Introduction

Senile cataract presents after the age of 45-55 years or more. It represents the effect of various combinations like chemical alteration and photolytic cleavage of lens proteins (crystalline) which leads to the accumulation of high molecular mass proteins, change in the refractive index of the lens with scattering of light and reduced transparency, and also cumulative damage of environmental effects in consideration with the genetic predisposition encoded in genes for lens proteins.1 Multiple surgical techniques are available for curative intent of senile cataract such as phacoemulsification and MSICS, each with its own advantages and disadvantages. One of the most common postoperative complications is cystoid macular edema (CME) following uneventful cataract surgery.

Although the pathogenesis of CME after uneventful cataract surgery is multifactorial, primary cause is the leakage of fluid with low protein and lipid content into the extracellular cavity from perifoveal capillaries, due to the deterioration of the blood – retinal barrier (BRB) with disruptions of tight junctions in both inner and outer parts of BRB. The anterior segment inflammation is due to Surgical interventions resulting in the leakage from the iris vessels with the release of prostaglandins (PGs), followed by increase in the vascular permeability of macula, due to diffusion of these inflammatory mediators into the vitreous and retina, finally resulting into the fluid accumulation in the inner nuclear and outer plexiform retinal layers.2

Incidence of CME is less (1%) with modern techniques like Phacoemulsification in comparison to MSICS (2%).3 One of the possible explanation to this can be a larger incision in older techniques (SICS) predisposing to increase risk of iris trauma followed by more inflammation in comparison to phacoemulsification. If complications happen during cataract extraction, such as posterior capsular rupture, vitreous damage or loss, severe trauma to iris, or vitreous traction at the wound, there may be significant increase in the incidence (up to 20%) of clinically apparent CME.4 However, the incidence of CME, which can be evidenced only as a perifoveal capillary leakage (angiographic leakage) without clinically significant macular edema has been shown upto 9 – 19% and more after cataract surgery.5, 6 Nowadays, OCT has become an advanced and important diagnostic tool to evaluate and manage retinal disorders. The aim of this prospective study is to compare Central Macular Thickness by using Spectral Domain OCT (Heidelberg Germany, Carl Zeiss Meditec) a device which uses 840 ± 10 nm light with a power at the pupil of 750 μW. The depth of resolution in tissue is 5 µm, and the transverse resolution is 15 µm. Each image covered a 6×6 mm area centered on the fovea, acquired at 26,000 A-scan/second and composed of 256 to 1024 Ascan/fram in patients undergoing Small Incision cataract surgery and Phacoemulsification.

Material and Methods

Patients who presented with senile cataract on clinical diagnosis were included in this prospective observational study conducted at Regional Institute of Ophthalmology (RIO), Institute of Medical Sciences, Banaras Hindu University from October 2022 to June 2024. A total of 120 study subjects were enrolled in RIO OPD who were having Senile Cataract of age group 45 to 75 years with negative viral markers, without any ocular or systemic pathology. Patients with preexisting macular pathologies, history of previous intra ocular surgery or laser treatment, using topical medications like steroid, prostaglandin analogues and diuretics, also the patients with Intraoperative complications that could cause macular edema after surgery were excluded from the study. Informed consents were obtained from all study subjects after getting ethical clearance from institute of ethical committee of IMS BHU. All the patients or attendant were described regarding the purpose of study and method of investigations needed to be performed like Visual acuity using Snellen’s chart and pin hole, best corrected visual acuity, Slit lamp examination and Spectral domain OCT.

These 120 patients were divided into two groups based on the procedure of cataract surgery under which they were operated (phacoemulsification and MSICS). The pre – operative central macular thickness was measured using SD- OCT. Follow-up central macular thickness measurement was performed the day after the surgery, at 1 week, 4 weeks and 6 weeks post-operatively. Patients were prescribed standard postoperative topical medications. Detailed slit lamp examination was done on every visit.

All the data were entered in predesigned and pretested proforma and data were analysed by using IBM SPSS, statistical program for social sciences (Trial version of California) version 25.0. Descriptive analysis was carried out by mean and standard deviation for quantitative variables, frequency and proportion for categorical variables. The association between categorical variables was assessed by cross tabulation and comparison of percentages. For normally distributed Quantitative parameters the mean values were compared between study groups using Independent sample t-test (2 groups). Chi square test was used to test statistical significance. P value < 0.05 was considered statistically significant.

Results

Out of total 120 cases included in the final analysis,

The mean age was 58.13 ± 7.77 years in phacoemulsification group and 59.38 ± 6.72 years in SICS group. The difference between two groups was statistically not significant (p value - 0.348).

Figure 1

Mean age of study subjects in both group

Among the study population male participants were 68 (56.7%) and remaining 52 (43.3%) were female participants.

The difference in the proportion of gender between two groups was not statistically significant (p value 0.713).

The mean pre op central macular thickness was 188.93 ± 13.17 in phacoemulsification group and 190.98 ± 18.57 in SICS group. The difference between two groups was statistically not significant (P value >0.05).

Figure 2

Represents OCT macula in phacoemulsification (left) and SICS (right) at pre-operative and consecutive follow up at 1^st POD, 1^st week, 4^th week and 6^th week (above to below)

The mean pre op central macular thickness was 188.93 ± 13.17 (baseline), 200.87 ± 15.26 at 1^st POD follow up, 213.15 ± 12.88 at 1st week follow up, 221 ± 13.86 at 4th week and 220.73 ± 12.75 at 6^th week follow up in group 1 patients. The differences in the central macular thickness score at post op 1st day, 1st week, 4th week and 6th week follow up period with baseline value were statistically significant (P value <0.05).

Figure 3

Shows CMT values atdifferent follow up visits in SICS

Figure 4

Shows CMT values at different follow up visits in phacoemulsification

(Figure 3) The mean pre op central macular thickness was 190.98 ± 18.57 (baseline), 221.45 ± 22.83 at post op 1^st week follow up, 230.02 ± 22.77 at 1st week follow up, 235.60 ± 20.30 at 4th week and 240.07 ± 21.28 at 6th week follow up in group 2 patients. The differences in the central macular thickness score at post op 1^st day, 1^st week, 4^th week and 6^th week follow up period with baseline value were statistically significant (P value <0.05)(Figure 4).

Figure 5

Shows comparison of CMT at different consecutive follow up visitsin Phacoemulsification and SICS

The mean post op 1^st day, 1^st week, 4th week and 6^th week central macular thickness was 200.87 ± 15.26, 213.15 ± 12.88, 221 ± 13.86 and 220.73 ± 12.75 in group 1 patients and 221.45 ± 22.83, 230.02 ± 22.77, 235.60 ± 20.30 and 240.07 ± 21.28 in group 2 patients which is found to be statistically significant between two groups (P value <0.05)(Figure 5).

Discussion

Central macular edema is one of the major causes of poor vision after a cataract surgery. Peak edema may vary between 4 and 12 weeks following the cataract surgery.7 After modern technique of phacoemulsification, complications are reduced to an extent. Thickness is significantly increased in the inner macular area8 while oedema is evident in the central macular region.9 Initially, many studies have used FFA as a gold standard for the estimation of macular thickness following the cataract surgery and the incidence of angiographic central macular oedema came up to 20%.10, 11 In our study, Mean age of patient was 58.13 ± 7.77 years in Group 1 and 59.38 ± 6.72 years in Group 2. There was no significant difference in age of the patients of both groups. Mean age in our study is slightly more than the mean age taken by Ritu Agarwal et al12 in their study (phacoemulsification group – 53.38 ± 6.97) (SICS group – 55.59 ± 5.62) and slightly less as compared to the mean age taken by Shaik Nasreen et al13 in their study (phacoemulsification group- 62.2 ± 10.4)(SICS group- 60.75 ± 11.5). There was a preponderance of Male patients (group 1- 58.3% males)(group 2 55% males) in both of the groups, similar to the study of Mehboob Dad et al14 (57.7% males) and Perente et al15 (>50%males). Preoperative Central macular thickness was taken as baseline value (Group 1- 188 ± 13.17)(Group 2- 190 ± 18.57) which was less as compared to baseline preoperative mean value (201.3 ± 24.8) taken by Mehboob Dad et al.14 In both groups, post-operative central macular thickness at day 1, after 1 week, 4 weeks and 6 weeks were compared with the pre-operative central macular thickness which was taken as baseline. In our study, in Group 1, central macular thickness continued to increase from day 1 to 4 weeks (221 ± 13.86) and after that became stable till 6 weeks(220.73 ± 12.75) while in Group 2, central macular thickness continued to increase from day 1 to 6 weeks (240.07 ± 21.28), while in Ritu Agarwal et al12 study CMT continued to increase in both groups upto 3 months (phacoemulsification group- 256.45 ± 17.36) (SICS group- 264.35 ± 23.96). This increase was found to be statistically significant at all intervals in both groups. Although, overall more edema was seen in Group 2 whether at post op day 1 or after that. There was no significant post-operative visual impairment related to post-operative central macular edema, seen in the study conducted by Burkhard von Jagow et al,16 while in our study we have not included the required data for the same. Our study of Group 1 was consistent with the results of Lars H.B. Mackenbrock et al17 as they concluded increased retinal thickness and volume significantly after the uneventful phacoemulsification which was reaching its maximum at 4 weeks post operatively. We have found the similar results of Group 2 with Garvita Dabas et al18 study as they also observed maximum macular edema at 6 weeks after the uneventful small incision cataract surgery. Our results do not correlate with the observations of Georgopopulos et al19 as they found that retinal thickness increased on post op day 1(171.8 ± 21), decreases after 2 weeks (159.7 ± 19) and returned to the initial levels on week 4(152 ± 17.1). Some other studies concluded peak edema at 12 weeks postoperatively after uneventful phacoemulsification20, 21 which is also inconsistent with our study, as we have observed decline(220.73 ± 12.75) in edema in phacoemulsification group within 6 weeks postoperatively. Our study falls in line with the results of Sumedha Sharma et al22 and strengthens the observation of more increased in post op CMT following SICS as compared to phacoemulsification.

Conclusion

In this single centered prospective study, we observed increase in CMT post cataract surgery which is more in patients who underwent SICS in comparison to patients who underwent phacoemulsification. However, CME caused post phacoemulsification regress after 4 weeks of follow up showing faster recovery rate in comparison to post SICS procedure in which CME continued to develop even at 6^th week. We conclude that newer techniques like phacoemulsification have low probability of CME post-surgery and hence, post-operative complications are less than older techniques like MSCIS.

Limitations

Although, limitations of this study involve bounded sample size, as we have not included variable factors which may be associated with post-operative central macular edema. Also, the study is conducted at one center in a particular time; it might have been extended to other centers also. Large scale, multicenter studies are required for the better evaluation. The similar study should be carried in the future with increased sample size and for a longer duration with other associated factors with post-operative central macular edema.

Source of Funding

None.

Conflict of Interest

None.