DR. TANVI GAONKER

Dr.Anju Rastogi, Dr. KAMLESH, Dr.Shweta

Semi Finals

Abstract

Purpose:To compare the functional outcomes of retropupillary iris claw lenses (RPIC-IOL) and scleral fixated intraocular lenses (SFIOL) in children with large lens subluxations.

Methods:A randomized comparative study of 1 year duration was conducted in 28 eyes of patients between 6-18 years of age having ˃7 clock hour lens subluxation. They were equally divided into two groups: A (RPIC-IOL implantation) and B (Gore-Tex sutured SFIOL implantation). The parameters compared were best corrected visual acuity (BCVA) and IOL tilt at 3 months follow up.

Results:The difference between mean BCVA in group A(0.63 ± 0.28 logMAR) and group B(0.58 ± 0.29 logMAR) was not statistically significant. The incidence of IOL tilt was higher in group B but not statistically significant (p=0.12).

Conclusion:Both procedures had comparable visual outcomes. However RPIC-IOL was relatively quick and technically simple. No significant posterior segment complications were seen showing safety of both techniques.

Full Text

aRETROPUPILLARY IRIS CLAW LENSES VERSUS SCLERAL FIXATED LENSES IN CHILDREN WITH LARGE SUBLUXATIONS
Abstract
Purpose: To compare the functional outcomes of retropupillary iris claw lenses (RPIC-IOL) and scleral fixated intraocular lenses (SFIOL) in children with large lens subluxations. Methods: A randomized comparative study was conducted in 28 eyes of patients between 6-18 years of age having ˃7 clock hours lens subluxation. They were equally divided into Group A (RPIC-IOL implantation) and group B (Gore-Tex sutured SFIOL implantation). Primary outcome was improvement in best corrected visual acuity (BCVA) at 3 months. Secondary outcomes were assessment of IOL tilt, mean change in astigmatism at 3 months and median operating time. Results: The difference in the mean post-operative BCVA between group A (0.63 ± 0.28 logMAR) and group B (0.54 ± 0.29 logMAR) was not statistically significant (p=0.399). Significant IOL tilt was seen in 2 eyes in group A (14.2%) and 4 eyes in group B (28.57%) (p= 0.120). Mean change in astigmatism was 4.38 ± 5.9 D in group A and 4.91 ± 4.4 D in group B (p= 0.299). The median operating time was 40 minutes in group A and 90 minutes in group B (p<0.001). No significant posterior segment complications were seen in either technique. Conclusion: Our study shows that both procedures have comparable visual outcomes. RPIC-IOL implantation was relatively quick and needed lesser manipulation. Hence, we recommend it in cases with high risk of retinal detachment. Keywords: subluxated lens, ectopia lentis, Gore-Tex, scleral fixated lens, iris claw lens, SFIOL

INTRODUCTION
Lens subluxation in children is a challenging problem. It can induce significant astigmatism and high refractive errors leading to amblyopia and thereby hindering early visual rehabilitation.
Management of subluxated lenses varies from optical correction using spectacles/contact lenses in low grades of subluxation to lens removal and intraocular lens (IOL) implantation in higher grades. “In-the-bag” placement of IOL with Cionni ring is the ideal method in cases of mild to moderate subluxations. However, in cases with large subluxations, a pars plana lensectomy-vitrectomy followed by the management of resultant aphakia is recommended. The treatment options available are Scleral Fixated IOLs (SFIOLs)-sutured or sutureless, Anterior chamber IOLs (ACIOLs) and Iris claw IOLs which can be placed in the posterior chamber (Retropupillary) or in the anterior chamber.

Even though ACIOLs are surgically easier to implant and modern-day open loop ACIOLs have proved to be safe in few studies in children, their use may be complicated by uveitis, hyphaema, glaucoma and corneal decompensation over long term.1,2 Therefore, they are not widely accepted in children.
SFIOLs have the advantage of the lens being placed in a more physiological position. The technique of sutured SFIOL has evolved over time, beginning with the use of 10-0 prolene which was complicated by suture degradation and breakage3 followed by use of 9-0 prolene which has a better safety profile. Currently, 8-0 Gore-Tex (polytetrafluoroethylene) which has greater tensile strength is being used and has shown relatively good results in adult eyes.4,5,6 However, there is paucity of studies documenting its safety profile in pediatric eyes.
In recent years, Sutureless Scleral Tunnel IOLs (SSTIOLs) have gained popularity. This technique eliminates the suture related complications of SFIOLs while maintaining advantages over ACIOLs. Also, smaller incision gives lesser astigmatism, globe stability and less frequent globe collapse intraoperatively. However, they are less suitable for cases with horizontal limbus-limbus diameter > 12 mm. Low scleral rigidity in pediatric eyes makes this surgery more difficult and challenging.

Retropupillary Iris Claw IOLs (RPIC-IOLs) are technically simpler than SFIOLs and avoid corneal complications of ACIOLs. However, they may be associated with problems like spontaneous disenclavation and pupil ovalization.7,8
Currently there is no consensus as to which of these techniques is best for management of large subluxations in children. Hence, we carried out this study to assess and compare the visual outcomes and stability of RPIC-IOL and sutured SFIOL (using Gore-Tex) in children. We have also addressed the questionable safety profile of Gore-Tex assisted SFIOL in pediatric eyes as there is paucity of similar studies in literature.

MATERIAL AND METHODS
We conducted a randomized comparative interventional study in a tertiary eye care centre, registered with Clinical trial registry – India (CTRI/2020/02/023156). Approval was taken from the Institutional Ethics Committee. Research adhered to the tenets of the Declaration of Helsinki. 28 eyes of children in age group 6-18 years with crystalline lens subluxation > 7 clock hours (ectopia lentis) were enrolled in the study after taking informed consent and were divided in two groups of 14 eyes each. Group A underwent retropupillary iris claw lens implantation (RPIC-IOL group) and Group B underwent sutured scleral fixated intraocular lens implantation using 8-0 Gore-Tex (SFIOL group). For allocation of the participants, a computer-generated list of random numbers was used. Cases with gross iris abnormality, glaucoma, uveitis, gross anterior segment trauma/traumatic mydriasis and posterior segment abnormalities were excluded.

A thorough pre-operative ophthalmic evaluation was performed including best corrected visual acuity (BCVA) using Snellen chart, retinoscopy (wherever possible), slit lamp examination, automated keratometry (UNICOS URK-700), endothelial cell count (SP-200P), intraocular pressure (IOP) measurement (SHIN-NIPPON NCT-10) and dilated posterior segment assessment. Contact biometry was done by SW-1000AP using SRK Ⅱ formula. Ultrasound B scan (APPASWAMY MARVELL-II) was done wherever fundus evaluation could not be performed. Pediatric review was done to rule out associated syndromes. Echocardiography was done and cardiology opinion was sought wherever needed. IOL used in group A was iris claw lens [Irifix, Model No J-IF54, overall diameter of 8.50mm, optic diameter of 5.40mm with an estimated A constant of 117.4 for posterior chamber]. In group B, SFIOL [Akreos A060 (Bausch and Lomb), overall diameter of 11mm, optic diameter of 6 mm with an estimated A constant of 118.0] was used. The target refraction was emmetropia.

SURGICAL TECHNIQUE
All surgeries were performed by same surgeon using Alcon Centurion machine under general anesthesia in younger children and local anesthesia in older children. Time taken for each procedure was noted.
GROUP A (RETROPUPILLARY IRIS CLAW LENS)

A 23 G infusion cannula was placed 3 mm behind the limbus infero-temporally. Pars plana lensectomy-vitrectomy was done using 23 G vitrectomy cutter. Paracentesis at 10 o’clock and 2 o’clock positions were made. A corneo-scleral section of 4.5 mm was created. The iris claw lens was inserted vertically in the anterior chamber and was nudged to horizontal position. It was slipped posteriorly with lens holding forceps. The midperipheral iris was enclaved at 3 o’clock and 9 o’clock positions 180o apart using a Sinskey hook one after the other. Peripheral iridectomy was done and the section was closed with 10-0 vicryl followed by sclerostomy closure with 8-0 vicryl.
GROUP B (SUTURED SCLERAL FIXATED INTRAOCULAR LENS)5:
Limbus was marked at two points in the horizontal plane 180o apart using toric lens marker. Nasal and temporal peritomies were done. Four sclerotomies were made (2 on each side) 3 mm behind the limbus and 5 mm apart using 23 G trocar. Pars plana lensectomy- vitrectomy was done. A clear corneal incision of 3.2 mm was made. The Gore-Tex suture was cut into half and each end was threaded through the two eyelets of the SFIOL on either side. The suture ends were then passed into the anterior chamber and pulled out of the corresponding sclerotomy using 23 G intravitreal forceps. The clear corneal incision was enlarged to 4.0 mm. The IOL was folded and introduced into the anterior chamber using Kelman-McPherson forceps. The sutures were tied using a 3-1-1 technique after ensuring IOL centration by adjusting the tension of sutures on either side. The knots were trimmed and buried into one of the sclerotomies. The sclerotomies were sutured with 8-0 vicryl and the corneal section with 10-0 vicryl. The conjunctiva was closed (Figure 2).

Post-operative analysis was done at day 1, 1 week, 1 month, 6 weeks, 3 months. IOL tilt was assessed by UBM by method described by Loya et al (>100 microns tilt with reference to iris plane was considered as significant).9
POST-OPERATIVE PERIOD
All patients received a 5-day course of systemic antibiotics (Amoxycillin 30 mg/kg/day in three divided doses) along with topical Prednisolone 1%, topical Tobramycin (0.3%) and Homatropine (2%). Timolol 0.5% eye drops and oral Acetazolamide (15 mg / kg in three divided doses) were prescribed in cases where the post-operative intraocular pressures were found to be high.

RESULTS
The mean age was 9.57 ± 4.13 years in group A and 9.64 ± 4.09 years in Group B. The cause of subluxation in Group A was high myopia in 8 cases (57.14%), Homocystinuria in 1 case (7.14%), Marfan’s syndrome in 1 case (7.14%) and idiopathic in 4 cases (28.57%) whereas in group B it was high myopia in 3 cases (21.43%), Homocystinuria in 1 case (7.14%), Marfan’s syndrome in 2 cases (14.29%) and idiopathic in 8 cases (57.14%). In Group A, the axial length (AL) ranged from 21.6- 28.8 mm with a mean of 25.25 ± 2.44 mm whereas in Group B, AL ranged from 20.75- 27.64 mm with a mean of 24.21 ± 2.27 mm (p=0.256).
Both the groups showed a significant change in best corrected visual acuity (BCVA) postoperatively at 3 months. In group A, the mean pre-operative BCVA was 0.91 ± 0.42 logMAR and mean post-operative BCVA at 3 months was 0.63 ± 0.28 logMAR (p=0.025). In group B, the mean pre-operative BCVA was 0.98 ± 0.38 and mean post-operative BCVA at 3 months was 0.54 ± 0.29 logMAR (p=0.003). In our study, the improvement in BCVA at 3 months was better in the SFIOL group (0.44 ± 0.45 logMAR) as compared to the RPIC-IOL group (0.28 ± 0.41 logMAR) but this difference was not statistically significant (p=0.322)

In group A, the mean pre-operative astigmatism was -5.85 ± 5.38 D and mean post-operative astigmatism at 3 months was -1.38 ± 1.65 D (p=0.044). In Group B, mean pre-operative astigmatism was -7.05 ± 4.13 D (p=0.572) and mean post-operative astigmatism at 3 months was -2.11 ± 1.99 D (p=0.004). However, the difference between the two groups at 3 months was not statistically significant (p=0.300).
The median operating time was 40 minutes in Group A and 90 minutes in Group B (values were not normally distributed, so median was taken). The difference in the two groups was statistically significant (p=<0.001). IOL centration was evaluated in all patients by slit lamp examination at every visit. The decentration was measured in millimeters from the margin of the pupil in undilated state. At 3 months follow-up, IOL decentration was seen in 1 eye in group A (1 mm) and in 3 eyes in Group B (1 mm, 1.2 mm, 1.5 mm). Since the visual acuity was good and it was evident only on pupillary dilatation, no surgical intervention was done. At 1-year follow-up, there was no further increase in decentration in the above eyes or in the eyes which had no decentration at 3 months. A significant IOL tilt was seen in 2 eyes (14.29%) of group A and in 4 eyes (28.57 %) of group B. The difference was not statistically significant between the groups (p=0.120). In group A, the mean LogMAR BCVA in eyes with significant tilt was 0.65 ± 0.21 and in eyes without significant tilt was 0.65 ± 0.29 (p=0.984). In Group B, the mean LogMAR BCVA in eyes with significant tilt was 0.5 ± 0.36 and in eyes without significant tilt was 0.63 ± 0.19 (p=0.428). Overall, the mean BCVA in eyes with significant tilt was 0.53 ± 0.32 logMAR and in eyes without significant tilt was 0.65 ± 0.26 logMAR. This difference was not statistically significant (p=0.334).

The mean postoperative astigmatism in eyes with significant tilt (both group A and B) was -2.33 ± 2.37 D and in eyes without significant tilt was -1.56 ± 1.57 D. This difference was not statistically significant (p=0.326)
The post-operative intraocular pressure (IOP) was measured at 1 week, 1 month and 3 months. The difference between the two groups at each visit was not statistically significant. 1 eye in group A and 3 eyes in group B developed immediate post-operative hypotony which resolved by 2 weeks on medical management. 1 eye in group A had small lens fragment drop and developed high IOP which was uncontrolled on oral as well as topical antiglaucoma medications. Complete vitrectomy and removal of lens material was done at second stage after which IOP was normalized.
In 1 eye with significant cataractous changes fundus could not be visualized. The ultrasound B-scan of this eye was anechoic. 1 eye in group B had lattice degeneration for which laser was done pre-operatively. Fundus evaluation was normal in all cases till last follow-up.

DISCUSSION
Management of large lens subluxation in children continues to be a perplexing problem for pediatric ophthalmologists. In-the-bag placement of IOL with the aid of Cionni ring remains most acceptable option but its technically challenging.10 In cases where it is not feasible, lens extraction can be done with the management of resultant aphakia. The choice of IOL to be implanted is the next challenge as early visual rehabilitation with minimal complications is the ultimate goal in children.
A wide variety of IOLs and various techniques of their implantation have been described in literature with associated merits and demerits of each. ACIOLs are technically easier to implant but they are not free of complications.1,2 SFIOL is a time-tested option for eyes with inadequate capsular support due to their placement in a more physiological position. However, it is also not without complications. Retinal detachment, IOL tilt, vitreous or suprachoroidal hemorrhage, endophthalmitis and suture erosion/breakage have all been reported.11,12,13 Iris claw lenses avoid potential complications of ACIOLs and SFIOLs. However, they may be associated with spontaneous disenclavation, iris chaffing/atrophy, pigment dispersion, hyphaema and pupil ovalization.
Many studies have evaluated 10-0 polypropylene for SFIOL in children and have reported IOL dislocation secondary to suture breakage.3 Use of thicker sutures like 9-0 prolene is considered a better alternative for scleral fixation in children due to its better safety profile.11,14 Current literature supports superiority of 8-0 Gore-Tex over 9-0 prolene for suturing SFIOL because of its greater tensile strength, high visibility due to its white color, minimal inflammatory response, minimal memory and easy manipulation. Khan et al did SFIOL (Akreos) implantation using 7-0 Gore-Tex suture in 85 eyes and there was no reported case of suture breakage during follow-up.4 Other studies have shown similar safety profile in adult eyes.15,16 However, there is lack of documentation of its safety profile and outcomes in pediatric eyes. Since, it is difficult to manage low scleral rigidity in pediatric eye, the technicality required in every step of SFIOL implantation using Gore-Tex has not been described till date. Also, there is lack of comparative data between RPIC-IOL and sutured SFIOL in pediatric eyes. This study highlights the comparison of functional outcomes in both the procedures and addresses the technical and safety concerns of Gore-Tex assisted SFIOL in children.

In our study, there was a statistically significant improvement in the mean BCVA in both the groups post-operatively. SFIOL group showed a better visual outcome at post-operative 3 months compared to RPIC-IOL group, but it was not statistically significant. Rashad et al reported a mean BCVA of 0.51 ± 0.25 logMAR in the RPIC-IOL group and 0.42 ± 0.16 logMAR in the SFIOL group at last follow-up (p=0.152).17 Their mean BCVA at all post-operative visits was better in the SFIOL group which is comparable to our study. Han Zhang et al reported a mean BCVA of 0.55 ± 0.22 logMAR in the RPIC-IOL group and 0.53 ± 0.19 logMAR in the SFIOL group (p=0.249).18 However, both these studies have been done in adult eyes (54 ± 11 years in the former; 15-75 years in the latter)
Visual recovery was found to be earlier in RPIC-IOL group (mean UCVA was better in group A when compared to group B at post-operative day 1). This could be attributed to a shorter median operating time as implantation of an iris claw lens is technically simpler with fewer steps as compared to group B where, surgeon faced difficulty due to low scleral rigidity. Since there were four suture ends, suture orientation and entanglement during SFIOL placement were encountered in few cases. The sclerotomies were created using 23 G trocars and thus they all had to be sutured at the end of the surgery. This also contributed to a longer operating time in Group B. Rashad et al has also reported an early visual recovery in their RPIC-IOL group which they attributed to the uncomplicated nature of the surgery and a shorter operating time.17 Amblyopia was a limiting factor for early visual recovery in 7 eyes in group A and 3 eyes in group B of our study.

The mean post-operative spherical equivalent (SE) showed a hypermetropic trend in group A and myopic trend in group B which correlates well with study by Botsford et al who did SFIOL implantation using Gore-Tex in 31 eyes and reported a post-operative myopic trend.6 However, this study was done in adult eyes. Rastogi et al reported mean post-operative SE -2.07± 0.91 with iris claw lens in 14 eyes between 8-7 years of age.19 However, the technique used to insert the IOL in the study was through corneo-scleral tunnel. Also, there is no mention of pre-operative and post-operative keratometric data. Gonnerman et al reported mean post-operative SE of 0.00 ± 1.21 diopters (D) (range −2.25 to +4.50 D) with iris claw lens which they implanted through scleral tunnel incision.20
In our study, 2 patients in group A and 4 patients in group B were noted to have a significant IOL tilt. However, the difference was not statistically significant (p=0.12). Also, the mean difference in BCVA in eyes with and without significant tilt was not statistically significant (p=0.334). Mahajan et al reported 2 cases of IOL tilt in RPIC-IOL group and 4 cases in SFIOL group.21 However, the method for IOL tilt measurement and its significance value is not described. Additionally, they did not compare the BCVA or astigmatism in eyes with and without significant tilt. Patel et al did SFIOL implantation with Gore-Tex in 49 eyes and reported IOL tilt in 2 eyes post-operatively but they did not quantify the amount of tilt.16

The mean change in astigmatism was statistically significant in each group and was comparable in between the groups at last follow-up. Our study showed a myopic trend in post-operative astigmatism in both the groups. Our results are not consistent with other studies. Han Zhang et al reported hyperopic astigmatism of 0.84 ± 0.53 D in sutured iris fixated group and 1.23 ± 0.70 D in SFIOL group. 18 Botsford et al reported a mean astigmatism of 1.65 ± 1.45 D with SFIOL using Gore-Tex. 6 A smaller incision helps limit the post-operative astigmatism to an acceptable range. The incision required to insert the non-foldable RPIC-IOL is 4.5 mm which is larger than that required for foldable SFIOL (4.0 mm). But post-operatively, eyes with IOL tilt were more in the SFIOL group compared to RPIC-IOL group resulting in higher astigmatism in the former and negating the benefit of a small incision. Since there is paucity of literature on Gore-Tex sutured SFIOL implantation in children, this data needs more documentation in future studies.

1 case in group A had intraoperative small lens fragment drop with high IOP uncontrolled with topical and oral anti glaucoma medications on follow-up for which pars plana vitrectomy was done in second stage. The post-operative period was uneventful. None of our cases had retinal detachment, pseudophacodonesis or IOL dislocation. No sclerotomy related complications were seen as all were sutured with 8-0 vicryl. The most common post-operative complication in group A was pupil ovalization which had no effect on the final BCVA or pupillary dilation. The most common post-operative complication in group B was IOL tilt. This could be attributed to not so precise markings in these eyes. Authors would like to highlight that meticulous marking is of utmost importance in achieving good IOL centration and stability. This especially becomes challenging in eyes under general anesthesia where globe tends to diverge.22 This coupled with multiple sclerotomies and post-vitrectomy hypotony makes globe handling difficult. We recommend use of smaller gauge instruments to reduce the need for additional suturing and to minimize sclerotomy site leakage and thus hypotony. For the ease of instrument transfer and suture passage, valved cannulas can also be used. Gore-Tex could be a stronger & safer option in pediatric eyes especially in non-Marfanoid cases. However, this study is limited by a small sample size. More studies with larger sample size are needed to support this.

Conclusion
Both RPIC-IOL and SFIOL respect the anterior segment anatomy and corneal endothelium as they are placed behind the iris plane. We conclude that both techniques provide good visual rehabilitation and IOL stability in children with large lens subluxations. RPIC-IOL implantation is technically simple and needs significantly lesser intraoperative manipulation. Hence, we recommend it in subjects with high risk of retinal detachment like Marfan’s syndrome, high myopia and presence of peripheral retinal degenerations.

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