[Study on microsurgical procedures for pterygium operation and its therapeutic effects]

To study the microsurgical procedures for the treatment of large primary pterygium and their therapeutic effects. To observe the recurrence rate, the changes of visual acuity after microsurgery and the pathological relationships between pterygium and cornea/sclera under the surgical microscope.

Forty-six eyes of forty-one patients with pterygium which invading the cornea over the pupil border were included. Pterygium was dissected by various methods under surgical microscope. The pathological relationship between the pterygium and cornea/sclera was observed. The lengths of the pterygium head and its three parts were measured. Degenerative Tenon's capsule was removed totally and the wound was covered by rotated conjunctival flaps. These patients were followed-up for 12.0 - 50.2 months (median: 22.4 months). Changes in visual acuity and recurrence rate after operation were observed.

The average length of the total pterygium heads was (6.3 +/- 0.4) mm. The head was divided into three parts: the apical, loose and adhesive parts. The apical part was located at the top of the pterygium head with a length of (1.7 +/- 0.4) mm. The tissue of apical part was compact, hard, translucent and adhered to the cornea tissue. The adhesive part was a band in front of the anterior border of the limbus and paralleled to the limbus. The width of adhesive part was (0.9 +/- 0.1) mm and was tightly adhered to the cornea. The loose part lied between the apical and the adhesive part. The length of which was (3.6 +/- 0.4) mm and could be separated from the cornea easily. The neck and the body parts of pterygium could be separated easily from the limbus and sclera. Non-corrected visual acuity averaged 0.3 (ranged from finger count to 0.7) before the operation and averaged 0.7 (ranged from finger count to 1.5) 1 month postoperatively (Wilcoxon signed rank test u = 5.435, P < 0.01). Pterygium relapsed in 5 eyes with a recurrence rate of 11% (5/46).

There is a regular pathological relationship between the pterygium and the cornea/sclera under surgical microscope, which is fundamental for the microsurgery of the pterygium. Extensively degenerated Tenon's capsule should be removed totally and the defect should be covered by rotated conjunctival flaps. The recurrence rate is low and the visual acuity increases significantly after the operation.