|Year : 2015 | Volume
| Issue : 1 | Page : 184-190
Macular thickness analysis following complicated versus uncomplicated cataract surgery using optical coherence tomography
Abdelrahman El-Sebaey Sarhan1, Osama Abdallah El Morsy1, Mohamed Gaber Abdallah Abdallah2
1 Department of Ophthalmology, Faulty of Medicine, Menoufia University, Menoufia, Egypt
2 Department of Ophthalmology, National Eye Center, Cairo, Egypt
|Date of Submission||14-Sep-2014|
|Date of Acceptance||19-Oct-2014|
|Date of Web Publication||29-Apr-2015|
Mohamed Gaber Abdallah Abdallah
Department of Ophthalmology, Faulty of Medicine, Menoufia University, Menoufia Governorate
Source of Support: None, Conflict of Interest: None
Evaluating the influence of risk factor of intraoperative complications such as rupture posterior capsule with vitrous loss on the postoperativemacular thickness using optical coherence tomography (OCT).
Cystoid macular edema (CME) remains an important cause limiting favorable visual outcomes following cataract surgery. Thecomplicated cataract surgery (with posterior capsular tear) could be a strong risk factor for development of macular edema than the uneventful surgeries.
70 cases, 62 patients underwent phacoemulsification surgeries divided into 5 groups anda healthy control group
Group I: Uncomplicated cataract surgery (non-diabetic)
Group II: Uncomplicated cataract surgery (Diabetic patient)
Group III: Complicated cases with PCR and Ant vitrectomy (non-diabetic)
Group IV: Complicated cases with PCR antvitrectomy (Diabetic patient)
Group V: Complicated cases with PCR ant vetrectomy, AC IOL
Group VI: Normal cases without cataract extraction
Patients follow up by Visual acuity, fundus ,IOP and Maculathickness map using OCT scan (RS-3000RetinaScan, NIDEK Co., Japan) was conducted after 1 month.
We found that, macular thickness was significantly higher after cataract surgeries with posterior capsular tear than the unevetiful surgeries, Also diabetes did not influence significantly the thickening of the macular regions after uncomplicated cataract surgery.
After cataractsurgery, there is non significant increase of foveal thicknessThe complicated cataract surgeries with rupture posterior capsule and vitrous loss may be a risk factor, while diabetes may not be a risk factor for development of post operative macular oedma.
Keywords: Cystoid macular edema, macular thickness, optical coherence tomography, phacoemulsification, posterior capsule rupture
|How to cite this article:|
Sarhan AE, El Morsy OA, Abdallah MG. Macular thickness analysis following complicated versus uncomplicated cataract surgery using optical coherence tomography. Menoufia Med J 2015;28:184-90
|How to cite this URL:|
Sarhan AE, El Morsy OA, Abdallah MG. Macular thickness analysis following complicated versus uncomplicated cataract surgery using optical coherence tomography. Menoufia Med J [serial online] 2015 [cited 2019 Jun 17];28:184-90. Available from: http://www.mmj.eg.net/text.asp?2015/28/1/184/155986
| Introduction|| |
Cystoid macular edema (CME) remains an important cause that limits favorable visual outcomes following cataract surgery. Although the incidence of CME has decreased in the small-incision phacoemulsification era, it has been reported that the incidence of CME (affecting visual outcome) after small-incision uneventful cataract surgery is between 0 and 9% (Mentes et al., 2003; Nicholas et al., 2006).
Evaluation of CME using optical coherence tomography (OCT) as a measurement tool has led many authors to investigate macular thickness quantitatively. Macular thickness was found to be increased even following uneventful cataract surgeries when compared with preoperative values . Biro et al.  reported a significant increase in the foveal and perifoveal thickness at 1 week, 1 month, and 2 months after uneventful cataract surgery.
The proposed causative factors for the development of CME following cataract surgery include surgical trauma (especially to the iris), postoperative inflammation, and tractional forces on the macula. An uncomplicated cataract surgery with intraocular lens implantation in the bag is not assumed to lead to the above-mentioned factors. However, a complicated cataract surgery (with posterior capsular tear) could be closely involved with the proposed mechanisms, but few studies have evaluated macular thickness and volume determined by OCT following a complicated cataract surgery .
| Patients and methods|| |
Seventy individuals were studied. Sixty-two patients underwent phacoemulsification surgeries and were divided into the following five groups and a healthy control group.
Group I: uncomplicated cataract surgery (nondiabetic patients).
Group II: uncomplicated cataract surgery (diabetic patients).
Group III: complicated cases with PCR and anterior vitrectomy (nondiabetic patients).
Group IV: complicated cases with PCR and anterior vitrectomy (diabetic patients).
Group V: complicated cases with PCR and anterior vitrectomy, AC IOL.
Group VI: normal cases without cataract extraction.
The exclusion criteria were as follows: previous history of ocular surgery, significant eye trauma, uveitis, optic nerve diseases, dense cataract grade IV or V, pre-existing diabetic retinopathy or macular edema in diabetic patients, and any coexisting ocular pathology that could affect visual acuity or macular thickness (e.g. corneal opacity, age-related macular degeneration, glaucoma).
Preoperative evaluation was performed by visual acuity, slit-lamp examination, indirect ophthalmoscopy and fundus examination, intraocular pressure using applanation tonometry, keratometry, axial length measurement, and intraocular lens power calculation.
For the phacoemulsification procedure (using Geuder Megatron S4 Machine), the mean ultrasonic time was 12 s. Phacoemulsification 1 (power 40-60 continuous, vacuum 50-60), phacoemulsification 2 (power 40-50 pulse, vacuum 200-300). Ruptured posterior capsule was managed by a viscoelastic injection before removal of the phacoemulsification probe through a side port and then adequate anterior vitrectomy with removal of the remaining lens matter, followed by sulcus implantation of acrylic IOL, except in cases with an insufficient rim of the anterior lens capsule in which the anterior chamber IOL were implanted.
Patients were followed up at 24 h, 7 days, 1 month, and at any time the patient developed new symptoms by visual acuity, slit-lamp biomicroscopy, fundus examinations, intraocular pressure, and the macula thickness map using an OCT scan after the first month.
OCT parameters: OCT images were created using an OCT RS-3000 Retina Scan (Nidek Co. Ltd, Japan) device that utilizes the spectral domain methodology. The OCT setting for the Macular Map scan was established by NAVIS-EX (Nidek Advanced Vision Information System-Extra, version 18.104.22.168; Nidek Co. Ltd) program. Macula Map acquisition X-Y [6.0 mm × 6.0 mm (256 × 256)] was performed by 1024 A scans with image acquisition number 50; width 6.0 mm release mode was single and fixation mode was large, LBS: ILM and LBE: RPE/BM [Figure 1].
|Figure 1: The nine Early Treatment Diabetic Retinopathy Study areas from which the three thickness fields were constructed.|
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Macular thickness analysis of macular maps was carried out in accordance with the guidelines of the Early Treatment Diabetic Retinopathy Study (ETDRS) from ILM to RPE/BM in three regions [Figure 1], which included within 1 mm (central foveal region), between 1 and 3 mm (inner perifoveal region), and between 3 and 6 mm (outer perifoveal region) of the diameter from the center. The macular thickness was measured in the nasal, temporal, superior, and inferior quadrants in accordance with ETDRS. Each quadrant was further divided into two cross meridians and three circular fields, which resulted in inner nasal (IN), inner temporal (IT), inner superior (IS), inner inferior (II), outer nasal (ON), outer temporal (OT), outer superior (OS), and outer inferior (OI) quadrants. If the images were not initially aligned, the center of the ETDRS circle of each image and the central fovea were manually placed together. The macular volume within the area covered by the total map, expressed in mm 3 , was also recorded. OCT scans were repeated when necessary to obtain adequate image quality.
We have classified the image qualitatively into four types [Figure 2] .
|Figure 2: Qualitative optical coherence tomography classifi cation. The top picture shows an example of a healthy macula. The three types are: 1, homogenous, 'smoothed-out', thickening of the fovea; 2, subfoveal low reflective macular detachment; and 3, thickening of the fovea with low refl ecting cystoid changes in the inner retinal layer. The bottom|
picture is a combination of types 2 and 3 .
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- Homogenous, 'smoothed-out', thickening of the fovea.
- Subfoveal low reflective macular detachment.
- Thickening of the fovea with low reflecting cystoid changes in the inner retinal layer.
- Combination of types 2 and 3.
| Results|| |
This study included 70 participants; 62 patients with immature senile cataract underwent phacoemulsification surgeries. There were eight healthy control participants. All demographic data according to age and sex were nonsignificant.
The mean central foveal thickness, mean inner 3 mm perifoveal, mean outer 6 mm perifoveal, and the mean macular volume in multiple comparisons of individual groups showed that the least significant difference was nonsignificant, except for group IV (complicated diabetics) and group V (complicated eyes with AC IOL) [Table 1].
On comparing complicated and uncomplicated cases with normal participants, we found nonsignificant changes in central foveal thickness, inner 3 mm perifoveal, outer 6 mm perifoveal, and macular volume between normal and uncomplicated cataract surgeries and a significant increase in these parameters in cases of complicated cataract surgery [Table 2] and [Figure 3].
|Figure 3: Comparison between complicated, uncomplicated, and normal cataract surgery according to macular thickness. CFT, central foveal thickness.|
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|Table 2: Comparison between complicated, uncomplicated, and normal catheter surgery according to macular thickness|
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We found that 16 of the total of 62 patients developed macular edema on the basis of the qualitative classification [Figure 2].
In terms of the incidence of CME, we found that 5.6% of the healthy participants without complications and 9.1% of the diabetic patients without complications developed CME (total 6.9%), whereas 27.8% of the healthy participants with complications and 50% of diabetic patients with complications developed CME. However, including the complicated cases with AC IOL with 80% positive cases made the total complicated positive cases 42.4 versus 6.9% of the total uncomplicated groups.
Comparison between the groups without complications versus and groups with complications was significant (P = 0.037 vs. 0.041, significant), whereas comparison between healthy controls without complications versus the diabetic group without complications was nonsignificant (P = 0.694, NS). However, comparison of all the groups with complications (including cases with AC IOL) with all the groups without complications was highly significant (P < 0.001, highly significant) [Table 3] and [Figure 4].
|Figure 4: Comparison between individual groups in terms of cystoid macular edema (CME).|
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|Table 3: Comparison between individual groups in terms of cystoid macular edema|
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The most recurrent form found in macular thickening was the first class (homogenous, 'smoothed-out', thickening of the fovea).
| Discussion|| |
In this study, we found that the OCT is a good noninvasive device to detect subclinical macular thickening in case of uncertain poor visual results after an uneventful cataract surgery. Evaluation of CME using OCT as a measurement tool has led many authors to investigate macular thickness quantitatively . Moreover, this study evaluated the influence of risk factors of intraoperative complications such as rupture posterior capsule on the postoperative course of macular thickness.
Macular thickness was found to be increased even following uneventful cataract surgeries compared with preoperative values. Biro et al.  reported a significant increase in the foveal and perifoveal thickness at 1 week, 1 month, and 2 months after an uneventful cataract surgery. In another study by Cagini et al. , an asymptomatic increase in macular thickness and volume at 12 weeks was observed with respect to the preoperative values. Lobo et al.  detected macular edema in 41% of patients (13 of 32 eyes) 4-6 weeks after a small incision cataract surgery. However, very few studies have evaluated macular thickness after a complicated cataract surgery using a quantitative method such as OCT. This study also enabled a comparison between healthy controls and diabetic patients with and without complications.
The parameters investigated were chosen according to the concepts of the etiology of pseudophakic macular edema [7,8]. These include the supposition that macular edema is caused by a subclinical inflammation triggered by the trauma of the operation and mediated by prostaglandins. Mechanical causes could be intraoperative trauma and alteration of the vitreous position after the removal of the lens as in posterior caps rupture.
We found that macular thickness was significantly higher after cataract surgeries with a posterior capsular tear than uneventful surgeries as only two ( 6.9%) of the total of 29 patients with cataract without complications developed macular thickening (5.6% among healthy controls and 9.1% among diabetic patients, mean total 6.9%). This figure increased significantly in patients with cataract with complications to reach 42.4%. This higher number may be attributed to the inclusion of diabetic eyes and eyes that needed extra manipulations (27.8% of healthy controls with complications, 50% of diabetic patients with complications, and 80% of patients with AC IOL without complications, mean total cases with complications 42.4%).
There is no consensus on OCT parameters for identifying the presence of CME after cataract surgery (Kim et al., 2008). In our study, we found an incidence of macular thickening after cataract surgery of 6.9% by OCT in all the healthy controls and diabetic patients without complications. Kim et al.  reported that the incidence of postoperative macular edema was 14% at 1 month for all diabetic patients and healthy controls without complications. Also, Perente et al.  reported that the incidence of CME was 10.9% at postoperative 4 weeks. Other studies had found angiographic leakage in 19% up to 88% of patients postoperatively . Lobo et al.  reported that the incidence of leakage sites was most prominent from 4-6 weeks.
Other studies evaluating cataract surgeries with a complication of posterior capsular tear reported that the incidences of CME in complicated cases were 6.8% , 8.7% , and 10% . Akçay et al.  reported that the incidence of CME was 10% after complicated surgeries, and none of the eyes with uneventful cataract surgery developed CME, whereas Sourdille and Santiago  found macular thickening and decreased visual acuity in 11 eyes out of 41 after uneventful cataract extraction. The definition of CME, the diagnostic method to evaluate CME (with angiography or OCT), and the total number of participants in the study were the main variables that led to the reported variability in incidences.
In agreement with our results, we found a nonsignificant increase between uncomplicated diabetics without preexisting retinopathy and uncomplicated healthy. Biró and Balla  also reported that diabetes did not significantly influence the thickening of the macular regions after an uncomplicated cataract surgery. However, postoperative changes in perifoveal macular thickness were found to be nonsignificantly higher in the diabetic group compared with the nondiabetic group . Also, these findings are in agreement with other studies ( [6, 16]). However, Neumaier et al.  reported that the percentage of postoperative foveal thickening was significantly higher in the diabetic group (60% 4 weeks after surgery) compared with the healthy participants in the other group (20% 4 weeks after surgery).
These variations may be attributed to the inclusion of diabetic patients with preexisting diabetic retinopathy, which might be associated with a high concentration of prostaglandins, other mediators, and a high incidence of subclinical changes in the macular blood-retinal barrier in the respective postoperative period [3,9]. Other published studies using OCT confirm the same findings (Van Velthoven et al., 2006).
Also, Biro et al.  reported that prostaglandin production secondary to both free-radical release and anterior segment ischemia after cataract surgery were suggested to be the main etiologic factors of the postoperative development of CME in eyes without mechanical traction and even without posterior vitreous detachment.
We believe that our rate of detection of CME was higher as a consequence of using SD-OCT. Typically, percentages of tomographic CME are much higher than angiographic or clinical CME . In other studies using FA, the rate of angiographic CME at 6 weeks after an uncomplicated cataract surgery was 18.7%, although the rate of clinical CME was only 2.1% . More specifically, in the subgroup with intraoperative complications, the rate of angiographic CME and clinical CME was 11 and 4.8%, respectively. Previously, Ching et al.  had used OCT to detect CME following uneventful phacoemulsification. They found that four out of 131 (3%) patients developed CME. Unfortunately, these patients were excluded from the analysis and the serial macular thickness was not reported.
We found that the incidences of CME were higher in the diabetic group with complications than the other groups; also, Eriksson et al.  reported an incidence of 6% CME in the eyes of control participants and 12% in the eyes of diabetic patients. This is lower than reported previously in the eyes of diabetic patients.
Measurements of macular thickness may be affected by surgical parameters such as the length of phacoemulsification surgery and the phacoemulsification time as well as the phacoemulsification energy, which may all influence the outcome . Von Jagow et al.  reported that surgical and biometric parameters such as phacoemulsification time and energy and axial length did not correlate to the degree of macular thickening. These parameters were not evaluated in our study. However, an average phacoemulsification time and energy was used in all of the cases.
In the present study, measurements outside the central macula were also recorded. Eriksson et al.  reported that in these areas, cataract surgery had a more pronounced effect on the eyes of diabetic patients than the eyes of normal controls. In agreement with our study, an increase in macular thickness was primarily detected in the perifoveal region. Lobo et al.  showed that an increase in macular thickness was primarily detected in the perifoveal region and the leakage accumulated later on in the fovea. They reported that leakage sites were primarily perifoveal vascular structures, and the leakage accumulates later on in the fovea. Biro et al.  also used the values of retinal thickness in the fovea and the perifoveal 3.0 and 6.0 mm sectors and detected mild subclinical perifoveal edema at postoperative day 7 to 6 months.
One of the limitations of the present study was the absence of preoperative OCT images because of significant cataracts, which prevented good-quality OCT scans. Several authors have commented that limited OCT image quality, because of media opacity such as cataract or vitreous opacifications, led to consecutive errors in macular thickness analysis [20-22]. In fact, it seems that errors in macular OCT scans are common, and can be found in more than 43% of the OCT maps [21,23]. Thus, this study did not compare the change in macular thickness before and after cataract surgery. However, the inclusion of a group of normal individuals without any ocular pathology or cataract provided a good comparative control group.
Moreover, one of the limitations of this study was a perfect comparison was quite difficult because when cataract surgeries become complicated, the use of a standard protocol is naturally impossible. However, we believe that this study has internal validity because all posterior capsular ruptures were managed using similar techniques (e.g. anterior vitrectomy, sulcus intraocular lens implantation) and eyes that needed extra manipulations (e.g. corneal suturing of main incisions, anterior chamber lens implantation) were included in a separate group in the study.
| Conclusion|| |
OCT is a valuable noninvasive device to detect subclinical macular thickening in case of uncertain poor visual results after cataract surgery. After cataract surgery, there is a non significant increase in foveal thickness. Complicated cataract surgeries with rupture posterior capsule and vitreous loss are considered a risk factor for the development of post operative macular edema. Also, diabetes did not significantly influence the macular thickness after an uncomplicated cataract surgery.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3]