|Ahead of print publication
Comparative evaluation of macular thickness following uneventful phacoemulsification and small incision cataract surgery
Mohammad Savarkar1, MS Usha1, Priya Taank2, Shalendra Singh3, Rolli Khurana2
1 Department of Ophthalmology, Mysore Race Club Eye Hospital, Mysore, Karnatka, India
2 Department of Ophthalmology, Command Hospital (SC), Pune, Maharashtra, India
3 Department of Anaesthesiology and Critical Care, Armed forces Medical College, Pune, Maharashtra, India
|Date of Submission||12-Jul-2020|
|Date of Decision||16-Dec-2020|
|Date of Acceptance||16-Dec-2020|
Department of Anaestheiology and Critical care, Armed Forces Medical College, Pune - 411 040, Maharashtra
Source of Support: None, Conflict of Interest: None
Backgrounds: To compare the change in central macular thickness (CMT) using optical coherence tomography (OCT) in subjects undergoing uneventful phacoemulsification and small incision cataract Surgeries (SICS). Methods: In this prospective observational study, patients undergoing uneventful cataract surgery were subdivided into two groups. Forty-five patients who underwent SICS were included in Group S (n = 45) whereas patients undergoing uneventful phacoemulsification were included in Group P (n = 50). Findings of slit-lamp examination, best-corrected visual acuity (BCVA), and fundus examination were recorded for all cases on the first postoperative day as well as 6 weeks after surgery. CMT of participants was determined using spectral-domain OCT preoperatively and at 6 weeks' postoperatively. Results: Overall three patients had postoperative cystoid macular edema, one case in Group P and two cases in Group S. 98%of patients in Group P and 95.5% of patients in Group S achieved BCVA of 6/9 or more. In Group S, a significant difference was observed between preoperative and postoperative central subfield mean thickness (P < 0.01). In Group P preoperative and 6th week, postoperative mean macular thickness showed a significant difference (P ≤ 0.03) only in the superior outer subfield. On comparing the change in CMT in the Group P with Group S, a significant difference was noted with markedly lesser chances of subclinical macular edema in the Group P. Conclusion: Although the increase in mean macular thickness postoperatively did not affect the final visual outcome in both the groups, Subclinical change in Group P was significantly lesser than that in Group S.
Keywords: Cataract, cystoid macular edema, optical coherence tomography, phacoemulsification
|How to cite this URL:|
Savarkar M, Usha M S, Taank P, Singh S, Khurana R. Comparative evaluation of macular thickness following uneventful phacoemulsification and small incision cataract surgery. Med J DY Patil Vidyapeeth [Epub ahead of print] [cited 2021 Jun 13]. Available from: https://www.mjdrdypv.org/preprintarticle.asp?id=316422
| Introduction|| |
Cystoid macular edema (CME) is one of the common postoperative complications following cataract surgery. CME has a peak incidence at 4–6 weeks following cataract surgery but can occur at any time between 4 and 16 weeks after surgery. Most cases spontaneously resolve within weeks to months. The incidence of clinical CME has been reported to be between 1% and 6% after cataract surgery., However, optical coherence tomography (OCT)-based incidence of pseudophakic CME ranges from 4% to as high as 41%., An uneventful cataract surgery carries less chance of release of inflammatory mediators and the development of CME. However, subclinical increase in Central macular thickness (CMT) after uncomplicated cataract surgery has a higher incidence. However, an increase in CMT is just a sign of disruption of the blood-retinal barrier and it sometimes does not affect the vision of postoperative patients.
The detection of a change in CMT can be either through clinical examination, fluorescein angiographic examination, or by OCT.,, More recently, OCT, being anon-invasive, tool for detection of CME, is the most commonly used modality. We could find only a few studies comparing clinical and subclinical CME after uneventful cataract surgery using OCT., Most studies compare 1st postoperative day and subsequent day data, but the present study compared pre- and post-operative data similar to Chaudhary et at. The purpose of this prospective study is to evaluate the incidence of CME and compare the incidence of change in CMT using OCT in subjects undergoing uneventful phacoemulsification surgeries versus small incision cataract surgeries (SICS).
| Methods|| |
Ethical clearance was obtained from the institutional ethics committee prior to the initiation of the study (SR9860207/MRCEH/Mysore, India, Date December 15, 2014). Ninety-five patients between age 40 and 80 years planned for senile cataract surgeries, in which fundoscopy and OCT evaluation of macular thickness were possible, were enrolled for this prospective interventional study. Cases with uveitis, diabetic maculopathy, macular scar, macular edema, age-related macular degeneration, myopia >5D, glaucoma, and patients with central corneal opacities were excluded from the study. Of these 95 patients, Group P (n = 50) patients underwent cataract surgery using the phacoemulsification technique, and Group S (n = 45) patients underwent under the SICS technique. During the study, the initial 50 patients fulfilling the study protocol underwent phacoemulsification (Group P) whereas the next 45 patients underwent SICS (Group S). Written informed consent was taken from all patients. Preoperatively, a thorough ocular examination was done, which included slit-lamp biomicroscopic examination, intraocular pressure by Goldmann applanation tonometer, fundoscopy using a 90D lens, A-scan biometry to measure axial length of the eye, and intraocular lens (IOL) power. Preoperative macular thickness measurement was done using Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA) by a single ophthalmologist. The three-dimensional macula protocol was used for macular thickness measurements using the Early Treatment Diabetic Retinopathy Study map. Postoperatively, all patients were prescribed moxifloxacin-prednisolone eye drops for 8 weeks in tapering doses and cyclopentolate eye drops once a day for 1 week. Postoperative slit-lamp findings, best-corrected visual acuity (BCVA), and fundus examination were recorded in all cases on the 1st postoperative day and in the 6th week. OCT was repeated on the 6th week postoperatively.
Data were analyzed by descriptive analysis. Cramer's v-test (cross tabs) was used for age, gender, and eye laterality. OCT results were analyzed using crosstabs (contingency tab analysis) and repeated measure ANOVA. Mean values were analyzed by Student's t-test. One way ANOVA was used to analyze nucleus grading and effective phacoemulsification time. Pearson Product moment correlation was used to correlate LogMAR BCVA, effective phacoemulsification time, and macular thickness. A P < 0.05 was considered to be statistically significant. All the statistical calculations were done through Statistical Package for the Social Sciences (SPSS), IBM, Chicago, USA for windows (v 16.0).
| Results|| |
Demographic parameters and clinical characteristics were comparable between the groups [Table 1]. The majority of patients in Group P (72%) and Group S (71.1%) were between 51 and 70 years the majority of patients in Group P (78%) and in Group S (82.2%) had nuclear sclerosis grades 2 and 3 [Table 1]. The mean effective phacoemulsification time in seconds for grades NS1, NS2, and NS3 were 0.94 ± 1.43 sec, 3.48 ± 1.62 sec, and 5.04 ± 1.40 s respectively (P < 0.00).
|Table 1: Demographic data and clinical characteristics in both groups (mean±2 standard deviation)|
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Sixty-four percent of patients in Group P and 86.7% of patients in Group S had preoperative visual acuity of 6/18 or less [Table 2]. BCVA of 6/9 or more was achieved by the 6th week in 100% patients in both groups. Preoperative BCVA in LogMAR (mean ± standard deviation) was 0.61 ± 0.29 in Group P and 0.92 ± 0.4 in Group S [Figure 1]. In Group P, BCVA (LogMAR) during first and last postoperative visits was 0.09 ± 0.10 and 0.009 ± 0.04, respectively. In Group S, BCVA (LogMAR) during first and last postoperative visits was 0.16 ± 0.10 and 0.03 ± 0.08, respectively. There was a significant difference in BCVA between Group P and Group S on the 1st postoperative day and also, in the 6th postoperative week [Figure 1].
|Figure 1: Preoperative and postoperative best-corrected visual acuity in LogMAR in both groups|
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|Table 2: Preoperative and postoperative Snellens chart values in both groups|
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Central 1 mm subfield mean thickness (CSMT) in Group P preoperatively and postoperatively was 212.78 ± 17.83 μm and 213.56 ± 24.24 μm, with no significant difference (P ≤ 0.72) [Table 1]. In Group S, a significant difference was seen between preoperative and postoperative CSMT values (P < 0.01) [Table 1]. In Group P, preoperative and 6th week postoperative mean macular thickness showed significant difference (P ≤ 0.03) only in the superior outer subfield and no significant difference was observed in superior inner (P ≤ 0.15), temporal inner (P ≤ 0.05), inferior inner (P ≤ 0.29), nasal inner (P ≤ 0.19), temporal outer (P ≤ 0.0), inferior outer (P ≤ 0.95), and nasal outer (P ≤ 0.08) subfields [Table 3].
|Table 3: Comparison of preoperative and 6th week postoperative mean macular thickness in subfields in both groups|
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In the present study, out of 95 patients who underwent cataract surgery, three cases (3.16%) showed CME, one case in Group P (2%), and two cases in Group S (2.22%). In Group P, 19 patients (38%) and in Group S, 13 patients (28.8%) were associated with one or more systemic comorbidities. Out of 95 patients, 13 patients had diabetes; 11 in Group P and 2 in Group S.
Out of 95 patients, 26.4% patients were associated with diabetes; whose CSMT preoperatively and 6th week postoperatively was 207.30 ± 17.76 μm and 209.23 ± 21.58 μm respectively, with no significant difference (P > 0.05) [Table 4]. In females (n = 38), CSMT preoperatively and 6th week postoperatively was 202.92 ± 17.92 μm and 211.63 ± 52.68 μm respectively, with no significant difference (P > 0.05) [Table 5].
|Table 4: Central 1 mm subfield means thickness between diabetics and nondiabetics in both groups|
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|Table 5: Central 1 mm subfield means thickness between male and female in both groups|
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| Discussion|| |
One of the important and common causes of reduced visual outcomes after cataract surgery is CME. The incidence of CME has decreased due to the improvement in the cataract surgery technique over the last few decades. However, the incidence of subclinical macular edema after uneventful cataract surgery has become an issue of safety for this frequently performed surgery since studies have found angiographic leakage in 19% to 88% of patients postoperatively even when visual acuity is not affected. Spectral is OCT used in this study is characterized by a higher repeatability index.
In our study, a significant difference was found only in the inferior inner (P < 0.03) subfield, and no significant difference was seen in other subfields preoperatively between both groups. Chaudhary et al. revealed that a statistically significant increase in macular thickness was noticed after 30 days of uneventful surgery by both phacoemulsification or SICS method which returned to near normal values by 3 months' postoperatively. Ghosh et al. revealed on the 1st postoperative day with no significant difference (P = 0.12) in CSMT in both groups. However, on the 7th and 42nd day, CSMT was significantly more in the SICS group than that in the phacoemulsification group (P = 0.04) (P = 0.007). An increase in macular thickness was detected by OCT after uncomplicated phacoemulsification and small incision cataract surgery in our study, starting from the preoperative values which were not significant. The increase in foveal thickness was significant at the 6th week postoperatively. This finding is consistent with other studies in the literature. It has been postulated in the literature that phacoemulsification even when uncomplicated may have an impact on the healthy retina; this could be attributed to factors such as the intraoperative photo stress due to the microscope light or the intraoperative changes of the intraocular pressure caused by surge; this impact may be expressed as temporary thickening of the central retina, without causing any permanent retinal damage or affecting visual acuity. Larger incision size as in SICS is associated with a more severe blood-retina barrier (BRB) breakdown when compared with phacoemulsification. The localized BRB defects were detected after SICS in 97% of the patients which eventually causes macular edema.
Few limitations of this study include the need to study these two surgical procedures with larger sample sizes and the need for a longer duration of the study.
| Conclusion|| |
In the present study, the overall incidence of CME is 3.2%, following phacoemulsification (2%) and SICS (4.4%). Precise surgical technique, in the bag implantation of IOL and good postoperative care, has reduced the occurrence of CME in both the surgery groups in this study. Out of the three patients with CME, one had hypertension and in the other two patients etiology could not be established. Spectral is OCT detected an increase in mean macular thickness at 6 weeks' postoperative follow-up in phacoemulsification and SICS group and the increase was statistically significant in the SICS group. The increase in mean macular thickness postoperatively did not affect the final visual outcome in both groups except in patients with clinical CME.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]