Group A included 50 eyes of 50 patients who underwent Phacoemulsification by ‘Divide and conquer’ technique with implantation of foldable lens, single piece hydrophilic acrylic lens.

Group B includes 50 eyes of 50 patients who underwent Phacoemulsification by ‘Phaco-chop’ technique with implantation of foldable lens, single piece hydrophilic acrylic lens.

Patient having senile cataract as diagnosed by slit lamp microscopy and distant direct ophthalmoscopy with nuclear sclerosis grade 1 to 4.

Patients without any history of ocular pathology and surgery.

Patients must be accessible and willing for follow-up.

Age group: 50-70 years.

Patients with additional visual comorbidity which may influence the visual outcome after surgery, viz., glaucoma, corneal and retinal pathologies.

Patients with nuclear sclerosis grade 5, mature cataract, traumatic, subluxated or complicated cataracts.

Systemic pathologies affecting visual outcome, viz., hypertensive retinopathy and diabetic retinopathy.

Cataract with pseudoexfoliation or posterior synechaie causing small pupil.

Patient not giving consent.

Any intraoperative or postoperative complications.

CCT <500 microns and >575 microns.

Endothelial count less than 1500 cells/mm².

Two clear corneal side port incisions were made using 15 degrees Lance tip at 3’o clock and 9’o clock

Anterior capsule was stained with trypan blue dye

Anterior chamber wash was given

AC filled with viscoelastic material

A 6 mm Continuous Curvilinear Capsulorrhexis was performed in a closed chamber with self-made bent 26 gauge needle (cystitome) through the side port.

Sodium hyaluronate 1.0% was then injected to fill the anterior chamber.

A superior self-sealing clear biplane corneal incision was done using 2.8 mm disposable metal keratome.

Hydrodissection and hydrodelineation was performed by injecting BSS through a 27 gauge cannula separating the cortex and epinucleus of the lens from the hard core nucleus, till it can be rotated freely clockwise or counter-clockwise in the bag.

AC filled with visco-elastic material

Nuclear fracturing technique was different for each group (group A- divide and conquer, group B: phaco-chop technique).

The parameters were same for both the techniques.

Phaco 1 was used for sculpting (maximum 50% continuous mode ultrasound (US) power, vacuum 40 mm Hg, flow rate 30-40 cc/min and bottle height 90-110 cm); and

Phaco 2 was used for quadrant removal (maximum 50% multi-burst mode (US) power, maximum vacuum 320 mm Hg, flow rate 25-30 cc/min and bottle height 90-110 cm).

Nuclear fracturing technique was different for each group as following:

By phaco 1, aspiration of the superficial cortex and epinucleus done

A vertical groove, trench, about two tip widths wide from 12 to 6 o’clock positions was created

The groove was deepened especially at the centre until the red reflex was seen through it

The nucleus was rotated 90 degree by the phaco probe assisted by a sinskey hook dialer introduced from the side port

Another trench cross-hatched across the first one was carved to make a ‘plus sign’

A sinskey hook and a chopper were used to divide the nucleus into four separate quadrants

Then quadrants removed with phaco parameters were those of phaco 2

The quadrants were engaged by the phaco probe, brought to the centre of the capsular bag and emulsified at the pupillary plane

Chopping and quadrant removal was repeated in the same way as for the first heminucleus

Using the phaco 1, the superficial cortex and epinucleus were aspirated

A vertical groove, trench was made sufficient enough to see the fundal glow

The nucleus was then divided into two halves using phaco probe and nagahara chopper

The phaco tip was then buried in the centre of the endonucleus and the Nagahara phaco chopper was brought through the side-port incision and the equator of endonucleus was engaged by the chopper under the capsulorrhexis

The chopper was moved toward the phaco probe to initiate nuclear cracking and the phaco tip impaled in the inferior hemisection of the nucleus and the chopper was used to break this half into two smaller fragments, which were then emulsified

The procedure was repeated on the second half of nucleus

The residual cortex was aspirated using a Simcoe’s 2-way irrigation and aspiration cannula

Sodium hyaluronate was injected into the anterior chamber to inflate the capsular bag.

Implantation of a foldable hydrophilic acrylic IOL was done.

The remaining visco-elastic material was aspirated; AC reformed with BSS and side port was hydrated.

Eye pad given.

The following were reported during the surgery: The total phaco time (seconds), the mean phaco power (%) and the total phaco energy (the absolute phaco time=APT) was calculated by multiplying the phaco time (seconds) by the mean phaco power (%).

APT=phaco time X average phaco power

Uncorrected visual acuity by Snellen’s chart or Landolt C chart in illiterate patients

Slit lamp examination for any anterior chamber reaction, wound sealing, corneal clarity and IOLs placing and slit lamp biomicroscopy

Corneal specular microscopy to study endothelial cell changes and CCT

ECL was then calculated as following:

An evaluation of grade of cataract revealed that, out of 50 cases in Divide and conquer group maximum of the cases that is 17 (34%) had nuclear sclerosis grade 2 with posterior subcapsular cataract with cortical cataract followed by 15 (30%) patients having nuclear sclerosis grade 2 along with posterior subcapsular cataract. Then, 5 (10%) patients had nuclear sclerosis grade 3 with posterior subcapsular cataract. Four (8%) patients had nuclear sclerosis grade 3 along with posterior subcapsular cataract and cortical cataract and 3 (6%) had nuclear sclerosis grade 3 with cortical cataract, followed by 2 (4%) patients having nuclear sclerosis grade 2 with cortical cataract, nuclear sclerosis grade 3 and nuclear sclerosis Grade 1 with posterior subcapsular cataract each. None of the patient had nuclear sclerosis grade 1, nuclear sclerosis grade 2, nuclear sclerosis grade 4, nuclear sclerosis grade 1 with posterior subcapsular cataract and cortical cataract, nuclear sclerosis with cortical cataract.

Out of 50 cases in Phaco-chop technique group, maximum of the cases that is 18 (36%) had nuclear sclerosis grade 2 along with posterior subcapsular cataract and cortical cataract followed by 13 (26%) patients having nuclear sclerosis grade 2 along with posterior subcapsular cataract. Then, 5 (10%) patients had nuclear sclerosis grade 2 with cortical cataract. Followed by 4 (8%) patients having nuclear sclerosis grade 1 with posterior subcapsular cataract. Whereas, 3 (6%) patients had nuclear sclerosis grade 3 and nuclear sclerosis Grade 3 with posterior subcapsular cataract each. And 2 (4%) patients had nuclear sclerosis grade 3 with posterior subcapsular cataract and cortical cataract and nuclear sclerosis grade 3 with cortical cataract each.

By using chi-square test, χ²-value was 7.04, p-value-0.42, there was no significant difference between the two groups.

The mean ECC in group A was 2508.66±315.99 and in group B it was 2584.88±305.94 preoperatively (p>0.05) [Table/Fig-3].

The mean CCT in group A was 515.98±19.98 and in group B it was 506.90±35.12 (p>0.05) [Table/Fig-4].

The mean APT in group A was 27.12±10.15. and 16.58±5.11 in group B (p=0.0001) [Table/Fig-5a,b]

On day 1, the mean postoperative CCT in group A was 543.98±20.97 and in group B it was 525.24±36.30 [Table/Fig-7a,b]. [Table/Fig-7a]:

[Table/Fig-7b]:

Distribution of postoperative Central Corneal Thickness (CCT) on day 1.

At first week, group A it was 532.26±20.63 and in group B it was 518.72±36.09 [Table/Fig-7-c,d]. [Table/Fig-7c]:

[Table/Fig-7d]:

Distribution of Postoperative Central Corneal Thickness (CCT) on first week.

At sixth week, in group A was 523.44±20.31 and in group B it was 512.56±35.64. [Table/Fig-7-e,f]

The mean postoperative ECC at sixth week in group A was 2102.14±264.37 and the cell loss was 406.52±52.27 cells/mm² and in group B it was 2365.38±265.94 and the cell loss was 219.50±66.47 cells/mm² [Table/Fig-8-a,b]. [Table/Fig-8a]:

[Table/Fig-8b]:

Postoperative mean Endothelial Cell Loss (ECL) in two groups on day 1, first week and sixth week.

Postoperative Endothelial Cell Loss (ECL) (%) in two groups on Day 1, First week, Sixth week.

On postoperative day 1 there was 19.45% ECL in group A, whereas it was 14.89% in group B.

The cell loss reduced on first week. There was 17.78% cell loss in group A, whereas it was 10.09% in group B.

On sixth week the ECL was 16.22% in group A and 8.51% in group B [Table/Fig-8c,d].

The mean postoperative CCT on day 1 in group A was 543.98±20.97, the mean increase was 28±1.59 and in group B it was 525.24±36.30 and the mean increase was 18.34±1.99 (p-value=0.0001).

On first week in group A was 532.26±20.63, the mean increase was 16.28±1.62 and in group B it was 518.72±36.09 and the mean increase was 11.82±1.48 (p-value=0.0001).

On sixth week in the group A was 523.44±20.31, the mean increase was 7.46±1.16 and in group B it was 512.56±35.64 and the mean increase was 5.66±1.17 (p-value=0.0001) [Table/Fig-9a,b].

On postoperative day 1 there was 5.43% increase in CCT in group A, whereas it was 3.62% in group B.

On first week, there was 3.16% increase in CCT in group A, whereas it was 2.34% in group B.

On 6^th week it was only 1.45% in group A and 1.12% in group B [Table/Fig-9c,d].

Nuclear sclerosis was the most prevalent morphology of cataract in the study group.

The same result was found in the study by Bandhu SD et al., where they found in population-based study of lens opacity that, among 198 patients, nuclear sclerosis was found in maximum of the patients [18].

As per the studies done by Chylack LT et al., a well -known clinical relationship exists between nuclear grade and ease of phacoemulsification [19].

Also, a study done by Tabandeh H et al., explains the importance of lens hardness as an important factor and also its association with increased phaco time and power [16].

The importance of this table is that the distribution of patients according to grade of cataract in various groups was not statistically significant which means that all the three groups had comparable characteristics.

Out of 100 eyes, maximum eyes that is 63 (63%) had preoperative unaided visual acuity of 6/60-CF ½ meter followed by 6/24-6/36 which included 26 (26%) eyes.

Then there were 11 (11%) eyes having preoperative unaided visual acuity of 6/12-6/18 and none of the eyes had preoperative unaided visual acuity of PL+ PR accurate.

It clearly shows that the preoperative unaided visual acuity in the three groups did not vary significantly (p>0.5).

In a study done in the year 2000 by Rao SK et al., in the Indian population the average endothelial cell density in the age group of 20-87 years was 2525±337 cells/mm² [20].

Also in a study done by Snellingen T et al., in the age range of 40-75 years showed mean endothelial cell density to be 2720 cell/mm² [21].

According to a study done by Elnaby EA et al., on comparing phacoprechop and divide and conquer showed that the mean preoperative ECC 2484.44 cells/mm2 and 2536.56 cells/mm² in the two group [22].

The mean ECC in group A was 515.98±19.98 and in group B it was 506.90±35.12 preoperatively.

According to study done by El-Din Farahat HG et al., of comparing divide and conquer and chopping, the mean CCT was 505.33±42.81, 508.87±39.70 in the two groups [23].

In a study done by Elnaby EA et al., on comparing phacoprechop and divide and conquer showed that the mean CCT was 545.60 μ±38.60 μ and 543.0 μ±25.47 μ in the two group [22].

The mean Absolute Phaco Time (APT) in Divide and conquer technique group was 27.12±10.15.

Whereas the mean APT in phaco-chop technique group was 16.58±5.11.

Similarly in a study done by Elnaby EA et al., comparing prechop and divide and conquer showed that the mean effective US time in prechop group was 19.36 seconds ± 8.51 [22]. While it was 24.44±7.86 seconds in divide and conquer group and the difference between the two groups was statistically significant (p=0.033). Thereby showing that the phaco-chop technique has lower APT than divide and conquer technique which was similar to our study.

Also according to study done by El-din Farahat HG et al., of comparing divide and conquer and chopping in the year 2016, the total US consumption (APT) in the divide and conquer group was 48.47 and phaco-chop technique was 22.57 [23]. This was comparable to present study.

Wong T et al., in a study comparing time and power requirements in divide and conquer and phaco-chop techniques reported an effective phaco time of 50.4 seconds in the divide and conquer technique compared to 17.4 seconds with phaco-chop which was comparable to the present study [24].

Also, in a study by Storr-Paulsen A et al., showed mean APT of 3.98 in phaco-chop technique [17], while 12.79 in divide and conquer group.

In a study done by Gross FJ et al., comparing phaco-chop and divide and conquer showed that the mean APT for divide and conquer method was 27.8 and 15 by phaco-chop method [25].

Our results are comparable to those reported by Auffarth G et al., which was a standardised laboratory set up in 10 pairs of human autopsy eyes randomised for the pre chopper or the divide and conquer technique [26]. They found that the average phaco time with the prechopper technique was 1.15±0.26 min versus 1.48±0.28 min with the divide and conquer technique.

Pirazzoli G et al., in a study assessing endothelial damage by phaco-chop and divide and conquer in 1996, reported an effective phaco time of 25.53 seconds with phaco-chop as compared to 87.26 seconds with divide and conquer which was similar to the present study [12].

Similarly, according to a study by Elnaby EA et al., comparing divide and conquer versus prechop showed that the APT in nuclear grade 1 was 21.62 seconds by divide and conquer and 14.57 seconds by phaco-chop technique [22]. Whereas, in nuclear grade 2 APT was 22.68 seconds by divide and conquer technique and 17.5 seconds by phaco-chop technique. Also, in nuclear grade 3 it was 36.75 seconds by divide and technique and 34.25 seconds by phaco-chop technique.

In a study done by Sangeeta P et al., showing effect of power used in phacoemulsification on corneal endothelium by phaco-chop showed that the mean EPT used in nuclear cataract grade 1 was 10 seconds [16]. Similarly, in nuclear cataract grade 2 and nuclear cataract grade 3 and mature cataract, average phaco time used was 14.3, 23 and 25.75 seconds, respectively. The EPT used for posterior subcapsular cataract was the least 9.1 seconds.

Nixon DR, found that effective phaco time varied significantly in cataracts of different grades [27].

Storr-Paulsen A et al., found that significantly less PKE power was used during phaco-chop surgery than during divide and conquer surgery [17].

Tabandeh H et al., stated that lens hardness is probably the important factor and is associated with increased phaco time and power [16].

In a randomised prospective study in 2000, Wong T et al., used a legacy system and found a mean phaco time of 1.2 minutes±0.1 (SD) for phaco-chop and 2.4±0.1 minutes for divide and conquer, with cataracts graded according to LOCS [24].

According to Chylack LT et al., there is a relationship between nuclear colour and ease of phacoemulsification [19].

In a study by Pirazolli G et al., comparing divide and conquer and phaco-chop showed that the mean US time was 63.7seconds in divide and conquer method and 52.58 seconds in phaco-chop method [12]. In grade 1 and 2 nuclear cataract, the phaco time in phaco-chop was less than that of divide and conquer method.

The mean ECC in the divide and conquer technique group was 2020.85±252.66 and in phaco-chop technique group was 2200.26±265.03 on postoperative day 1 showing the difference between the two groups was statistically significant. (p=0.0058).

The mean ECC in the divide and conquer technique group was 2062.78±260.54 and in phaco-chop technique group was 2324.20±276.11 on postoperative first week showing the difference between the two groups was statistically significant. (p=0.0016).

The mean ECC in the divide and conquer technique group was 2102.14±264.37 and in phaco-chop technique group was 2365.38±265.94 on postoperative sixth week showing the difference between the two groups was statistically significant. (p=0.0003).

In the study by Storr-Paulsen A et al., comparing endothelial cell damage between divide and conquer and phaco-chop technique stated that postoperatively, both groups had a significant but equal decrease in endothelial cell density [17].

Likewise, in a study by El-din Farahat HG et al., the mean ECC on first week was 2114.73±472.66 by divide and conquer method and 2440.07±256.83 by phaco-chop method [23]. Also, the mean ECC after three months was 2068.20±463.83 by divide and conquer method. And, it was 2381.67±270.68 by phaco-chop method which was statistically significant.

Thus, showing that there was significant decrease in ECC in both the methods but it was less in phaco-chop than divide and conquer method.

Similar to our study, Elnaby EA et al., showed that there was loss of ECC in both the groups but it was less in phaco-chop method than divide and conquer method [22].

In the present study, there was a significant increase in CCT at the immediate postoperative day.

Similar to the study by Elnaby EA et al., showed CCT of 561.72 μ±38.55 μ at first postoperative week and 550.36 μ±39.20 μ at twelvth week in divide and conquer technique [22]. While in phaco-chop technique it showed 562.72 μ±34.93 μ on first week and 548.20 μ±26.13 μ at twelvth week.

Also El-din Farahat HG et al., also showed similar result of increase in CCT immediate after postoperative day. But then there was increase in the thickness which was similar to our study [23].

In a study by Salvi SM et al., it was found that CCT remained increased by 6.44% on day 1 postoperatively compared with preoperative values and gradually reduced to preoperative levels by the first-week postoperative period (0.57% difference) [28]. We agree with them that pachymetric changes after phacoemulsification surgery are reversible.

In a study by Elnaby EA et al., comparing phaco-chop and divide and conquer showed that the mean ECL three months postoperatively in Phaco-chop technique was 344.56 (13.86%) and in divide and conquer group [22], the mean ECL three months postoperatively was 449.48 (17.72%) that was statistically significant (p<0.05). The difference in ECL three months postoperatively between the two groups was statistically significant. (p=0.001) This was similar to our study.

Similar to our study, El-din Farahat HG et al., showed similar result showing that there was significant ECC loss in both the groups but the ECC loss was more in divide and conquer group than phaco-chop method till the third month [23]. It was 511.73±408.68 on first week in divide and conquer method and 172.87±154.75 by phaco-chop method. Whereas it was 558.33±403.36 on third month by divide and conquer method and 223.53±169.94 by phaco-chop method.

In the present study, on postoperative day 1 there was 19.45% ECL in divide and conquer technique group, whereas it was 14.89% in phaco-chop group and was statistically significant.

However, the cell loss reduced on first week. There was 17.78% cell loss in divide and conquer technique group, whereas, it was 10.09% in phaco-chop group and was statistically significant.

And also, on sixth week the ECL was 16.22% in divide and conquer group and 8.51% in phaco-chop group and was statistically significant.

Storr-Paulsen A et al., in the study comparing endothelial damage in divide and conquer versus phaco-chop techniques reported that, the mean cell loss was 173 cells/mm² (6.3%) and 155 cells/mm² (5.7%) at 3 and 12 months, respectively, in the divide and conquer group and 138 cells/mm² (5.0%) and 94 cells/mm² (3.5%), respectively, in the phaco-chop group [17].

In a study by Pirazzolli G et al., the mean preoperative ECD was 2623 cells/mm² in the phaco-chop group and 2590 cells/mm² in the phaco fracture group [12]. Postoperatively, it was 2499 and 2233 cells/mm², respectively. The mean cell loss was 4.72 and 13.8%, respectively which was similar to our study.

In the present study, there was a significant increase in CCT at the immediate postoperative day. However, then the CCT recovered to the preoperative values at the final follow-up.

Can I et al., reported a shorter time interval (10-14 days) [29].

In the study by El-Din Farahat HG et al., there was a significant increase in CCT at the immediate postoperative day [23]. At first week it was 14±5.7 (2.7%) in divide and conquer group and 10.5±11.4 (2.1%) in chop group. While at three months it was 1.4±1.8 (0.3%) in divide and conquer group and 0.6±2.3 (0.1%) in chop group, which was statistically significant.

The two groups gained improvement in visual acuity. There was a significant difference between the studied groups at immediate postoperative day.

The reduced visual acuity on the first postoperative day in both groups is due to the anterior chamber reaction and some amount of corneal oedema. But visual recovery is early in phaco-chop group than divide and conquer group.

The early improvement in visual acuity in phaco-chop group was due to the fact that there is less amount of ECL as there is less amount of energy usage and less time is taken in it.

The postoperative vision at the final follow-up at sixth week was 6/9 or better in 82% of cases in divide and conquer group and 86% in phaco-chop group.