Implantable Polypropylene Capsular Hook(s) for Managing Subluxated Lenses: A Prospective Study

Highlights

•
First prospective study of implantable polypropylene capsular hooks.
•
In-the-bag IOL implantation for subluxated lenses.
•
Postoperative stable IOL position with acceptable IOL decentration and tilt.
•
Efficacy in visual rehabilitation.
•
Procedural safety with acceptable complication rates.

Purpose

To report the clinical outcomes of intrascleral fixation of implantable capsular hooks for managing subluxated lenses.

Design

Prospective, noncomparative, interventional case series.

Methods

Patients with subluxated lenses who underwent in-the-bag intraocular lens (IOL) implantation assisted by capsular tension ring and implantable capsular hook(s) made of 7-0 polypropylene sutures were included. The main postoperative outcome measure was IOL position, including IOL decentration, tilt, postoperative anterior chamber depth, and the distance between IOL and iris. Secondary postoperative outcomes included best-corrected visual acuity, spherical equivalent, corneal endothelial cell density, intraocular pressure, and complications.

Results

Seventy-four eyes of 74 patients were enrolled, with a mean follow-up of 13.2 ± 8.9 months (range: 6-36 months). The IOL position remained stable throughout the follow-up period, with a mean IOL decentration of 0.31 ± 0.24 mm and a mean tilt of 1.83 ± 1.35° at the final follow-up visit. Both postoperative anterior chamber depth and the distance between IOL and iris remained stable, with values of 3.91 ± 0.33 mm and 0.65 ± 0.26 mm at the final follow-up visit, respectively. The mean best-corrected visual acuity improved from 0.75 ± 0.73 logarithm of the minimum angle of resolution (Snellen 20/112) preoperatively to 0.24 ± 0.28 logarithm of the minimum angle of resolution (Snellen 20/35) at the final follow-up visit ( P <.05). The mean spherical equivalent was −2.37 ± 4.68 D preoperatively and −1.09 ± 1.33 D at the final follow-up visit ( P <.05). The mean endothelial cell density decreased from 2577.64 ± 486.10 cells/mm ² preoperatively to 2171.31 ± 707.23 cells/mm ² at the final follow-up visit with a mean loss of 14.70 ± 14.60% ( P <.05). The intraoperative complication was transient mild bleeding during penetration of the scleral wall ( n = 4, 5.4%). Postoperative complications included intraocular pressure elevation ( n = 9, 12.2%), hypotony ( n = 2, 2.7%), grade 2 anterior chamber cells ( n = 2, 2.7%), retinal detachment ( n = 1, 1.4%), cystoid macular edema ( n = 1, 1.4%), and posterior capsule opacification ( n = 1, 1.4%).

Conclusions

Intrascleral fixation of implantable capsular hooks enables in-the-bag IOL implantation in eyes with subluxated lenses and represents a feasible, stable, and safe approach.

INTRODUCTION

Z onular dialysis can lead to subluxated lenses, potentially impairing vision. Several surgical strategies have been described, ranging from lens extraction with intraocular lens (IOL) fixation (via intrascleral, transscleral, or iris fixation) to capsular bag preservation techniques that enable in-the-bag IOL implantation using endocapsular support devices anchored to the scleral wall. ^,^,^,^,^,^,^,^, Whenever feasible, preserving the capsular bag for in-the-bag IOL implantation is preferable, as it maintains vitreous integrity, minimizes chafing between the IOL and uvea, and provides more predictable, stable and physiologic IOL position. Currently, several devices are used for preservation of the capsular bag for subluxated lenses, including the modified capsular tension ring (MCTR), capsular tension segment, and the capsular anchor. ^,^, A common feature of these devices is the requirement for suture fixation to the scleral wall, which has limitations, including increased surgical time, conjunctival dissection and scleral manipulations (flap, pocket, or groove), and the potential for long-term suture-related complications.

We have previously developed a sutureless technique in which a polypropylene suture is thermoplastically fashioned into an implantable capsular hook, followed by intrascleral fixation to stabilize the capsular bag for in-the-bag IOL implantation. ^, This approach builds upon the well-established safety profile of polypropylene, demonstrating excellent intraocular biocompatibility. Besides, the application of thermoplastic polypropylene sutures or IOL haptics with thermocautery devices has been successfully applied in iridodialysis repair and IOL fixation. ^, Moreover, intrascleral fixation avoids conjunctival and scleral dissections, reduces surgical trauma, and simplifies intraocular manipulation by eliminating suturing and knotting maneuvers. The technique has been adopted by various publications to stabilize the capsular bag in various situations. ^,^,^, However, to our knowledge, no prospective study has been published to evaluate the feasibility, stability, and safety of the technique. We designed a prospective study aimed to evaluate the safety and efficacy of the technique in the management of subluxated lenses.

METHODS

study design and patients

This prospective study was approved by the Ethics Committee of Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China, and adhered to the Declaration of Helsinki (Approval No. 2022YS-221). All patients were fully informed of the study protocol, potential benefits, and risks. Written informed consents were obtained before surgery. The inclusion criteria were patients aged ≥18 years with subluxated lenses dislocated more than 4 clock hours. The exclusion criteria were preoperative intraocular pressure (IOP) >21 mm Hg; history of corneal diseases; corneal endothelial cell density (ECD) less than 1200 cells/mm²; macular diseases; concomitant vitreoretinal diseases requiring treatment, including vitreous hemorrhage, proliferative diabetic retinopathy, or retinal detachment (RD); and postoperative follow-up for less than 6 months. Follow-up visits were conducted at 1 day, 1 week, 1 month, 3 months, 6 months, and annually thereafter.

preoperative examinations

Comprehensive ophthalmologic examinations were conducted including uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), spherical equivalent (SE), IOP, slit-lamp examination, ECD (EM-3000; TOMEY CORP), Scheimpflug images of the anterior segment (Pentacam; Oculus), ultrawide-field color fundus imaging (Daytona; Optos), and optical coherence tomography (OCT, Cirrus HD-5000; Carl Zeiss AG). Axial length (AL) and preoperative anterior chamber depth (ACD) were measured by partial coherence interferometry (IOLMaster; Carl Zeiss AG). The extent of subluxated lenses was assessed by slit-lamp microscope. The grading of subluxated lenses is defined by the percentage of the pupil uncovered: Grade 1 (mild, 0%-25%), Grade 2 (moderate, 25%-50%), and Grade 3 (severe, >50%). Because ACD and lens thickness measurements are unreliable for IOL power calculation in eyes with subluxated lenses, IOL power was calculated using ACD and lens thickness independent formulas (SRK/T, Holladay 1, and Hoffer Q ).

surgical technique

All surgeries were performed under retrobulbar anesthesia by one of us (H.J.) at Shanghai East Hospital, Tongji University, between October 2022 and August 2024. Surgeries were performed based on our previous published technique with minor modification. The schematic diagram is shown in Figure 1, A . After creating a 2.4 mm clear corneal main incision at 130° and performing continuous curvilinear capsulorhexis, a temporary capsular stabilizing hook was used to engage the capsulorhexis margin and stabilize the capsular bag during phacoemulsification. After lens nucleus removal and cortex aspiration, a CTR was implanted into the capsular bag to maintain the contour of the capsular equator. The temporary capsular stabilizing hook was removed. A 26-gauge needle attached to a 1 ml syringe was bent at its base and passed ab interno through the scleral wall 2 to 2.5 mm posterior to the limbus. A 7-0 polypropylene suture (Prolene, Polypropylene Suture, Ethicon, Johnson & Johnson) was threaded into the lumen of the needle and guided into the anterior chamber by retracting the needle. The suture was retrieved from the anterior chamber via the main corneal incision. The suture was then thermoplastically fashioned outside the eye to form an implantable capsular hook, featuring a curved terminal segment of 2.0 mm ( Figure 1, B ). The exterior of the suture was intrasclerally fixated by the aid of the attached curved needle. The hook was then introduced into the anterior chamber and engaged the capsulorhexis margin to stabilize the capsular bag for in-the-bag IOL implantation. The number of implantable capsular hooks was determined according to the assessment of the residual strength of the zonular apparatus. For lens subluxation involving up to 6 clock hours, a single hook was used. When the subluxation extended to 8 clock hours, two hooks were required. For cases exceeding 8 clock hours, three hooks were placed to mitigate late IOL decentration from asymmetric capsular contraction. IOL was implanted into the capsular bag. IOL centration was accomplished by pulling the exterior suture to adjust the tension of the implantable capsular hook(s). Finally, the hook shaft exterior to the sclera was trimmed flush to the scleral surface. The surgical procedures are demonstrated in Video 1.

main outcome measures

From 1 month postoperatively until the final follow-up visit, IOL position parameters, including decentration, tilt, distances between the IOL anterior surface and the iris margin (IOL-iris distance), were evaluated. Axial position of the IOL, defined as the distance from posterior corneal surface to anterior IOL surface (aqueous ACD), was also evaluated. The parameters were assessed from Scheimpflug images using ImageJ (version 1.8.0). IOL tilt and decentration were quantified along the vertical (90°) and horizontal (180°) meridians. The IOL axis was defined as the perpendicular bisector of the IOL surfaces, while the pupillary axis was the line passing through the center of the pupil. The angle and distance between the two axes indicated tilt and decentration ( Figure 2, A ). An IOL tilt >7° and/or decentration >0.5 mm was considered clinically significant. ^, Horizontal and vertical distances between the IOL anterior surface and the iris margin were measured. Measurements were obtained along two axes (D1 and D2), and the mean D was calculated accordingly ( Figure 2, B ). ^, All data were measured three times and averaged by one experienced operator. Standardized slit-lamp photographs were taken to document and assess the status of the IOL-capsular bag complex, the capsular hooks, and the grade of anterior capsular opacification (ACO).

secondary outcome measures

Patients underwent ophthalmologic examinations consisting of UCVA, BCVA, IOP, and ECD at each follow-up visit. The anterior segment was evaluated using slit-lamp microscope, and anterior chamber cells were graded. In addition, fundus examination was performed to assess retina and the central foveal thickness. The visibility of the hook shaft was graded as 0 (none), 1 (mild), 2 (moderate), and 3 (severe) according to previous publication. Intraoperative and postoperative complications were recorded. Postoperative hypotony and IOP elevation were defined as an IOP ≤ 5 mm Hg and IOP ≥ 21 mm Hg, respectively.

The prediction error (PE) was calculated as the difference between the postoperative SE and the formula-predicted refraction. A negative PE indicated a myopic outcome, while a positive value indicated hyperopia. The arithmetic mean of the PE was calculated for each formula. The absolute prediction error was defined as the absolute value of the PE for each patient. The mean absolute error and median absolute error were then derived from these values. Surgically induced astigmatism (SIA) was calculated using the ASCRS online SIA Calculator ( https://www.ascrs.org/tools/corneal-sia-tool ), based on pre- and postoperative keratometry (K) values measured by Pentacam. The centroid of SIA is determined by both the magnitude and direction of astigmatism. The arithmetic mean is derived only from the magnitude of astigmatism, without regard to its direction.

statistical analysis

Both UCVA and BCVA were expressed as the logarithm of the minimum angle of resolution (logMAR) units. Counting fingers vision was assigned 1.8 logMAR (Snellen 20/1262), while hand movement was recorded as 1.9 logMAR (Snellen 20/1589). Statistical analysis was performed using Excel (Microsoft Corp), Prism (version 8.0.1; GraphPad Software), and SPSS software (version 26; IBM Corp). Data distribution was assessed using the Kolmogorov–Smirnov test. Pre- and postoperative values were compared using the Wilcoxon signed-rank or paired t test. A P value <.05 was defined as statistical significance.

RESULTS

Patient characteristics and intraoperative conditions: Seventy-five patients with subluxated lenses were enrolled. One eye was excluded due to intraoperative capsular rupture, resulting in 74 eyes from 74 patients being ultimately included in this study. Forty-nine eyes (66.2%) were from male, and 25 eyes (33.8%) were from female. The mean age at the time of surgery was 58.17 ± 12.77 years (range: 25-85 years). Forty-six patients were followed up for more than 1 year. Nine patients were followed up for more than 2 years, and 6 were followed up for 3 years. The mean follow-up time was 13.2 ± 8.9 months (range: 6-36 months). Trauma was the most common cause of zonular dialysis ( n = 28, 37.8%), followed by idiopathic zonular dialysis ( n = 25, 33.8%), high myopia ( n = 7, 9.5%), and history of intraocular surgery ( n = 5, 6.8%). Moderate subluxations were the most common ( n = 65, 87.8%), followed by severe ( n = 5, 6.8%), and mild ( n = 4, 5.4%). Demographic data and clinical characteristics were detailed in Table 1 . Limbal vitrectomy was performed in 45 eyes due to vitreous prolapse into the anterior chamber. Single-point pars plana vitrectomy was required in 2 eyes to manage infusion misdirection syndrome during surgery. One-piece IOL (SN60WF, Alcon) was implanted in this study. The number of the capsular hook used was as follows: one hook in 49 eyes, two hooks in 20 eyes, and three hooks in 5 eyes. The patients who required three hooks were preoperatively graded as having severe subluxation.

TABLE 1

Baseline Characteristics of Patients With Subluxated Lenses.

Characteristic	n (%)
No. of eyes (patients)	74 (74)
Age at the surgery (y)	58.17 ± 12.77 (25, 85)
Male/female ( n )	49/25
OD/OS ( n )	34/40
Follow-up period (mo)	13.2 ± 8.9 (6, 36)
Axial length (mm)	25.35 ± 3.10 (21.95, 33.23)
Anterior chamber depth (mm)	2.24 ± 0.97 (0.77, 3.92)
Etiology, no. of eyes (%)
Trauma	28 (37.8)
Idiopathic	25 (33.8)
High myopia	7 (9.5)
History of intraocular surgery	5 (6.8)
Congenital ectopia lentis	4 (5.4)
Retinitis pigmentosa	3 (4.1)
Uveitis	2 (2.7)
Extent of ectopia lentis, no. of eyes (%)
Mild	4 (5.4)
Moderate	65 (87.8)
Severe	5 (6.8)

Mean ± SD.

IOL position: The IOL-capsular bag complex remained stable throughout the follow-up period without pseudophacodonesis. The postoperative IOL decentration, tilt, aqueous ACD, and IOL-iris distance remained stable, with no statistically significant differences between postoperative follow-up time points ( Table 2 ). The IOL decentration was 0.33 ± 0.24 mm vertically and 0.29 ± 0.24 mm horizontally at the final follow-up visit. The mean IOL decentration was 0.31 ± 0.28 mm, 0.30 ± 0.25 mm, 0.33 ± 0.25 mm, and 0.31 ± 0.24 mm at 1, 3, 6 months, and the final follow-up visit, respectively. Ten eyes (13.5%) exhibited decentration greater than 0.5 mm, all of which remained within 1.0 mm at the final follow-up visit. Besides, none of these patients reported visual symptoms. The IOL tilt along the vertical and horizontal meridian were 1.55 ± 1.33° and 2.11 ± 1.34° at the final follow-up visit, respectively. The mean IOL tilt was 2.17 ± 1.52°, 1.97 ± 1.32°, 2.10 ± 1.48°, and 1.83 ± 1.35° at 1, 3, 6 months, and the final follow-up visit, respectively. No eye demonstrated clinically significant tilt (≥7°). The mean value of postoperative aqueous ACD was 3.88 ± 0.51 mm, 3.87 ± 0.43 mm, 3.91 ± 0.39 mm, and 3.91 ± 0.33 mm at 1, 3, 6 months, and the final follow-up visit, respectively. At the final follow-up visit, the IOL-iris distance was 0.63 ± 0.25 mm vertically and 0.66 ± 0.27 mm horizontally. The mean IOL-iris distance was 0.63 ± 0.28 mm, 0.62 ± 0.26 mm, 0.64 ± 0.23 mm, and 0.65 ± 0.26 mm at 1, 3, 6 months, and the final follow-up visit, respectively. A total of 104 capsular hooks were implanted in 74 eyes. No postoperative displacement of the capsular hooks was observed. The mean decentration in 5 eyes of severe subluxation implanted with three hooks was 0.29 ± 0.15 mm (range: 0.16-0.51 mm) at the final follow-up visit. Among these, 4 eyes had decentration less than 0.50 mm, while 1 eye exhibited a mean decentration of 0.51 mm (horizontal 0.51 mm, vertical 0.50 mm). The mean tilt in the 5 eyes was 1.75 ± 1.15° (range: 0.95-3.03°) at the final follow-up visit.

TABLE 2

IOL Position at 1, 3, 6 Months and Final Follow-Up.

Parameters		1 Mo	3 Mo	6 Mo	Final Follow-Up
Decentration (mm)	Vertical	0.35 ± 0.29 (0.05, 1.32)	0.34 ± 0.26 (0.05, 1.15)	0.35 ± 0.24 (0.03, 0.95)	0.33 ± 0.24 (0.07, 0.90)
	Horizontal	0.30 ± 0.27 (0.01, 0.92)	0.31 ± 0.25 (0.01, 0.85)	0.30 ± 0.27 (0.00, 0.84)	0.29 ± 0.24 (0.00, 0.79)
	Mean	0.31 ± 0.28 (0.01, 1.32)	0.30 ± 0.25 (0.01, 1.11)	0.33 ± 0.25 (0.00, 0.95)	0.31 ± 0.24 (0.0, 0.90)
Tilt (°)	Vertical	1.97 ± 1.64 (0.10, 7.40)	1.65 ± 1.14 (0.10, 4.3)	1.81 ± 1.31 (0.06, 5.40)	1.55 ± 1.33 (0.10, 5.53)
	Horizontal	2.38 ± 1.38 (0.23, 5.12)	2.28 ± 1.43 (0.10, 6.42)	2.38 ± 1.59 (0.08, 7.52)	2.11 ± 1.34 (0.12, 5.32)
	Mean	2.17 ± 1.52 (0.10, 7.40)	1.97 ± 1.32 (0.10, 6.42)	2.10 ± 1.48 (0.06, 7.52)	1.83 ± 1.35 (0.10, 5.53)
Aqueous ACD (mm)	/	3.88 ± 0.51 (2.22, 4.73)	3.87 ± 0.43 (2.69, 4.43)	3.91 ± 0.39 (2.85, 4.53)	3.91 ± 0.33 (3.10, 4.43)
IOL-iris distance (mm)	Vertical	0.61 ± 0.28 (0.13, 1.14)	0.61 ± 0.26 (0.15, 1.24)	0.65 ± 0.23 (0.27, 1.28)	0.63 ± 0.25 (0.29, 1.25)
	Horizontal	0.65 ± 0.28 (0.22, 1.40)	0.63 ± 0.26 (0.19, 1.16)	0.64 ± 0.24 (0.21, 1.06)	0.66 ± 0.27 (0.19, 1.39)
	Mean	0.63 ± 0.28 (0.13, 1.40)	0.62 ± 0.26 (0.15, 1.24)	0.64 ± 0.23 (0.21, 1.28)	0.65 ± 0.26 (0.19, 1.39)

ACD = anterior chamber depth.

The grade of ACO over time was recorded as follows: 0.014 ± 0.12 at 1 week (range: 0-1), 1.13 ± 0.52 at 1 month (range: 0-2), 1.57 ± 0.53 at 3 months (range: 1-2), and 1.71 ± 0.76 at the final follow-up visit (range: 1-3). No grade IV ACO was observed throughout the follow-up period. Fibrosis was observed on the anterior capsular surface and around the capsular hook, accompanied by progressive circularization of the capsulorhexis margin ( Figure 3 ). The capsular hooks remained stable and in situ throughout the follow-up period.

secondary outcomes

The efficacy of the technique was evaluated by assessing visual and refractive outcomes. Both UCVA and BCVA improved statistically after surgery and remained relatively stable within the follow-up period ( Table 3 ). The mean UCVA improved from 1.02 ± 0.52 logMAR (Snellen 20/209) preoperatively to 0.54 ± 0.36 logMAR (Snellen 20/69) at the final follow-up visit ( P <.05). The mean preoperative BCVA was 0.75 ± 0.73 logMAR (Snellen 20/112) and improved to 0.24 ± 0.28 logMAR (Snellen 20/35) at the final follow-up visit ( P <.05). The distribution and change of pre- and postoperative BCVA are shown in Figure 4 . At the final follow-up visit, 83.8% of eyes ( n = 62) exhibited improved BCVA, 14.9% ( n = 11) exhibited unchanged. One eye (1.4%) exhibited worsened BCVA due to postoperative RD. The mean SE was −2.37 ± 4.68 D preoperatively and −1.09 ± 1.33 D at the final follow-up visit ( Table 3 , P <.05). The SE remained stable from the first week after surgery onward. The accuracy of IOL power calculation in terms of PE, mean absolute error, and median absolute error according to the SRKT, Holladay 1, and Hoffer-Q formulas are presented in Table 4 . The absolute prediction error was within ±0.50 D in 73.0% to 81.1% and was within ±1.00 D in 93.2% of eyes. The centroid for SIA was 0.14 ± 0.71 D @ 63 degrees, and the arithmetic mean of SIA was 0.59 ± 0.38 D ( Figure 5 ).

TABLE 3

Comparison of Clinical Outcomes Before and After Surgery.

Parameters	Before Surgery	After Surgery
Parameters	Before Surgery	1 D	1 Wk	1 Mo	3 Mo	6 Mo	Final Follow-Up
UCVA LogMAR (Snellen)	1.02 ± 0.52 (0, 1.9) (20/209)	0.80 ± 0.51 ^a (0, 1.9) (20/126)	0.65 ± 0.47 ^a (0, 1.8) (20/89)	0.51 ± 0.37 ^a (0, 1.8) (20/65)	0.53 ± 0.45 ^a (0, 1.8) (20/68)	0.52 ± 0.46 ^a (0, 1.8) (20/66)	0.54 ± 0.36 ^a (0, 1.8) (20/69)
BCVA LogMAR (Snellen)	0.75 ± 0.73 (0, 1.9) (20/112)	0.58 ± 0.70 ^a (0, 1.9) (20/76)	0.42 ± 0.53 ^a (0, 1.8) (20/53)	0.26 ± 0.29 ^a (0, 1.1) (20/36)	0.23 ± 0.28 ^a (0, 1.1) (20/34)	0.22 ± 0.28 ^a (0, 1.1) (20/33)	0.24 ± 0.28 ^a (0, 1.1) (20/35)
Spherical equivalent (D)	−2.37 ± 4.68 (−20.25, 11.50)	−1.39 ± 1.42 ^a (−5.38, 1.25)	−1.18 ± 1.38 ^a (−5.38, 0.50)	−1.21 ± 1.32 ^a (−5.25, 0.88)	−1.17 ± 1.33 ^a (−5.25, 0.13)	−1.17 ± 1.35 ^a (−5.25, 0.88)	−1.09 ± 1.33 ^a (−4.75, 0.88)
Intraocular pressure (mm Hg)	16.03 ± 3.88 (7.1, 21.0)	14.17 ± 6.54 (5.0, 44.0)	14.79 ± 5.63 (8.4, 40.0)	14.52 ± 6.86 (10.3, 28.0)	14.37 ± 5.46 (10.3, 20.2)	13.56 ± 4.04 (10.3, 19.2)	15.88 ± 5.66 (4.0, 22.0)
Corneal endothelial cell density (cells/mm ²)	2577.64 ± 486.10 (1200, 3634)	2481.55 ± 615.29 ^a (985, 4250)	2232.76 ± 662.36 ^a (1000, 3657)	2106.92 ± 691.90 ^a (1067, 3240)	2093.82 ± 612.75 ^a (803, 3320)	2177.77 ± 670.37 ^a (795, 3320)	2171.31 ± 707.23 ^a (974, 3232)
Central foveal thickness (µm)	229.88 ± 41.08 (107, 379)	229.08 ± 43.34 (101, 387)	231.00 ± 40.40 (113, 380)	231.10 ± 41.72 (115, 375)	237.24 ± 83.16 (106, 847)	230.48 ± 40.55 (115, 378)	228.36 ± 50.44 (106, 379)

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Tags: American Journal of Ophthalmology Volume 288

Sep 20, 2026 | Posted by drzezo in OPHTHALMOLOGY | Comments Off

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