The OSI, MTF cutoff, Strehl ratio (SR) parameters are used for evaluating the optical quality in OQAS. A lower OSI value indicates improved optical quality, a lower value of the MTF cutoff indicates a worse optical quality of the eye, and a higher SR confers to a better quality of the vision. In our study, compared with the suturing group, the modified sutureless and glue-free group demonstrated significantly lower mean OSI, higher mean MTF, and higher mean SR at 1 month and 3 months after surgery, and it had significantly lower mean OSDI at 1 month, while this was similar to the suturing group at 3 months. These results have confirmed that the modified sutureless and glue-free method can improve the visual quality of patients in the early postoperative stage, with the outcomes measured both objectively and subjectively.
The dual-channel visual quality analysis system (OQAS II) developed by Visiometries of Spain provides comprehensive information on diffraction, intraocular scattering, and higher-order aberrations in the ocular optical system . The early clinical application of the OQAS has focused on the area of refractive error and cataract, which is especially valuable for the evaluation of cataract surgery . Several previous studies have acknowledged the importance of visual quality in ophthalmic diseases [17, 18], and optical quality and visual function are affected by aging . Currently, the OQAS is commonly applied when evaluating numerous ophthalmic conditions such as age-related macular disease, diabetic macular edema, retinal vein occlusion , dry eye disease [15, 19], central serous chorioretinopathy , and primary open-angle glaucoma . However, few studies have reported the use of OQAS in pterygium.
The overall results of our study have shown that all OQAS parameters have been significantly improved at the postoperative follow-ups, indicating the improvement of the visual quality. The pterygium modifies adversely the characteristics of the ocular surface and cornea, resulting in optical quality undermined. Pterygium growth can lead to irregular astigmatism, corneal scarring, restriction of ocular motility, or chronic ocular surface inflammation . Moreover, pterygium has significant influence on high-order aberrations . All of these factors have a great influence on optical quality. A previous study has confirmed that pterygium results in a deterioration in the visual quality , and excision can lead to significant improvement that is consistent with our findings. Besides this, our study has demonstrated that the visual quality of the modified sutureless and glue-free group was superior to that of the suturing group both at 1 month and 3 months after surgery. Our previous studies revealed that the average conjunctival autograft thickness were 577 ± 287 mm, 353 ± 159 mm, 185 ± 74 mm in group 1 and 658 ± 205 mm, 408 ± 243 mm, 183 ± 142 mm in group 2 at 1 week, 1 month, 3 months postoperative, respectively. However, no significant differences were found between groups at 1 week or at 1 and 3 months postoperative . The modified surgery method required minimal operating time results in lower trauma and light inflammatory reaction. Improvement of the visual quality may be mainly related to shorter operating time, less inflammation and tear film tear film stability. This suggested that the modified sutureless method has clinical advantages over the more widely used 10/0 nylon sutures method currently, likely because the ocular surface irritation and dry eye symptoms have been significantly alleviated in the modified sutureless group.
A recent study has shown that the OSDI questionnaire has a good correlation and also consistent with patients’ subjective symptoms . Using a standardized OSDI questionnaire, our study has demonstrated that the modified sutureless and glue-free treatment resulted in a statistically significant improvement in patients’ symptoms compared with the suturing method at 1 month after surgery in the early postoperative period, but no difference has been observed at 3 months. Moreover, without the friction of the tied sutures, this method leads to improved postoperative patient comfort. It may enhance the recovery of tear film stability, decrease the tear film scattering, and improve visual quality in pterygium patients. Conventionally, surgical sutures, as a foreign body, can induce more inflammatory reactions which may influence the visual quality in the early postoperative stage. Furthermore, suture removal can cause pain results in greater postoperative discomfort. All of these may explain the lower OSDI score in our study.
The grade of pterygium correlates with the visual quality, with higher grade associated with lower visual quality, as demonstrated in our study. Compared with the modified sutureless and glue-free group, the suturing group had worse visual quality, which may suggest the impact of different surgical treatments on the outcomes of optical quality assessment. The OSDI score, as a questionnaire-based survey, may have some drawbacks because it relies on the patient’s subjective self-reporting. Meanwhile, the OQAS is a valuable tool for an objective evaluation together with all the optical information provided on one surface that is rarely influenced by subjective factors. Our study has suggested that the clinical application of OQAS may be useful in evaluating the visual quality of both preoperative and postoperative patients undergoing treatments for pterygium. Our study contributes new knowledge to the field with a novel method of surgery for pterygium. Nevertheless, there were several limitations to our study. First, the follow-up time was relatively short. Second, the sample size was rather small, and quantitative indices of inflammation and tear film should be more considered during the follow-up. Therefore, a large-scale and stringently-controlled clinical trial with longer follow-up is warranted to validate our findings from this study.