Central corneal thickness changes in bevel-up versus bevel-down phacoemulsification cataract surgery: study protocol for a randomised, triple-blind, parallel group trial

Does the phaco TIp position during clear corneal Phacoemulsification Surgery adversely affect corneal endothelium? TIPS study protocol for a randomised, triple-masked, parallel-group trial of bevel-up versus bevel-down phacoemulsification

Introduction: Globally, at least 30 million cataract surgeries are required annually to prevent cataract-related blindness. Corneal endothelial decompensation is one of the most common causes of poor visual outcome following cataract surgery, particularly in those with predisposing factors. The increasing ageing population and reduced visual impairment threshold for cataract surgery have resulted in rising cataract surgical rates and hence, an increase in corneal endothelial decompensation is expected. The role of phaco tip position on corneal endothelial damage is ambiguous. Previous studies have reported contradictory results and were also underpowered to detect a significant difference due to small sample sizes. With no consensus regarding the most cornea-friendly phaco tip position (bevel-up versus bevel-down) during phacoemulsification, we propose a randomised clinical trial with a robust design using direct chop phaco-technique. Objective: To compare the effect of phaco tip position (bevel-up vs. bevel-down) on corneal endothelial cell count during phacoemulsification. Methods: A randomised, multicentre, parallel-group, triple-masked (participant, outcome assessor, and statistician) trial with 1:1 allocation ratio is proposed. By adopting stratified randomisation (according to cataract grade), we will randomly allocate 480 patients aged >18 years with immature cataract into bevel-up and bevel-down groups at two centres. History of significant ocular trauma, previous intraocular surgery, shallow anterior chamber, low endothelial cell count, pseudoexfoliation syndrome, intraocular inflammation, and corneal endothelial dystrophy are the key exclusion criteria. The primary outcome is postoperative endothelial cell count at one month. Secondary outcomes are central corneal thickness on postoperative days 1, 15, and 30, and intraoperative complications. Trial registration: Clinical Trial Registry of India CTRI/2019/02/017464 (05/02/2019).

Evaluation of Ocular Biometric Parameters Following Cataract Surgery

Background: The aim of this study was to highlight the structural changes in patients with cataract following surgery and the repercussions on the anterior pole. Methods: A total of 83 patients diagnosed with cataract who underwent uneventful phacoemulsification was included. Every patient was examined one week prior to and two weeks after the surgery. Pre- and postoperative assessment included examination of the anterior and posterior segment, keratometry, and optical biometry. Results: The pre- vs. postoperative axial length (AL) mean difference was 0.07 ± 0.18 mm (p < 0.001).The mean difference of the postoperative anterior chamber depth (ACD) vs. preoperative ACD values (1.11 ± 0.50 mm) was also statistically significant (p < 0.001). The linear regression function postoperative central corneal thickness (CCT) = 0.9004 × (preoperative CCT) + 0.0668, where it characterized a reduced positive correlation (R2) of 68.89% between the postoperative CCT and preoperative CCT. The mean pre-/post-operative differences in the K1 values were 0.08 ± 0.38 D, with a statistically significant difference between the two datasets (p = 0.0152). The mean pre/postoperative difference in the K2 values was 0.002 ± 0.58 D (p = 0.4854). Conclusions: ACD deepened significantly postoperatively. Regarding AL, there was a decrease after surgery, and a very good positive correlation between the post and preoperative values. The CCT values decreased with age. The 2.2-mm corneal incision during cataract surgery resulted in a relatively small postoperative residual astigmatism.

Impact of surgical experience on early post-operative regional corneal thickness after phacoemulsification

Background: Currently, phacoemulsification is a very common cataract surgical procedure in which the lens is emulsified and aspirated from the eye through a small corneal incision.Aim: To compare early regional corneal thickness changes following phacoemulsification done by experienced surgeons versus trainee surgeons.Setting: A prospective cohort study was done at Ibn Al Haitham tertiary eye hospital in Baghdad, Iraq.Methods: The data were collected for 5 months, from 01 March 2018 until 31 July 2018. Adult patients undergoing phacoemulsification and intraocular lens surgery were prospectively evaluated and divided into two groups. Group 1 comprised those operated by experienced surgeons, whilst Group 2 patients were operated by trainee surgeons. Slit lamp examination and endothelial specular microscopy were assessed with the measurement of central corneal thickness (CCT) and peripheral corneal thickness (PCT), using Scheimpflug imaging (Pentacam).Results: There was a significant statistical difference in post-operative CCT between Groups 1 and 2, being 596.72 ± 50.69 µm compared to 631.54 ± 67.84 µm in Groups 1 and 2, respectively, with a mean difference of 34.82 µm (p = 0.000). More difference was observed in post-operative PCT (148.38 µm) as it was 734.8 ± 88.55 µm in the experienced group, compared to 883.18 ± 128.43 µm in the trainee group (p = 0.005).Conclusion: Phacoemulsification done by trainee surgeons was associated with higher CCT and PCT.

Changes of lactate dehydrogenase in corneal edema after cataract surgery treated with trans-corneal oxygenation therapy

AIM

To investigate the changes in levels of the lactate dehydrogenase (LDH) enzyme in corneal edema after cataract surgery with trans-corneal oxygenation therapy.

METHODS

This pre-post design study design conducted on 15 patients with corneal edema after cataract surgery and receiving trans-corneal oxygenation therapy. Tear sample (using Schirmer paper, from the inferior fornix of the conjunctiva) was carried out prior to trans-corneal oxygenation therapy, on the day 2 (D2) and day 5 (D5) postoperatively before and after trans-corneal oxygenation therapy. Visual acuity [VA (LogMAR)], corneal endothelial density, central corneal thickness (CCT), and coefficient of variation corneal endothelial (CoV) were recorded. The value of LDH was measured using ELISA. The difference in mean LDH value before and after trans-corneal oxygenation therapy, between two groups were analyzed using Wilcoxon signed rank test.

RESULTS

There was a decrease in LDH tear concentration at D2 (pre vs post: 1127.54±497.09 vs 696.91±489.49; P=0.002) and D5 (pre vs post: 1064.17±677.77 vs 780.28±428.95; P=0.027) after trans-corneal oxygenation therapy as well as decrease in LDH concentration on the D2 compared to D5 (P=0.041). The mean CCT was decreased significantly after the administration of trans-corneal oxygenation (pre vs post: 632.10±25.66 vs 563.90±51.54; P=0.005). The mean VA and CoV increased significantly after the administration of trans-corneal oxygenation (P=0.001 and P=0.028, respectively). However, there was no difference in mean of corneal endothelial density (P=0.814).

CONCLUSION

Trans-corneal oxygenation therapy is associated with significant decrease of tears LDH levels in post cataract surgery with corneal edema. It is accompanied by clinical improvement such as significant reduction of CCT.

Does the phaco TIp position during clear corneal Phacoemulsification Surgery adversely affect corneal endothelium? TIPS study protocol for a randomised, triple-masked, parallel-group trial of bevel-up versus bevel-down phacoemulsification

Introduction: Globally, at least 30 million cataract surgeries are required annually to prevent cataract-related blindness. Corneal endothelial decompensation is one of the most common causes of poor visual outcome following cataract surgery, particularly in those with predisposing factors. The increasing ageing population and reduced visual impairment threshold for cataract surgery have resulted in rising cataract surgical rates and hence, an increase in corneal endothelial decompensation is expected. The role of phaco tip position on corneal endothelial damage is ambiguous. Previous studies have reported contradictory results and were also underpowered to detect a significant difference due to small sample sizes. With no consensus regarding the most cornea-friendly phaco tip position (bevel-up versus bevel-down) during phacoemulsification, we propose a randomised clinical trial with a robust design using direct chop phaco-technique. Objective: To compare the effect of phaco tip position (bevel-up vs. bevel-down) on corneal endothelial cell count during phacoemulsification. Methods: A randomised, multicentre, parallel-group, triple-masked (participant, outcome assessor, and statistician) trial with 1:1 allocation ratio is proposed. By adopting stratified randomisation (according to cataract grade), we will randomly allocate 480 patients aged >18 years with immature cataract into bevel-up and bevel-down groups at two centres. History of significant ocular trauma, previous intraocular surgery, shallow anterior chamber, low endothelial cell count, pseudoexfoliation syndrome, intraocular inflammation, and corneal endothelial dystrophy are the key exclusion criteria. The primary outcome is postoperative endothelial cell count at one month. Secondary outcomes are central corneal thickness on postoperative days 1, 15, and 30, and intraoperative complications. Trial registration: Clinical Trial Registry of India CTRI/2019/02/017464 (05/02/2019).

Effects of ultrasound energy on the porcine corneal endothelium - Establishment of a phacoemulsification damage model

PURPOSE

The purpose of this study was to establish a standardized in vitro phacoemulsification damage model for future investigations of the effects of phacoemulsification, surgical devices, protective ophthalmic viscoelastic devices (OVDs), irrigation solutions and other aspects related to cataract phacoemulsification surgery on the corneal endothelium using porcine eyes.

METHODS

Thirty-four porcine eyes were randomly assigned to three groups (phacoemulsification (n = 13), irrigation (n = 9), control (n = 12)). A total of 5 min of ultrasound energy with intermittent irrigation/aspiration was applied in the eyes of the phacoemulsification group. The eyes of the irrigation group received the identical treatment, but without the application of ultrasound energy. The control group was left untreated. All eyes were then prepared to split corneal buttons followed by 15 days of cultivation. Endothelial cell density (ECD) was assessed blinded on day 15.

RESULTS

Endothelial cell density declined significantly more until day 15 in the phacoemulsification group (2567 ± 317/267 cells/mm² (median ± 25%/75%-quartiles), -32.5 ± 7.0/6.4%) compared to the irrigation (3450 ± 350/383 cells/mm², -11.8 ± 5.3/2.6%; p < 0.001) and the control group (3650 ± 288/258 cells/mm², -10.2 ± 3.2/4.6%; p < 0.001).

CONCLUSION

The phacoemulsification damage model presented in this study is sensitive to phacoemulsification energy and may reliably be used to investigate various factors involved in phacoemulsification with regard to their influence on corneal endothelial cells. This method is able to replace animal experiments or in vitro cell culture experiments that often do not translate well to the in vivo situation in humans.

Central corneal epithelial thickness changes after half-moon supracapsular nucleofractis phacoemulsification technique

PURPOSE

To find out the effect of half-moon supracapsular nucleofractis technique on central corneal epithelial thickness (CET) measured by spectral domain anterior segment optical coherence tomography (AS-OCT).

MATERIALS AND METHODS

Patients who underwent uneventful cataract surgery by the same surgeon with the same technique were recruited in this study. The effective phaco time (EPT) was recorded in each surgery. Central CET was measured by AS-OCT 1 day before and 1, 3, 7 days after surgery. CET was measured without precorneal tear film layer, and non-epithelial central corneal thickness was also calculated manually. Preoperative and postoperative values were compared by statistical analysis.

RESULTS

Thirty-one eyes of 31 patients were included in this study. The mean age of patients was 65.03 ± 11.47 years. On the first day of surgery, increase in mean CET was statistically significant, but on the 3rd and 7th day after surgery, this increase was declined (p = 0.001, p = 0.367, p = 1, respectively). A statistically significant positive correlation was found between mean EPT and mean CET on the first postoperative day (p = 0.013, r = 0.470). On the 3rd and 7th day, this correlation was not statistically significant (p = 0.055, p = 0.454, respectively).

CONCLUSION

Mean central CET was statistically thicker and positive correlated with EPT on the first postoperative day. But on the 7th day, it declined to preoperative values.

Torsional phacoemulsification: A pilot study to revise the "harm scale" evaluating the endothelial damage and the visual acuity after cataract surgery

PURPOSE

To study the effect of torsional phacoemulsification energy on corneal endothelium evaluating the relationship between changes of endothelial cells and postoperative visual acuity.

METHODS

This prospective clinical observational cohort study included 50 patients with cataract who underwent torsional phacoemulsification. Sequential quantitative and qualitative morphometric endothelial cell analyses of the cornea were performed four weeks preoperatively and six weeks postoperatively using noncontact specular microscopy.

RESULTS

This work confirmed the strong relationship, described by a linear model (one-way ANOVA, R2 = 77.9%, P < 0.0001), between the percentage of endothelial cell loss (ECL%) and the 5-score harm scale. According to the Tukey post-hoc pairwise comparison test, distinct values of ECL% are grouped in 3 subsets. The value of ECL = 10% has been identified as cut-off to discriminate patients with excellent postoperative best-corrected visual acuity (BCVA > 85 letters) from those with just a good/satisfied visual outcome (BCVA ≤ 85 letters). Within the 5-score harm scale, there was a significant correlation among phaco energy intraoperatively delivered and the average endothelial cell loss.

CONCLUSIONS

This study confirms the validity of the 5-score harm scale first proposed by Sorrentino and colleagues in 2016. This time, the method categorizes cataracts taking into account nucleus hardness and phaco cumulative dissipated energy. Predicting the harm on corneal endothelium, we can discriminate patients with excellent BCVA and with just good/satisfied BCVA. With torsional phacoemulsification with respect to longitudinal, the percentage of patients who can reach excellent BCVA is remarkably increased.