Pterygium is known to induce with-the-rule astigmatism. Excision of pterygium will steepen the cornea and reduce corneal astigmatism. We postulate that the alteration of keratometry reading will indirectly affect the IOL power calculation in cases with concurrent pterygium and cataract. Concurrent pterygium and cataract is common in Hong Kong and other tropical regions. The effect of pterygium excision on intraocular lens power calculation is investigated.

Inclusion Criteria:

• All cases with concomitant cataract and primary pterygium, which are indicated for surgery.

Exclusion Criteria:

• Pterygium smaller than 1mm, which is not visually significant.
• Double headed pterygium
• Pterygium obscuring visual axis that preclude keratometry or autorefraction measurements.
• Previous corneal refractive surgery that alter the keratometric power of the cornea.
• Patients with medical problems that preclude staged ocular surgery, e.g. dementia, heart disease, on warfarin.