Flanged intraocular lens fixation via 27‐gauge trocars using a double‐needle technique decreases surgical wounds without losing its therapeutic effect

Abstract Purpose Intraocular lens (IOL) fixation using a sutureless 27‐gauge needle intrascleral IOL implantation technique requires six surgical wounds. We developed a modified technique using two 27‐gauge trocars for vitrectomy and indwelling flanged IOL haptics to reduce the number of surgical wounds. Setting Department of Ophthalmology, Hyogo College of Medicine. Design This retrospective study enrolled 54 patients who had undergone IOL scleral fixation between January 2016 and April 2019. Methods Patients who underwent IOL scleral fixation and were observed for >12 weeks were analysed using medical record data. Before October 2017, patients underwent normal flanged IOL scleral fixation. Between November 2017 and April 2019, patients underwent the modified method (flanged IOL via 27‐gauge trocars with double‐needle technique). Primary end‐point was superiority or non‐inferiority of modified IOL scleral fixation compared with normal IOL scleral fixation for visual acuity (VA). Changes in corneal endothelium cell number, refractivity, astigmatisms and surgery‐related complications, were secondary end‐points. Results There were no significant differences in baseline characteristics between groups. Raw VA and best collected VA (BCVA) were significantly improved in all eyes (p−). There were no statistical significances in raw VA, BCVA and surgery‐related complications between groups. Conclusions Results of the modified technique were not inferior compared with the original technique although it was less invasive. Therefore, flanged IOL fixation via trocars using a double‐needle technique is a useful technique for IOL implantation.


Introduction
There are many reports of intraocular lens (IOL) fixation in eyes without sufficient capsular support. Representative techniques include anterior chamber IOL, iris-fixed IOL and trans-scleral fixed posterior chamber IOL with or without suture. In 2014, Dr. Yamane and colleagues reported sutureless 27gauge needle guided intrascleral IOL implantation (double-needle technique) (Yamane et al. 2014). Since then, the IOL scleral fixation method has rapidly expanded globally.
To investigate a minimally invasive technique, we modified the flanged IOL scleral fixation with double-needle technique to attempt to decrease the number of surgical wounds to four by using two 27-gauge trocars for vitrectomy and indwelling flanged IOL haptics. We compared our modified technique with the original regarding their effects on visual acuity and surgical complications.

Study design and eligibility
This was a retrospective study of 54 enrolled patients who had undergone IOL scleral fixation between January 2016 and April 2019. The current study was performed in accordance with the Declaration of Helsinki and with approval from the ethics committees of Hyogo College of Medicine (3236).

Patients
Patients who had undergone IOL scleral fixation were analysed using data from medical records (observation period after surgery was greater than 12 weeks for all analysed subjects). Finally, we recruited 60 eyes from 54 patients.

Surgical procedure
All patients had undergone IOL scleral fixation, which was performed by a single surgeon (HI). All patients received full vitrectomy using a 27-gauge system. Before October 2017, normal flanged IOL scleral fixation (Yamane-flanged IOL with 27-gauge double-needle technique: YFD) was performed. Subsequently, a modified method (flanged IOL via 27-gauge trocars with doubleneedle technique: FvTD) was performed between November 2017 and April 2019. The modified technique was performed as follows: (1) 27-gauge trocar setting: two of three trocars set at 2 and 8 o'clock 2 mm behind the corneal limbus, (2) full vitrectomy with or without removing dislocated lens or IOL, (3) IOL scleral fixation via two trocars using a double-needle technique (tip: do not pull the double needle alone, pull double trocars with the needle) and (4) flanged IOL: irrigation length of IOL haptics was 1.5 mm despite 0.7 mm in the YFD group, because the scleral tunnel size formed by the 27-gauge trocar is larger than that formed by a 27-gauge needle, to avoid re-dislocation of the newly inserted IOL during and after surgery ( Fig. 1). Also, the surgery video is available at the online (Video S1). All IOLs were a 7.0 mm 3-piece IOL (NX-70; Santen, Osaka, Japan).

Study protocol
We extracted data from medical records including: age, gender, raw and bestcorrected visual acuity (BCVA) at preoperation, 4 and 12 weeks postoperation, refractivity, lens condition before surgery, reasons for performing IOL scleral fixation (PE, eye trauma, atopic dermatitis, artificial aphakia and trouble during cataract surgery), changes in number of corneal endothelial cells, changes of astigmatism, gaps between preoperative refractive predictability and postoperative spherical equivalent power, and surgery-related complications. Decimal VA was determined using the Landolt chart with consistent conditions: distance = 5 m and chart illuminance was 500-1000 lux. The decimal VA was then converted to log (minimum angle of resolution) (logMAR) VA as follows: logMAR = Àlog (decimal VA). For 'off-chart' VA, such as count fingers (CF), hand motion (HM) and light perception (LP), logMAR values were set at 2.0, 2.3 and 2.6, respectively (Lange et al. 2009).
Patients were followed up for more than 12 weeks after surgery. Ophthalmological examinations were performed at postoperative weeks 4 and 12. Then, we compared changes in raw VA, BCVA, refractivity and number of corneal endothelial cells from baseline to postoperative weeks 4 and 12.

Study end-points
The primary end-point was superiority or non-inferiority of our modified technique compared with the original technique for VA. Changes of the number of corneal endothelium cells in all patients at 12 weeks between the two groups (the YFD and the FvTD), as well as refractivity, astigmatisms and surgery-related complications, were secondary endpoints. We determined the baseline characteristics of all patients.

Statistical analyses
For continuous variables, the mean, standard deviation (SD), standard error (SE), median and range were calculated. For discrete variables, the number of values in each category and the percentages in each category were calculated. The Student's t-test or Wilcoxon signedrank test for continuous variables and Fisher's extract test or the Pearson chisquared test for categorical variables were used to assess group differences. Analyses were performed with JMP Ò Pro (version 14.0.0, SAS Institute Inc., Cary, NC, USA). For all analyses, pvalues were reported as well as two-sided 95% confidence intervals for point estimates. Statistical significance was determined when p-values were <0.05.
Primary end-point: efficacy of current modified intraocular lens scleral fixation for visual acuity The raw VA and BCVA were significantly improved postoperatively in all eyes. Several parameters regarding VA are shown in Table 2. Briefly, there were no differences in pre-and postoperative raw VA, pre-and postoperative BCVA, pre-and postoperative spherical equivalent power and pre-and postoperative astigmatism of keratometry between the two groups.
Secondary end-points: other changes before and after surgery The gap between postoperative spherical equivalent power and refractive predictability (reflective error) in the FvTD group (0.46 AE 0.84 dioptres) showed greater hyperopia compared with the YFD group (À0.12 AE 1.16 dioptres; p = 0.031; Table 2).
Regarding surgery-related complications, two patients with ocular hypotension, six patients with vitreous haemorrhage (VH) and four patients with postoperative cystoid macular oedema (CME) were noted in the YFD group (12/31; 38.7%), despite one patient with ocular hypotension and two patients with VH noted in the FvTD group (3/29; 10.3%). There was no statistical significance between the groups. Patients with ocular hypotension and VH improved within a few days after surgery; however, only one case in the YFD group underwent additional surgery for protracted VH. Patients with CME received a sub-Tenon injection of 5 mg triamcinolone acetonide, which improved their condition.

Discussion
Intraocular lens (IOL) sutureless scleral fixation might be a convenient procedure rather than scleral fixation with suture. However, in the era of minimum invasive surgery, fewer surgical wounds would be preferable. Therefore, we developed a modified technique, flanged IOL-double needle via trocar technique, to decrease operative stress by decreasing the number of required surgical wounds. Several studies previously reported the use of trocars for scleral fixation, but they used retinal forceps to grab the IOL haptics  or suture, and not used double-needle technique (Khan et al. 2016;Wang et al. 2016;Thanos et al. 2017;Walsh 2017;Hu et al. 2018). Raw VA and BCVA were significantly improved postoperatively when using the original and modified technique. For the primary outcome, there were no significantly changes in all parameters regarding the VA between the YFD and FvTD groups at any timepoints. These results suggest that the FvTD technique has similar beneficial effects for VA with fewer surgical wounds when compared with YFD. This suggests our modified technique was not inferior compared with the original technique.
Regarding the secondary outcomes, the reflective error by our modified technique showed greater hyperopia compared with the original technique. Interestingly, we irrigated 1.5 mm of the IOL haptics to form flanges compared with 0.7 mm irrigation in the original technique. This suggests our modified technique might induce myopia compared with the original technique because the depth of IOL using our technique may be closer to the iris more compared with the original. However, the results suggested the opposite outcome, indicating that the scleral tunnel length made by the trocars was shorter than in the original technique, with a greater IOL depth.
Changes in the mean number of corneal endothelial cells were À14.3 AE 18.7% in all eyes, and there were no significant differences changes between the two groups. Regarding surgery-related complications, only three eyes (10.3%) had VH and ocular hypotension when using our modified technique; however, 12 eyes (38.7%) had several complications. There were no significant differences in the incidence of these complications, supporting the idea that the technical invasion by our modified technique was not inferior compared with the original technique. In a previous report, 22% of eyes had VH, similar to the incidence of technique related complications in our study (Todorich et al. 2018).
There were several limitations in our study. First, the surgeon 'HI' performed over 100 cases of IOL scleral fixation using the old Yamane technique (double needle without flange IOL), then the original technique and finally our modified technique. Therefore, HI's surgical skill might have increased when performing our modified technique. Furthermore, the decrease in surgery-related complications might be due to the surgeon's technical improvement. Second, we performed the original technique using a 27-gauge needle before October 2017, despite Dr. Yamane using 31-gauge needle in 2017. When we use the original technique using a 31-gauge needle, the surgery-related complications might be decreased. Thus, the present study did not entirely reflect the comparison between the newest Yamane technique and our modified technique.
An advantage of our modified technique is decreasing surgical wounds.
Our results showed that PE was the most common reason for performing IOL fixation, suggesting that patients who received IOL fixation might also undergo glaucoma surgery in the future. Therefore, decreasing surgical wounds is very important for maintaining intact conjunctiva for further potential glaucoma surgery.

Conclusions
Although many retinal surgeons have investigated several methods for IOL fixation, the flanged IOL-double-needle technique seems to have provided the best results for IOL fixation. Our modified technique was not inferior compared with the original technique of Dr. Yamane; however, the number of required wounds was reduced and therefore flanged IOL fixation via trocars using a double-needle technique should be useful for retinal surgeons.