|Year : 2015 | Volume
| Issue : 1 | Page : 162-167
Bimanual microincision versus coaxial phacoemulsification cataract surgery
Saber H El-Sayed, Amin F Ellakwa, Nermeen M Badawi, Abeer M Wahba
Department of Ophthalmology, Faculty of Medicine, Menoufia University; Shibin El-Kom Ophthalmology Hospital, Menoufia Governorate, Menoufia, Egypt
|Date of Submission||11-May-2013|
|Date of Acceptance||22-Jul-2013|
|Date of Web Publication||29-Apr-2015|
Abeer M Wahba
El-Bagour, Menoufia, Gamal Abdel Nasser St., 11160
Source of Support: None, Conflict of Interest: None
Bimanual microincision and coaxial phacoemulsification are the modalities of cataract surgery.
The aim of the study was to evaluate bimanual microincision phacoemulsification versus coaxial phacoemulsification cataract surgery.
Patients and methods
Thirty patients were enrolled between December 2011 and March 2013, all with symptoms related to cataract. Fifteen patients were randomly assigned to the bimanual microincision group and another 15 patients to the coaxial phacoemulsification group. All patients were followed after 1 day, 1 week, 1 month, and 3 months of the procedure. The primary outcome of our study was lowering of astigmatism in the bimanual microincision procedure.
The bimanual group demonstrated a reduced surgically induced astigmatism (SIA). The coaxial group demonstrated a slight rise in SIA. There is a highly significant difference between postoperative SIA in both groups during the postoperative period (P < 0.001).
Microincisional cataract surgery using bimanual phacoemulsification has many advantages but it is limited by the lack of suitable intraocular lenses for implantation through microincisions; hence, switching to this technique from the conventional one still depends on the surgeon's performance.
Keywords: Bimanual microincision, cataract surgery, coaxial phacoemulsification
|How to cite this article:|
El-Sayed SH, Ellakwa AF, Badawi NM, Wahba AM. Bimanual microincision versus coaxial phacoemulsification cataract surgery. Menoufia Med J 2015;28:162-7
|How to cite this URL:|
El-Sayed SH, Ellakwa AF, Badawi NM, Wahba AM. Bimanual microincision versus coaxial phacoemulsification cataract surgery. Menoufia Med J [serial online] 2015 [cited 2019 Sep 20];28:162-7. Available from: http://www.mmj.eg.net/text.asp?2015/28/1/162/155976
| Introduction|| |
Cataract surgery continues to evolve, embracing smaller incisions that allow quicker recovery, better wound strength, and increased surgical control, resulting in lower complication rates and better outcomes. Phacoemulsification was carried out through an ~3-mm incision using an ultrasound (US) tip that is within a silicon sleeve, allowing irrigation, US delivery, and aspiration of lens matter through the same instrument .
Microincision phacoemulsification through a sub 2-mm incision was reported in the mid 1980s. However, it has only become popular in recent years, as technical improvements have allowed this to be performed with safety in addition to the availability of intraocular lenses (IOLs) that can be implanted through a sub 2-mm incision .
Microincision cataract surgery offers quicker visual recovery, reduced surgically induced astigmatism (SIA), and reduced complication rates with more secure wounds, and some unique advantages offered by bimanual microincision phacoemulsification make it the preferred technique for some surgeons .
| Patients and methods|| |
This prospective study was conducted on 30 patients suffering from symptomatic cataract. Patients were selected randomly from the outpatient clinics of the Department of Ophthalmology, Menoufia University. All study participants signed an informed consent agreement as a part of the initial enrollment.
Patients with cataract were evaluated for treatment. Clinical examination and noninvasive studies [slit-lamp examination, fundus examination, and ultrasound (US)] were used to confirm cataract. Patients considered for treatment subsequently underwent biometry to calculate IOL power.
Inclusion criteria consisted of patients with degree of nuclear sclerosis grading of I, II, III, or IV, intact zonules, moderately deep anterior chamber, and completely dilatable pupil. Patients with anterior segment diseases other than cataract, such as those with cornel opacities, chronic uveitis, and glaucoma or exfoliation syndrome, were excluded. Patients with posterior segment pathology hindering the visual outcome after surgery, traumatic, pediatric, or complicated cataract were also excluded. Patients had to be acceptable for surgery. Enrolled patients were prospectively randomized before intervention into one of the two treatment groups (each group included 15 patients): bimanual microincision phacoemulsification and coaxial phacoemulsification.
The coaxial procedure was performed by a two-step clear corneal incision (3.2 mm) created at the steep axis, as determined by preoperative keratometry, and a paracentesis of 1.5 mm was performed at 90° to the main incision. Curvilinear capsulorhexis was then performed using an Utrata capsulorhexis forceps under viscoelastic agent. Following hydrodissection, nucleus cracking was carried out by phacoemulsification within the capsular bag. A Megatron S3 Hanse Geuder phacoemulsification machine was used for all coaxial phacoemulsification procedures. Following irrigation/aspiration of soft lens matter, an Acrysofa IOL was inserted into the capsular bag using an IOL injector. Thereafter, the remaining viscoelastic was removed by irrigation/aspiration, and the corneal section was hydrated using balanced salt solution. Once the surgeon confirmed the integrity of the corneal wound, a subconjunctival injection of corticosteroid and antibiotic was given .
For bimanual microincision phacoemulsification, a 1.1-mm incision was made in the temporal cornea using a 19-G MVR blade with a sleeveless phacoemulsification tip. An infusion side port of 1.3 mm was also created at 90° from the first incision. A Megatron S3 Hanse Geuder phacoemulsification machine with custom control software system was used in all the MICS procedures. Bimanual phacoemulsification was used with a sleeveless phacoemulsification tip and an irrigating chopper. Both vertical and horizontal chopping techniques were used. Bimanual irrigation/aspiration of cortical lens remnants was then performed, and the capsular bag was inflated with the viscoelastic substance. The initial corneal incision was enlarged to 1.7 mm, and an Acrysofa IOL was implanted into the capsular bag. Both corneal wounds were hydrated with balanced salt solution, and when the surgeon was satisfied with the integrity of the corneal wound, a subconjunctival injection of corticosteroids and antibiotic was given .
After discharge, all patients in both groups were entitled to postoperative assessment and follow-up examination after 1 day, 1 week, 1 month, and 3 months. Patient assessment was essentially focused on slit-lamp microscopy, uncorrected visual acuity, best-corrected visual acuity (BCVA), refraction, and K readings. Both uncorrected visual acuity and BCVA were measured using a Landolt Broken Ring Chart and were converted to logMAR decimal fraction for easy statistical analysis.
Continuous variables were presented as mean and SD, whereas categorical variables were presented as counts and percentages. Differences between continuous variables were assessed by two-tailed unpaired t-test. A P-value less than 0.05 was considered statistically significant.
Comparison between the mean values of the operative time in both groups with respect to the nuclear grading was made using the analysis of variance test.
Comparison between the differences of mean values of visual acuity (VA) readings, BCVA readings, cylinder readings, K1 readings, K2 readings, and SIA in both groups during the postoperative period was carried out using the paired t-test.
| Results|| |
Between December 2011 and March 2013, 15 patients were operated using conventional coaxial phacoemulsification and 15 patients were operated using bimanual microincision phacoemulsification.
The analysis was carried out on 30 patients consisting of 16 female patients and 14 male patients ranging in age between 45 and 71 years. Baseline characteristics were similar in both treatment groups. Patients in group A were operated using the conventional coaxial phacoemulsification, whereas patients in group B were operated using bimanual cool phacoemulsification.
The two groups were chosen with no statistically significant difference with respect to the preoperative data or the distribution of nuclear grading within each group. This was carried out to avoid undesirable influence on the results as Hayashi et al.  found that the nuclear firmness was the most significant risk factor for endothelial cell injury after phacoemulsification [Table 1].
|Table 1: Demographic details and outcomes for study eyes undergoing bimanual microincision cataract surgery and |
standard coaxial phacoemulsifi cation
Click here to view
Comparison between the mean effective phacoemulsification time (EPT) values (s) in both groups with respect to the nuclear grading showed that there was a statistically significant increase in the mean EPT in group A compared with that in group B, and in addition the operative time increased with the increase in nuclear grading (P<0.05; [Table 1]).
Comparison between the mean values of the operative time in both groups with respect to the nuclear grading using analysis of variance test showed that there was a statistically significant increase in the mean operative time in group B compared with that in group A, and in addition the operative time increased with the increase in nuclear grading (P<0.05; [Table 1]).
Comparison between the difference in mean values of VA readings in both groups during the postoperative period using paired t-test showed that there was no statistically significant difference between the postoperative VA in both groups (P>0.05; [Table 1]).
Comparison between the difference in mean values of the BCVA readings in both groups during the postoperative period using paired t-test showed that there was no statistically significant difference between the postoperative BCVA in both groups (P>0.05; [Table 1]).
Comparison between the difference in mean values of the cylinder readings in both groups during the postoperative period using paired t-test showed that there was no statistically significant difference between the postoperative cylinder in both groups (P>0.05; [Table 1]).
Comparison between the difference in mean values of the K1 readings in both groups during the postoperative period using paired t-test showed that there was no statistically significant difference between the postoperative K1 in both groups (P>0.05; [Table 1]).
Comparison between the difference in mean values of the K2 readings in both groups during the postoperative period using paired t-test showed that there was no statistically significant difference between the postoperative K2 in both groups (P>0.05; [Table 1]).
Comparison between the mean values of the SIA in both groups during the postoperative period using paired t-test showed that there was a highly significant difference between postoperative SIA in both groups (P<0.001; [Table 1]).
Intraoperative complications such as collapse of the AC (surge) was reported in one patient in group A with slippage of the side ports of the phacoemulsification tip sleeve outside the wound and also in one patient in group B, and difficulty during lens implantation was reported in two patients in group B with a risk of tearing of the posterior capsule. This complication was not reported in group A.
| Discussion|| |
The drive toward less traumatic surgery and more rapid visual rehabilitation after cataract surgery has given rise to various modalities for reducing incision size and decreasing energy utilization. One of these modalities is microincisional cataract surgery, for example, bimanual phacoemulsification, which is being evaluated in this study .
In this study, two groups of patients were operated upon using two different techniques: group A (coaxial phacoemulsification) and group B (bimanual phacoemulsification).
The two groups were chosen with no statistically significant difference with respect to the preoperative data or the distribution of nuclear grading within each group. This was carried out to avoid undesirable influence on the results as Hayashi et al.  found that the nuclear firmness was the most significant risk factor for endothelial cell injury after phacoemulsification.
Although increased energy can allow phacoemulsification of dense nuclei, it can also damage the corneal endothelium; hence, the surgeon must utilize the minimal effective phacoemulsification power to obtain the best results without scarifying the corneal integrity .
The phacoemulsification chop technique was chosen in this study because it is one of the low energy producing techniques of phacoemulsification. It is a high vacuum technique that evolved with a main target to reduce the amount of US energy during phacoemulsification  and is characterized by the use of mechanical forces (chopper) rather than the US to disassemble the nucleus . The analysis of the intraoperative data in this study proved that there is a clinically significant reduction in the EPT used in the bimanual phacoemulsification group (1.10 ± 1.43) compared with that used in the coaxial phacoemulsification group (2.85 ± 1.56). In a study conducted by Olson et al. , the mean EPT used was 1.14 ± 1.3 for performing bimanual phacoemulsification.
However, as the US power increases with the increase in nuclear hardness the mean EPT used for each nuclear grade was compared with that of the other group for more accuracy. [Table 1] shows that the EPT was 0.1, 2.79, 3.13, and 5.18 in group A and 0.08, 0.49, 1.36, and 1.53 in group B for N+I, N+II, N+III, and N+IV, respectively, which showed that there was a statistically significant reduction in the energy needed for emulsification of each nuclear grade when performing bimanual phacoemulsification.
However, there is still much debate on the statement that the US is the most critical factor of corneal damage after phacoemulsification; many other studies showed other associated factors such as contact with surgical instruments, lens nucleus, lens fragments, air bubbles, and the IOL itself .
AC stability is a crucial factor for a safe operative technique; the incision size is critical in maintaining the anterior chamber stability and avoiding an incision leak. An incision oversized by as little as 0.2 mm will result in AC instability and fragment coming toward the wound instead of the phacoemulsification tip .
Despite the fact that a less amount of fluid is required to perform bimanual phacoemulsification, it is mandatory to increase the bottle height to 110 cm instead of 90 cm for conventional coaxial phacoemulsification to maintain the stability of AC.
The routine bottle height in most phacoemulsification equipment is inadequate; thus, an extender must be added or irrigating bottle be placed on intravenous pole and rose as high as the tube allows .
As for the operative time, the time required for performing phacoemulsification (19.16 ± 3.84) was statistically more significant than that for conventional phacoemulsification (15.08 ± 3.26). This time increases for harder nuclei: 10.25 ± 1.26, 14.44 ± 2.55, 16.50 ± 1.41, and 18.50 ± 2.89 for group A and 15.40 ± 0.55, 17.13 ± 1.55, 20.63 ± 2.50, and 25 ± 3.37 for group B. Similar results were obtained by Tsuneoka et al.  with a total group mean operative time of 8.42 ± 2.20 and also reported the same increase according to the nuclear grading (7.94 ± 1.24, 8.06 ± 1.50, 9.46 ± 2.06, and 13.48 ± ± 2.14 for N+I, N+II, N+III, and N+IV, respectively; ); studies showed a comparable time between the two techniques. However, the beginning of the learning curve may explain the need for more time to perform the operation in this study.
The intraoperative complications or difficulties in maintaining the depth of the AC associated with a surge due to slippage of the side ports of the phacoemulsification tip sleeve outside the wound were faced in group A.
The postoperative data can be considered as a parameter to detect the efficacy of the bimanual phacoemulsification technique. One of the main advantages of such a low power phacoemulsification technology is that it minimizes intraoperative damage to ocular structures, maximizing the level of rapidity of patient's visual rehabilitation . The main interest of the study was to evaluate the effect of bimanual phacoemulsification on the cornea and this was carried out by studying the effect of increasing power on the increase in the nuclear hardness.
By observing the data of VA and BCVA, it was found that the mean values of the VA were 0.25 ± 0.16, 0.41 ± 0.20, 0.43 ± 0.19, and 0.43 ± 0.19 for group A and 0.28 ± 0.18, 0.32 ± 0.15, 0.47 ± 0.17, and 0.47 ± 0.17 for group B. The patients with a VA 6/12 (0.50) or better were 34, 41, 4%, and 73% for group A and 53, 74, 87, and 87% for group B after 1 day, 1 week, 1 month, and 3 months, respectively. The mean values of the VA showed no statistically significant difference between the two groups. Similar results were obtained by Dogru et al.  in 14 of 16 eyes (87.5%), showing a VA 20/40 or better after 6 months.
The mean values of the BCVA were 0.49 ± 0.16, 0.76 ± 0.22, 0.70 ± 0.22, and 0.70 ± 0.22 for group A and 0.54 ± 0.23, 0.58 ± 0.24, 0.71 ± 0.20, and 0.72 ± 0.19 for group B after 1 day, 1 week, 1 month, and 3 months, respectively. The BCVA of 6/12 or better was 67, 73, 87, and 93% for group A and 80, 90, 94, and 94% for group B. The mean values of the BCVA showed no statistically significant difference between the two groups. The BCVA of 20/40 or better found by Agarwal et al.  was 78.75, 80.5, 83.1, and 87.23% after 1 day, 1 week, 1 month, and 3 months, respectively; all patients  achieved this level by 6 months.
One of the expected advantages of bimanual phacoemulsification is that it causes a less SIA due to creation of a small self-sealing incision  in addition to performing less manipulation within the wound. The ability to switch instruments between the two incisions increase the overall maneuverability, which facilitate removal of subincisional nuclear fragments or cortex or manipulation when there is a complication or when a nucleus is not rotating appropriately, making this approach safer on wound integrity than coaxial phacoemulsification [8,14].
The effect of both techniques on the postoperative astigmatism was studied by observing the corneal K readings and the cylinder readings. Analysis of the data showed that the difference in mean values of K1 was 0.33 ± 0.83, 0.28 ± 0.76, 0.32 ± 0.68, and 0.32 ± 0.68 for group A and 0.48 ± 0.35, 088 ± 0.38, 0.088 ± 0.38, and 0.088 ± 0.38 for group B after 1 day, 1 week, 1 month, and 3 months, respectively, during the postoperative period, with no statistically significant difference between the data in both groups.
The difference in mean values of K2 was 0.47 ± 0.72, 0.36 ± 0.63, 0.16 ± 0.47, and 0.16 ± 0.47 for group A and 0.24 ± 0.67, 0.29 ± 0.55, 0.29 ± 0.55, and 0.29 ± 0.55 for group B after 1 day, 1 week, 1 month, and 3 months, respectively, with no statistically significant difference between the data in both groups.
As for the cylinder, it was found that the mean values in group A were 0.9 ± 1.2, 0.70 ± 1.05, 0.55 ± 1.03, and 0.51 ± 0.99 and in group B were 0.19 ± 0.46, 0.17 ± 0.34, 0.17 ± 0.34, and 0.17 ± 0.34 after 1 day, 1 week, 1 month, and 3 months, respectively, with no statistically significant difference between the data in both groups. The absence of statistically significant difference in the cylinder was also reported: 0.07 ± 1.08 for coaxial phacoemulsification and 0.03 ± 0.5 for bimanual phacoemulsification .
Although the difference did not reach a statistically significant level, it was still obvious that the changes in both K readings and cylinder in group B was less than that in group A. Ortiz et al.  attributed this to a small number of patients and recommended to perform the study on a larger number of patients.
For the results that were more accurate, the effect of both techniques on the SIA was studied. [Table 1] shows that the SIA in group B is 0.79 ± 0.18, 0.65 ± 0.17, 0.65 ± 0.21, and 0.65 ± 0.21 and in group A is 1.62 ± 0.33, 1.47 ± 0.28, 1.09 ± 0.29, and 1.09 ± 0.29 after 1 day, 1 week, 1 month, and 3 months, respectively, with a highly statistically significant difference between the two groups.
However, by observing the previous data it was shown that the K readings values and cylinder in group B were stabilized earlier than those in group A, which indicates a trend toward earlier visual rehabilitation in case of bimanual phacoemulsification.
Alio et al.  indicated that the MICS surgery technique compared with standard coaxial phacoemulsification diminishes the mean incision size with statistical significance and mean EPT (P<0.001). Kahraman et al.  showed that in MICS the mean US time was statistically lower than in the coaxial group. In the study by Kurz et al.  , the microincision group had shorter EPT and BCVA improved more rapidly than in the coaxial group. In addition, Cavallini et al.  explained that microincision surgery can be less invasive and safer, resulting in less postoperative intraocular inflammation, fewer incision-related complications, and shorter surgical time.
| Conclusion|| |
Microincisional cataract surgery using bimanual cool phacoemulsification has many advantages as a technique for cataract removal, including elimination of wound burn, drastic reduction in used US power, increased stability of AC, and better postoperative corneal integrity. However, the procedure requires greater accuracy on behalf of the surgeon when it comes to the incision size and proper adjustment of the machine parameters. Using high vacuum for the first time can also be challenging. The technique is also limited by the lack of suitable IOLs for implantation through microincisions. Therefore, switching to this technique from the conventional one still depends on the surgeon's performance [Figure 1].
|Figure 1: Comparison between the mean values of the surgically induced astigmatism (SIA) in both groups during the postoperative period.|
Click here to view
| Acknowledgements|| |
Conflicts of interest
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