Randomised controlled single-blind study of conventional versus depot mydriatic drug delivery prior to cataract surgery

Pharmacologic interventions for mydriasis in cataract surgery

BACKGROUND

Cataract surgery is one of the most common surgical procedures performed worldwide. Achieving appropriate intraoperative mydriasis is one of the critical factors associated with the safety and performance of the surgery. Inadequate pupillary dilation or constriction of the pupil during cataract surgery can impair the surgeon's field of view and make it difficult to maneuver instruments.

OBJECTIVES

To evaluate the relative effectiveness of achieving pupillary dilation during phacoemulsification for cataract extraction using three methods of pupillary dilation: topical mydriatics, intracameral mydriatics, or depot delivery systems. We also planned to document and compare the risk of intraoperative and postoperative complications following phacoemulsification for cataract extraction, as well as the cost-effectiveness of these methods for pupillary dilation.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Trials Register) (2021, Issue 1); Ovid MEDLINE; Embase.com; PubMed; Latin American and Caribbean Health Sciences Literature Database (LILACS); ClinicalTrials.gov; and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 22 January 2021.

SELECTION CRITERIA

We included only randomized controlled trial (RCTs) in which participants underwent phacoemulsification for cataract extraction.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology.

MAIN RESULTS

We included a total of 14 RCTs (1670 eyes of 1652 participants) in this review. Of the 14 trials, 7 compared topical versus intracameral mydriatics, 6 compared topical mydriatics versus depot delivery systems, and 1 compared all three methods. We were unable to calculate overall estimates of comparative effectiveness for most outcomes due to statistical heterogeneity among the estimates from individual studies or because outcome data were available from only a single study. Furthermore, the certainty of evidence for most outcomes was low or very low, due primarily to imprecision and risk of bias. Comparison 1: topical mydriatics versus intracameral mydriatics Four RCTs (739 participants, 757 eyes) of the 8 RCTs that had compared these two methods reported mean pupillary diameters at the time surgeons had performed capsulorhexis; all favored topical mydriatics, but heterogeneity was high (I2 = 95%). After omitting 1 RCT that used a paired-eyes design, evidence from three RCTs (721 participants and eyes) suggests that mean pupil diameter at the time of capsulorhexis may be greater with topical mydriatics than with intracameral mydriatics, but the evidence is of low certainty (mean difference 1.06 mm, 95% confidence interval (CI) 0.81 mm to 1.31 mm; I2 = 49%). Four RCTs (224 participants, 242 eyes) reported mean pupillary diameter at the beginning of cataract surgery; the effect estimates from all trials favored topical mydriatics, with very low-certainty evidence. Five RCTs (799 participants, 817 eyes) reported mean pupillary diameter at the end of cataract surgery. Data for this outcome from the largest RCT (549 participants and eyes) provided evidence of a small difference in favor of intracameral mydriasis. On the other hand, 2 small RCTs (78 participants, 96 eyes) favored topical mydriatics, and the remaining 2 RCTs (172 participants) found no meaningful difference between the two methods, with very low-certainty evidence. Five RCTs (799 participants, 817 eyes) reported total intraoperative surgical time. The largest RCT (549 participants and eyes) reported decreased total intraoperative time with intracameral mydriatics, whereas 1 RCT (18 participants, 36 eyes) favored topical mydriatics, and the remaining 3 RCTs (232 participants) found no difference between the two methods, with very low-certainty evidence. Comparison 2: topical mydriatics versus depot delivery systems Of the 7 RCTs that compared these two methods, none reported mean pupillary diameter at the time surgeons performed capsulorhexis. Six RCTs (434 participants) reported mean pupillary diameter at the beginning of cataract surgery. After omitting 1 RCT suspected to be responsible for high heterogeneity (I2 = 80%), meta-analysis of the other 5 RCTs (324 participants and eyes) found no evidence of a meaningful difference between the two methods, with very low-certainty evidence. Three RCTs (210 participants) reported mean pupillary diameter at the end of cataract surgery, with high heterogeneity among effect estimates for this outcome. Estimates of mean differences and confidence intervals from these three RCTs were consistent with no difference between the two methods. A fourth RCT reported only means for this outcome, with low-certainty evidence. Two small RCTs (118 participants) reported total intraoperative time. Surgical times were lower when depot delivery was used, but the confidence interval estimated from one trial was consistent with no difference, and only mean times were reported from the other trial, with very low-certainty evidence. Comparison 3: Intracameral mydriatics versus depot delivery systems Only one RCT (60 participants) compared intracameral mydriatics versus depot delivery system. Mean pupillary diameter at the time the surgeon performed capsulorhexis, phacoemulsification time, and cost outcomes were not reported. Mean pupil diameter at the beginning and end of cataract surgery favored the depot delivery system, with very low-certainty evidence. Adverse events Evidence from one RCT (555 participants and eyes) comparing topical mydriatics versus intracameral mydriatics suggests that ocular discomfort may be greater with topical mydriatics than with intracameral mydriatics at one week (risk ratio (RR) 10.57, 95% CI 1.37 to 81.34) and one month (RR 2.51, 95% CI 1.36 to 4.65) after cataract surgery, with moderate-certainty evidence at both time points. Another RCT (30 participants) reported iris-related complications in 11 participants in the intracameral mydriatics group versus no complications in the depot delivery system group, with very low-certainty evidence. Cardiovascular related adverse events were rarely mentioned.

AUTHORS' CONCLUSIONS

Data from 14 completed RCTs were inadequate to establish the superiority of any of three methods to achieve mydriasis for cataract surgery, based on pupillary dilation at different times during the surgery or on time required for surgery. Only one trial had a sample size adequate to yield a robust effect estimate. Larger, well-designed trials are needed to provide robust estimates for the comparison of mydriasis approaches for beneficial and adverse effects.

Mydriatics release from solid and semi-solid ophthalmic formulations using different in vitro methods

The aim of the present paper was the development of semi-solid (hydrogels) and solid (film) ophthalmic formulations for the controlled release of two mydriatics: phenylephrine and tropicamide. The formulations - based on polyvinylalcohol and hyaluronic acid - were characterized, and release studies were performed with three different in vitro set-ups, i.e. Franz-type diffusion cell, vial method and inclined plane; for comparison, a solution and a commercial insert, both clinically used to induce mydriasis, were evaluated. Both gels and film allowed for a controlled release of drugs, appearing a useful alternative for mydriatics administration. However, the release kinetic was significantly influenced by the method used, highlighting the need for optimization and standardization of in vitro models for the evaluation of drug release from ophthalmic dosage forms.

Phacoemulsification without preoperative topical mydriatics: induction and sustainability of mydriasis with intracameral mydriatic solution

Context:

Intracameral mydriatic solution can eliminate the disadvantages of repeated eye drop instillation regimen and provide adequate mydriasis for phacoemulsification with added advantages.

Aims:

Evaluating the role of intracameral irrigating solution (0.5% lignocaine + 0.001% epinephrine) in initiating and maintaining the pupillary mydriasis during phacoemulsification. Secondary aims were to observe the effect of surgical time, nucleus density and ultrasound time on mydriasis during the procedure.

Settings and Design:

The study is a prospective interventional case series, conducted at tertiary care institution.

Materials and Methods:

Thirty patients underwent phacoemulsification under topical anesthesia for visually significant cataract. Pupillary dilatation was achieved by intracameral irrigation of mydriatic solution alone. Pupillary diameter was measured serially during surgery and ultrasound time and total surgical time were noted.

Statistical Analysis Used:

Paired samples student–t test was done to compare means. Spearman correlation coefficient was used to study the effect of various parameters on mydriasis.

Results:

Thirty eyes completed the study. The pupil size increased from 2.1 mm (Range 2-3.5 mm SD ± 0.32) to 6.9 mm (Range 5-9 mm SD ± 1.02) in 30 seconds time after intracameral mydriatic solution delivery, and was 7.0 mm (Range 3.5 - 9 mm SD ± 0.20) at the end of surgery. Duration of surgery, grade of nucleus and ultrasound time had statistically insignificant effect on mydriasis.

Conclusions:

Intracameral solution containing 0.5% lignocaine and 0.001% epinephrine provides rapid mydriasis which is adequate for safe phacoemulsification and is unaffected by other parameters.

Pupil dilation using drops vs gel: a comparative study

Purpose

To compare the efficacy in pupil dilation and degree of discomfort between topical instillation of mydriatic drops and gel.

Methods

The study included 60 patients with no previous ocular history of trauma and surgery. One eye was dilated with two drops (tropicamide 0.5% and phenylephrine 10%), and the other with one drop of gel (tropicamide 0.5%+phenylephrine 5%). Pupil size was measured by a Colvard pupillometer at baseline and 5, 15, 30, and 45 min following instillation. Pain upon instillation was measured by visual analog scale (VAS).

Results

There was no difference in pupil size at baseline. Use of the gel achieved greater mydriasis than drops (P=0.01), and was also associated with lower pain scores (P=0.003). In diabetic patients, pupil size was smaller at baseline and following instillation of drops and gel. Use of the gel achieved an even greater degree of pupil dilation in this subset of patients than drops (P=0.019).

Conclusions

Gel formulation achieved significantly greater pupil dilation than drops, despite a lower concentration of phenylephrine, and was also associated with significantly lower patient discomfort. This study is the first report of improved mydriatic efficacy in diabetic patients.

Comparing the efficacy of mydriatic cocktail-soaked sponge and conventional pupil dilation in patients using tamsulosin - a randomized controlled trial

BACKGROUND

A strong association exists between the use of tamsulosin and the occurance of intraoperative floppy iris syndrome. Several methods were advocated to overcome the progressive intraopertive miosis.Our purpose was to investigate the effect of a mydriatic-cocktail soaked cellulose sponge on perioperative pupil diameter in tamsulosin-treated patients undergoing elective cataract surgery.

METHODS

Patients using tamsulosin were dilated either with mydriatic-cocktail soaked sponge (group 1) or with conventional eyedrop regimen (group 2). Control patients not taking any α1 adrenergic receptor inhibtors were also dilated with mydriatic sponge (group 3).In all groups oxybuprocain 0.4%, cocain 4%, tropicamide 1%, phenylephrine 10%, diclophenac 0.1% along with chloramphenicol 0.5% were used preoperatively.Pupil diameter (mm) was measured preoperatively, after nucleus delivery, and before IOL implantation. Adverse effects associated with the use of sponge, minor and major intraoperative complications, the use of iris retractors and operation time were recorded.Differences in general between groups were analyzed with a one way analysis of variance (ANOVA); differences between groups in proportions were assessed by Fisher's exact test.

RESULTS

Mean pupil diameter (mm) was preopertively: 7.52 ± 1.21, 7.30 ± 1.55 and 7.99 ± 0.96 (ANOVA: p = 0.079); after nucleus delivery: 6 ± 1.20, 6.29 ± 1.12 and 6.52 ± 0.81 (ANOVA: p = 0.123); before IOL implantation: 5.46 ± 1.06, 5.83 ± 1.09 and 6.17 ± 0.89 (ANOVA: p = 0.0291).No adverse effect related to sponge use was detected. Frequency of minor complications, and iris hook use was similar in the two tamsulosin treated group. Operation time did not differ significantly in the three groups.

CONCLUSION

We have found that using a mydriatic cocktail-soaked wick - an alternative way to achieve intraoperative mydriasis for cataract surgery - was as effective and safe as the conventional repeated eyedrops regiment for tamsulosin treated patients.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN37834752.

Comparative study measuring the dilatory effect of a mydriatic device (Mydriasert(®)) versus topical drops

AIM

To compare the mydriatic efficacy of an ophthalmic insert (Mydriasert, MY) versus phenylephrine and tropicamide (PT) eye drops.

METHODS

Two controlled, prospective, randomized, single-blind studies were performed. In the first study, a total of 80 eyes from 40 outpatient-clinic patients were analyzed. PT drops were applied to the right eye, and a MY device was inserted in the left eye for 30min. Time until maximal pupil dilation for each eye was then assessed. In the second study, 80 eyes from 80 patients undergoing cataract surgery were analyzed. Pupil dilation was achieved using either PT drops three-times for one hour prior to surgery (40 patients), or a MY device was inserted one hour prior to surgery (40 patients).

RESULTS

In the first study, MY achieved superior mydriasis compared to PT eye drops at 90min (9.04±1.33mm vs 8.78±1.37mm, P=0.012). However MY took longer than PT drops to achieve maximal dilation, and mydriasis was inferior in eyes with MY compared to PT drops at 30min (7.21±1.73mm vs 8.22±1.43mm, P<0.001), the two groups only becoming similar by 60min (8.85±1.44mm vs 8.71±1.27mm, P=0.236). In the second study, both MY and PT achieved similar levels of mydriasis at the beginning of surgery (8.75±0.76mm with MY vs 8.77±0.63mm with PT), and also at the end of surgery (7.96±1.06mm with MY vs 8.32±0.72mm with PT), with no significant difference between groups (P=0.08). MY was well tolerated and cardiovascular effects were not influenced by dilation method.

CONCLUSION

MY could be a safe and efficacious alternative for mydriasis. The mydriatic effect of MY is as good as conventional PT eye drops after 60min, and is superior after 90min. MY also maintains good pupil dilation during cataract surgery.

Lower conjunctival fornix packing for mydriasis in premature infants: a randomized trial

Objective

To compare the mydriatic effect of lower conjunctival fornix packing to conventional instillation of eyedrops containing 2.5% phenylephrine and 1% tropicamide in premature infants undergoing examination for retinopathy of prematurity.

Methods

The patients were randomized to receive either conventional instillation of mydriatic drops or lower conjunctival fornix packing in one eye and the alternate method in the fellow eye. For the eyes receiving lower conjunctival fornix packing (study group), one small piece of the cotton wool soaked with one drop of 2.5% phenylephrine and one drop of 1% tropicamide was packed in the lower conjunctival fornix for 15 minutes. For the eyes receiving the conventional instillation (control group), 2.5% phenylephrine and 1% tropicamide were alternately instilled every 5 minutes for two doses each. Horizontal pupil diameter was measured with a ruler in millimeters 40 minutes later.

Results

The mean dilated pupil diameter in study group and control group were 5.76 ± 1.01 mm and 4.50 ± 1.08 mm, respectively. This difference was statistically significant (P < 0.05).

Conclusion

The dilated pupil diameter after receiving the lower conjunctival fornix packing was larger than conventional instillation with a statistically significant difference. We recommended the packing method to dilate the preterm infant pupil, especially if the pupil is difficult to dilate.