Immediate Versus Delayed Sequential Bilateral Cataract Surgery: A Systematic Review

Introduction

Advances in cataract surgery have evolved over decades, progressing from earlier techniques such as intracapsular and extracapsular extraction to modern phacoemulsification. These ongoing improvements have resulted in surgical methods that significantly decrease patient complications and shorten recovery periods.¹ Cataracts remain a major cause of vision loss, and with an aging global population, the need for treatment is increasing. Approximately 65.2 million individuals are estimated to require cataract surgery.² Immediately Sequential Bilateral Cataract Surgery (ISBCS) offers a potential solution to address this growing demand. Several countries have integrated ISBCS into their standard cataract care. For example, it accounts for 80% of cataract surgeries in the Canary Islands and up to 50% in Finland. While ISBCS is performed in other nations like Sweden, the USA, the UK, Germany, Spain, Australia, India, Korea, and Chile, the adoption rate is currently lower.^3,4

Traditionally, cataract surgery has been performed on one eye at a time, with a delay between surgeries, known as Delayed Sequential Bilateral Cataract Surgery (DSBCS). However, advancements in surgical techniques, anesthesia, and infection control have led to the emergence of Immediately Sequential Bilateral Cataract Surgery (ISBCS), where both eyes are operated on during the same surgical session. ISBCS offers potential benefits, including reduced recovery time, fewer hospital visits, and lower healthcare costs, but it also raises concerns about the risk of bilateral complications, such as endophthalmitis, and logistical challenges in postoperative care.⁵ In the published literature, ISBCS has generally been offered to carefully selected patients, typically those with bilateral uncomplicated cataracts, absence of significant ocular comorbidities, and suitability for standardized surgical protocols, including strict aseptic measures and intracameral antibiotic use.⁵ While Delayed Sequential Bilateral Cataract Surgery (DSBCS) remains the more prevalent approach to cataract treatment, ISBCS is not yet widely considered standard practice.⁶ Exceptions to this general preference include specific cases, such as pediatric patients or those requiring general anesthesia.⁷ The limited availability of research comparing the benefits and risks of ISBCS and DSBCS makes it challenging to advocate for the widespread adoption of ISBCS as the new standard of care.

The debate over the safety and efficacy of ISBCS versus DSBCS has gained significant attention in ophthalmology. Proponents of ISBCS argue that modern protocols, including strict aseptic techniques and intracameral antibiotics, have minimized risks, making it a viable option for appropriately selected patients.⁸ On the other hand, critics emphasize the importance of maintaining DSBCS as the gold standard, citing its long-standing safety record and ability to mitigate the rare but serious risk of bilateral complications.⁹ Understanding the comparative outcomes of these two approaches are critical for optimizing patient care, improving resource utilization, and addressing growing demands for cataract surgery in aging populations.

Despite increasing interest in immediately sequential bilateral cataract surgery, its adoption remains variable across regions, largely due to concerns regarding bilateral complications and the absence of universal guideline endorsement. Existing evidence is derived from heterogeneous study designs and populations, making interpretation challenging. A systematic synthesis of comparative outcomes is therefore necessary to inform clinical practice and policy decisions.

Methodology

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive search was conducted in PubMed, Embase, Cochrane CENTRAL, and Web of Science using terms related to “cataract surgery,” “immediate sequential,” “same-day” and “delayed sequential.” No date restrictions were applied. Gray literature, including conference proceedings and clinical trial registries, was also searched. Reference lists of included studies were screened for additional eligible reports.

Two reviewers (SH, AJ) independently screened titles and abstracts, and full texts of potentially relevant studies were reviewed against predefined inclusion criteria. Disagreements were resolved by discussion or consultation with a third reviewer. Eligible studies included randomized controlled trials and comparative observational studies of adults undergoing cataract surgery, in which ISBCS was compared with DSBCS. Outcomes of interest included BCVA at specified follow-up intervals, intraoperative and postoperative complications, refractive accuracy, and patient-reported outcomes. Studies not directly comparing ISBCS with DSBCS, or those with insufficient outcome data, were excluded.

Data extraction was performed independently using a standardized form, capturing study design, sample size, patient demographics, surgical technique, intraocular lens type, and outcome measures. A qualitative synthesis of findings was undertaken. Meta-analysis was initially considered but not performed due to significant heterogeneity in study designs, populations, and outcome reporting. This study did not involve direct participation of human subjects. All data analyzed during this study are included in this published article and its references. Ethical approval and informed consent were not required as this work is based on previously published studies.

Results

Study Characteristics

The PRISMA flow diagram shows the systematic review process, beginning with the identification of 355 records through database searching across Medline (n=100), PubMed (n=152), Embase (n=67), and CINAHL (n=36). Following the removal of duplicates, a count of 272 records remained. Of these, 95 records were screened by title and abstract, resulting in the exclusion of 82 records that did not meet the inclusion criteria. The remaining 13 full-text articles were assessed for eligibility. Of these, 4 were excluded, because they focused on another outcome. The results of this systematic review were reported by the PRISMA guidelines [Figure 1]. The systematic review included a total of 9 studies published between 2011 and 2023, spanning the Netherlands, USA, Sweden, South Korea, Pakistan, Canada, Spain, and Finland. Different study designs were included, with three randomized controlled trials (RCTs), five retrospective cohort studies, and one systematic review [Table 1].

Table 1 Summary of Studies Comparing ISBCS and DSBCS

Figure 1 PRISMA flow diagram of study selection process. Notes: Flowchart illustrating the identification, screening, eligibility assessment, and inclusion of studies comparing immediate sequential bilateral cataract surgery (ISBCS) and delayed sequential bilateral cataract surgery (DSBCS) in this systematic review. A total of 355 records were identified through database searching, 272 records remained after duplicate removal, 95 records were screened by title and abstract, and 9 studies met the inclusion criteria for qualitative synthesis.

The sample sizes ranged from 298 patients in a single-center study to 95,606 eyes in a large-scale review. The study populations primarily consisted of patients undergoing cataract surgery, with a focus on comparing immediate sequential bilateral cataract surgery (ISBCS) and delayed sequential bilateral cataract surgery (DSBCS). The age of participants differed across studies, with some reporting mean ages of 73.5 years in Serrano-Aguilar et al¹¹ and others providing wide age ranges for ISBCS (21.4–100.6 years) and DSBCS (18.0–112.5 years) reflecting the inclusion of diverse patient demographics.¹⁷

The study populations were predominantly composed of patients with bilateral cataracts, with some studies specifically excluding complex cases or those with significant comorbidities. Retrospective cohort studies, such as those by Friling et al¹³ and Hong et al¹⁸ focused on large datasets from national registries or hospital records, providing insights into real-world outcomes. Geographically, the studies were distributed across high-income countries, with a notable concentration in the USA and Europe.

Pre-Operative Assessment

This systematic review examined the outcomes of immediate sequential bilateral cataract surgery (ISBCS) compared to delayed sequential bilateral cataract surgery (DSBCS) and unilateral cataract surgery. Several studies investigated the impact of ISBCS versus DSBCS on visual acuity and other outcomes. Herrinton et al¹⁵ reported preoperative utility scores and BCVA for both ISBCS and DSBCS groups, finding an average preoperative BCVA of 20/53 (0.42 logMAR) for ISBCS and 20/55 (0.44 logMAR) for DSBCS.

Spekreijse et al¹⁶ outlined a study protocol comparing ISBCS and DSBCS, including planned assessments of visual acuity and patient-reported outcomes. Dickman et al¹⁷ reported preoperative BCVA ranges for both ISBCS and DSBCS, with ISBCS ranging from 20/60 to 20/25 and DSBCS from 20/100 to 20/25. Serrano-Aguilar et al¹¹ and Sarikkola et al¹² also compared ISBCS and DSBCS using standard phacoemulsification procedures. Friling et al¹³ reported a lower percentage of patients with visual acuity of 20/200 or worse in the ISBCS group (10.03%) compared to the unilateral group (17.05%). Hong et al¹⁸ found statistically significant differences in postoperative logMAR BCVA, with the ISBCS group demonstrating better visual acuity (0.28 ± 0.30 logMAR) compared to the unilateral group (0.40 ± 0.45 logMAR). Siddiqui et al¹⁰ and Arshinoff et al⁵ investigated ISBCS procedures, including phacoemulsification and IOL implantation, but did not report comparative data.

Outcomes

The systematic review provides a comprehensive comparison between immediate sequential bilateral cataract surgery (ISBCS) and delayed sequential bilateral cataract surgery (DSBCS) across multiple outcomes, including visual acuity, refractive accuracy, complications, and patient-reported outcomes. Several studies, such as Spekreijse et al¹⁶ and Dickman et al¹⁷ reported that both ISBCS and DSBCS achieved similar refractive outcomes, with a high proportion of patients attaining target refraction within ±1.0 diopter. Herrinton et al¹⁵ and Hong et al¹⁸ further confirmed that postoperative best-corrected visual acuity (BCVA) was comparable between the two techniques, with ISBCS demonstrating a slightly higher percentage of eyes achieving 20/20 vision. The safety profile of ISBCS was also confirmed by Friling et al¹³ who found no significant difference in the incidence of postoperative endophthalmitis, the absolute risk of unilateral endophthalmitis with ISBCS was estimated at 0.019% and 0.029% respectively. No cases of bilateral endophthalmitis were reported.

Although risk factors such as capsule complications and the absence of intracameral antibiotics were associated with higher infection rates. Additionally, complications like cystoid macular edema and posterior capsular rupture were reported at similar rates in both surgical approaches.^10,11 However, some studies indicated a slightly higher incidence of intraoperative complications in DSBCS, as noted by Dickman et al¹⁷ Regarding patient-reported outcomes, studies like Sarikkola et al¹² and Dickman et al¹⁷ suggested a marginally higher post-operative utility score for ISBCS (0.97) compared to DSBCS (0.89), reflecting greater patient satisfaction.

Discussion

This systematic review analyzed data from nine studies published between 2011 and 2023 and provides insights into the comparative effectiveness and safety of immediate sequential bilateral cataract surgery (ISBCS) and delayed sequential bilateral cataract surgery (DSBCS). The heterogeneity observed in sample sizes, ranging from small single-center studies to large-scale reviews involving hundreds of thousands of eyes, as well as variability in patient demographics, may limit the ability to draw definitive conclusions applicable to all patients. However, this diversity also strengthens the review by encompassing a broader spectrum of patient populations and surgical practices, thereby enhancing its external validity. Most included studies were conducted in high-income healthcare systems with established infection-control protocols. Caution is therefore warranted when extrapolating these findings to low-resource settings, where surgical infrastructure and postoperative follow-up may differ.

Preoperative assessments, as documented by Herrinton et al¹⁵ and Dickman et al¹⁷ revealed generally comparable baseline visual acuity between the ISBCS and DSBCS groups. However, the wider ranges reported by Dickman et al¹⁷ suggest potentially greater variability in preoperative visual function within these groups. Establishing clear baseline characteristics is essential for accurately interpreting postoperative outcomes and discerning the true impact of each surgical approach. This is particularly important given that cataract surgery is primarily performed to improve visual function, and any comparison between techniques must account for pre-existing visual impairment.

In terms of refractive outcomes, the review indicates that both ISBCS and DSBCS achieve similar levels of accuracy, with a high proportion of patients attaining target refraction within ±1.0 diopter.^16,17 This finding is consistent with the broader literature on modern cataract surgery, which generally reports excellent refractive outcomes with contemporary techniques such as phacoemulsification and intraocular lens implantation.^14,19,20 The comparable refractive results suggest that both ISBCS and DSBCS can effectively correct refractive errors associated with cataracts.

Postoperative best-corrected visual acuity (BCVA) also appears to be similar between the two groups, with some studies suggesting a trend toward slightly better vision in the ISBCS group.^15,18 This subtle difference, while potentially clinically relevant, requires further investigation in larger, rigorously designed studies with standardized visual acuity testing protocols. It is important to determine whether this observed trend is statistically significant and whether it translates into meaningful improvements in patients’ daily lives.

The safety of ISBCS is a critical consideration, and this review offers reassuring evidence in this regard. Study Friling et al¹³ found no significant difference in the incidence of postoperative endophthalmitis between ISBCS and DSBCS. This finding is in line with large-scale studies and national registry data that have consistently demonstrated low rates of endophthalmitis after cataract surgery.^21,22 While the overall risk of endophthalmitis is low, it is crucial to emphasize that adherence to strict aseptic techniques and the use of intracameral antibiotics are essential to minimize this devastating complication in both ISBCS and DSBCS.²³

Regarding other complications, such as cystoid macular edema and posterior capsular rupture, the review suggests similar rates in both surgical approaches.^10,11 However, the observation of potentially higher intraoperative complication rates in DSBCS by Dickman et al¹⁷ warrants further investigation. It is important to understand the specific types of intraoperative complications that may be more common in DSBCS and to identify any modifiable risk factors.

Patient-reported outcomes, while assessed in only a few studies, hint at a potential advantage for ISBCS in terms of patient satisfaction.^12,17 This is likely attributable to the convenience of undergoing a single surgical procedure and the potential for faster visual rehabilitation. However, more research is needed to comprehensively evaluate the impact of ISBCS on various patient-reported outcomes, including quality of life, visual function, and overall satisfaction. Such studies should employ validated questionnaires and assess outcomes at multiple time points after surgery.

A limitation of this review is that a meta-analysis could not be conducted due to the heterogeneity of study designs, populations, and outcome measures. In addition, direct comparison between randomized controlled trials and observational studies was limited by heterogeneity in design and outcome reporting, and excluded studies were not analyzed as they did not meet predefined inclusion criteria. While this limits the ability to provide pooled quantitative estimates, the qualitative synthesis still offers meaningful insights into the comparative safety and effectiveness of ISBCS and DSBCS.

Conclusions and Recommendations

In conclusion, this systematic review indicates that immediate sequential bilateral cataract surgery (ISBCS) is a safe and effective alternative to delayed sequential bilateral cataract surgery (DSBCS) in carefully selected patients when strict safety protocols are followed. Patients with bilateral uncomplicated cataracts, those at risk of significant postoperative anisometropia, and individuals requiring general anesthesia may particularly benefit from this approach. Successful outcomes rely on appropriate patient selection, meticulous surgical technique, and adherence to established infection-control measures.

Future research should focus on standardizing outcome measures, particularly patient-reported outcomes, and on conducting larger, well-designed studies with longer follow-up to further define the role of ISBCS across different healthcare settings.