The relationship between nuclear colour and opalescence on the LOCSIII scale and physical characteristics of cataract nuclei

Narrative review after post-hoc trial analysis of factors that predict corneal endothelial cell loss after phacoemulsification: Tips for improving cataract surgery research

PURPOSE

Identifying pre/perioperative factors that predict corneal endothelial-cell loss (ECL) after phacoemulsification may reveal ways to reduce ECL. Our literature analysis showed that 37 studies have investigated one or several such factors but all have significant limitations. Therefore, the data of a large randomized controlled trial (PERCEPOLIS) were subjected to post-hoc multivariate analysis determining the ability of nine pre/perioperative variables to predict ECL.

METHODS

PERCEPOLIS was conducted in 2015-2016 to compare two phacoemulsification techniques (subluxation and divide-and-conquer) in terms of 3-month ECL. Non-inferiority between the techniques was found. In the present study, post-hoc univariate and multivariate analyses were conducted to determine associations between ECL and age, sex, cataract density, preoperative endothelial-cell density, phacoemulsification technique, effective phaco time (EPT), and 2-hour central-corneal thickness. The data are presented in the context of a narrative review of the literature.

RESULTS

Three-month data were available for 275 patients (94% of the randomized cohort; mean age, 74 years; 58% women). Mean LOCSIII cataract grade was 3.2. Mean EPT was 6 seconds. Mean ECL was 13%. Only an older age (beta = 0.2%, p = 0.049) and higher EPT (beta = 1.2%, p = 0.0002) predicted 3-month ECL. Cataract density was significant on univariate (p = 0.04) but not multivariate analysis. The other variables did not associate with ECL.

CONCLUSIONS

Older age may amplify ECL due to increased endothelial cell fragility. EPT may promote ECL via cataract density-dependent and -independent mechanisms that should be considered in future phacoemulsification research aiming to reduce ECL. Our literature analysis showed that the average ECL for relatively unselected consecutively-sampled cohorts is 12%.

Application of prechop technique in phacoemulsification for cataract patients with highly liquefied vitreous: a retrospective study

Background

Phacoemulsification using phaco-chop technique has many challenging features in cataract patients with highly liquefied vitreous. This study aimed to compare the intraoperative parameters and safety between prechop technique and traditional phaco-chop in phacoemulsification for these patients.

Methods

A total of 54 eyes of 54 patients with high myopia-related or post-vitrectomy cataract that underwent phacoemulsification combined with intraocular lens implantation were included in this retrospective study. Of them, 25 eyes that received manual prechop were included in the prechop group, and 29 eyes with best match of age, axial length and nuclear opalescence (NO) that received standardized phaco-chop were included as the control group. The intraoperative complications and surgery parameters were compared between groups.

Results

No surgical complications were observed in the prechop group, while 2 eyes with posterior capsular rupture and 1 eye with a broken ciliary zonule (10.3%) were found in the control group. There was no significant difference in phaco time, average energy, and cumulative dissipated energy (CDE) between groups (all P > 0.05), but for hard nuclear cataracts with NO grading ≥ 5, prechop group required less phaco time (P = 0.008) and CDE (P = 0.029). There were significant correlations between phaco time vs. NO (r = 0.762 vs. 0.581, both P < 0.005) and CDE vs. NO (r = 0.717 vs. 0.668, both P < 0.001) in the prechop group and control group, respectively.

Conclusions

The prechop technique which seemed to have less intraoperative complications, reduced phaco time and CDE compared to standardized phaco-chop might be a good alternative for cataract patients with highly liquefied or vitrectomized vitreous, especially those with hard nuclear cataracts.

Evaluation of the relation between Lens Opacities Classification System III grading and nuclear size by direct measurement

CONTEXT:

Although relation between Lens Opacities Classification System III (LOCS III) and nuclear density is established, no data are available about nuclear size at different LOCS III grades.

AIMS:

The aim of this study is to evaluate the relation between LOCS III grading of nuclear opacity obtained preoperatively and the size of the nucleus obtained during cataract surgery.

SETTINGS AND DESIGN:

This was a prospective observational study carried out in a hospital attached to medical college.

MATERIALS AND METHODS:

Patients who underwent manual small-incision cataract surgery or extra-large temporal tunnel cataract extraction and gave consent were included in this study. Institutional Ethics Committee clearance was taken for the study. Preoperative LOCS III grading was obtained at slit-lamp biomicroscope. Ocular dimensions were obtained by preoperative immersion biometry. The thickness and diameter of the nucleus obtained by extraction were measured up to 10 μ accuracy. Data were analyzed for the change in nuclear thickness, nuclear diameter, age, lens thickness, and anterior chamber depth in relation to the LOCS III grade of the nucleus.

STATISTICAL ANALYSIS USED:

Statistical analysis used in this study was one-way ANOVA, mean, and range.

RESULTS:

There was a significant increase (P < 0.05) in nuclear thickness, nuclear diameter, and age with increasing LOCS III grade of the nucleus. The change in nuclear size was linear between Grades 1 and 4. The nuclear size did not increase between Grades 4 and 5. It increased steeply from Grade 5 to Grade 6.9.

CONCLUSION:

LOCS III grading of the nucleus can be utilized for determining the nuclear thickness and diameter preoperatively. These data can be helpful in adjusting machine parameters during phacoemulsification.

Comparison of Divide and Conquer and Phaco-Chop Techniques during Fluid-Based Phacoemulsification

PURPOSE

To determine whether, similar to ultrasound phaco-emulsification, applied energy and surgery time decrease using phaco-chop nucleus fragmentation method compared to divide and conquer technique using the fluid-based system.

METHODS

This prospective, comparative, randomized clinical study included patients with cataract who were randomly assigned to use either standard divide and conquer technique (25 eyes of 25 patients, Group 1) or Nagahara phaco-chop maneuver (25 eyes of 25 patients, Group 2) during fluid-based phaco-emulsification. Surgical parameters were recorded and patients were examined 1 day, 10 days, and 1 month after surgery. Statistical analyses were performed using the paired test of Wilcoxon.

RESULTS

Fluid-based time, mean fluid-based magnitude, effective fluid-based time, and the number of pulses were significantly less using phaco-chop technique compared to divide and conquer method (p<0.001). Surgery time was similar using the two nucleofractis techniques (p=0.97). Visual acuities showed no statistical differences between the two groups (p>0.05).

CONCLUSIONS

Nuclear fragmentation can be performed with Nagahara phaco-chop technique using the fluid-based system as well. The applied fluid-based energy decreases compared to divide and conquer method. However, surgery time is not reduced due to the difficulties reaching the full occlusion necessary to hold the nucleus during the chop maneuver.

[Phacoemulsification versus manual small incision cataract surgery: Anatomic and functional results]

PURPOSE

Prospective randomised study to compare the impact of phacoemusification (PHACO) and small incision cataract surgery (SICS) on endothelial structure (cell density and morphology) and refractive results (visual acuity, induced astigmatism).

METHODS

Prospective study of 57 patients (63 eyes) over 20 months (May 2012-January 2014) undergoing surgery by 2 experienced surgeons. We included patients with senile or presenile cataracts, LOCS III class 2, 3 and 4. Patients were randomized into 2 groups based on their birth month (group 1: PHACO [33]; group 2: SICS [30]). All pre- intra- and postoperative data were collected prospectively. The minimum follow-up was 6 months. We used the SPSS 18.0 for statistical analysis. Statistical tests used included the test-t Student, the Anova test, the Mann-Witney non-parametric test and the Khi² test. A threshold of significance was set at 0.05.

RESULTS

The mean preoperative endothelial cell density was 2447.5±225 c/mm² with no significant difference between the two groups (P=0.207). The mean percentage of hexagonality was 55.5±8.2% in groups 1 and 2. The most significant cell loss was during the first immediate postoperative period for both groups. At Day 15 postoperative, the decrease in cell loss was significant (P<0.001) with a mean loss of 312.9±208.9 c/mm² (P<10^-2). Postoperatively, the mean best-corrected visual acuity was 0.057 log MAR for all of our patients (P=0.170); no patient had an acuity ≤1/10. The mean astigmatism at the conclusion of follow-up was 1.08±0.42 D in group 1 and 1.51±0.55 D in group 2, with a significant difference (P=0.001).

CONCLUSION

Both SICS and PHACO give excellent results, both anatomical and refractive. However, SICS appears to be more advantageous than PHACO in terms of speed, cost, and independence from technology, and appears to be better suited to dense cataracts and mass surgery.

Intraindividual comparison of surgical trauma after bimanual microincision and conventional small-incision coaxial phacoemulsification

PURPOSE

To compare the surgical trauma after microincision phacoemulsification and small-incision coaxial phacoemulsification after implantation of conventional, foldable, hydrophobic acrylic intraocular lenses (IOLs).

SETTING

Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.

METHODS

A prospective investigator-masked case series comprised patients with bilateral cataract who had cataract surgery on the same day. Thirty-three patients (66 eyes) were randomized. Microincision cataract surgery (MICS) was performed through 2, 1.4 mm clear corneal incisions (CCIs) using bimanual sleeveless phacoemulsification (cool phaco) in 1 eye. Small-incision cataract surgery (SICS) was performed on the other eye through a 3.2 mm CCI. In all cases, an AcrySof SA60AT IOL was inserted, in the MICS group after the CCI was enlarged. Laser flare photometry, specular microscopy, corneal endothelial cell density, and pachymetry were evaluated preoperatively and postoperatively. Intraindividual comparison and statistical analyses were performed.

RESULTS

There were no relevant clinical differences or perioperative complications in either group. There were no statistically significant differences between preoperative and postoperative anterior chamber flare or endothelial cell loss. On the first postoperative day, the MICS group had statistically significantly increased corneal swelling (P = .008). Postoperatively, the mean endothelial cell density loss was higher in the MICS group (6.2%) than in the SICS group (3.10%); however, the difference between groups was not significant (P = .08)

CONCLUSIONS

Microincision cataract surgery was a safe and reproducible technique. The postoperative results in the MICS group were comparable to those in the SICS group.

Stiffness gradient in the crystalline lens

BACKGROUND

While the overall stiffness of the lens has been measured in a number of studies, the knowledge about the stiffness distribution within the lens is still limited. The purpose of this study was to determine the stiffness gradient in the human crystalline lens. A secondary purpose was to determine whether the stiffness gradient depends on age.

METHODS

The local dynamic stiffness was measured in 10 human crystalline lenses (age range: 19 to 78 years). The lenses were stored at -70 degrees C before being measured. The influence of freezing on the mechanical properties has been determined in a previous study. A small oscillating probe was used to measure the local dynamic shear modulus as a measure of lens stiffness. The measurements were taken in the cross-sectional plane through the lens equator.

RESULTS

The local dynamic shear modulus varied with location for all tested lenses. The central stiffness of the oldest lens (78 years) was 10(4) times higher than the youngest (19 years) lens. The equatorial stiffness of the oldest lens was 10(2) times higher than the youngest lens. For the older lenses, the centre was 5.8-210 times stiffer than the periphery, as opposed to earlier results described by Fisher (1971), who found that the periphery was up to 3 times softer than the centre for lenses younger than 70-years-old. For the three youngest lenses (19 to 49 years), the periphery was 2.2-16.6 times stiffer than the centre.

CONCLUSIONS

The dynamic stiffness of the crystalline lens varies with location within the lens. The stiffness gradient depends on the age of the lens. The results of the 10 lenses indicate that the stiffness of both centre and periphery increase with age, but at a different rate.

Influence of severity of nuclear cataract on optical biometry

PURPOSE

To compare preoperative and postoperative measurements of the axial length (AL) performed with the IOLMaster (Carl Zeiss Meditec) to evaluate the effect of nuclear cataract on the optical biometry.

SETTING

Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.

METHODS

In 245 consecutive eyes of 162 patients scheduled for cataract surgery, type and severity of cataract was evaluated using the Lens Opacities Classification System III. Preoperative and postoperative axial length measurements were performed with the IOLMaster. The postoperative readings of AL were corrected for the IOL optic material implanted.

RESULTS

The preoperative AL measurements were 0.07 mm +/- 0.05 (SD) (range -0.18 to 0.11 mm) longer than the postoperative measurements (P<.001). These differences in AL were only weakly correlated (r = -0.28, P = .01) with the nuclear cataract grade, mean 3.5 +/- 0.9.

CONCLUSION

In this study, AL measurements with optical biometry using the IOLMaster were not influenced by the severity of nuclear cataract to a clinically relevant degree. Furthermore, it was found that AL in the phakic eye was overestimated by about 0.07 mm because of a slightly too low value of the group refractive index used for the crystalline lens.

Corneal endothelial function after phacoemulsification using the fluid-based system compared to conventional ultrasound technique

AIM

To quantitatively assess corneal endothelial changes after phacoemulsification with the fluid-based system compared to conventional ultrasound technique.

METHODS

This prospective, randomized clinical study included patients with cataract who were randomly assigned either to have phacoemulsification with the fluid-based system (30 eyes of 30 patients--Group 1) or with traditional ultrasound (30 eyes of 30 patients--Group 2). Patients who were available at each follow-up visit (25 eyes in both groups) were enrolled in the statistical analysis. Endothelial function was evaluated by measuring central corneal thickness, central endothelial cell density (ECD), mean cell size, and coefficient of variation in cell size preoperatively, 10 days, 1 and 3 months, and 1 year after surgery. Statistical analyses were performed using two-way repeated measure ANOVA.

RESULTS

An acute, reversible increase of central corneal thickness (CCT) was found 10 days after surgery, which was similar in both groups (P=0.35). ECD decreased, whereas mean cell size increased significantly immediately after surgery. However, the impairments were finished after 1 month. The alterations were similar in both groups (ECD: P=0.99; mean cell size: P=0.85). The coefficient of variation in cell size remained stable after surgery (P=0.08), and significant difference was not found between groups (P=0.99). The endothelial cell loss (ECL) was 6.5+/-8.4% in Group 1 and 6.5+/-11.7% in Group 2 (P=0.69).

CONCLUSIONS

Corneal endothelial changes were similar using the fluid-based system compared to the traditional ultrasound technique. The fluid-based method proved to be as safe as conventional ultrasound in cataract surgery.