*2.1. Patients*

This retrospective study comprised patients who underwent standard cataract surgery or transscleral fixation of the IOL. Inclusion criteria were as follows: patients with pseudophakia with in-bag or scleral-fixated IOLs, 20 years or older, no complications during IOL implantation, no ocular disorders such as severe non-proliferative diabetic retinopathy (NPDR) or PDR, corneal opacities or epithelial defects, severe macular degeneration or dystrophy, optic atrophy, amblyopia in the operated eye, or posterior capsule opacification after cataract surgery that could degrade visual quality. Indications for scleral fixation included aphakia and subluxation or dislocation of the crystalline lens or IOL. Only monofocal IOL implantation was studied because multifocal IOLs would have introduced a confounding effect with respect to dysphotopsia. We recruited patients between September 2019 and March 2020. Patients who could not undergo examination as a result of dementia or mental disorders were not included. All eyes had a minimum postoperative time of 1 month when the inflammation subsided without postoperative steroid use, corneal edema, or anterior chamber reaction, to ensure the wound and visual acuity were stable. We excluded patients with postoperative corrected distance visual acuity (CDVA) of more than 0.5 logarithm of the minimum angle of resolution (logMAR) because they could lose contrast sensitivity [12]. 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). Written informed consent was waived because of the retrospective nature of the study.

#### *2.2. Postoperative Ophthalmic Examinations*

The CDVA was measured, and slit-lamp biomicroscopy, contrast sensitivity testing, pneumatic tonometry, indirect ophthalmoscopy, and aberrometry were performed. The postoperative CDVA was converted to logMAR values and compared between the scleralfixation group and the in-bag group.

#### *2.3. Contrast Sensitivity Test*

Contrast sensitivity was evaluated with best refractive correction without pupil dilation using a CGT-2000 contrast glaretester (Takagi Seiko, Takaoka, Japan). Contrast sensitivity testing was performed under daytime (100 cd/m2), twilight (10 cd/m2), and nighttime (5 cd/m2) luminance conditions with and without glare at a test distance of 5 m. The area under the log contrast sensitivity function (AULCSF) was calculated for statistical analysis [13].

Postoperative perceptive dysphotopsia was assessed using a questionnaire, with a point given for each category. Subjective photic phenomena, including glare, halo, starburst, and coma, were evaluated with a penlight held 1 m in front of the tested eye under mesopic conditions at the outpatient department. Symptoms were rated as 0 = none, 1 = mild, 2 = moderate, or 3 = severe. Additionally, this questionnaire was filled out by the nurse.

Higher mean scores indicated less satisfactory results. The mean score for each category was calculated and tested for significance.

#### *2.4. Optical Aberrations*

Wavefront measurements were postoperatively obtained using a refractive power and corneal analyzer (OPD-Scan III, NIDEK, Tokyo, Japan). This device used the fundamental principle of automatic retinoscopy, and it provided integrated corneal topography and wavefront measurement. The retina was scanned with a slit-shaped light beam, and the reflected light was captured by an array of rotating photodetectors over a 360◦ area. The aberrometer offered an aberration profile of the whole eye, and the root mean square values for aberrations, HOAs, tilt, coma, spherical aberrations, trefoil, and astigmatism were measured for statistical analysis. Wavefront maps were analyzed with a 3-mm pupil diameter up to the fourth-order Zernike coefficients. The pupil sizes were also measured by this wavefront aberrometer under mesopic condition.

#### *2.5. Surgical Technique*

Mydriasis was achieved preoperatively with 1% tropicamide eyedrops and 10% phenylephrine eyedrops. Sutured scleral fixation was performed by an experienced surgeon (LL), and phacoemulsification and in-bag IOL implantation were done by another (CHH). Scleral fixation was conducted using the four-point fixation technique described by Khan et al. [14], with some modifications. A 2.65-mm transparent corneal incision was made after retrobulbar anesthesia, and the IOL was loaded in the injector and injected into the anterior chamber. The two haptics were looped with a 10-0 polypropylene suture intraocularly at the nasal sclera 2 mm posterior to the limbus. The same step was repeated on the temporal side. Additional procedures such as vitrectomy and IOL exchange may have been performed at the time of scleral fixation. The standard phacoemulsification surgery was performed using the following procedures under topical anesthesia: clear corneal incision of 2.65 mm, continuous curvilinear capsulorrhexis with an approximate diameter of 5.0 mm, hydrodissection, phacoemulsification, irrigation and aspiration, and in-bag IOL implantation using an injector.

#### *2.6. Statistical Analysis*

All statistical analyses were performed using Stata, version 15 (StataCorp, College Station, TX, USA). Independent *t* tests were employed to compare the visual quality between the two groups. Generalized estimate equation method (GEE) was performed to identify factors affecting contrast sensitivity, which was set as the dependent variable (AULCSF). The following parameters were included as explanatory variables: age, sex, pupil size, surgical technique (scleral fixation or in-bag IOL implantation), IOL type (spherical, aspheric, or toric), logMAR, and ocular aberrations. Another GEE was conducted to determine the factors affecting subjective dysphotopsia (glare, halo, starburst, and coma), with the same aforementioned explanatory variables. A *p* value of less than 0.05 was considered statistically significant.
