A Biomechanical Study of Flanged Intrascleral Haptic Fixation of Three-Piece Intraocular Lenses

Potential role of the light-adjustable lens in flanged intrascleral haptic fixation

PURPOSE

To compare maximum tensile strength between commonly used 3-piece intraocular lens (IOL) for flanged intrascleral haptic fixation (FISHF).

SETTING

Willis-Knight Eye Institute, Shreveport, Louisiana.

DESIGN

Laboratory investigation.

METHODS

Haptic tensile strength was compared with MA60AC, CT Lucia 602, AR40E, and the light-adjustable lens (LAL). Haptic strength with a 24-diopter (D) IOL was compared across all lenses, as well as across a range of 10 to 30 D with the MA60AC. A custom device was created to hold the IOL in correct haptic orientation. The maximum tension (mean ± SD) was recorded in Newtons (N) when the haptic lost tension or broke.

RESULTS

CT Lucia was the strongest at 1.53 ± 0.11 N vs 1.00 ± 0.15 (MA60AC), 0.87 ± 0.19 (AR40E), and 0.83 ± 0.14 N (LAL) ( P < .001). The LAL and AR40E were similar to a 9-0 polypropylene suture while being significantly stronger than 10-0 polypropylene suture ( P < .001). No difference in haptic tension for the MA60AC from 10 to 30 D ( P > .05). High magnification revealed the highest haptic fractures for MA60AC at 40% compared with LAL, AR40E, and CT Lucia at 0%. CT Lucia and AR40E had 100% of haptics disinserted from the IOL without any damage compared with 60% LAL and 60% MA60AC. CT Lucia, AR40E, and LAL have a flatter haptic angulation at 5 degrees.

CONCLUSIONS

Haptic strength, durability, and angulation of the LAL may support the possibility of FISHF in the hands of experienced surgeons. However, further testing is strongly recommended to verify whether physiologic conditions or light treatments may compromise long-term haptic stability.

Severe Spontaneous Tilt of Scleral-Fixated Intraocular Lenses

PURPOSE

To report and evaluate a multicenter series of 18 cases of severe, spontaneous IOL tilt involving the flanged intrascleral haptic fixation technique (FISHF).

DESIGN

Clinical study with historical controls.

METHODS

We report a cross-sectional study of 46 FISHF cases using the CT Lucia 602 IOL at a single academic center over a period of 24 weeks to determine the incidence of severe rotisserie-style rotational tilt. These rates were then compared with the same time-frame the prior year to help determine if this is a new phenomenon. Additional cases of severe tilt were solicited from another 4 academic centers.

RESULTS

Among 46 FISHF cases at a single center, 5 developed severe tilt. No clear pattern in surgical technique, ocular history, or ocular anatomy was evident in these cases compared with controls, although the involved IOLs clustered within a narrow diopter range, indicative of a batch effect. In the same 24-week interval the year before, 33 FISHF cases were performed, none of which exhibited severe rotational tilt. In our multicenter dataset, 18 cases of tilt were identified. Surgeons included fellow and early-career physicians as well as surgeons with multiple years of experience with the Yamane technique. A variety of surgical approaches for FISHF were represented. In at least 8 of the cases, haptic rotation and/or dehiscence at the optic-haptic junction were documented.

CONCLUSIONS

The identification of haptic rotation and dehiscence intraoperatively in several cases may reflect a new stability issue involving the optic-haptic junction.

Haptic curing with endolaser after lens tilt in the Yamane technique

Purpose

To describe a case of intraocular lens (IOL) tilt following transscleral IOL fixation with the Yamane technique and subsequent correction of tilt using 810-nm endoscopic diode laser.

Observations

Our patient required lens exchange and secondary IOL implantation due to a dislocated 1-piece IOL in the bag causing iris chafe. After routine IOL fixation with the Yamane technique and a Zeiss CT Lucia 602 lens, the IOL tilted significantly in the immediate postoperative period. The lens tilt was subsequently corrected in the operating room using endolaser to melt and reshape (cure) the optic-haptic junction.

Conclusions

IOL tilt is a known complication associated with the Yamane technique, which has seen increasing reports with the Zeiss CT Lucia 602 lens. Using endolaser to reconfigure the tilted optic into the desired orientation is a more novel procedure that can correct the lens tilt without the need for IOL exchange.

Flange depth for scleral pocket vs no pocket techniques for intrascleral intraocular lens fixation

PURPOSE

To compare flange depth for a modified scleral pocket (SP) vs no scleral pocket (NSP) technique (Yamane technique) for intrascleral intraocular lens (IOL) fixation.

SETTING

Instituto de Oftalmología Santa Fe, Santa Fe, Argentina.

DESIGN

Prospective, randomized, single-surgeon, observational study.

METHODS

Eyes with aphakia and no capsular support were included. They were divided into 2 groups: one was programmed for a double-needle flanged intrascleral IOL fixation as originally described by Shin Yamane with NSP and the second group had a modified SP technique. Flange depth was measured with anterior-segment optical coherence tomography (AS-OCT) at 1 month, 3 months, 6 months, and 12 months postoperatively, and the results were compared.

RESULTS

Each group comprised 18 eyes of 18 patients, giving a total of 36 flanges per group. The groups were comparable preoperatively. At 12 months, uncorrected distance visual acuity and corrected distance visual acuity (CDVA) were not statistically different for both groups (P = .333; P = .448). Spherical equivalent (SEQ) was not significantly different between groups at 12 months postoperatively (P = .078). AS-OCT revealed a significantly deeper flange position for the SP group at 1 month, 3 months, 6 months, and 12 months postoperatively (P < .05).

CONCLUSIONS

When performing a double-needle intrascleral IOL fixation in aphakic eyes with no capsular support, a modified scleral pocket technique provides a significantly deeper flange position with no difference in CDVA or SEQ 12 months postoperatively.

Dislocation force of scleral flange-fixated intraocular lens haptics

PURPOSE

To measure the dislocation forces in relation to haptic material, flange size and needle used.

SETTING

Hanusch Hospital, Vienna, Austria.

DESIGN

Laboratory Investigation.

METHODS, MAIN OUTCOME MEASURES

30 G (gauge) thin wall and 27 G standard needles were used for a 2 mm tangential scleral tunnel in combination with different PVDF (polyvinylidene fluoride) and PMMA (polymethylmethacrylate haptics). Flanges were created by heating 1 mm of the haptic end, non-forceps assisted in PVDF and forceps assisted in PMMA haptics. The dislocation force was measured in non-preserved cadaver sclera using a tensiometer device.

RESULTS

PVDF flanges achieved were of a mushroom-like shape and PMMA flanges were of a conic shape. For 30 G needle tunnels the dislocation forces for PVDF and PMMA haptic flanges were 1.58 ± 0.68 N (n = 10) and 0.70 ± 0.14 N (n = 9) (p = 0.003) respectively. For 27 G needle tunnels the dislocation forces for PVDF and PMMA haptic flanges were 0.31 ± 0.35 N (n = 3) and 0.0 N (n = 4), respectively. The flange size correlated with the occurring dislocation force in experiments with 30 G needle tunnels (r = 0.92), when flanges were bigger than 384 micrometres.

CONCLUSIONS

The highest dislocation forces were found for PVDF haptic flanges and their characteristic mushroom-like shape for 30 G thin wall needle scleral tunnels. Forceps assisted flange creation in PMMA haptics did not compensate the disadvantage of PMMA haptics with their characteristic conic shape flange.

Scleral Fixated Secondary IOLs: An Outcomes Comparison Between the Yamane and Gore-Tex-Sutured Techniques

BACKGROUND AND OBJECTIVE

Among secondary intraocular lens (IOL) techniques, scleral fixated IOLs (SFIOLs) offer advantages in cases without capsular support. In this article, we compare outcomes between two types of Gore-Tex scleral sutured IOLs with the Yamane technique.

PATIENTS AND METHODS

This study was a retrospective chart review of patients who underwent SFIOL implantation.

RESULTS

Analysis revealed a statistically significant improvement in final postoperative visual acuity (VA) for sutured SFIOLs (P < 0.001, Envista (n = 29) 95% CI 0.47-1.04, Akreos (n = 23) 95% CI 0.32-0.81) with no statistical improvement in the Yamane group (P = 0.44, n = 15, 95% CI -0.33-0.71). Outcomes analysis revealed greater incidences of cystoid macular edema (CME) in the Yamane cohort (P < 0.05) and a higher rate of reoperations in the Akreos cohort (P < 0.02). All complications related to suture material (n = 4) and IOL decentration (n = 2) occurred in the sutured SFIOL group.

CONCLUSIONS

The sutureless Yamane technique offered fewer subsequent surgeries and suture-specific complications while revealing diminished VA improvement in long-term follow-up compared to the sutured SFIOLs. [Ophthalmic Surg Lasers Imaging Retina 2024;55:xx-xx.].

CONTRIBUTION FACTORS OF EFFECTIVE LENS POSITION, TILT, AND DECENTRATION DURING FLANGED SCLERAL FIXATION OF INTRAOCULAR LENS: A Model Eye Study

PURPOSE

The authors aimed to elucidate the factors related to effective lens position, tilt, and decentration of scleral fixed intraocular lenses (IOLs) with a flanged haptic technique in an artificial eye model using anterior segment optical coherence tomography.

METHODS

Two bent 27-gauge needles were passed through a 1.0- or 2.0-mm scleral tunnel, 2.0 mm posterior to the limbus and 180° apart. Both haptics of a three-piece IOL were docked with guide needles and externalized. Factors related to the IOL position were analyzed using anterior segment optical coherence tomography and a stereomicroscope.

RESULTS

The 1.0-mm scleral tunnel induced a significantly longer effective lens position than the 2.0-mm tunnel and suture fixation ( P < 0.05 and P < 0.01, respectively). Discrepancy in scleral tunnel length induced higher decentration of the optic to the opposite side of the haptic-embedded shorter tunnel and tilt perpendicular to the fixed axis than that in the scleral tunnel of the same length ( P < 0.001 and P < 0.05, respectively). If the scleral fixation points of both haptics are not exactly 180° apart, the IOL may become decentered and tilted ( P < 0.01 and P < 0.05, respectively).

CONCLUSION

In the flanged haptic technique, the length, balance, and position of both scleral tunnels determine IOL effective lens position, tilt, and decentration.

Light adjustable intraocular lenses in cataract surgery: considerations

PURPOSE OF REVIEW

Light adjustable intraocular lens (LAL) is a promising concept in cataract surgery. This review explores considerations for the use of LALs.

RECENT FINDINGS

Through updates, the safety of LALs and light delivery devices have been enhanced, enabling more efficient treatment with lower ultraviolet (UV) energy. Preoperative topography and aberration are essential for understanding indications for LALs. Furthermore, when determining intraocular lens power, it is crucial to factor in potential postoperative myopia or hyperopic adjustments. This is achieved by establishing a proper postimplantation refractive target and considering potential wavefront changes. Postoperative adjustments for defocus and astigmatism have demonstrated excellent outcomes. Monovision strategy by adjustable blended vision of LALs revealed distance vision of 20/20 along with near vision of J2 in 96% of patients. However, the results of clinical studies on postrefractive cataract surgery showed contrasting outcomes at distance, indicating the need for further research results regarding its effectiveness. A new postoperative workflow needs to be designed to enable a systematic follow-up process.

SUMMARY

LALs are safe and demonstrate promising refractive outcomes. To achieve appropriate results, understanding the changes in optical characteristics associated with adjustment and constructing a new postoperative workflow are necessary.

Intraocular lens tilt due to optic-haptic junction distortion following intrascleral haptic fixation with the Yamane technique

Purpose

To report two patients with a complication of Yamane intrascleral haptic fixation surgery (ISHF) with the Zeiss CT Lucia 602 lens: severely tilted intraocular lens (IOL) leading to significantly decreased vision in the early post-operative period.

Observations

We report two patients presenting with severely tilted IOL implants one day and one month following Yamane ISHF. The first patient is a monocular 81-year-old woman referred for treatment of cornea edema. Initial surgery involved replacement of an anterior chamber lens with a CT Lucia 602 posterior chamber lens using Yamane technique and Descemet's stripping endothelial keratoplasty. The patient returned at one month follow-up with poor vision and IOL tilt observable at the slit lamp through a peripheral iridectomy site. Explanation of the Zeiss lens revealed haptic distortion at the optic-haptic insertion point such that each haptic was about 45° off axis to the plane of the optic in approximately equal and opposite directions. The second patient, a 75-year-old woman, was referred with a completely dislocated lens-bag complex in the right eye. The initial operative treatment for this patient included pars plana vitrectomy, retrieval and removal of the dislocated lens-bag complex, and placement of a Zeiss 602 lens via Yamane ISHF technique. On the first postoperative day, the patient was count fingers in the right eye with an intraocular pressure of 5 mm Hg and obvious IOL tilt on slit lamp examination. Explanation of the lens revealed severely distorted haptics relative to the optic by more than a 60-degree angle on both sides. In both cases, initial surgery was performed with an IOL inspected prior to implantation and found to have normal appearing haptics. At the end of each case, there was adequate centration and no tilt of the IOL. Management in both patients included removal of the defective lens and placement of a new, same power CT Lucia 602 lens via the Yamane technique. Visual acuity improved from CF to 20/30 best corrected after reoperation in both cases.

Conclusions and importance

In summary, we describe a complication of Yamane ISHF with the CT Lucia 602 lens in which there is lens tilting associated with distortion at the optic-haptic fastening zone in the early postoperative period. In the event of a titled lens following Yamane ISHF, awareness of this complication may help surgeons consider lens replacement, as the haptics may be permanently distorted or damaged.

Long-term outcomes of modified glued versus flanged intrascleral haptic fixation techniques for secondary intraocular lenses

PURPOSE

To report the long-term refractive outcomes and complications of two scleral fixation techniques for secondary intraocular lenses (IOL).

METHODS

Consecutive patients who underwent secondary IOL insertion at a tertiary care academic hospital using either modified glued ("glued") or flanged intrascleral haptic fixation (FISHF) techniques with over 12 months of follow-up were retrospectively reviewed. Pre- and postoperative corrected distance visual acuity (CDVA), postoperative complications, and refractive surprises were reported.

RESULTS

Thirty-eight patients underwent "glued" fixation and 22 underwent FISHF, with mean follow-up times of 3.1 ± 0.5 and 2.0 ± 1.2 years, respectively. Aphakia secondary to trauma was the main surgical indication. MA50BM or MA60AC IOLs (Alcon Laboratories Inc., Fort Worth, TX) were implanted in 92% of "glued" patients, while CT Lucia 602 IOLs (Carl Zeiss Meditec Inc., Dublin, CA) were used in 96% of FISHF patients. Postoperative spherical equivalent significantly improved compared to preoperative values (p < 0.001). No significant difference in CDVA was seen between the two techniques. FISHF resulted in mean hyperopic surprises of + 0.81D and + 0.69D using the Holladay 2 and Barrett Universal II formulae, respectively, which was significantly greater than the "glued" patients. A higher rate of IOL dislocation was seen in the "glued" cohort (13%) compared to FISHF (0%).

CONCLUSIONS

Retrospective long-term outcomes of patients with complex ocular comorbidities undergoing a modified "glued" technique demonstrated a higher rate of IOL dislocation but more predictable refractive outcomes compared to the FISHF technique. The FISHF technique resulted in a significant hyperopic shift using fourth-generation IOL calculators.

Photo-cross-linked Gelatin Glycidyl Methacrylate/N-Vinylpyrrolidone Copolymeric Hydrogel with Tunable Mechanical Properties for Ocular Tissue Engineering Applications

Corneal transplantation is currently the primary treatment for corneal blindness. However, severe global scarcity of donor corneas is driving the scientific community to find novel solutions. One potential solution is to replace the damaged tissue with a biocompatible artificial cornea. Here, gelatin glycidyl methacrylate (GM) and N-vinylpyrrolidone (VP) were cocrosslinked to afford a hybrid bicomponent copolymeric hydrogel with excellent mechanical, structural, and biological properties. Our studies showed that the GM/VP ratio can be adjusted to generate a construct with high tensile modulus and strength of 1.6 and 1.0 MPa, respectively, compared to 14 and 7.5 MPa for human cornea. The construct can tolerate up to 22.4 kPa pressure before retention sutures can tear through it. Due to the presence of a synthetic component, it has a significantly higher stability against collagenase induced degradation, yet it is biocompatible and promotes cellular adhesion, proliferation, and migration under in vitro settings.

Biomechanical Testing of Flanged Polypropylene Sutures in Scleral Fixation

OBJECTIVE

To optimize the flanged belt-loop technique of scleral fixation through biomechanical testing and report clinical outcomes of resultant modifications.

DESIGN

Experimental study.

METHODS

The force to disinsert flanged polypropylene suture from human cadaveric sclera was assessed using a tensile testing machine and compared to the breaking strengths of 9-0 and 10-0 polypropylene. The effects of modifying suture gauge (5-0, 6-0, 7-0, or 8-0), amount of suture cauterized (0.5 or 1.0 mm), and sclerotomy size (27, 30, 32, 33 gauge) were investigated. Belt-loop intrascleral fixation using 6-0 and 7-0 polypropylene with 30 and 32 gauge needles, respectively, was performed in 4 patients. Main outcome measures were flanged suture disinsertion forces in cadaveric sclera.

RESULTS

The average force to disinsert a flange created by melting 1.0 mm of 5-0, 6-0, 7-0, and 8-0 polypropylene suture from human cadaveric sclera via 27, 30, 32, and 33 gauge needle sclerotomies was 3.0 ± 0.5 N, 2.1 ± 0.3 N, 0.9 ± 0.2 N, and 0.4 ± 0.1 N, respectively. The disinsertion forces for flanges formed by melting 0.5 mm of the same gauges were 72%-79% lower (P < .001). In comparison, the breaking strengths of 9-0 and 10-0 polypropylene were 0.91 ± 0.4 N and 0.52 ± 0.03 N. Belt-loop fixation using 6-0 and 7-0 polypropylene with 30 and 32 gauge sclerotomies demonstrated good outcomes at 6 months.

CONCLUSIONS

The flanged belt-loop technique is a biomechanically sound method of scleral fixation using 1.0 mm flanges of 5-0 to 7-0 polypropylene paired with 27, 30, and 32 gauge sclerotomies. In contrast, 8-0 polypropylene and 0.5 mm flanges of any suture gauge will likely be unstable with this technique.