Comparison of 2 pupil expansion devices for small-pupil cataract surgery

A randomized control study on post-operative iris distortion following small-pupil cataract surgery using B-HEX pupil expander versus Malyugin ring

Background

The aim of the study was to evaluate postoperative pupil distortion following small pupil cataract surgeries performed using B-HEX and Malyugin rings (MR).

Methods

A randomized control trial was conducted from June 2020 to June 2023 at a tertiary eye-care hospital. The study consisted of 64 participants for cataract surgery with small pupil. There were two groups, one undergoing surgery with the use of B-HEX pupil expander and other with MR intraoperatively and the rest of the surgery was proceeded as per the convention. Areas of preoperative and postoperative images was calculated, put into an online software and pupil distortion was calculated in percentage. Two-tailed t-test was used to see the difference between the two groups.

Results

Mean age at presentation was 70.5 ± 10.12 years. Most common cause for small pupil was tamsulosin therapy. Mean size of small-pupil was 3.0 ± 1.1 mm. With the application of two rings, mean pupillary area preoperatively was 4178.23 ± 1589.46 and postoperatively was 6100.44 ± 2658.28 following the use of MR, respectively and 30,002.93 ± 13,193.40 preoperatively and 37,648.26 ± 15,207.01 postoperatively following the use of B-Hex ring respectively. Comparing baseline area from pupillary area at 1-month follow-up, a significant increase was noted for both the rings. Also, MR caused significantly more pupillary distortion compared to B-HEX ring (p < 0.05).

Conclusion

MR causes significantly more pupillary distortion in the postoperative period compared to B-HEX ring. Though, both the rings cause pupillary distortion, these devices expand the surgical area adequately, ease the procedure, decrease risk of complications achieving good functional visual outcomes.

Dilation devices in cataract surgery

PURPOSE OF REVIEW

Cataract surgery in the setting of small pupil represent a major challenge and it is associated with a higher risk of complications. When pharmacologic pupil dilation fails, mechanical pupil expansion devices are needed to obtain and maintain sufficient intraoperative mydriasis. The purpose of this review is to assess the pupil expansion devices currently available.

RECENT FINDINGS

A variety of pupil expansion devices are offered on the market. They differ for design, material, shape, size, cost, and easiness of insertion/removal, nonetheless they all seem to be effective in improving the pupil size and easing the cataract surgery.

SUMMARY

Mechanical pupil expansion can be effectively achieved with a variety of devices, which are well tolerated and can facilitate cataract surgery in the setting of poor mydriasis.

Cataract Surgery Considerations for Diabetic Patients

PURPOSE OF REVIEW

Given the epidemiology and demographic trends of diabetes mellitus and cataracts, ophthalmologists are likely to encounter patients with both comorbidities at an increasing frequency. Patients with diabetes represent a higher risk population than healthy patients for cataract surgery. In this review, we discuss key risks and risk-mitigation practices when performing cataract surgery on these patients.

RECENT FINDINGS

Patients with diabetes continue to represent a high-risk surgical population: Nagar et al. suggest a dose-dependent relationship may exist between number of intravitreal injections and likelihood of posterior capsular rupture. However, novel treatments are improving outcomes for patients with diabetes. Several studies have reported intracameral phenylephrine/ketorolac may reduce the incidence of post-operative cystoid macular edema while others have discussed the efficacy of pre-treatment and post-treatment with intravitreal bevacizumab on improving cataract surgery outcomes in patients with diabetic retinopathy. Pre-operatively, ophthalmologists should perform an enhanced evaluation, consider timing and lens selection decisions, and complete any appropriate pre-operative treatment. Peri-operatively, surgeons should be aware of pupillary dilation adjustments, combination surgery options, and potential complications. Post-operatively, clinicians should address pseudophakic cystoid macular edema, diabetic macular edema, diabetic retinopathy, and posterior capsular opacification.

Efficacy of a hinged pupil expansion device in small pupil cataract surgery

Purpose:

To evaluate the efficacy and safety of a hinged pupil expansion device (PED) in eyes with small pupils undergoing phacoemulsification.

Methods:

In this prospective, multicenter, interventional case series of 57 eyes with suboptimal pharmacologic pupil dilation (<5 mm diameter), a hinged PED (I-Ring, Beaver-Visitec International, Waltham, MA) was applied to facilitate surgical visualization during cataract surgery. The pupil diameters (PD) were measured at different stages of the procedure and at the 1-month follow-up visit. Rate of successful intraoperative PED deployment, pupil size, and shape were assessed.

Results:

The mean patient age was 70.5 ± 12.1 years. The I-Ring PED was successfully applied in all eyes. The mean PD at various stages were 4.1 ± 1.1 mm (dilation with eye drops only preoperatively), 4.3 ± 1.1 mm (dilation after intracameral epinephrine and ophthalmic viscoelastic device), 6.80 ± 0.00 mm (with PED applied), and 5.7 ± 1.1 mm (end of surgery). A statistically significant difference (P < 0.001) was observed between the mean PD with intracameral medications and with PED application. Postoperative circular pupil was observed in 54 of 57 eyes (94.7%) and the mean eccentricity index (n = 57 eyes) was 0.11 ± 0.22. No significant adverse events were observed.

Conclusion:

The I-Ring PED safely and effectively provided and maintained adequate pupil expansion and surgical visualization in eyes with small pupils undergoing cataract surgery. Postoperatively 95% of eyes attained circular pupils. This hinged PED is an additional instrumentation option for the safe and effective expansion of inadequately sized pupils during cataract surgery.

Outcomes of first 50 cases using a new pupil expander

PURPOSE

To describe the initial experience with the Assia Pupil Expander 200 (APX-200, APX Ophthalmology) in eyes that underwent phacoemulsification or intraocular lens repositioning surgery that required mechanical pupil expansion.

SETTING

Department of Ophthalmology, Meir Medical Center, Kfar-Saba, and Ein-Tal Eye Center, Tel Aviv, Israel.

DESIGN

Retrospective case series.

METHODS

The APX-200 is a single-use device, intended for mechanical expansion of the pupil during intraocular surgery. Two devices are inserted through 2 opposite 19-gauge incisions using designated forceps. The surgical course and early postoperative follow-up was recorded in 50 eyes.

RESULTS

The study included 50 consecutive eyes, with mean preoperative pupil diameter was 3.7 mm. The APX effectively dilated the pupils in all cases. No complication related to the use of the APX such as hyphema, iridodialysis, or Descemet membrane detachment were noted in this series. A central and round pupil was restored in all eyes at 1-month postoperatively, with 14 eyes (28%) having mild sphincter tears. Pupilloplasty was not required in any of the cases.

CONCLUSIONS

The APX-200 was an effective and safe device for pupil expansion during intraocular surgery.

Modelling floppy iris syndrome and the impact of pupil size and ring devices on iris displacement

Introduction

The aim of this paper was to further develop a previously described finite element model which equates clinical iris billowing movements with mechanical buckling behaviour, simulating floppy iris syndrome. We wished to evaluate the impact of pupil dilation and mechanical devices on normal iris and floppy iris models.

Methods

Theoretical mathematical modelling and computer simulations were used to assess billowing/buckling patterns of the iris under loading pressures for the undilated and dilated normal iris, the undilated and dilated floppy iris, and additionally with a mechanical ring device.

Results

For the normal iris, billowing/buckling occurred at a critical pressure of 19.92 mmHg for 5 mm pupil size, which increased to 28.00 mmHg (40.56%) with a 7 mm pupil. The Malyugin ring device significantly increased critical initiating buckling pressures in the normal iris scenario, to 34.58 mmHg (73.59%) for 7 mm ring with boundary conditions I (BC I) and 34.51 mmHg (73.24%) with BC II. For the most floppy iris modelling (40% degradation), initiating buckling value was 18.04 mmHg (−9.44%), which increased to 28.39 mmHg (42.52%) with the 7 mm ring. These results were much greater than for normal undilated iris without restrictive mechanical expansion (19.92 mmHg).

Conclusion

This simulation demonstrates that pupil expansion devices inhibit iris billowing even in the setting of floppy iris syndrome. Our work also provides a model to further investigate the impact of pupil size or pharmacological interventions on anterior segment conditions affected by iris position.

Methods for achieving adequate pupil size in cataract surgery

PURPOSE OF REVIEW

Cataract surgery is the most common surgical procedure performed worldwide. Small pupils have been an eternal challenge for cataract surgeons; insufficient pupil dilation is associated with increased complication rates, including capsule rupture, vitreous loss, iris trauma or postoperative inflammation. The aim of the current review is to present the methods for pupil dilation and the risk factors for a small pupil in a cataract patient.

RECENT FINDINGS

Risk factors for intraoperative small pupil include diabetes, intraoperative floppy iris syndrome, pseudoexfoliation syndrome, receiving glaucoma medications, having undergone previous ocular surgery and iris sphincter sclerosis from aging. There is a wide range of options to manage the small pupil, including pharmacological treatment, mechanical stretching, dilation with iris hooks or pupil expanders. We recommend a stepwise approach for intraoperative pupil dilation, from pharmacological mydriasis to pupil expanders.

SUMMARY

The current article discusses risk factors for a small pupil and the methods for pupil dilation in a cataract patient. Every cataract surgeon needs to be ready to cope with a small pupil, both manifesting preoperatively and intraoperatively.

Series of cataract surgeries with I-ring pupil expansion ring

BACKGROUND

The retrospective review of I-ring pupil expansion ring use is designed to examine the patient characteristics and associated surgical challenges in a clinical practice. The hypothesis is that I-ring provides a necessary additive tool in dealing with challenging cataract surgeries with small pupils.

AIM

To document the safety profile and use of I-ring pupil expansion ring in a clinical practice.

METHODS

A retrospective chart review of 12 consecutive cases within the same year (2016) of cataract surgeries employing I-ring pupil expansion ring (Beaver-Visitec, International) by a single surgeon at the same ambulatory surgical center was conducted. Demographic, pre-op, intra-op, and post-op data were recorded. Total number of cataract cases performed was also recorded.

RESULTS

8 of 12 cases were planned I-ring cases. 1 case was decided intraoperatively when femtosecond laser caused the pupil to shrink. The other 3 cases were also decided upon intraoperatively when pupil was deemed to be small. 7 patients had IFIS from Flomax use. 2 patients had pseudoexfoliation syndrome as the cause of small pupil. 2 patients had narrow angles with brunescent cataracts. 2 patients had pre-op partial zonular dehiscence. 1 patient had 360^o of posterior synechiae. 2 cases had ruptured posterior capsule that required anterior vitrectomy. No complications were attributed to the pupil expansion ring. A total of 296 cataract surgeries were performed that year by the surgeon, making the rate of pupil ring use 4.1%.

CONCLUSION

Small pupil requiring pupil expansion ring during cataract surgery is often associated with other challenges, such as brunescent cataract, zonular weakness, and posterior synechiae in this series. I-ring helped to reduce at least one challenge in these difficult cases.

Diabetes and Phacoemulsification Cataract Surgery: Difficulties, Risks and Potential Complications

Diabetes mellitus is one of the most prevalent chronic diseases worldwide. Diabetic patients are at risk of developing cataract and present for surgery at an earlier age than non-diabetics. The aim of this study was to review the problems associated with cataract surgery in a diabetic patient. Corneal complications in diabetic patients include delayed wound healing, risk of developing epithelial defects or recurrent erosions due to the impairment of epithelial basement membranes and epithelial-stromal interactions. Diabetic patients present lower endothelial cell density and their endothelium is more susceptible to trauma associated with cataract surgery. A small pupil is common in diabetic patients making cataract surgery technically challenging. Finally diabetic patients have an increased risk for developing postoperative pseudophakic cystoid macular edema, posterior capsule opacification or endophthalmitis. In patients with pre-proliferative or proliferative diabetic retinopathy, diabetic macular edema or iris neovascularization adjunctive therapy such as an intravitreal anti-vascular endothelial growth factor injection, can inhibit exacerbation related to cataract surgery.

Intraoperative Complications of Cataract Surgery Using Intracameral Illumination in the Elderly over 75 Years

Purpose

To evaluate intraoperative complications and utilization of adjunctive devices between microscope and intracameral illuminations during cataract surgery in the elderly over 75 years.

Design

A retrospective, consecutive, interventional case series Participants. Two hundred eighty-six eyes of 184 patients older than 75 years who underwent cataract surgery using microscope and intracameral illuminations.

Methods

A chart review was performed on an advanced cataract surgery group of 141 consecutive cases in which the intracameral illumination was used and on a standard cataract surgery group of 145 consecutive cases in which the intracameral illumination was not used.

Main Outcome Measures

Intraoperative complications (posterior capsule rupture, radial tear of the anterior capsule, dropped nucleus, or sulcus-implanted/sclera-fixated IOL) and utilization of adjunctive devices (pupil expansion device or anterior capsule staining).

Results

The frequency of use of the pupil expansion device was lower in the advanced cataract surgery group than that in the standard cataract surgery group (0.7% vs 6.9%; p=0.007). Furthermore, the rates of a posterior capsule rupture and at least one intraoperative complication were lower in the advanced cataract surgery group than those in the standard cataract surgery group (0.7% vs 4.8%; p=0.067) (0.7% vs 7.6%; p=0.004).

Conclusions

In the current cohort of patients over 75 years, the rate of intraoperative complications was lower when using the intracameral illumination than that when using the conventional method. Cataract surgery using intracameral illumination would be good option for elderly people.

[Mechanical pupillary dilatation using rings in small pupils during cataract surgery : Video article]

OBJECTIVE

The purpose of mechanical pupillary dilatation in small pupils is a sufficient visualization of the lens to be able to perform capsulorhexis, phacoemulsification and intraocular lens implantation.

INDICATIONS

The indications for mechanical dilatation are fulfilled in patients where a sufficient pharmacological preoperative pupil dilatation is not possible.

SURGICAL TECHNIQUE

During routine cataract surgery specific foldable rings can be employed to dilate the pupil with the appropriate injector under viscoelastic substances. These rings are carefully placed at the pupillary margin until circular pupillary dilatation up to 6-7 mm is achieved. After intraocular lens implantation and before removing the viscoelastic substance the rings are slowly folded into the injector and then removed. The surgical technique is demonstrated in detail with the help of a video of the operation, which is available online.

RESULTS

Mechanical pupillary dilatation was possible in all patients studied (n = 14), which allowed uncomplicated phacoemulsification and intraocular lens implantation. For both ring systems studied the mean pupillary dilatation was 6.6 mm. At the end of surgery, the pupillary diameter was 4.89 mm using a Malyugin ring (MST, Redmond, Washington, USA) and 4.93 mm with an I‑ring (Visitec, Waltham, MA, USA; P > 0.05). Small lesions at the pupillary margin or pigment dispersion during implantation or explantation depended mostly on the individual patient situation and not on the ring used.

CONCLUSION

Mechanical pupillary dilatation with rings allows sufficient dilatation to perform cataract surgery. Both the Malyugin ring and the I‑ring achieved smooth and atraumatic pupillary dilatation.

Cataract surgery in small pupils

This paper presents the review of historical aspects and the current state-of-the-art in various pupil dilatation methods to be used in cataract surgery. The surgical algorithm in managing small pupil cases should include topical and intraocular mydriatics, appropriately selected viscosurgical device and mechanical dilatation with instruments, iris hooks, and/or pupil expanders.

Recent advances in small pupil cataract surgery

PURPOSE OF REVIEW

To highlight the existing and emerging cataract surgery trends in patients with insufficient mydriasis. Discuss the latest pharmacological approaches for pre and intraoperative pupil dilatation. Present the variety of newest pupil expansion devices; critically review their advantages and possible limitations to be considered by the surgeon.

RECENT FINDINGS

The intracameral use of various mydriatic combinations augmenting the preoperative mydriatic instillations is currently gaining popularity in cataract surgery. Two main options are available: bolus injection of pharmacological agent or its constant irrigation during the phacoemulsification procedure. The former is aimed to expand the pupil, whereas the latter is mostly preventing the pupil from constriction. Introduction of femtosecond-assisted cataract surgery, apart from some benefits was followed by a variety of adverse effects including prostaglandin release into the aqueous humor causing pupil constriction. Preoperative administration of nonsteroidal anti-inflammatory drugs at least 1 day prior to surgery significantly decreases the chance of pupil constriction after laser energy is applied to the eye. However, pupil expansion devices may be needed in up to 10% of cases. Following the success of the Malyugin ring (MicroSurgical Technology Inc., Redmond, Washington, USA) several manufacturers introduced pupil expansion devices of various designs. They are differing with materials, pupillary margin fixation mechanisms, and easiness of manipulations during implantation and removal.

SUMMARY

Combination of proper use of pre and intraoperative pharmacological pupil dilatation protocols combined with pupil expander rings allow for well tolerated and effective cataract surgery in the vast majority of patients with insufficient mydriasis.