Comparison of simultaneous vs sequential pars plana vitrectomy and cataract surgery

In a subset of cataract patients, concomitant posterior segment disease warrants the combination of pars plana vitrectomy (PPV) and cataract surgery. Performing simultaneous PPV and cataract removal may be beneficial since hastened cataract progression is one of the most common complications in patients undergoing PPV [1, 2]. Other possible advantages of simultaneous surgery include the ability to avoid accidental lens touch with vitrectomy instruments, and enhanced visualization of the posterior segment for membrane peeling and vitrectomy [3]. Apart from minimizing the added risks of intra and postoperative complications associated with increased trips to the operating room, simultaneous surgery leads to decreased clinic visits and the associated burden on the patient and the family. On the other hand, simultaneous surgery may have drawbacks such as difficulty coordinating the schedules of vitreoretinal and cataract surgeons. Furthermore, a longer procedure time may cause intraoperative corneal edema, increased postoperative inflammation and intraocular pressure, higher rate of synechia, and cystoid macular edema [4‐6].

Performing a sequential PPV followed by cataract surgery can also have advantages, particularly in patients with vitreous hemorrhage that may have a decreased red reflex prior to PPV. Limitations to sequential surgery include visual acuity decline due to delayed onset cataract formation following PPV. Higher rates of intraoperative lens-iris diaphragm retropulsion syndrome and posterior capsule rupture in patients undergoing sequential surgery have also been reported [7, 8].

On occasion, a vitreoretinal pathology may be missed due to the poor view secondary to the cataract. Such patients will present to the vitreoretinal surgeon requiring PPV after their initial cataract surgery.

The purpose of this study was to compare intraoperative and postoperative outcomes of simultaneous versus sequential cataract surgery and PPV in terms of visual acuity, refractive outcomes, and intraoperative and postoperative complications.

We conducted a retrospective chart review of electronic health records (EHR) of patients undergoing PPV and cataract surgery between March 2016 and May 2021 at the Wilmer Eye Institute, Johns Hopkins Hospital. This study was approved by the institutional review board (IRB) at The Johns Hopkins University and conducted in accordance with the tenets of the Declaration of Helsinki. Written informed consent was waived by the IRB for this study. HIPAA regulations were followed.

We divided our study population into three different cohorts: PPV/CE were patients undergoing PPV followed by cataract surgery; PPV + CE were patients undergoing simultaneous PPV and cataract surgery; and CE/PPV were patients undergoing cataract surgery followed by PPV. Visual acuity (VA), refractive error, slit lamp and fundus examination findings, and surgical complications were assessed at pre-specified time points relative to the date of cataract surgery in PPV/CE, date of simultaneous surgery in PPV + CE, and date of cataract surgery in CE/PPV.

The electronic health record (Epic, Verona, WI, USA) was used to review patient demographics, history of prior surgeries, and intraoperative and postoperative complications. EHR review also included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SEQ), and intraocular pressure (IOP). Data recorded included the preoperative visit, as well as the 1 day (UDVA and IOP only), 1 week (UDVA and IOP only), 1-month (POM1), 3-month (POM3), 6-month (POM6), 1-year (POM12), and 2-year (POM24) postoperative visits. Snellen visual acuity was converted to logarithm of minimum angle of resolution (logMAR) for statistical analysis. Due to the duration of postoperative recovery, the 1-month and 3-month (POM 1 + 3), as well as the 6-month to 24-month (POM6-24) refractive data were combined, ensuring that only unique values were included.

Preoperative optical biometry was obtained by optical coherence interferometry (IOLMaster 500 or IOLMaster 700, Carl Zeiss Meditec, Jena, Germany). The Holladay I + II, SRK/T, and Barrett formulas were used to calculate the power of the implanted intraocular lens (IOL) in the majority of cases.

Refractive prediction error (RPE) was calculated as the difference between actual postoperative SEQ and the predicted SEQ. Visual acuity (UDVA + CDVA) and refractive outcomes were analyzed starting from the 1 + 3 month visit and ending at the 2-year follow-up visit. Only patients who received a three-piece foldable acrylic IOL (MA50BM; Alcon Laboratories, Inc, Fort Worth, TX, USA), or a one-piece acrylic IOL (Acrysof SA60AT, Acrysof IQ SN60WF, or Acrysof Aspheric SA60WF; Alcon Laboratories, Inc, Fort Worth, TX, USA), were eligible for inclusion in visual and refractive calculations (373 eyes). Patients who had prior history of refractive surgery (34 eyes) or had no clearly defined target refraction (13 eyes) were excluded from the UDVA, SEQ, and RPE calculations. Patients with a postoperative refractive target for near vision (between -1.0 to -7.0 diopters) were excluded from the UDVA and SEQ analysis (100 eyes). Patients without a minimum of one postoperative follow-up visit that included manifest refraction measurements (83 eyes) were excluded from SEQ and RPE calculations. Patients with history of endophthalmitis or with other vision-limiting diseases (e.g., macula off retinal detachment, severe diabetic retinopathy with macular involvement) were excluded from visual and refractive analysis.

To assess whether including patients with emergent retinal pathologies such as rhegmatogenous retinal detachment (RRD) or tractional retinal detachment (TRD) had a considerable impact on our visual acuity and refractive data results, we performed a sub-group analysis to include only those with non-emergent indications for surgery such as epiretinal membrane (ERM) and vitreous opacities (VO). SEQ and RPE analyses were only done on this subgroup to avoid incorrect refractive data in patients with poorer visual acuity.

The primary outcomes examined included both visual (UDVA, CDVA) and refractive (SEQ, RPE) variables. Secondary outcomes included intraoperative and postoperative complications, as well as IOP measurements. Binary variables are presented as N (%), and continuous variables are presented as mean ± standard deviation. Differences in proportions of binary variables were assessed using the chi-squared test. For continuous data, normality was determined using the Shapiro Wilk test (p < 0.05 was categorized as non-normal data). For data with a normal distribution, analysis of variance (ANOVA) was used to determine significant differences in means among the three comparison groups. For non-normal data, the nonparametric Kruskal–Wallis test was used in substitution of the ANOVA test. A p value cutoff of < 0.05 was defined as statistically significant. Statistical analysis was performed using STATA version 16.1 (StataCorp, College Station, Texas, USA).

This study compared the visual acuity and refractive outcomes, along with intraoperative and postoperative complication rates between PPV/CE, PPV + CE, and CE/PPV. In our patient population, VA outcomes and postoperative complications incidence did not vary across all three groups. An improvement in VA measurements was seen in all three groups when compared to baseline. Similar satisfactory refractive outcomes was seen in the ERM and VO sub-group.

The risk of developing lens opacification or progression of cataracts is recognized as one of the most frequent postoperative complications following PPV. Approximately, 68 to 100% of patients with vitrectomized eyes develop lens opacification or progression of their cataracts at their 2-year follow-up [1, 2, 9, 10]. This may be due to an increase in oxygen tension and subsequent oxidative damage to the lens following vitreous removal, accidental lens touch with intraocular instruments, and light toxicity induced by the operating microscope [3, 11, 12]. In our study, the timing of the sequential PPV/CE surgery highlighted the rapid progression of cataracts that is seen following PPV, with 62.8 and 93.8% of eyes having to undergo cataract surgery within 1 and 2 years following PPV, respectively (Fig. 1).

Patients who underwent CE within 6 months after PPV were older (63.5 ± 8.8 years) than those between 6 months and one year (mean age 60.3 ± 8.6 years), followed by those after one year ([mean age 57.8 ± 8.9 years]; P = 0.08). These findings were consistent with other reports that highlighted the impact of age on cataract progression following PPV, noting a 6- to 9- fold increase in cataract progression in patients older than 50 years in comparison to patients less than 50 years of age [10, 13]. Our findings may argue in favor of combined CEIOL and PPV in routine non-urgent cases, especially for patients older than 60 years of age.

In all three cohorts, improvement in UDVA and CDVA logMAR scores was observed in every follow-up visit when compared to baseline values. Although eyes in the PPV/CE group had better CDVA values, this only reached statistical significance in the POM1 and POM12 visits (P ≤ 0.001, P = 0.04, respectively).

We carried out a subgroup analysis to only include those with ERM or VO. Analysis of this subgroup did not show any significant difference in the UDVA or CDVA among the three groups. Based on the subgroup analysis, we believe that the sequence of the surgeries does not have a real impact on the postoperative UDVA or CDVA.

The SEQ and RPE outcomes were acceptable, with no significant difference seen in the PPV/CE and PPV + CE groups. Achieving a desirable refractive outcome is a challenge in patients undergoing PPV and cataract surgery, regardless of surgical timing. Some factors that must be taken into consideration when calculating postoperative refractive outcomes include anterior chamber depth (ACD), effective lens position (ELP), axial length (AL), use of intraocular gas tamponade, and type of formula used to determine IOL power. Obtaining an accurate AL measurement is regarded as the most influential step in calculating IOL power, with Olsen et al. [14] showing 54% of total prediction errors being caused by inaccuracies in measuring the AL. Obtaining an accurate AL measurement is more difficult and nuanced in patients with retinal pathology (such as RRD or significant ERM with macular edema) compared to the average population of cataract patients.

In our study, PCO was found to be the most frequent postoperative complication in all three cohorts. The frequency of PCO in PPV/CE was the highest, but was comparable in the PPV + CE and CE/PPV groups. This may be due to the fact that, in the PPV/CE group, there were higher incidents of posterior capsular fibrosis due to the previous PPV. Cataract surgeons may be more conservative in this patient population regarding thorough cleanup of the capsule at the end of the cataract surgery. This, in turn, may lead to higher rates of PCO. PCO has been identified as a common postoperative complication in 19.4 to 24.5% of eyes undergoing sequential PPV and cataract surgery [15, 16], and 21.5 to 23.5% of eyes following simultaneous phacovitrectomy [17, 18]. Various etiologies have been suggested for PCO development following simultaneous phacovitrectomy, including prolonged duration of surgery, extensive manipulation intraoperatively, and development of anterior chamber inflammatory reaction [19]. In a longitudinal cohort study investigating the development of PCO in patients undergoing phacovitrectomy with and without posterior capsulotomy, Shin et al. [20] noted a 6.4-fold increase in PCO incidence in the non-capsulotomy group in comparison to the capsulotomy group. Performing a posterior capsulotomy at the time of phacovitrectomy surgery may offer a better fundus view for the vitreoretinal surgery and reduce postoperative visits for management of PCO.

Strengths of this study include the large number of patient records reviewed in considerable detail, analysis of all three different possible combinations of PPV and cataract surgery, and two year follow-up duration. Limitations of this study include the retrospective study design. Also, determining axial length in the presence of retinal detachment is challenging and can be unreliable. Additionally, using spherical equivalent data did not allow us to determine the potential increased astigmatism due to the surgical procedure. Lastly, the procedures were performed by different surgeons with likely variations in surgical technique.

In conclusion, simultaneous PPV and cataract surgery demonstrated similar improvements in visual acuity and refractive outcomes. Simultaneous and sequential PPV/cataract surgery showed comparable intraoperative and postoperative complication profiles. As advanced patient age played a significant factor in the timing of sequential surgery and hastened cataract development requiring extraction following PPV, a simultaneous approach may be a suitable option for patients over the age of 60. Such an approach may avoid the likely deterioration in vision that arises with the progression of cataracts following PPV while eliminating the need for a second surgery.