Mydriatic insert and intracameral injections compared with mydriatic eyedrops in cataract surgery: controlled studies

Sodium Metabisulfite Inhibits Acanthamoeba Trophozoite Growth through Thiamine Depletion

Acanthamoeba keratitis (AK) is a severe infection of the cornea. Prevention and treatment are difficult due to the inefficacy of currently available compounds. The impact of many commonly used compounds for routine examinations of Acanthamoeba is unexplored but might offer insight useful in combatting AK. In this study, we demonstrate that sodium metabisulfite, a common preservation constituent of eye care solutions, was found to be active against Acanthamoeba trophozoites at concentrations lower than that commonly found in eye drops (IC50 0.03 mg/mL). We demonstrate that sodium metabisulfite depletes thiamine from growth medium and that Acanthamoeba is a thiamine auxotroph, requiring thiamine salvage for growth. The inhibitory effects of sodium metabisulfite can be overcome by thiamine supplementation. These results are consistent with the lack of key enzymes for thiamine biosynthesis in the genome of Acanthamoeba, an area which might prove exploitable using new or existing compounds. Indeed, this study highlights sodium metabisulfite as a useful inhibitor of Acanthamoeba castellanii trophozoites in vitro and that it acts, at least in part, by limiting available thiamine.

Safety of an Intracameral Fixed Combination for Mydriasis and Intraocular Anaesthesia During Cataract Surgery

Purpose

To compare the safety of a standardized, commercially available intracameral combination of mydriatics and anesthetic (ICMA) with a reference topical mydriatic regimen for cataract surgery.

Patients and Methods

The safety results from two international, randomized, controlled clinical studies were combined to compare ICMA at the beginning of cataract surgery (ICMA group) to the reference topical mydriatic regimen (reference group). Data were collected on ocular and systemic adverse events, corneal and anterior chamber examination, endothelial cell density, retinal thickness and visual acuity. Analysis was performed on a pooled safety set from both studies, preoperatively and up to 1 month postoperatively.

Results

342 patients received ICMA and 318 the reference topical regimen. Ocular adverse events were reported in 17.0% of patients in the ICMA group and 18.6% in the reference group. No difference was shown between groups in endothelial cell density (2208 ± 498 cells/mm2 for ICMA group versus 2241 ± 513 cells/mm2 for the reference group; p=0.547) and retinal thickness (change from baseline less than 50 µm in 94.7% versus 95.0% of patients, respectively) at 1 month postoperatively. At 1-day post-surgery, less patients in the ICMA group had moderate or severe (Grades 2 and 3) superficial punctate corneal staining (3.9% versus 7.0% for the reference group; p=0.064). Postoperatively, some ocular symptoms were also less frequently reported in the ICMA group. Best-corrected visual acuity increased in 96.0% of patients in the ICMA group and 95.8% in the reference group at 1 month.

Conclusion

ICMA injection at the beginning of cataract surgery was demonstrated to be safe and may also provide perioperative and postoperative advantages over the standard topical mydriatic regimen.

Intracameral phenylephrine for surgical mydriasis and intraoperative floppy-iris syndrome: systemic adverse effects and optimal dose

Phenylephrine, a potent sympathomimetic, induces mydriasis via iris dilator muscle contraction. Intracameral (IC) phenylephrine has been successfully used in cataract surgery for initial mydriasis, maintaining mydriasis, and management of intraoperative floppy-iris syndrome. Serious systemic adverse events (mainly cardiovascular) have been described with topical phenylephrine drops, but we found very little evidence of such adverse events associated with IC phenylephrine use. However, we suspect under-reporting of such adverse events, as they may instead be ascribed to anxiety, positioning, anesthesia, etc. Optimal dosage/concentrations for IC phenylephrine use in different purposes have not been fully studied. In the absence of robust evidence, we suggest that lower but effective IC phenylephrine concentrations are used: a lower concentration (0.31%), in conjunction with an anticholinergic and lidocaine, may be used for initial mydriasis. For management of intraoperative floppy-iris syndrome, 0.31% may be effective, though a higher concentration (1% to 1.25%) may be required.

Effectiveness of a Standardized Combination of Intracameral Mydriatics and Anaesthetic on Mydriasis during Cataract Surgery with Coexisting Diseases

PURPOSE

To examine the effectiveness of a standardized combination of intracameral mydriatics and anesthetic (SCIMA) on mydriasis in patients with coexisting diseases such as diabetes mellitus (DM) and pseudoexfoliation syndrome (PXF) during phacoemulsification.

METHODS

Patients with cataract were included in the study if they achieved pupil dilation diameter ≥ 6.0 mm after the administration of mydriatic eyedrops (ME) during the first visit (V1). During the second visit (V2), pupil size measurements were obtained for phacoemulsification surgery with SCIMA. Effective mydriasis was defined as a pupil diameter ≥ 6.0 mm just prior to capsulorhexis without the use of additional pupil dilating agents. The measurements after ME administration during V1 and after SCIMA use during V2 were compared.

RESULTS

103 patients (103 eyes) were divided into 3 groups: cataract and DM (n = 35), cataract and PXF (n = 32), and cataract without DM or PXF (n = 36). SCIMA administration allowed the achievement of effective mydriasis (≥6.0 mm) in all groups (n = 103; 100%). Mydriasis was significantly larger (p ≤ 0.001) after ME (7.3 mm) than after SCIMA (6.8 mm) administration.

CONCLUSIONS

Patients with cataract and such comorbidities as DM or PXF are likely to achieve effective pharmacological mydriasis during cataract phacoemulsification after SCIMA application. Mydriasis after ME is slower and larger, while SCIMA is faster.

Pupil diameter during cataract surgery after intracameral injection of the first ready-to-use combination of mydriatics and anaesthetic at the beginning of surgery in patients with a preoperative pupil diameter <6 mm

PURPOSE

We evaluated, in a real-life setting, the effect of Mydrane® (ready-to-use combination of tropicamide, phenylephrine hydrochloride and lidocaine, injected into the anterior chamber at the beginning of cataract surgery to induce mydriasis and intraocular anaesthesia) on the pupil diameter during cataract surgery in patients with a preoperative pupil diameter <6 mm after the use of topical mydriatics.

METHODS

We collected and analysed the data of 59 consecutive patients whose pupils dilated to a diameter <6 mm after the administration of mydriatic eye drops during the preoperative visit and who received Mydrane® during cataract surgery.

RESULTS

In the group of 59 patients with a preoperative pupil diameter <6 mm after topical mydriatics, cataract surgery was performed in 36 patients (61.0%) using only Mydrane® to obtain mydriasis, with no additional drug or medical device. The mean pupil diameters in this group (36 of 59) during the preoperative assessment after topical mydriatics and just before capsulorhexis when Mydrane® was injected during surgery were 5.1 ± 0.74 and 6.15 ± 1.14 mm. Additional drugs were used in 23 patients (39%). In this group, the mean pupil diameters after topical mydriatics and just before capsulorhexis using Mydrane® were 4.58 ± 1.06 and 5.6 ± 1.26 mm, respectively.

CONCLUSION

In a real-life setting, the mean pupil diameter achieved during cataract surgery after the intracameral injection of Mydrane® in patients with a preoperative pupil diameter <6 mm was over 1 mm larger than the mean pupil diameter after topical mydriatics, despite the trauma caused by the operation.

Efficacy of the intracamerally administered mydriatics for cataract surgery in patients with primary open-angle glaucoma

PURPOSE

To compare Mydrane®, mydriatic eye drops, and Mydriasert® in terms of pupil site stability, surgical time, visual field, and anterior chamber configuration modifications among patients with primary open-angle glaucoma (POAG) during cataract extraction surgery.

METHODS

Retrospective analysis of sixty patients with POAG and cataract who underwent elective cataract extraction. All patients underwent routine ophthalmic examinations, including automatic visual field examination, anterior chamber configuration, specular microscopy, and arterial blood pressure measurement prior to surgery, and 24 h and 30 days postoperatively. All cataract surgeries were video-recorded and all measurements were performed using a media player. Patients divided into groups 1, 2, and 3 (n = 20 in each group) received topical mydriatic eye drops, Mydriasert®, and an intracameral injection of Mydrane®, respectively, immediately after the first incision.

RESULTS

The mean change in pupil size from just before capsulorhexis to the end of surgery was 0.43 ± 0.09, 0.42 ± 0.08, and 0.36 ± 0.02 mm in groups 1, 2, and 3, respectively. The mean surgery duration was similar among all the groups. The baseline main cell density slightly decreased at 24 h and remained stable for 30 days postoperatively. The mean deviation and pattern standard deviation remained stable at 1 month after surgery. At 24 h after surgery, the nasal irido-corneal angle, temporal-iridocorneal angle, and anterior chamber depth increased compared with the baseline, remaining stable for 30 days after surgery.

CONCLUSIONS

Mydrane® produced adequate and stable mydriasis as effectively as produced by Mydriasert® and topical eye drops.

The safety of intracameral phenylephrine - A systematic review

Intracameral phenylephrine is commonly used in ophthalmic surgery as an alternative or supplement to mydriatic eye drops; hence, the importance of an evidence-based understanding of its risk-benefit profile is vital. We performed a comprehensive search in the PubMed, Google Scholar and Cochrane databases for published studies and case reports relating to the use of intracameral phenylephrine. Articles from 1958 to 2021 with the following keywords were used: "intracameral phenylephrine", "intracameral mydriatics", "phenylephrine", "pupil dilation", "complications". Intracameral phenylephrine was first used in 2003 as an alternative to topical mydriatics. Since then, it is being increasingly used with a variety of benefits, including rapid onset of mydriasis, and cost-effectiveness. There are various case reports, however, of ocular and systemic complications associated with intracameral phenylephrine such as generation of free radicals, toxic anterior segment syndrome, inconsistent pupillary dilation during surgery, and ventricular fibrillation. Alternatives to intracameral phenylephrine such as iris hooks, a Malyugin ring, intracameral epinephrine, and intracameral tropicamide were compared with intracameral phenylephrine. Intracameral phenylephrine appears to have a good safety profile.

Cost analysis of mydriasis strategies in cataract surgery care in the Netherlands

PURPOSE

To investigate the economic impact of an intracameral mydriatics and anesthetic agent (ICMA), topical mydriatics, and a mydriatic ocular insert in cataract patients.

SETTING

One public hospital in the Netherlands.

DESIGN

Prospective cohort study.

METHODS

Resource use data were collected from a healthcare and societal perspective on the day of surgery. Other outcome parameters included pupil size, surgeon satisfaction, postoperative pain, and Catquest-9SF scores.

RESULTS

A total of 368 patients were included, the mean costs per patient were €506 in the ICMA group (n = 122), €474 in the ocular insert group (n = 115), and €451 in the topical group (n = 131). The acquisition cost of ICMA was highest and resulted in longer surgical time. After correction for an imbalance in the distribution of fast and slow surgeons, the mean costs in the ocular insert and topical groups were comparable (€450 vs €444). There was no statistically significant difference in the use of additional mydriatics intraoperatively (P = .521). The mean ratio of pupil size to white-to-white distance was lower in the ICMA group during all intraoperative measurements (P < .001) but similar between the topical and ocular insert groups (P range .11-.82).

CONCLUSIONS

In the investigated setting in the Netherlands, ICMA was the most costly strategy. In addition, pupil size was lowest in the ICMA group but did not result in more additional mydriasis measures intraoperatively. The ocular insert was comparable with topical mydriatics in costs and pupil size. Implementation of ICMA could be considered when availability of nurses or physical space for perioperative care is limited.

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.

Stable Mydriasis After Intracameral Injection of a Combination of Mydriatics and Anesthetic During Cataract Surgery: A Real-Life, Multicenter Study

Purpose: To evaluate the effect of Mydrane (contains tropicamide, phenylephrine hydrochloride, and lidocaine hydrochloride) on time needed to induce mydriasis and mydriasis stability during cataract surgery. Methods: This was an observational, non-interventional, multicenter study of patients undergoing cataract surgery who received Mydrane for mydriasis and intraocular anesthesia. The study was conducted at seven ophthalmology departments at university hospitals in Poland. Patients admitted for cataract surgery within a 2-week period were asked to participate in the study. Patients whose pupils dilated to a diameter ≥6 mm after topical mydriatic administration during preoperative examinations were scheduled to receive Mydrane and included in the registry. No additional inclusion criteria were used. Patients' medical histories, examination results, and operative details were recorded. Pupil diameter was measured during surgery. Surgeons were asked to complete a Likert-based survey in parallel. Results: A total of 307 patients were enrolled. The mean pupil diameter was 7.0 ± 1.0 mm before capsulorhexis and 6.9 ± 1.2 mm before lens implementation. A pupil diameter ≥6 mm was achieved in 91.9% and 87.6% of patients before capsulorhexis and lens implantation, respectively. We asked 58 surgeons whether they agreed with the statement "Mydriasis was obtained in a short time after the administration of Mydrane"; the surgeons agreed with this statement after 92.2% (283/307) of surgeries. In addition, after 88.2% of surgeries, the surgeons agreed with the statement "Mydriasis was stable after the administration of Mydrane." Conclusions: Mydriasis was rapidly and stably obtained after Mydrane injection, as demonstrated by pupil diameter measurements during surgery and surgeons' feedback.

Protecting the Ocular Surface at the Time of Cataract Surgery: Intracameral Mydriatic and Anaesthetic Combination Versus A Standard Topical Protocol

Introduction

An intracameral mydriatic and anaesthetic combination has been approved for injection into the anterior chamber in order to provide rapid and stable mydriasis and sustained intraocular anaesthesia during cataract surgery.

Methods

In this prospective study, conducted at the Eye Clinic, University of Florence, Italy, we compared phacoemulsification using the standard mydriatic-anaesthetic eye-drop protocol with that using the standard protocol in terms of corneal changes, ocular surface parameters and visual quality. Sixty patients (60 eyes) were included in the study, with 30 eyes receiving Mydrane®, a novel injectable intracameral solution, during phacoemulsification (Mydrane protocol, MP) and 30 eyes receiving the standard mydriatic-anaesthetic eye drops (standard protocol, SP). The following parameters were assessed using in vivo confocal microscopy (IVCM): central corneal thickness (CCT); flare and cells in the aqueous humor (Flare); keratocyte activation (KA), Langerhans’ cell density (LCD), nerve fibre density (NFD) and endothelial cell density (ECD). The Ocular Surface Disease Index (OSDI) score, tear breakup time (TBUT) and Schirmer’s test I (STI) were also evaluated. The Optical Scattering Index (OSI) and its standard deviation (OSI-SD) were assessed using the Optical Quality Analysing System (Visiometrics SL, Terrassa, Spain).

Results

In the MP group, CCT, Flare, KA and LCD values returned to baseline values within 15 postoperative days. The mean ECD and NFD decreased significantly in both groups from baseline at all follow-up assessments, with no statistically significant difference between groups. TBUT returned to the preoperative level at postoperative day 15 in the MP group. OSDI scores and STI were significantly worse in both groups at all follow-up assessments compared to baseline. At postoperative day 15 OSI and OSI-SD values were significantly better in the MP group than in the SP group.

Conclusions

The use of Mydrane during cataract surgery showed a good safety profile and few toxic side effects, ensuring better optical quality and tear film stability.

In Situ Gelling Ophthalmic Drug Delivery System for the Optimization of Diagnostic and Preoperative Mydriasis: In Vitro Drug Release, Cytotoxicity and Mydriasis Pharmacodynamics

Mydriasis is required prior to many eye examinations and ophthalmic surgeries. Nowadays, phenylephrine hydrochloride (PHE) and tropicamide (TPC) are extensively used to induce mydriasis. Several pharmaceutic dosage forms of these two active ingredients have been described. However, no optimal therapeutic strategy has reached the market. The present work focuses on the formulation and evaluation of a mucoadhesive ion-activated in situ gelling delivery system based on gellan gum and hydroxyethylcellulose (HEC) for the delivery of phenylephrine and tropicamide. First, in vitro drug release was studied to assess appropriate sustained drug delivery on the ocular surface region. Drug release mechanisms were explored and explained using mathematical modeling. Then, in situ gelling delivery systems were visualized using scanning electron microscopy illustrating the drug release phenomena involved. Afterward, cytotoxicity of the developed formulations was studied and compared with those of commercially available eye drops. Human epithelial corneal cells were used. Finally, mydriasis intensity and kinetic was investigated in vivo. Mydriasis pharmacodynamics was studied by non-invasive optical imaging on vigilant rabbits, allowing eye blinking and nasolacrimal drainage to occur physiologically. In situ gelling delivery systems mydriasis profiles exhibited a significant increase of intensity and duration compared with those of conventional eye drops. Efficient mydriasis was achieved following the administration of a single drop of in situ gel reducing the required amount of administered active ingredients by four- to eight-fold compared with classic eye drop regimen.

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.

Antiseptic effect of low-concentration povidone-iodine applied with a depot device in the conjunctiva before cataract surgery

Purpose

Examine the antiseptic effect of long-term low-concentration (0.3%) povidone-iodine (PI) before cataract surgery.

Setting

St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.

Design

Single-armed prospective clinical study.

Methods

Repeated measure of preoperative conjunctival samples from 51 participants were obtained the day before surgery (T1), the day of surgery after treatment with ophthalmic NSAID (T2), and after additional treatment with low-concentration PI (T3) given by placing a pledget soaked in a mix of eye-drops in fornix inferior for 20 min.

Results

Before surgery, and before any type of treatment (T1), bacterial growth (≥5 BC) in the conjunctiva was identified in 36 (66.7%) of the participants. After treatment with ophthalmic NSAID (T2), and after additional treatment with low-concentration PI (T3), bacteria were identified in 31 (60.8%) and 12 (23.4%) participants, respectively. All except one of the participants with a measurable change from T2 to T3 (n = 31, 60.8% of total sample), experienced a decrease in number of bacterial colonies (BC) after treatment with low-concentration PI (96.8 vs. 3.2%, p < 0.001). A complete removal of bacteria was seen in 20 (n = 31, 64,5%) of the colonized participants after treatment with PI.

Conclusions

Preoperative treatment with long-term, low-concentration PI applied via a depot device in fornix inferior, seem to be an easy and effective way to reduce the number of BC in the conjunctiva.

Assessing the accuracy of intracameral phenylephrine preparation in cataract surgery

PURPOSE

Unpreserved phenylephrine is often used as an off-licence intracameral surgical adjunct during cataract surgery to assist with pupil dilation and/or stabilise the iris in floppy iris syndrome. It can be delivered as a neat 0.2 ml bolus of either 2.5 or 10% strength, or in a range of ad-hoc dilutions. We wished to assess the accuracy of intracameral phenylephrine preparation in clinical practice.

METHODS

Phenylephrine 0.2 ml was analysed both neat (2.5 and 10%) and in diluted form (ratio of 1:1 and 1:3). Samples were analysed using the validated spectrophotometric method.

RESULTS

A total of 36 samples were analysed. The standard curve showed linearity for phenylephrine (R² = 0.99). Wide variability was observed across all dilution groups. There was evidence of significant differences in the percentage deviations from intended results between dilutions (p < 0.001). Mean percentage deviation for 1:3 dilution was significantly greater than neat (p = 0.003) and 1:1 dilution (p = 0.001). There was no evidence of a significant difference between 1:1 and neat (p = 0.827).

CONCLUSIONS

Current ad-hoc dilution methods used to prepare intracameral phenylephrine are inaccurate and highly variable. Small volume 1 ml syringes should not be used for mixing or dilution of drug. Commercial intracameral phenylephrine products would address dosage concerns and could improve surgical outcomes in cases of poor pupil dilation and/or floppy iris syndrome.

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.

Stability of Adrenaline in Irrigating Solution for Intraocular Surgery

Intraocular irrigating solution containing 1 µg/mL adrenaline is widely used during cataract surgery to maintain pupil dilation. Prepared intraocular irrigating solutions are recommended for use within 6 h. After the irrigating solution is admistered for dilution, the adrenaline may become oxidized, and this may result in a decrease in its biological activity. However, the stability of adrenaline in intraocular irrigating solution is not fully understood. The aim of this study was to evaluate the stability of adrenaline in clinically used irrigating solutions of varying pH. Six hours after mixing, the adrenaline percentages remaining were 90.6%±3.7 (pH 7.2), 91.1%±2.2 (pH 7.5), and 65.2%±2.8 (pH 8.0) of the initial concentration. One hour after mixing, the percentages remaining were 97.6%±2.0 (pH 7.2), 97.4%±2.7 (pH 7.5), and 95.6%±3.3 (pH 8.0). The degradation was especially remarkable and time dependent in the solution at pH 8.0. These results indicate that the concentration of adrenaline is decreased after preparation. Moreover, we investigated the influence of sodium bisulfite on adrenaline stability in irrigating solution. The percentage adrenaline remaining at 6 h after mixing in irrigating solution (pH 8.0) containing sodium bisulfite at 0.5 µg/mL (concentration in irrigating solution) or at 500 µg/mL (concentration in the undiluted adrenaline preparation) were 57.5 and 97.3%, respectively. Therefore, the low concentration of sodium bisulfite in the irrigating solution may be a cause of the adrenaline loss. In conclusion, intraocular irrigation solution with adrenaline should be prepared just prior to its use in surgery.