Surgical Treatment of Concurrent Cataract and Primary Pterygium

Study Overview
=================
Brief Summary
-----------------
Pterygium is known to induce with-the-rule astigmatism. The corneal curvature along the long axis of the pterygium body is flattened. The excision of pterygium will result in steepening of the cornea and reduction of astigmatism. Therefore, the effect of pterygium excision on intraocular lens (IOL) power calculation has been examined in our previous study. The study confirmed that pterygium can cause alteration of IOL power. The determination of IOL power for cataract surgery is usually calculated from IOL formula called SRK II formula. IOL power = A - (2.5 x AL)-(0.9 x K). Variable A denotes the A-constant of the intraocular lens which is dependent on the IOL material and refractive index. Other variables for input include axial length (AL) and keratometry (K). A larger K reading will result in a lower estimated IOL power and vice versa. Previous studies have documented simultaneous cataract and pterygium operation resulted in reasonable visual outcome without adjustment of IOL power. With the presence of a pterygium, the cornea is flattened and lead to a reduction of K value and over-estimation of calculated IOL power. This randomized controlled trial is designed to compare the refractive outcomes of sequential and simultaneous pterygium and cataract operation. Pterygium excision should be done with various adjuvant therapies to minimize recurrence. Our previous studies reliably demonstrated limbal conjunctival graft and mitomycin C were effective methods to achieve low pterygium recurrence. We use limbal conjunctival autograft as the adjuvant therapy in the current study because this method is safer to be performed either alone or in combination with phacoemulsification. We avoid using mitomycin C as the adjuvant therapy in order to minimize the possibility of intraocular toxicity due to seepage.

Official Title
-----------------
Surgical Treatment of Concurrent Cataract and Primary Pterygium: A Randomized Control Trial

Conditions
-----------------
Pterygium, Cataract, Lenses, Intraocular

Intervention / Treatment
-----------------
* Procedure: combined pterygium and cataract operation
* Procedure: pterygium excision followed by cataract operation


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: >18 years old Primary pterygium > 2mm across corneal limbus [Measurement made from the imaginary line of surgical limbus to the most advance edge of the visible pterygium tissue] Concurrent visually significant cataract ( BCVA < 20/70 ) Informed consent for both pterygium and cataract surgery Exclusion Criteria: Temporal pterygium Double headed pterygium Previous ocular surgery in which conjunctival-limbal graft is not feasible Pterygium covering visual axis that preclude keratometric assessment History of scleritis or autoimmune diseases

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Intervention/Treatment |
| --- |
|Procedure: combined pterygium and cataract operation|nan|
|Procedure: pterygium excision followed by cataract operation|nan|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| final refraction deviation from target |  | 1 and 3 months post cataract operation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change of IOL power from pre-pterygium estimated power |  | 1 and 3 months post pterygium excision | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Pterygium, Cataract, Intraocular lens power calculation accuracy