Clinical Outcomes of the Eight-Chop Technique in White Cataract: A Retrospective Case Seriese

1. Introduction

White cataracts represent one of the most technically challenging conditions in modern cataract surgery [1,2,3,4]. They are characterized by complete opacification of the crystalline lens with an absent or markedly reduced red reflex, which precludes preoperative visualization of the lens nucleus and posterior capsule. As a result, surgeons must manage increased risks of anterior capsule tear, posterior capsule rupture, zonular instability, and corneal endothelial damage during phacoemulsification [1,3,4]. Unlike ordinary cataracts, white cataracts do not allow accurate preoperative assessment of nuclear hardness. Surgical difficulty is therefore determined intraoperatively, often after capsulorrhexis and partial debulking of the lens material. Furthermore, these eyes frequently exhibit elevated intralenticular pressure, fragile capsules, and weakened zonules, all of which contribute to an increased incidence of intraoperative complications [1,4,5,6]. Consequently, safe and efficient nucleus management remains a critical issue in the surgical treatment of white cataracts.

Various surgical techniques have been proposed to address the challenges associated with white cataracts, including extracapsular cataract extraction, divide-and-conquer, phaco-chop, and stop-and-chop techniques [3,4,7,8,9,10]. However, many of these techniques rely on initial phacoemulsification of an undivided hard nucleus, which can transmit substantial stress to the posterior capsule and zonules. This limitation is particularly problematic in white cataracts, where capsular and zonular fragility is frequently encountered [1,3]. Therefore, an ideal surgical technique for white cataracts should enable reliable nucleus fragmentation while minimizing ultrasound energy, fluid usage, and mechanical stress on intraocular structures. The eight-chop technique was developed to address these specific challenges by mechanically dividing the lens nucleus into eight small fragments prior to emulsification [11]. Unlike conventional prechop techniques, which typically divide the nucleus into four sections, the eight-chop technique consistently achieves eight-piece nuclear fragmentation using specialized instruments designed for precise and controlled mechanical splitting. This approach allows subsequent phacoemulsification and aspiration to be performed efficiently at the iris plane with reduced ultrasound energy and fluidics, thereby potentially minimizing corneal endothelial damage and intraoperative complications.

In eyes with white cataracts, successful completion of continuous curvilinear capsulorhexis (CCC) is a critical initial step, which requires adequate staining and visualization of the anterior lens capsule [6,12]. The use of brilliant blue G (BBG) has been shown to improve capsular visualization and to enable complete capsulorhexis without evidence of ocular toxicity in experimental models [13]. However, previous clinical studies involving eyes with white cataracts have primarily employed trypan blue for anterior capsule staining, and the use of BBG in this setting has not been reported [1,4]. Thus, the clinical applicability of BBG for anterior capsule staining in eyes with white cataracts remains to be elucidated.

Although the eight-chop technique has been reported to be effective for hard cataracts [11,14], evidence regarding its performance specifically in white cataracts remains limited. Moreover, few studies have systematically evaluated intraoperative efficiency, corneal endothelial outcomes, intraocular pressure changes, and visual recovery in white cataracts according to intraoperative nuclear hardness. Given that nuclear hardness is a major determinant of surgical difficulty and postoperative outcomes, such stratified analyses are essential for accurately assessing the clinical value of surgical techniques in this setting. Therefore, the purpose of the present study was to evaluate the safety and efficacy of the eight-chop technique in eyes with white cataracts by analyzing intraoperative parameters, corneal endothelial cell density and morphology, intraocular pressure, visual outcomes, and surgical complications. Furthermore, outcomes were compared according to intraoperatively assessed nuclear hardness to clarify the applicability of the eight-chop technique across a wide spectrum of lens hardness in white cataracts.

2. Materials and Methods

2.1. Ethical Considerations

This retrospective, single-center, single-surgeon, single-arm observational study included eyes of patients with white cataracts who underwent phacoemulsification and posterior chamber intraocular lens (IOL) implantation between January 4, 2010, and March 25, 2025. The study was conducted in accordance with the tenets of the Declaration of Helsinki and was approved by the Ethics Committee of Sato Eye Clinic (the approval number: 20091101). Written informed consent was obtained from all patients prior to enrollment. Brilliant Blue G (BBG), which has been approved for human intraocular use in the European Union and is currently under regulatory review by the Ministry of Health, Labour and Welfare in Japan, was used at a concentration of 0.025% for anterior capsule staining in the present study. Because the study was initiated on January 4, 2010, BBG was permitted for use at that time with approval from the institutional review board, which was obtained prior to patient enrollment.

2.2. Study Population

Patients who presented to our institution with white cataracts were enrolled in this study. In this study, white cataract was defined as a cataract in which the entire lens appeared white and opaque on slit-lamp examination, with absent or markedly reduced red reflex. Eyes with corneal disease or corneal opacity, uveitis, a history of ocular trauma, or previous intraocular surgery were excluded from the study.

2.3. Preoperative Assessment

All patients underwent comprehensive preoperative ophthalmic examinations. The preoperative assessment included slit-lamp biomicroscopy and fundus examination. Best-corrected visual acuity (BCVA) was measured using a Snellen visual acuity chart, and intraocular pressure (IOP) was measured using standard tonometric methods. Corneal endothelial cell density (CECD, cells/mm²), central corneal thickness (CCT), the coefficient of variation in cell size (CV), and the percentage of hexagonal cells (PHC) were evaluated using a non-contact specular microscope (EM-3000; Topcon Corporation, Tokyo, Japan). Axial length and anterior chamber depth were assessed using a swept-source optical coherence tomography biometer with a wavelength of 1060 nm (OA-2000; TOMEY, Tokyo, Japan) when available. In earlier cases, axial length was measured using other commercially available biometry devices, and anterior chamber depth was not consistently assessed in all patients.

2.4. Classification of Nuclear Hardness

The hardness of the lens nucleus was assessed intraoperatively by the surgeon based on the Emery classification [15]. Because the lens nucleus in white cataracts cannot be evaluated preoperatively, nuclear hardness was classified according to intraoperative findings. After completion of continuous curvilinear capsulorrhexis (CCC) and aspiration of the emulsified lens material, an eight-chopper was inserted into the exposed lens nucleus, and its color and hardness were evaluated.

2.5. Surgical Technique

All surgeries were performed by a single surgeon (T.S.) who was fully experienced in the eight-chop technique, following the same standardized surgical protocol. Phacoemulsification was performed using the Centurion® Vision System (Alcon Laboratories, Inc., Fort Worth, TX, USA). All procedures were recorded using a video camera (MKC-704KHD; Ikegami Tsushinki Co., Ltd., Tokyo, Japan). The eight-chop technique was performed using an Eight-chopper II (SP-8402; ASICO, Westmont, IL, USA) and a Lance chopper (SP-9989; ASICO, Westmont, IL, USA). A 3.0-mm temporal clear corneal incision was created using a steel keratome. In all cases, Brilliant Blue G (BBG; 0.025%) was used to enhance visualization of the anterior capsule (Figure 1). Anterior capsule staining was confirmed by video recordings in each case. After intentionally creating a small continuous curvilinear capsulorrhexis (CCC), the capsulorrhexis was subsequently enlarged to a final diameter of 6.2–6.5 mm using a two-step CCC technique. Hydrodissection was performed using a 27-gauge cannula (AMO Japan, Inc., Tokyo, Japan). The lens nucleus was mechanically divided into eight segments using the Eight-chopper II in 18 cases and the Lance chopper in 87 cases (Figure 2). In eyes with Grade III or IV nuclear hardness, an additional side-port incision was created using a 23-gauge microvitreoretinal knife at approximately 90° from the main corneal incision, through which a sustainer was inserted. After removal of cortical material from the capsular bag using an irrigation–aspiration tip, a viscoelastic agent was injected, and a foldable posterior chamber intraocular lens (Acrysof^® MN60AC; Alcon Laboratories, Inc., Fort Worth, TX, USA) with polymethyl methacrylate haptics was implanted into the capsular bag using an injector system. Residual viscoelastic material was then thoroughly aspirated. At the end of surgery, moxifloxacin (0.5 mg/mL) was injected into the anterior chamber

2.6. Postoperative Examinations

Intraoperative outcome measures included surgical time (minutes), ultrasound time (seconds), aspiration time (minutes), cumulative dissipated energy (CDE), total volume of irrigation fluid used (mL), and the incidence of intraoperative complications. Surgical time was defined as the duration from the initiation of the corneal incision to the completion of viscoelastic material removal. Postoperative examinations were performed on postoperative days 1 and 2, and at 1, 3, 7, and 19 weeks after surgery. Postoperative outcome measures included best-corrected visual acuity, intraocular pressure, and corneal endothelial cell density. For the purposes of analysis in this study, data obtained at 7 and 19 weeks postoperatively were used.

2.7. Handling of Missing Data and Bilateral Cases

Because this was a retrospective study, postoperative data were missing for some eyes. The primary reasons for missing data were loss to follow-up or the inability to obtain corneal endothelial cell measurements. Therefore, statistical analyses were performed using a complete-case analysis approach, and no imputation of missing values was conducted. A total of 12 eyes were derived from bilateral cases. These eyes accounted for a small proportion of the overall study population, and no patient contributed more than two eyes to the dataset. Given the limited number of bilateral cases and the predominance of unilateral observations, the potential impact of inter-eye correlation on the overall estimates was considered minimal. Therefore, no statistical adjustment for within-subject correlation, such as the use of mixed-effects models or generalized estimating equations, was applied in the analyses.

2.8. Statistical Analysis

Statistical analyses were performed using R software (version 4.5.2; R Foundation for Statistical Computing, Vienna, Austria). Continuous variables are presented as mean ± standard deviation. Categorical variables are presented as counts and percentages. Comparisons among groups stratified by nuclear hardness were performed using one-way analysis of variance (ANOVA) for continuous variables. When overall significance was detected, post hoc pairwise comparisons were conducted using the Tukey–Kramer method. For comparisons of categorical variables, the chi-square test or Fisher’s exact test was applied, as appropriate. Longitudinal changes in postoperative outcomes were evaluated by comparing values at each postoperative time point. Because this was a retrospective study and postoperative data were missing for some eyes, all analyses were conducted using a complete-case analysis approach without imputation of missing values. A p-value < 0.05 was considered statistically significant. All statistical tests were two-tailed.

3. Results

During the observation period from January 4, 2010, to March 25, 2025, a total of 12,642 cataract surgeries were performed at our institution. Among these, 126 eyes were diagnosed with white cataracts. Of the 126 eyes, 20 eyes were excluded due to loss to follow-up, and 1 eye was excluded because of progression to lens dislocation. Consequently, data from 105 eyes were included in the final analysis. Among the 105 eyes with white cataracts, 22 eyes were from patients with diabetes mellitus. Postoperatively, 4 eyes were excluded from visual acuity analyses due to diabetic retinopathy, 3 eyes due to age-related macular degeneration, and 1 eye due to branch retinal vein occlusion. All other missing data were attributable to lack of patient follow-up or inability to perform the required examinations.

3.1. Preoperative Characteristics and Intraoperative Parameters by Lens Hardness

Preoperative patient characteristics and intraoperative parameters are summarized according to lens hardness (Table 1). The number of eyes was 13 in the Grade I–II group, 28 in the Grade III group, and 64 in the Grade IV group. The mean age increased significantly with lens hardness, being 44.4 ± 12.0 years in the Grade I–II group, 60.1 ± 11.5 years in the Grade III group, and 73.1 ± 9.0 years in the Grade IV group (p < 0.001). There was no significant difference in sex distribution among the groups (male: 61.5%, 67.9%, and 46.9%, respectively; p = 0.152). Anterior chamber depth (ACD) did not differ significantly among the groups (p = 0.269), whereas axial length decreased significantly with increasing lens hardness (Grade I–II: 24.7 ± 0.9 mm; Grade III: 24.1 ± 1.2 mm; Grade IV: 23.1 ± 1.0 mm; p < 0.001). Lens hardness itself differed significantly among the groups (1.3 ± 0.5, 3.3 ± 0.3, and 4.3 ± 0.3, respectively; p < 0.001). Regarding intraoperative parameters, both operative time and phacoemulsification time (Phaco time) increased significantly with lens hardness (operative time: 8.9 ± 4.3, 10.1 ± 4.4, 12.8 ± 4.4 min; p = 0.003; Phaco time: 5.8 ± 6.5, 18.9 ± 13, 34 ± 14.6 s; p < 0.001). Aspiration time and volume of fluid used did not differ significantly among the groups (p = 0.108 and p = 0.32, respectively). Cumulative Dissipated Energy (CDE) increased significantly with lens hardness (1.6 ± 2, 7.4 ± 5.5, 15.3 ± 6.4, respectively; p < 0.001).

3.2. Corneal Endothelial Cell Density Changes by Lens Hardness

Preoperative and postoperative corneal endothelial cell density (CECD) values are shown according to lens hardness (Table 2). Preoperatively, the mean CECD was 2585.9 ± 403.6 cells/mm² in the Grade I–II group, 2676 ± 180.4 cells/mm² in the Grade III group, and 2627.2 ± 269.6 cells/mm² in the Grade IV group, with no significant difference among the groups (p = 0.593). At 7 weeks postoperatively, CECD values were 2491.8 ± 322.3, 2598.8 ± 241.5, and 2421.6 ± 489.3 cells/mm² in the Grade I–II, III, and IV groups, respectively. The mean percentage decrease from preoperative values was -2.7 ± 11.5% in Grade I–II, -1.6 ± 7.1% in Grade III, and -6.4 ± 17.4% in Grade IV, with no significant difference among the groups (p = 0.242 for CECD, p = 0.389 for % decrease). At 19 weeks postoperatively, CECD values were 2539.3 ± 110.6, 2629.1 ± 235.6, and 2433.4 ± 418.1 cells/mm², with mean percentage decreases of -0.9 ± 6.8%, -0.5 ± 5.7%, and -6.7 ± 13.5% in the Grade I–II, III, and IV groups, respectively. No statistically significant differences were observed among the groups (p = 0.238 for CECD, p = 0.105 for % decrease).

3.3. Corneal Endothelial Parameters According to Lens Hardness

The pre- and postoperative central corneal thickness (CCT), coefficient of variation of cell size (CV), and percentage of hexagonal cells (PHC) according to lens hardness are shown in Table 3. Preoperatively, CCT was 550.0 ± 46.2 μm in the Grade I–II group, 544.0 ± 49.0 μm in the Grade III group, and 541.1 ± 41.9 μm in the Grade IV group, with no significant differences among the groups (p = 0.820). At 7 weeks postoperatively, CCT was 551.8 ± 45.2, 563.2 ± 60.9, and 552.3 ± 56.6 μm, and at 19 weeks postoperatively, 518.3 ± 20.9, 536.2 ± 44.2, and 542.6 ± 45.7 μm, with no significant differences among the groups at either time point. Preoperative CV was 48.3 ± 9.6 in the Grade I–II group, 39.8 ± 4.9 in the Grade III group, and 44.3 ± 10.7 in the Grade IV group, showing a significant difference among groups (p = 0.023). At 7 weeks postoperatively, CV was 50.4 ± 10.3, 39.9 ± 5.7, and 43.9 ± 8.2, with significant differences (p = 0.001), whereas at 19 weeks postoperatively, CV was 41.6 ± 5.7, 39.7 ± 8.1, and 39.5 ± 5.7, and the differences were no longer significant (p = 0.686). Preoperative PHC was 39.0 ± 10.6% in the Grade I–II group, 44.3 ± 8.3% in the Grade III group, and 49.8 ± 54.2% in the Grade IV group, with no significant differences among groups (p = 0.665). At 7 weeks postoperatively, PHC was 39.0 ± 8.3%, 45.2 ± 8.9%, and 41.3 ± 8.3%, and at 19 weeks postoperatively, 39.3 ± 7.2%, 46.6 ± 7.8%, and 43.4 ± 7.9%, with no significant differences at either time point.

3.4. Intraocular Pressure Changes According to Lens Hardness

The mean intraocular pressure (IOP) and percentage decrease from baseline according to lens hardness are shown in Table 4. Preoperatively, the mean IOP was 13.9 ± 2.0 mmHg in the Grade I–II group, 13.7 ± 2.3 mmHg in the Grade III group, and 13.6 ± 2.5 mmHg in the Grade IV group, with no significant differences among the groups (p = 0.948). At 7 weeks postoperatively, the mean IOP was 14.0 ± 1.5, 13.0 ± 2.4, and 12.2 ± 2.0 mmHg, with significant differences among the groups (p = 0.018). The percentage decrease from baseline IOP was -3.0 ± 11.6% in the Grade I–II group, 4.8 ± 12.0% in the Grade III group, and 9.7 ± 14.0% in the Grade IV group, showing a significant difference (p = 0.013). At 19 weeks postoperatively, mean IOP was 14.8 ± 1.6, 12.9 ± 2.0, and 12.0 ± 2.1 mmHg (p = 0.003), and the percentage decrease from baseline was -7.5 ± 13.3%, 5.5 ± 7.6%, and 10.0 ± 15.3%, respectively, with significant differences among groups (p = 0.007). These results indicate that higher lens hardness was associated with greater postoperative IOP reduction.

3.5. Best-Corrected Visual Acuity According to Lens Hardness

The pre- and postoperative best-corrected visual acuity (BCVA) in logMAR according to lens hardness are shown in Table 5. Preoperatively, BCVA was 1.935 ± 0.408 in the Grade I–II group, 2.120 ± 0.293 in the Grade III group, and 2.183 ± 0.334 in the Grade IV group, with no significant differences among the groups (p = 0.107). At 7 weeks postoper-atively, BCVA was -0.079 ± 0.001, -0.041 ± 0.053, and -0.014 ± 0.091, showing a significant difference among groups (p = 0.022). At 19 weeks postoperatively, BCVA was -0.079 ± 0.001, -0.036 ± 0.050, and -0.019 ± 0.084, with no significant differences among groups (p = 0.057). These results suggest that differences in BCVA according to lens hardness were observed in the early postoperative period but tended to disappear over the long term.

4. Complications and Additional Procedures during Surgerys 

In this study, posterior capsule rupture was observed in 2 of 105 eyes. In 7 eyes, a complete con-tinuous curvilinear capsulorrhexis (CCC) could not be achieved. Iris retractor hooks were used in 25 eyes. No cases of lens nucleus drop occurred during surgery.

5. Conclusion

In conclusion, the eight-chop technique enables safe and efficient phacoemulsification in eyes with white cataract. The technique achieves favorable intraoperative efficiency, preserves corneal endothelial integrity, and provides excellent visual outcomes with a low rate of complications. These findings support the eight-chop technique as a valuable surgical option for the management of white cataract, particularly in cases with hard nuclei and increased surgical risk.