Themen HCI, Mans DRA, Forster C, Pawiroredjo JC, Siban M, Bueno de Mesquita AT and Bipat R
Background: To provide evidence that besides the common known causes of pterygium, horizontal ocular version exerts chronic intermittent tension on predisposed limbal area, possibly initiating this affliction.
Methods and findings: Tensile force on the conjunctiva was assessed through the measurement of intraocular pressure during outward eye version compared to that found in the primary position of the eye. A laser pointer mounted on the head allowed to measure the movement of this body part. Subtraction of the angle of head movement from the angle of 45° degrees, where the left and right fixation points were situated, yielded the angle of voluntary lateral eye movement. Patients presenting with a pterygium had a higher intraocular pressure (17.3 ± 0.4) in the affected eyes during a fixed eye version compared to the healthy controls (15.2 ± 0.2 mmHg, p<0.05) and a higher degree of ocular motion (28 ± 4°) compared to the controls (21 ± 2°, p<0.05) when voluntarily gazing to a lateral fixation point at 45°. Finally, the increase of intraocular pressure dropped from 3.9 ± 0.2 to 0.1 ± 0.1 mmHg, (p<0.05) after application of conjunctival limbal autograft and remained low in the group of patients without recurrence of pterygium, while this drop was less (from 4.0 ± 0.8 to 1.7 ± 0.8) and returned to the pre-surgical level in eyes with a recurrence of pterygium.
Conclusion: Traction on limbal conjunctiva through horizontal ocular version may contribute to the development of pterygia, hence adequate surgical release of tension may prevent recurrence of the disorder. Long term clinical studies with a substantial amount of patients to confirm these findings are necessary.
