Risk factors for complications in resident-performed cataract surgery: A systematic review

Authors: Kang C, Lee MJ, Chomsky A, Oetting TA, Greenberg PB.

Geographical coverage: the USA, India, Iran, and Ireland

Sector: Cataract surgery

Sub-sector: Risk factors

Equity focus: Not reported

Study population: Patients with cataract

Review type: Effectiveness review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background:

Cataract surgery is one of the most common surgical procedures and a cornerstone of ophthalmology residency training. While generally safe, it carries a risk of vision-threatening complications such as vitreous loss and macular oedema, especially when performed by residents. Resident involvement has also been linked to longer operative times and higher reoperation rates. Previous studies have examined complication risks and the influence of case volume and risk stratification on outcomes, but findings have been inconsistent. A comprehensive understanding of contributing risk factors is needed to promote safer training practices in cataract surgery.

Objective

To evaluate the risk factors associated with intraoperative and postoperative complications in cataract surgeries performed by ophthalmology residents.

Main Findings

Fifteen studies published between 2004 and 2023 (with a combined 23,356 patients) met the inclusion criteria for this review. These studies were conducted in the USA (10 studies), India (3), Iran (1), and Ireland (1). Where reported, a total of 215 resident surgeons participated (training levels ranging from postgraduate year 2 through 4). The majority of cataract procedures performed by residents were phacoemulsification (approximately 80% of cases). The methodological quality of the included studies was assessed as high in five studies, moderate in eight studies, and low in two studies.

Complication rates in resident-performed cataract surgeries varied widely, ranging from 2.0% in straightforward cases to as high as 63.1% in a study focused on high-risk cases. Notably, the highest complication rate (63.1%) came from a single-institution study examining patients with pre-existing iris challenges – such as poorly dilating pupils, intraoperative iris prolapse, or intraoperative floppy iris syndrome – which are known to make surgery more difficult. In general, outcomes like final visual acuity and incidence of issues like cystoid macular oedema were comparable to those in attending-performed surgeries for typical cases, but risks spiked in the presence of certain risk factors.

Patient-related risk factors identified across the studies included:

• Older age of the patient (more advanced age was associated with higher complication risk).
• Systemic hypertension (patients with hypertension had a higher likelihood of surgical complications in some studies).
• History of prior vitrectomy (eyes that had previous retinal surgery were at greater risk due to altered ocular anatomy).
• Zonular pathology, such as pseudoexfoliation syndrome (which leads to weak lens support and increased chance of lens instability during surgery).
• Poor preoperative visual acuity (very low vision pre-surgery often correlates with dense cataracts that are harder to remove).
• Small pupil size (inadequate pupil dilation made the surgery more challenging and raised complication odds).
• Certain types of cataract (e.g., mature or white cataracts) that inherently pose more difficulty during removal.

Surgeon-related risk factors were also significant. These included:

• Level of training of the resident – Complication rates were higher with junior residents (those in earlier postgraduate years), and tended to decrease as residents became more experienced. In other words, a PGY-2 resident was more likely to encounter complications than a PGY-4 resident, highlighting the importance of experience.
• Surgeon’s handedness – Interestingly, one study noted that right-handed resident surgeons had a higher complication rate, possibly because certain maneuvers (especially in left eyes) can be more awkward for right-handed surgeons. This suggests that ergonomics and handedness could play a role in surgical risk, although this finding may not have been uniformly reported across all studies.

Intraoperative factors were also linked to higher complication rates:

• Lack of adequate supervision – Surgeries performed without a senior attending physician’s close supervision tended to have more errors.
• Long phacoemulsification time – Extended duration of phacoemulsification (indicating a difficult case or slower surgical technique) was associated with more frequent complications.
• High phacoemulsification power or aggressive settings – The use of high ultrasound power and certain torsional settings can stress the eye, and their use was identified as a risk factor for complications in resident cases, likely reflecting more challenging cataracts or suboptimal technique.

Methodology:

The searches were conducted in PubMed, Embase, Web of Science, and CINAHL for studies investigating risk factors for intraoperative or postoperative complications in cataract surgery performed by residents. The search covered all entries up to 22 September 2023 and was limited to English-language articles published in peer-reviewed journals. Studies were included if they examined factors associated with complications during surgery, or outcomes requiring a return to the operating theatre or referral to a specialist after cataract surgery by resident physicians.

Two reviewers independently screened all titles and abstracts against the eligibility criteria and then reviewed full texts of relevant papers. They extracted data and assessed the quality of each study using the GRADE framework (Grading of Recommendations, Assessment, Development and Evaluation). Any disagreements in selection or data extraction were resolved through discussion with a senior reviewer. The review did not report any manual search of conference proceedings or unpublished data. Given the variability in study designs and reported outcomes, the findings were synthesised in a narrative format rather than a quantitative meta-analysis.

Applicability/external validity:

The review incorporated studies from diverse regions and surgical settings, supporting the generalisability of risk factors for cataract surgery performed by residents. However, methodological limitations—such as retrospective designs, inconsistent complication definitions, and restricting to English-language studies—may limit applicability. Differences in resident training and case complexity across locations also affect external validity. The authors highlight the need for standardised, prospective research to better inform residency training and improve surgical safety.

Geographic focus:

No explicit geographic restrictions were placed on the search strategy. The 15 studies included in this review were conducted in a range of countries: the USA (10 studies), India (3 studies), Iran (1 study), and Ireland (1 study). This mix reflects a concentration of data from the United States alongside contributions from both Asia and Europe. The lack of studies from other regions (such as East Asia, Africa, or Latin America) means that additional data from those areas were not represented, possibly due to the language limitation or fewer publications on this topic from those regions.

Summary of quality assessment:

There is medium confidence in the review’s conclusions due to both strengths and limitations. Its rigorous multi-database search, clear inclusion criteria, dual-review process, and use of the GRADE tool provide transparency and thoroughness. However, it lacked a list of excluded studies, omitted grey literature, and limited itself to English-language publications, potentially missing relevant data. The risk of bias was assessed, but results weren’t analysed by study quality. Despite these factors, the review usefully identifies risk factors for resident-performed cataract surgeries, though findings should be applied with caution due to variability in evidence quality and training contexts.