Long-term changes and effect of pterygium size on corneal topographic irregularity after recurrent pterygium surgery

Abstract

This retrospective observational study compared long-term topographic changes after recurrent- and primary-pterygium surgery depending on pterygium size. Patients who underwent recurrent-pterygium excision between 2002-2013 and age, sex, and pterygium size-matched controls who underwent primary-pterygium surgery were included (33 eyes of 33 patients in each group). Pterygium size was graded per advancing edge position: <1/3 of corneal diameter (grade 1), outside the pupil (grade 2), and within the pupillary area (grade 3). Surface asymmetry index (SAI), surface regularity index (SRI) in corneal topography, and uncorrected and best-spectacle-corrected visual acuity were compared before and 1, 3, 6, and 12 months postoperatively. Three, 17, and 13 eyes had grades 1, 2, and 3, respectively. In grade 2, the SAI and SRI were respectively significantly larger at all observation points (p = 0.01, 0.03, 0.02, 0.02, and 0.004) and before and 6 and 12 months postoperatively (p = 0.02, 0.04, and 0.03) in recurrent pterygium. In grade 3, the SAI was significantly larger before and 1, 3, and 12 months postoperatively (p = 0.04, 0.01, 0.01, and 0.02) and the SRI was significantly larger before and 12 months postoperatively (p < 0.001, 0.02) in recurrent pterygium. Corneal irregularity persisted 12 months after recurrent-pterygium surgery compared with that in same-size primary pterygium.

Figure 1

Surface asymmetry index (SAI) and surface regularity index (SRI) of grade 2 pterygium. (a) Preoperative and postoperative SAI of grade 2 pterygium. There was significant difference between primary and recurrent pterygium before and at 1, 3, 6, and 12 months after surgery (*p = 0.01, 0.03, 0.02, 0.02, and 0.004, respectively). Compared to the preoperative values, there was no significant difference at any observation point in both primary and recurrent pterygium. (b) Preoperative and postoperative SRI of grade 2 pterygium. There was significant difference between primary and recurrent pterygium before and at 6 and 12 months after surgery (*p = 0.02, 0.04, and 0.03, respectively). Compared to the preoperative values, there was no significant difference at any observation point in both primary and recurrent pterygium.

Figure 2

Surface asymmetry index (SAI) and surface regularity index (SRI) of grade 3 pterygium. (a) Preoperative and postoperative SAI of grade 3 pterygium. There was significant difference between primary and recurrent pterygium before and at 1, 3, and 12 months after surgery (*:p = 0.04, 0.01, 0.01, and 0.02, respectively). Compared to the preoperative value, the SAI in primary pterygium significantly decreased at 1, 3, 6, and 12 months (p = 0.005, 0.003, 0.007, and 0.003, respectively) and the SAI in recurrent pterygium significantly decreased at 1, 3, 6, and 12 months (0.01, 0.01, 0.01, and 0.004, respectively). (b) Preoperative and postoperative SRI of grade 3 pterygium. There was a significant difference between primary and recurrent pterygium before and at 12 months after surgery (*p < 0.001 and p = 0.02, respectively). Compared to the preoperative values, the SRI in primary pterygium significantly decreased at 3 months (p = 0.03) and the SRI in recurrent pterygium significantly decreased at 1, 3, 6, and 12 months (p = 0.005, 0.004, <0.001, and 0.002, respectively).