Pac-Man Method: A New Technique for Nuclear Management Of Posterior Polar Cataract

Purpose We introduce an innovative technique, “Pac-Man”, for the nuclear management of posterior polar cataracts and compare it with “Chop in situ” and “Fishbowl” techniques. Method A total of 60 eyes from 60 patients were randomly assigned to groups A, B, and C, with 20 eyes in each group. Pac-Man, Chop in situ, and Fishbowl techniques were used for groups A, B, and C. In the Pac-Man method, adequate single trench sculpts, and a right-sided lateral sculpt were performed and cracked. The triangular piece was emulsified, after which the rest of the nucleus looked like a “Pac-Man” cartoon. Techniques were compared by age, visual outcome, Posterior Capsule Rupture (PCR), Cumulative Dissipated Energy (CDE), and time of surgery. Result Postoperative BCVA was significantly improved after surgery ( P = 0.0001, paired t-test). Time taken for surgeries were 25 ± 2.57, 30 ± 3.78, 40 ± 3.25 min, the CDE were 10 ± 0.95, 20 ± 1.2, 15 ± 0.48, and the PCR were 0%, 5%, and 10% for group A,B,C respectively. The total number of PCR was 3 out of 60 patients, and the percentage was 5.00%. Conclusion The “Pac-Man” method is a recommended technique due to its visual outcome, reduced surgical time, less CDE, and less chance of PCR.

Factors impacting cumulative dissipated energy levels and postoperative visual acuity outcome in cataract surgery

Purpose To determine factors impacting cumulative dissipated energy (CDE) and postoperative best-corrected visual acuity (BCVA) in phacoemulsification. Design Review of 1102 cases at University of California, San Francisco (UCSF) and at Zhongshan Ophthalmic Center (ZOC), China. Subjects Patients who underwent cataract surgery at UCSF 03/2014–03/2019 and at ZOC 10/2018–05/2019. Methods Patient demographics, medical history, routine ocular examination, and surgical information, including disassembly method, complications, and surgeon training level were recorded. Univariable and multivariable regression models were used to determine factors associated with CDE and good postoperative BCVA (20/40 or better) at 1 month. Outcome measures CDE, postoperative BCVA. Results In multivariable analysis, patient age at time of surgery, diabetes, degree of nuclear sclerosis (NS), white-to-white corneal diameter, disassembly method, preoperative BCVA, surgeon training level, and surgical center were significantly associated with CDE. Log10CDE increased by 0.20–0.31 for patient age ≥ 70 years, by 0.07 if the patient had diabetes, by 0.12–0.41 for NS grade ≥ 2, by 0.48 per 10 mm increase in white-to-white corneal diameter, by 0.34–0.47 for disassembly method other than non-stop chop, by 0.16 per unit increase in preoperative logMAR BCVA, and by > 0.09 when phacoemulsification was performed by residents early in their training. Log10CDE was 0.33 higher at UCSF than ZOC. In multivariable analysis, worse baseline visual acuity and age above 90 years at time of surgery decreased the odds of good BCVA (OR = 0.26 per unit increase in preoperative logMAR BCVA; OR = 0.12 for age > 90); comorbid retinal issues decreased the odds of good postoperative BCVA (OR = 0.13–0.39); greater anterior chamber depth (ACD) or shorter axial length (AL), increased the odds of good postoperative outcome (OR = 2.64 per 1 mm increase ACD, OR = 0.84 per 1 mm increase AL). Conclusions Cataract grade determined by slit lamp exam and, for the first time, older patient age, were noted to be important predictors of high CDE. CDE was not a risk factor for postoperative BCVA measured at postoperative 1 month. When surgery was performed by trainees under supervision, lower training level was associated with higher CDE, but not with worse postoperative BCVA.

Safety and effectiveness of an iris hook assisted phacoemulsification in vitrectomized eyes

AIM: To introduce a simple iris hook assisted phacoemulsification (PE) procedure and evaluate the safety and efficacy of it in completely vitrectomized eyes. METHODS: A single centre study which included 65 previously completely vitrectomized eyes of 62 patients who underwent cataract surgery. Patients were randomly divided into 3 groups. Patients received PE, and intraocular lens (IOL) implantation with the assistance of iris hook (SynergetiesTM) as group A (25 eyes); patients who received PE assisted with a 25G pars plana irrigation as group B (20 eyes), and patients who received PE performed without the help of any instrument as group C (20 eyes). Main outcome measures were surgery duration, Ultrasound (U/S) total time, endothelial cell density (ECD), cumulative dissipated energy (CDE) and complications of the procedures. RESULTS: With the help of iris hook, the patients in group A had the lowest ECD loss rate (0.07±0.03, 0.09±0.03, and 0.10±0.03, P<0.05), shortest CDE (12.2±4.1, 15.8±6.0, and 16.0±6.0, P<0.05) and U/S total time (36.6±13.0s, 46.3±16.4s, and 47.6±16.1s, P<0.05), and minimal incidence of complications. The longest surgery duration was in group B (19.4±1.6min) and maximum complications rate in group C (20% miosis, 10% posterior capsular tears, 5% zonular dialysis, 5% cystoid macular edema). While best-corrected visual acuity (BCVA), intraocular pressure (IOP) and ECD did not show a significant difference among the three groups. CONCLUSION: Without prolonged surgery duration, the iris hook assistant method can minimize heat generation during surgery and incidence of complications, which transfer the challenged PE in vitrectomized eyes into a regular surgery. It does not need any change in the hydrodynamic parameters and in the bag PE technique, easy to operate even for junior surgeons.

Changes in pupillometry associated with dissipated energy during phacoemulsification

Purpose: To investigate the effect of ultrasound level during phacoemulsification on pupil dynamics. Methods: Comparative retrospective study on patients who underwent routine cataract surgery at the Royal Liverpool University Hospital. Clinical parameters, anterior chamber measurements, axial length, surgeon grade, time of surgery, level of ultrasound used (cumulative dissipated energy, CDE), intra- and post-operative complications were collected. Pupil diameters were collected before and 4 ± 1 weeks after surgery in static scotopic, mesopic, photopic pupil conditions. Also, pupil dynamic measurements after luminous stimulus were recorded. Changes in static pupil diameters, relative dilation at 3.5 s after luminous stimulus, and time to reach 75% and 95% of maximum dilation were measured. Results: Forty-eight eyes of 24 patients (13 males) were included with a mean age of 73.1 ± 14.6 years. Mean CDE value was 18.11 ± 10.56. Mean scotopic pupil diameters decreased by 0.24 ± 0.48 mm ( p = 0.021) in the operated eye. Significant correlation was found between reduction in scotopic pupil diameter and CDE ( p = 0.05). A generalized linear model confirmed that the level of CDE was significantly associated with reduction in scotopic pupil diameter ( p = 0.026). Patients who underwent surgeries with lower CDE (0 < CDE ⩽ 10 and 10 < CDE ⩽ 20) did not experience significant changes in scotopic pupil diameter after surgery ( p = 0.28 and p = 0.79, respectively) as opposed to those with higher CDE (CDE > 20; p = 0.03). Conclusion: Phacoemulsification cataract surgery and the cumulative dissipated energy may be associated with changes in pupil behaviour.

A Simple Pre-Operative Nuclear Classification Score (SPONCS) for Grading Cataract Hardness in Clinical Studies

Background: The aim of this study was to evaluate whether a simplified pre-operative nuclear classification score (SPONCS) was valid, both for clinical trials and real-world settings. Methods: Cataract classification was based on posterior nuclear color: 0 (clear), 1 (subcapsular/posterior cataract with clear nucleus), 2 (mild “green nucleus” with plus sign for yellow reflection of the posterior cortex), 3 (medium “yellow nucleus” with plus sign for brown/red posterior cortex reflection), 4 (advanced with 4 being “red/brown nucleus” and 4+ white nucleus), and 5 (hypermature/Morgagnian nucleus). Inter- and intra-observer validity was assessed by 30 Ophthalmologists for 15 cataract cases. The reliability of the cataract grading score in a surgical setting was evaluated. Correlation of nuclear scores was compared with phacoemulsification cumulative dissipated energy (CDE) in 596 patients. Results: Analysis of mean intra-observer Cohen kappa agreement was 0.55 with an inter-observer score of 0.54 for the first assessment and 0.49 for the repeat assessment one week later. When evaluating results by nuclear color alone, there was a substantial agreement for both the intra-observer (0.70) and inter-observer parameters: 0.70 for the first test, and 0.66 on repetition with randomization of the cases after a week. CDE levels were found to be significantly different between all SPONCS score groups (p < 0.001), with a lower CDE related to a lower SPONCS score. A strong correlation was found between the SPONCS score and CDE (Spearman′s rho = 0.8, p < 0.001). Conclusion: This method of grading cataract hardness is both simple and repeatable. This system can be easily incorporated in randomized controlled trials to lower bias and confounding effects regarding nuclear density along with application in the clinical setting.

Comparison of real-world treatment outcomes of femtosecond laser-assisted cataract surgery and phacoemulsification cataract surgery: A retrospective, observational study from an outpatient clinic in France

Purpose: This study compared real-world safety and efficacy outcomes of cataract surgery performed with LenSx femtosecond laser-assisted cataract surgery or manual phacoemulsification cataract surgery procedures. Methods: A retrospective observational study used data from anonymised electronic medical records to compare mean cumulative dissipated energy, the proportion of eyes reaching emmetropia, mean change in best-corrected distance visual acuity and the proportion of eyes with post-surgical complications, including corneal oedema and posterior capsule opacification. Results were adjusted for multiple comparisons for primary and secondary objectives. Results: Data from 811 phacoemulsification cataract surgery and 496 femtosecond laser-assisted cataract surgery procedures were analysed. Mean cumulative dissipated energy was significantly lower for femtosecond laser-assisted cataract surgery (6.5 percent-seconds) than for phacoemulsification cataract surgery (14.3 percent-seconds; p < 0.0001) procedures. More femtosecond laser-assisted cataract surgery (81.2%) procedures achieved emmetropia (⩽ 0.5 dioptre) than did phacoemulsification cataract surgery (73.5%) procedures, although this difference was not statistically significant. Mean change in best-corrected distance visual acuity and the proportion of eyes with corneal oedema, posterior capsule opacification or other complications were not significantly different between cohorts when adjusted for multiple comparisons. Conclusions: In this single-centre, single-surgeon retrospective electronic medical record database study using divide and conquer technique, femtosecond laser-assisted cataract surgery was associated with significantly lower cumulative dissipated energy when compared to manual phacoemulsification cataract surgery. This supports the hypothesis that femtosecond laser-assisted cataract surgery involves less mechanical trauma, which might lead to more consistent refractive and safety outcomes than manual phacoemulsification cataract surgery, though such outcomes were found to be comparable in this study.

Hollow bridge columns with triangular confining reinforcement

The purpose of this study is to assess the structural performance of hollow bridge columns with triangular confining reinforcement. The proposed triangular reinforcement details were equal to the conventional reinforcement details in terms of required structural performance. The triangular confining reinforcement is also economically feasible and rational, and facilitate shorter construction periods. Three hollow cast-in-situ concrete and three precast concrete bridge columns were tested. The behavior of the hollow columns is discussed in terms of their lateral load-drift relationship, cumulative dissipated energy, and lateral load-strain curves. The nonlinear finite element analysis program RCAHEST (reinforced concrete analysis in higher evaluation system technology) was used to analyze hollow bridge columns, and adopted a modified joint element for the precast concrete bridge columns. The results showed that the proposed innovative reinforcement details were superior to the conventional reinforcement details, in terms of the required structural performance.

Practical Approach to Mix Design with High Binder and Aggregate Replacement in Iowa using Fractionation

A laboratory study was conducted to examine the effect of fractionated reclaimed asphalt pavement (FRAP) materials on the performance of a standard surface hot mix asphalt (HMA), as well as a HMA crack relief interlayer. The surface mix contained a PG58-28S binder, 3.3% of a bio-rejuvenator (0.12% by total mix weight), and 50% FRAP containing 30% fine fraction and 70% coarse fraction. The interlayer mix contained a polymer modified PG76-28 binder, 3.5% of the bio-rejuvenator (0.16% by total mix weight), and 50% FRAP containing 100% fine fraction. The surface mix was evaluated for HMA rutting resistance, moisture susceptibility, and low temperature fracture resistance, while the interlayer mix was evaluated for interlayer fatigue resistance. The rejuvenated FRAP surface mix performed better than the control FRAP surface mix in rutting and moisture susceptibility (stripping inflection point of 19,582 versus 17,805 for the control), and had a 100% improvement in low temperature fracture (768 J/m2 versus 354 J/m2 for the control) all due to the addition of 0.12% of a bio-rejuvenator by total mix weight. From the interlayer test there was a 57.7% and 33.6% improvement in number of cycles to failure and cumulative dissipated energy due to the addition of 0.16% of a bio-rejuvenator by total mix weight. Neither the FRAP control nor rejuvenated FRAP interlayer mixtures passed the interlayer test criteria. There is room for further improvement in the future, however, and the bio-rejuvenator is shown to improve performance substantially for mixtures with high asphalt binder and high aggregate replacement.