**3. Results**

This study comprised 100 eyes from 70 patients. Three eyes from three patients were excluded because the CDVA was greater than 0.5 logMAR. A total of 97 eyes from 67 patients were analyzed, of which 23 eyes underwent sutured scleral fixation, with a mean patient age of 58.13 years (range 36–79 years), and 74 eyes underwent in-bag IOL implantation, with a mean patient age of 69.76 years (range 46–96 years). A total of 15 eyes (20.27%) of 10 patients had diabetes mellitus in the in-bag group, while 6 eyes (26.09%) of 5 patients were affected in the scleral-fixated group. One patient in the in-bag group had Sjogren's syndrome. The mean spherical equivalent was −1.09 ± 3.32 D in the scleral-fixation group and −0.23 ± 0.75 D in the in-bag group. The CDVA of the in-bag group was slightly better (mean logMAR 0.11 vs. 0.20). Statistically significant differences were observed between the two groups in terms of

age, sex, IOL type, CDVA, and spherical equivalent (Table 1). Although 33 eyes (34%) were followed within 3 months after the surgery, the mean CDVA could reach 0.16 logMAR. In the scleral-fixation group, 14 eyes had IOL subluxation or dislocation; 4 eyes had lens dislocation, and 5 had aphakia following complications with cataract extraction. The majority of sutured IOLs in the scleral-fixated group (56.52%) received Akreos Adapt Advanced Optics lenses (Bausch + Lomb, Laval, QC, Canada).

**Table 1.** Demographics and visual outcomes of eyes following in-bag and scleral-fixated intraocular lens implantation.


CDVA = corrected distance visual acuity; IOL = intraocular lens; logMAR = logarithm of the minimum angle of resolution; OD = right eye; OS = left eye; SD = standard deviation; SE = spherical equivalent; \* *p* < 0.05.

The postoperative wavefront data including ocular, internal, and corneal aberrations for both groups are listed in Table 2. Ocular aberrations differed markedly from corneal aberrations between the scleral-fixation and the in-bag group in terms of overall aberrations, HOAs, tilt, coma, trefoil, and astigmatism, with the exception of spherical aberrations.

**Table 2.** Postoperative ocular, corneal, and internal aberrations for 3-mm pupil diameters in eyes following in-bag and scleral-fixated intraocular lens implantation.


HOAs = higher-order aberrations; \* *p* < 0.05; a lower and higher-order aberrations included; b astigmatism and secondary astigmatism included.

In terms of contrast sensitivity testing, the in-bag group performed better under daytime luminance conditions with or without glare interference but similar to those in the scleral-fixation group under twilight or night conditions (Table 3). For the in-bag group and scleral-fixation group, 53 (71.62%) and 11 eyes (47.83%) were tested for perceptive dysphotopsia, respectively. The mean questionnaire scores for subjective dysphotopsia under mesopic conditions with glare showed no significant differences between the two groups. Symptoms of glare, halo, coma, and starburst were similar in both groups (*p* > 0.5).

**Table 3.** Postoperative contrast sensitivity of eyes following in-bag and scleral-fixated intraocular lens implantation.


AULCSF = area under the log contrast sensitivity function; \* *p* < 0.05.

The results of GEE for contrast sensitivity are described in Figure 1 and Table 4. Age had significantly negative effects on contrast sensitivity under photopic and mesopic conditions, and the surgical technique (in-bag and scleral fixation) did not affect the results of contrast sensitivity after controlling for the age effect. LogMAR and ocular aberrations had significantly negative effects on contrast sensitivity under every luminance condition with or without glare interference. No significant variable was determined in the GEE for dysphotopsia.

**Figure 1.** Forest plot depicts the coefficient of each factor and its 95% confidence interval (CI) in a multiple regression analysis for factors associated with contrast sensitivity. The x-axis represents the reference line (dashed), the value of coefficient (dot), and 95% CI (strip). AULCSF = area under the log contrast sensitivity function; IOL = intraocular lens; LogMAR = logarithm of the minimum angle of resolution.


**Table 4.** Multivariate generalized estimating equation (GEE) analysis of contrast sensitivity under every luminance condition with or without glare interference.

IOL = intraocular lens; logMAR = logarithm of the minimum angle of resolution; SE = standard error; \* *p* < 0.05; \*\* *p* < 0.01; \*\*\* *p* < 0.001.

## **4. Discussion**

This study demonstrated that the mean CDVA, spherical equivalent, and ocular HOAs were significantly better in the in-bag group than in the scleral-fixation group. However, in the contrast sensitivity test, no difference was noted between the groups except under photopic conditions, which was compatible with the result of the subjective dysphotopsia questionnaire. The factors related to low-contrast sensitivity were age, logMAR, and ocular aberrations.

Mimura et al. [15] reported that the mean spherical equivalent was –1.16 ± 2.28 D for transscleral-fixated IOL implantation at 2 years, and Mizuno et al. [16] indicated that the mean postoperative CDVA in the logMAR at 1 month was 0.25 ± 0.41. Both results were similar to those of our study. Huang et al. [17] determined that IOL scleral fixation induced an average 1.66 D myopic shift, which may be caused by the more anterior placement of the scleral-fixated IOLs [16]. Hayashi et al. [8] demonstrated that anterior chamber depth with sutured IOLs was shallower than that with in-bag IOLs, which caused a significant myopic shift. Other studies [18–21] have also reported an increase in spherical equivalent in those who underwent IOL scleral fixation.

Most of our patients who received transscleral IOL fixation were men, and they were much younger than those who underwent in-bag IOL implantation. The main reason for scleral fixation was trauma experienced during labor work, and the majority of laborers were men. One study [15] with a 12-year follow-up noted that the mean patient age after scleral fixation was 61.7 years, and another study [10] recorded more men in their scleral-fixation group than in the in-bag group (44.4% vs. 41%), which was similar to our study.

Ocular coma aberration was significantly greater in the scleral-fixation group than in the in-bag group. A study [10] indicated that IOL tilt correlated with ocular coma-like aberrations. Therefore, an increase in ocular coma aberrations in the scleral-fixation group in our study suggests the contribution of an IOL tilt. Ocular trefoil aberration was also greater after scleral fixation. Torii et al. [22] noted the same results and reported that postoperative ocular, corneal, and internal trefoil-like aberrations were significantly greater in their scleral-fixation group than in the intracapsular group. Spherical aberration was correlated with the implanted IOL type, and aspheric IOLs were associated with lower spherical aberrations than spherical IOLs. Our results demonstrated that the percentage of aspheric IOLs, including those that were toric, in the scleral-fixation group was comparable to that in the in-bag group (74.32% vs. 60.87%, *p* = 0.21), indicating no difference in ocular spherical aberration between the two groups.

In this study, we observed that patients with scleral-fixated IOLs had worse contrast sensitivity only under photopic conditions, which may be attributable to poor visual acuity and more ocular aberrations in this group. Additionally, visual acuity may predict contrast sensitivity. Rubin et al. [23] reported a linear regression with a correlation coefficient of −0.56 for the logMAR and contrast sensitivity in patients with cataracts. Another study [24]

demonstrated consistent results, with a significant correlation between the logMAR and contrast sensitivity (*r* = −0.55). Contrast sensitivity was also affected by ocular aberrations in this study. Many studies [25,26] have reported that deteriorated contrast sensitivity is related to increased HOAs in eyes that underwent keratorefractive surgery. For cataract surgery, however, no studies have indicated such results. Our result suggested that an increase in ocular aberrations contributed to the loss of contrast sensitivity in pseudophakic eyes, which has never before been published. Research into contrast sensitivity in patients with scleral-fixated IOLs was scarce. Gao et al. [27] concluded that IOL decentration and a tilt less than 0.5 mm and 5◦, respectively, did not affect postoperative contrast sensitivity under dim light conditions. The results of perceptive dysphotopsia tested in our study also indicated no significant difference between these two groups under mesopic conditions. In the multivariate regression, surgical technique did not significantly affect the extent of subjective glare disability.

Most patients in the scleral-fixation group received Akreos IOLs four-point fixation. Compared with traditional two-point scleral fixation, this technique has a low risk of IOL tilt and decentration. In addition, cystoid macular edema and glaucoma were less commonly observed with four-point fixation [28]. With regard to other complications after suture-fixated IOL procedures, only one suture exposure was noted in our study, which was markedly low compared with a report indicating a 6–27% probability of suture-related complications in transscleral-sutured IOL surgery [5].

Our study had several limitations. First, the sample size of the scleral-fixation group was not large, but the subjective and the objective refraction were both consistent with those of other studies. Second, in this study, we could not evaluate the preoperative visual function because many of our patients were referred from other medical facilities for IOL fixation, and we could not assess the extent of visual improvement following surgery in the scleral fixation group. The causes for inferior CDVA in scleral fixation group could be our fixation method or prior insults, such as trauma or a complication of cataract surgery. This is intrinsic, and it is not possible to differentiate. However, our result showed that with an advanced scleral fixation technique, patients subjectively did not suffer from worse contrast sensitivity than patients with in-bag IOL implantation. Third, several different IOL types were used in our study, providing different spherical aberrations of IOLs, which affected ocular spherical aberrations [2,29–31]. However, the percentage of spherical or aspheric IOLs in these two groups was similar, as were the ocular and the internal spherical aberrations. In our multivariate generalized estimating equation analysis, the IOL type (spherical, aspheric, or toric) had no significant effect on contrast sensitivity. Fourth, the patients in the scleral-fixated group were younger than those in the in-bag group, and age was reported to have a negative effect on contrast sensitivity [32,33]. Our result also demonstrated that patients with older age were associated with worse contrast sensitivity. However, after controlling for the age effect, the surgical technique (in-bag and scleral fixation) did not affect the results of contrast sensitivity. Finally, instead of using commercially available dysphotopsia questionnaires [34], we utilized a newly designed method of evaluating dysphotopsia under simulated nighttime luminance. The strength of our study was the simultaneous investigation of objective contrast sensitivity and subjective glare disability following transscleral-sutured IOLs procedures, both of which provided consistent results.

In summary, our study demonstrated that although the logMAR, spherical equivalent, and higher-order aberrations were greater following scleral fixation, there was no significant difference between scleral-fixated IOLs and in-bag IOL implantation in terms of the visual quality and the contrast sensitivity under mesopic conditions. The age, logMAR, and ocular aberrations had negative effects on contrast sensitivity in patients with pseudophakia under different luminance conditions. It is noteworthy that perceptive dysphotopsia under a dim light was similar between these two groups, which means the patients' satisfaction was comparable, and it is as convincing as the objective measurements when evaluating visual quality. In addition, our study suggested that careful manipulation by a well-experienced

surgeon could provide satisfactory outcomes in patients who received transscleral-sutured IOLs with four-point fixation. However, refinement of suturing techniques in scleral fixation is still required to reduce ocular aberrations and to preserve contrast sensitivity under daylight conditions. Further studies should include a larger sample size, sutureless technique, and matched case-control study design, such as age, sex, and visual outcome, to deepen our understanding of the visual quality of IOL scleral fixation.

**Author Contributions:** Conceptualization, K.-K.L., J.-S.L. and C.-H.H.; Data curation, Y.-L.C., L.L. and C.-H.H.; Formal analysis, Y.-L.C., C.P. and C.-H.H.; Investigation, L.L. and C.-H.H.; Methodology, C.P., L.L. and C.-H.H.; Project administration, Y.-L.C. and C.P.; Resources, K.-K.L., J.-S.L., L.L. and C.-H.H.; Software, C.P.; Supervision, K.-K.L. and J.-S.L.; Validation, K.-K.L. and J.-S.L.; Visualization, Y.-L.C. and C.P.; Writing—original draft, Y.-L.C.; Writing—review & editing, L.L. and C.-H.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** The study adhered to the tenets of the Declaration of Helsinki, and it was approved by the Institutional Review Board of Chang Gung Memorial Hospital, Taoyuan, Taiwan (Approval number: 2101220033).

**Informed Consent Statement:** Written informed consent was waived because of the retrospective nature of the study.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
