The current study evaluated the visual and refractive outcomes after SFPCIOL implantation with PPV. Despite the high frequency of ocular comorbidities, as well as concurrent surgical procedures in our cohort, the results demonstrated minimal side effects, an improvement of vision, and achievement of refractive goals in the post-operative period.
AK IOL provides a stable four-point fixation with resilient suture material (Gore-Tex), has made this procedure increasingly popular for scleral fixated IOLs. The four-point suture fixation is less prone to tilt, and Gore-tex suture has greater tensile strength and long-term durability than prolene, which reports up to 27.9% suture erosion in adults at a mean follow-up of 6 years9, 16, 17. It is, however, associated with increased surgical time due to greater technical complexity and reported sporadic cases of lens opacification18–20. In contrast, sutureless IOL implantation inherently avoids suture-associated complications, such as suture degradation and IOL dislocation, and shortens surgical time. Results of a two-point sutureless flanged intrascleral fixation technique reported by Yamane demonstrated good visual and refractive outcomes with a stable IOL location after a maximum follow up of 36 months.
Flanged IOL fixation with a double-needle technique presented by Yamane with four different lenses positioned 2 mm behind the limbus (n = 97) notably reported no IOL dislocation or haptic related scleral fixation issues after over three years of follow up6. The most common postoperative complication reported by the referenced study6 was iris and vitreous capture in 8% and 5% of the patients, respectively, which can possibly be avoided by placing the lens farther from the limbus. In this study, the lens was positioned 2.5 mm behind the limbus, and no postoperative hemorrhage cases were reported. Our study demonstrated favorable outcomes for combined PPV with two different secondary IOL implantation techniques: four-point Gore-tex suture fixated IOL positioned 3.0 mm behind the limbus, and 2-point sutureless IOL positioned 2.5 mm behind the limbus.
Significant improvements in visual outcomes (p < 0.05), despite multiple comorbidities, were shown for both lenses. Patient groups for the two lenses had similar baseline VA. However, the mean final BCVA was better for the CTL group, which is most likely due to lesser prevalence of comorbidities. For secondary IOL AK implantation21 22 11 and flanged IOL fixation23, similar visual and refractive outcomes were reported taking into consideration common ocular history of patients which included RD repair, glaucoma, trauma with and without globe rupture, complicated cataract surgery8 24. The likelihood of certain postoperative complications may be linked to specific surgical procedures, and the degree of improvement in visual outcomes may be linked to the patient’s ocular history24. The majority of the patients had one or more ocular comorbidities (75%) and underwent concurrent surgical procedure (22%), which is more than reported in other studies15, 22 and some had longer surgical times for cases involving combined corneal and glaucoma surgeries. Despite that, our patients experienced relatively fewer complications in the postsurgical period.
Preoperative refractive goals were achieved by the majority of patients in our study. Similar refractive outcomes have been reported by others implanting SFPCIOL, with variable refractive outcomes: more myopic outcomes reported by Terveen21 and Fass25, and slightly hyperopic outcomes reported by Yang and Abbey despite the SFPCIOL being positioned 1.5 mm and 2mm behind the limbus respectively26. A study by Brunin et al. found that SFPCIOL had the most myopic refractive outcomes when compared to the combination of iris, anterior chamber and sulcus fixated IOLs11.
The most common complication in this study was ocular hypotension in 4 eyes (2 patients in AK group, 2 patients in CTL group). Three out of four patients in whom it was detected had a previous history of ocular surgery, underwent a concurrent DSAEK procedure, and had a history of glaucoma. Hypotension did not extend beyond the post-operative week 1. While the source of this finding is not clear, incompetence of the self-sealing sclerotomies may be the cause. During the study period, a change in the surgical technique for the sclerotomies was created from radial sclerotomies to limbus-parallel incisions. This change appeared to reduce the incidence of postoperative hypotony.
One of the concerns implanting any hydroxyethyl methacrylate (HEMA) IOLs such as AK is opacification. Unlike foldable silicone lens opacification occurring intraoperatively, HEMA lens opacification can occur late in the postoperative period27. Although quite rarely observed, opacification can occur at any time as early as 2 months and as late as 24 months post-operatively18, 28. Opacification is reported to be caused by crystalline deposits and is associated with any exposure to air such as gas tamponade or combined surgery with DSAEK and Descemet's membrane endothelial keratoplasty (DMEK)29. In this study, there were no cases with AK opacification, despite several patients undergoing concomitant Akreos fixation and DSAEK with gas tamponade with the longest follow up of over 4 years.
Both PFTE sutured and flanged haptic sutureless methods carry a risk of suture erosion. In our study, haptic extrusion in sutureless flanged haptic IOL fixation occurred in two patients. Usage of appropriate haptic material to create a proper flange shape and size is critical. In a technique described by Yamane, the haptics are made of polyvinylidene fluoride (PVDF), although some IOLs used in the study have restricted commercial availability in the United States. CTL’s use same PVDF material, which has a melting temperature around 177°C. Less heat resistant materials, such as PMMA (melting temperature around 110°C), are not able to consistently provide appropriate haptics30, increasing lens susceptibility to dislocation as reported by Stem using 3-piece (Alcon) IOLs with PMMA haptics.
Several limitations of this study can be noted. The retrospective design restricted patient selection to those only with existing visual and refractive data. Inconsistent follow-up and small group sizes decreased the power of analysis and statistical significance. It is worth noting that we can only report our experience with two techniques but not compare them to each other. Too many variables, such as comorbidities and previous surgical history, unavoidably made the outcomes difficult to reliably compare. In certain patients, severe late stages of the comorbidities such as glaucoma prohibited the evaluation of visual outcomes related to the refractive surgery. It is also much more difficult to predict the refractive outcomes due to comorbidities. Despite the differences in the lens implantation technique, however, surgical procedure from the same ophthalmic center allows to account for intangible differences between the two.
Our report demonstrated good visual and refractive outcomes, as well as minimal side effects occurring in the post-operative period, despite patients having multiple ocular comorbidities and concurrent surgeries. Although there are differences in surgical technique and specifications, surgical techniques discussed provide good visual and clinical outcomes and are equally well tolerated by patients with multiple comorbidities. Careful selection of surgical technique and concurrent surgery planning can lead to excellent visual and refractive outcomes accompanied by a low incidence of postoperative complications.