passed under neck of pterygium. 

Complications:  

1. ocular discomfort 

2. Astigmatism

3. visual impairment

4. cosmetic disfigurement

5. occasional diplopia due to restriction of ocular motility

Progressive verses atrophic pterygium.

Progressive pterygium is thick fleshy and vascular growing towards apex. Atrophic is pale thin and not growing.

Treatment: 

Its is left alone unless progressive and approaching pupillary axis.  It cannot be removed without leaving a scar.

1. simple excision: It has high recurrence rate.

2. Following techniques reduce recurrence

   1. Excision with stem cell graft 

   2. excision with conjunctival autograft

   3. postoperative Beta radiation 

   4. postoperative mitomycin b:  Eye drops are made by 2 mg powder dissolved in 5 ml of normal saline continued for 7 days. Complications like scleral necrosis, cataract and iritis have been reported

   5. use of ultraviolet protective glasses

3. Peripheral lamellar keratoplasty for deep lesion