|Year : 2016 | Volume
| Issue : 3 | Page : 623-626
Phacoemulsification, topography guided
Saber H El-Sayed1, Ghada Z El.Abedin Rajab1, Sabry A. S. El-Banna2
1 Department of Ophthalmology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Ophthalmology, Faculty of Medicine, Mansoura University, Mansoura, Egypt
|Date of Submission||30-Jun-2015|
|Date of Acceptance||29-Aug-2015|
|Date of Web Publication||23-Jan-2017|
Sabry A. S. El-Banna
10, Gehan Street, Mansoura, Dakahlia Governorate, 35511
Source of Support: None, Conflict of Interest: None
The aim of this study was to evaluate the astigmatic correcting effect of paired opposite clear corneal incisions (OCCIs) on steep axis in cataract patients with preoperative regular astigmatism undergoing phacoemulsification.
Phacoemulsification in the era of refractive surgery is hitting new frontiers through the correction of preoperative astigmatism at the same time of cataract surgery.
Materials and methods
A total of 80 eyes of 80 patients were enrolled in this prospective study. All eyes had cataract, which necessitated undergoing phacoemulsification. Each patient underwent phacoemulsification surgery combined with OCCIs, to correct preoperative astigmatism. All patients were scheduled to postoperative visits at 1 week, 1, 2, and 3 months postoperatively. Corneal topography was performed at each visit.
Our patients revealed a decrease in preoperative astigmatism throughout the follow-up period. The decrease in the mean astigmatism values was 1.56 ± 0.73 D. This was a statistically significant result (P < 0.05). However, the decrease was most evident in patients with vertical or oblique axes astigmatism, and least evident in patients with horizontal axis astigmatism.
OCCIs are innovative on-axis technique for correcting astigmatism at the time of cataract surgery. This is advantageous due to the simplicity of the technique and nearly avoidable complications.
Keywords: corneal topography, opposite clear corneal incision, phacoemulsification, preoperative astigmatism
|How to cite this article:|
El-Sayed SH, El.Abedin Rajab GZ, El-Banna SA. Phacoemulsification, topography guided. Menoufia Med J 2016;29:623-6
| Introduction|| |
Modern cataract surgery is a refractive procedure whereby one basically can achieve the targeted postoperative refraction. To achieve this goal, biometry, mathematical calculation of intraocular lens (IOL) power, and astigmatism management are important factors  .
Patients undergoing cataract surgery expect clear vision and less dependence on spectacles. To attain this goal, one important consideration is reduction of astigmatism. Modern cataract surgery using small incisions and foldable IOLs has led to achieving emmetropia in a great number of patients. Modifications in surgical technique and incisions may further improve refractive outcomes through the reduction of astigmatism  .
Although astigmatism can be corrected after cataract surgery, it is more appropriate to combine both procedures. Pre-existing corneal astigmatism at the time of cataract surgery can be treated through the manipulation of cataract incision, limbal relaxing incision, astigmatic keratotomy, or implantation of toric IOLs  .
Incision construction during cataract surgery, making it on the steep corneal axis, is the simplest method for astigmatism correction  . Adding an extra opposite clear corneal incision (OCCI) was tried by many, and proved to be effective for the correction of mild-to-moderate corneal astigmatism. However, in eyes with higher degrees of astigmatism, it is recommended to use an alternative method or a combination of two or more methods  .
| Materials and methods|| |
A total of 80 eyes of 80 cataractous patients were enrolled in this study. The effect of OCCIs on preoperative corneal astigmatism was studied using preoperative and postoperative corneal topography.
All surgeries were carried out at Menoufia University Hospital between January 2014 and January 2015 using the Geuder Megatron G (Geuder Megatron, G. Heidelberg, Germany).
All eyes had cataracts, and were candidates for cataract surgery through phacoemulsification. All eyes had a corneal astigmatism of more than 2 D. Eyes with any previous ocular surgery, corneal lesions, scars, degenerations, dystrophies, glaucomas, or irregular astigmatism were excluded.
All patients were subjected to complete history taking, including the general medical condition and the ocular morbidity, with emphasis on history of ocular trauma and surgeries. Complete ophthalmic examination was carried out, including uncorrected and best-corrected visual acuities, slit lamp biomicroscopy, IOP measurement, and fundus examination. Corneal topography was performed to determine the diopteric power of the cornea in the principal meridians and to calculate the preoperative corneal astigmatism. The SHIN-NIPPON CT-1000 (Rexxam Co., Ltd., Takamatsu, Kagawa, Japan) corneal topography machine was used for all cases of the study.
Immediately preoperatively, the steepest meridian was carefully marked on the slit lamp. This marked meridian was the site of the main incision and was 180° away from OCCI.
All patients were operated under retrobulbar anesthesia. Mepivacaine HCl 2% and bupivacaine 0.5% were used for local infiltration.
In cases with vertical axis astigmatism, the main incision was made at 12 O'clock position. However, in cases with horizontal axis astigmatism, the main incision was made temporally at 9 O'clock position. In oblique axis astigmatism, the main incision was made according to the steepest meridian.
Phacoemulsification was performed using the divide and conquer technique. After IOL implantation and ahead of aspirating the remaining viscoelastic material, an OCCI was then made 180°away from the main clear corneal incision on the same detected meridian.
All patients were examined on the first postoperative day, and then had follow-up visits planned after 1 week, 1, 2, and 3 months postoperatively. At each visit, a corneal topography was obtained to assess the astigmatic lowering effect of the procedure.
These data were tabulated and statistically analyzed using an IBM compatible personal computer with SPSS statistical package, version 17 (IBM, New York, USA). The statistical data were descriptive and were expressed in the form of number, percentage, and mean ± SD.
| Results|| |
The mean age of participants was 60.64 ± 6.8 years. In all, 48 (60%) cases were female, and the remaining 32 (40%) cases were male.
The mean preoperative astigmatism was −2.52 ± 1.4 D, with a mean preoperative axis of 88.07 ± 47.04°.
Overall, 44 (55%) patients had astigmatism of a vertical axis (between 60° and 120°), and 24 (30%) patients had astigmatism of a horizontal axis (between 0° and 30° and 150° and 180°), whereas the remaining 12 (15%) patients had astigmatism of oblique axis (between 30° and 60° and 120° and 150°).
At the last postoperative visit, the mean corneal astigmatism value decreased to −0.96 ± 1.66 D, with a mean corrected value of 1.56 ± 0.73 D.
The mean preoperative K1 reading was 47.03 ± 2.83, whereas the mean K2 reading preoperatively was 44.49 ± 2.24. These values decreased at the last visit postoperatively to a mean K1 value of 46.53 ± 2.52 and a mean K2 value of 44.49 ± 2.29, which was nearly the same as preoperative K2 values.
According to the axis of astigmatism, patients were statistically divided into three groups: horizontal, vertical, and oblique axis groups. Changes in astigmatism were assessed in each group independently.
In the horizontal axis astigmatism group, there were 24 (30%) patients with a mean preoperative corneal astigmatism of 1.75 ± 0.84 D. This value decreased in the third month postoperatively to 1.62 ± 0.51 D. This result was statistically significant (P < 0.05).
However, in the vertical axis astigmatism, there were 44 (55%) patients with a mean preoperative corneal astigmatism of 2.84 ± 1.01 D. This value decreased in the third month postoperatively to 1.86 ± 0.92 D. This result was statistically significant (P < 0.05).
The last group with oblique axis astigmatism included 12 (15%) patients. These patients had a mean preoperative corneal astigmatism of 2.68 ± 0.66 D, which decreased at the last visit postoperatively to 1.73 ± 0.89 D. This result was statistically significant (P < 0.05).
The decrease in the mean astigmatism values in the three groups was statistically significant (P < 0.05). However, the decrease was most evident in the groups with vertical or oblique axes astigmatism, and least evident in the group with horizontal axis astigmatism.
As regards visual outcomes, the mean logMAR preoperative uncorrected visual acuity (UCVA) was 1.1 ± 1.85, which was slightly corrected to 1.0 ± 0.36. Three months postoperatively, patients achieved a mean logMAR UCVA of 0.6 ± 0.22, which was corrected to a mean of 0.22 ± 0.09 (∼6/9). It is remarkable that postoperative UCVA of 6/24 or more was achieved in 77.5% of patients (62 patients), whereas 95% of patients (76 patients) achieved a postoperative best-corrected visual acuity of 6/9 or more ([Table 1], [Table 2] and [Table 3]).
| Discussion|| |
In this study, 80 eyes of 80 patients have been operated on for cataract. All patients underwent phacoemulsification surgery. In a step forward toward patients' welfare, corneal topography for each patient was obtained. OCCIs have been planned in an attempt to decrease the preoperative astigmatism, which could have compromised the visual outcomes of our patients.
In this study, the steepest axis was marked preoperatively on the slit lamp using an astigmatic marker. The same was carried out by some authors, who recommended marking the steep axis before anesthesia, and the patient was in sitting position to avoid cyclotorsion effect of the oblique muscles  . However, others marked the steepest axis on table after complete anesthesia  .
In this study, the OCCIs were constructed as a one-step clear corneal incision for each incision using a 3.2 mm disposable keratome. We have affected an incision length of around 2 mm. However, other studies used a diamond knife to create a one-step OCCIs of 2.8-3.2 mm in width and around 1.5 mm in length  .
Technically, the procedure requires a stable anterior chamber, best achieved with the newer generations ophthalmic viscosurgical devices  . This was how the AC stability was maintained during this study. However, some authors favored the anterior chamber maintainer to achieve the same result  .
In this study, the OCCIs were not used for phacoemulsification, as they were made at the end of the procedure. Lever and Dahan  performed the OCCIs at the start of the procedure; however, they recommended not using it for phacoemulsification. However, Lever J, Dahan E reported that the OCCIs could be used for hydrodissection, irrigation/aspiration, and even posterior capsular polishing  .
OCCIs were never sutured in this study, only hydration was used for affecting tight closure of the incisions. Cases that required suturing were excluded from that study. The same strategy was used by most other studies ,, .
In that study, the mean astigmatic correction was 1.56 ± 0.73 D (P < 0.05). In the initial study by Lever and Dahan, they have reported a mean astigmatic correction of 2 D. This difference between the two studies may be attributed to the fact that Lever and Dahan used variable incision lengths, ranging from 2.8 to 3.5 mm, according to variability in preoperative astigmatism, ranging from 2 to 5 D. However, we used a fixed incision length (3.2 mm) for all patients, with a preoperative range of astigmatism between 2.25 and 5.5 D  .
Khokhar et al.  reported a mean astigmatic correction of 1.6 D  . Tadros and colleagues reported 0.5 D as a mean astigmatic correction using the OCCIs technique  . Both studies used a standard incision length of 3.5 mm.
In patients with horizontal axis astigmatism, a mean preoperative corneal astigmatism of 1.75 ± 0.84 D was recorded, which decreased in the third month postoperatively to 1.62 ± 0.51 D (P < 0.05).
In patients with vertical axis astigmatism a mean preoperative corneal astigmatism of 2.84 ± 1.01 D was recorded, decreasing in the third month postoperatively to 1.86 ± 0.92 D (P < 0.05).
The last group with oblique axis astigmatism recorded a mean preoperative corneal astigmatism of 2.68 ± 0.66 D, decreasing in the last visit postoperatively to 1.73 ± 0.89 D (P < 0.05).
The present study showed stable results, from the first postoperative visit to the end at the third month postoperatively. The reduction in astigmatism was statistically significant throughout the follow-up period (P < 0.05). It is also remarkable that there was no regression recorded during the follow-up period. The best results were recorded in patients with a preoperative vertical or oblique axis astigmatism.
In the present study, we recorded no clear corneal incision-related complications. All wounds were perfectly sealed from the first postoperative day.
| Conclusion|| |
OCCIs provide an innovative technique for managing preoperative, regular, corneal astigmatism. This is a simple, easy-to-learn technique, with no extra instrumentation.
The OCCIs in this study was safe, with no wound-related complications. However, OCCIs require careful early postoperative care due to their penetrating nature. Once the wounds are sealed, risk for further complications approaches zero.
Authors' contribution: Saber H. El-Sayed: concepts, design, definition of intellectual content; Ghada Z. El-Abedin Rajab: manuscript preparation, manuscript editing, and manuscript review; Sabry A.S. El-Banna: clinical studies, data acquisition, data analysis, and statistical analysis.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
El-Sayed S, El-Sobky H, Badawy N, El-Shafy E. Phacoemulsification versus manual small incision cataract surgery for treatment of cataract. Menoufia Med J 2015; 28
Mullaney P. Paired opposite clear corneal incisions to correct preexisting astigmatism in cataract patients. J Cat Ref Surg 2005; 31
Buckhurst P, Wolffsohn J, Davies L, Naroo S. Surgical correction of astigmatism during cataract surgery. Clin Exp Optom 2010; 93
Lever J, Dahan E. Opposite clear corneal incisions to correct pre-existing astigmatism in cataract surgery. J Cat Ref Surg 2000; 26
Bazzazi N, Barazandeh B, Kashani M, Rasouli M. Opposite clear corneal incisions versus steep meridian incision phacoemulsification for correction of pre-existing astigmatism. J Ophthalmic Vis Res 2008; 3
Qammar A, Mullaney P. Paired opposite clear corneal incisions to correct preexisting astigmatism in cataract patients. J Cat Ref Surg 2008; 31
Borasio E, Mehta J, Maurino V. Surgically induced astigmatism after phacoemulsification in eyes with mild to moderate corneal astigmatism: temporal versus on-axis clear corneal incisions. J Cat Ref Surg 2006; 32
Nassar M, Said-Ahmed K, Al-Morsy O, Gawish D. Management of pre-existing regular astigmatism in phacoemulsification. Menoufia Med J 2015; 28
Khokhar S, Lohiya P, Murugiesan V, Panda A. Corneal astigmatism correction with opposite clear corneal incisions or single clear corneal incision: comparative analysis. J Cat Ref Surg 2006; 32
[Table 1], [Table 2], [Table 3]