Comparison of Corneal Endothelial Cell Loss between Torsional and Linear Phacoemulsification

Comparison of Corneal Endothelial Cell Loss between Torsional and Linear Phacoemulsification Delhi J Ophthalmol 2014; 25 (1): 23-27 DOI: http://dx.doi.org/10.7869/djo.68 Amrita Sawhney, Uma Sridhar, Charu Tandon Icare Hospital NOIDA, UP, India *Address for correspondence Amrita Sawhney DNB Icare Hospital, NOIDA, UP, India Email: amrita.sawhney3@gmail.com Purpose: To compare corneal endothelial cell loss between Torsional phacoemulsification and Linear phacoemulsification systems for cataract surgery. Materials and Methods: A prospective randomized study of 100 eyes of 100 patients, who underwent cataract surgery between September 2011 and September 2013, was done. They were divided into two groups, 50 patients underwent torsional phacoemulsification (phaco) and 50 patients underwent linear phacoemulsification. All patients were operated on same phaco machine by the same surgeon. Corneal endothelial cell loss comparison between the two groups was done using specular microscopy. Patients more than 40 years of age of either sex with senile cataract of nuclear sclerosis (NS) grade 2-3 (according to LOCSII) were included in the study. Age <40, >70 years, corneal pathologies, poorly dilating pupil or posterior synechiae, pseudoexfoliation, subluxated lens, retinal pathology, glaucoma, diabetes mellitus, collagen vascular diseases, post refractive surgeries were excluded. Results: The mean percentage change of corneal endothelial cell density (ECD) from baseline was 3.5% in torsional group and 5.1% in linear group on postoperative day1 (p value= 0.026) 6.3% in torsional group and 9.8% in linear group on postoperative day 7 (p < 0.001) and 8.1% in torsional group and 10.78% in linear group on postoperative day 30 (p =0.001). Conclusions: There was statistically significant difference in corneal endothelial cell loss between torsional phacoemulsification and linear phacoemulsification systems for cataract surgery. The mean loss of corneal endothelial cells was statistically significantly less in torsional phacoemulsification than linear Phacoemulsification. Keywords : torsional phacoemulsification linear phacoemulsification corneal endothelial cell loss specular microscopy Phacoemulsification comes from Greek word phako meaning lentil therefore prefix phaco refers to lens (which is lentil shaped) and emulsification meaning to liquefy. Charles D Kelman in 1967 introduced a procedure called phacoemulsification to remove cataract through small 3mm incision. 1 Kelman originally devised a metallic combination probe that fragmented cataract due to ultrasonic vibrations and gently aspirated these fragments from anterior chamber. The postulated advantages of phacoemulsification (phaco) over other techniques are- small incision, painless surgery, reduction of period of hospital stay and decreased visual rehabilitation time. Amongst the complications of phacoemulsification, one of the most important is corneal endothelial cell loss. Other complications include-corneal burn, corneal edema, posterior capsular tear. Corneal endothelium consists of monolayer of hexagonal cells which form a continuous mosaic pattern; hence, endothelium achieves mechanically the most stable pattern within a small area. 2 The normal endothelial cell density in new born is 3500-4000 cells/mm 2 ; in adult is 1400-2500 cells/mm. 2 The mean endothelial cell decrease is 0.5-1 % per year from age of 2 years. The mean reduction in cells between 20-80 years is 0.52% per year. 3-5 The damaged endothelial cells are sequestered in anterior chamber and there is stimulus for remaining endothelial cells to fill in the gap. 23

Sawhney A et al ISSN 0972-0200 In order to make contact with neighboring cells, endothelial cells undergo increase in size (called polymegathism) and change in shape (called pleomorphism). 6 Specular microscopy is used to measure corneal endothelial cells. The two types of Phacoemulsification (phaco) methods used in the study include Linear Phacoemulsification and Torsional Phacoemulsification. In linear mode, the phaco tip moves forward and backward in a linear direction along axis of shaft Jackhammer effect plays a major role in linear phacoemulsification. Torsional phacoemulsification is a new cataract removal modality which utilizes ultrasonic oscillations of an angulated tip. In this mode there is torsional motion of the tip i.e. side to side cutting. Shearing action plays major role in cutting lens. The important causes of corneal endothelial cell loss during phacoemulsification are: Repulsion, Ultrasound energy (USG), excessive heat production and chamber instability. In order to overcome these problems torsional phacoemulsification was introduced. OZIL a new modality for cataract removal on Infinity vision system was introduced during AAO meeting in 2005. Advantages of OZIL over linear mode are: zero repulsion, less energy used and stable anterior chamber. 7-9 The purpose of this study is to compare corneal endothelial cell loss between Torsional phacoemulsification and linear phacoemulsification systems for cataract surgery. Materials and Methods A prospective randomized study was conducted from September 2011to September 2013 to compare corneal endothelial cell loss after linear phacoemulsification and torsional phacoemulsification. A total of number of 100 patients with nuclear sclerosis grade 2-3 (LOCS II) cataract were selected from outpatient department and screened and total 100 eyes were operated. Group 1 50 patients underwent torsional phacoemulsification with foldable intraocular lens implantation. Group 2 50 patients underwent linear phacoemulsification with foldable intraocular lens implantation. Inclusion criteria: Patients with more than 40years of age of either sex with senile cataract of nuclear sclerosis grade 2-3 (the grading of cataract was done according to the Lens Opacities Classification System II) with clear cornea and adequate pupillary dilatation of 8mm and with no other ocular complications in anterior segment and posterior segment were included in the study. All patients underwent uneventful cataract surgery. Exclusion criteria: Patients less than 40 years of age and more than 70 years of age were excluded from the study. Other exclusion criteria were patients with corneal pathologies (like dystrophies, degenerations, keratoconus, opacities, scar), poorly dilating pupil or posterior synechiae, pseudoexfoliation, subluxated lens, retinal pathology, glaucoma, diabetes mellitus, collagen vascular diseases, post refractive surgeries. Patients who underwent extension of incision intraoperatively and needed sutures were also excluded. Patients with inadequate follow up were included in exclusion criteria. Informed consent was obtained from all patients prior to their inclusion in the study. Patient s name, age, sex, chief complaints and past medical history was recorded. Standard preoperative evaluation was done. Ophthalmologic Evaluation Pre-operative Meticulous history was taken to rule out exclusion criteria.visual Acuity testing was done with Snellen's Test types. Detailed evaluation of the anterior segment was done using oblique illumination and slit lamp examination along with measurement of intraocular pressure by Goldmann applanation tonometer. A detailed fundus examination was performed wherever possible under full mydriasis by indirect ophthalmoscope to evaluate retinal pathology. Retinoscopy was done using a streak retinoscope wherever possible. Distant direct ophthalmoscopy was done to evaluate dark glow against red glow. Preoperative keratometry was performed on all patients using a Bausch and Lomb type keratometer Kv and Kh noted for site of incision, astigmatism and for calculation of IOL Power. IOL power was calculated by Alcon biometry machine with SRK-T method along with pre operative Specular microscopy to measure corneal endothelial cells. Specular Microscopy: Non-contact type of specular microscope was used in the study. Model- Tomey: EM3000 (automatic digital). The methods of analysis used was the Fixed frame method. Cell density (cells/mm 2 ) = total number of cells / area of frame Surgical procedure: All surgeries were performed using the same phaco machine (Alcon Laboratories), and the same USG and fluidic settings were used by a single experienced surgeon (Dr.Uma). Informed consent of the patient was obtained. Eye lashes was trimmed. Pupil was dilated by using 2% tropic amide and 5% phenylepherine. Akinesia and anesthesia was achieved by 5-6ml peribulbar block (Lidocaine 2% with 1:1, 00,000 adrenaline with 50 units of Hyaluronidase) or topical anesthesia with 4% Xylocaine jelly. Eye to be operated was prepared with 5% povidone-iodine solution and draped in usual manner. Conjunctival-cul-de sac was cleaned with 5% povidone-iodine solution. Eye was exposed with eye speculum. Continuous corneal hydration is done with BSS solution. Biplanar corneal incision was made along steeper axis with keratome. Two side ports were made with 15 degree lance tip at 90 degree to first incision. Continuous Curvilinear Capsulorrhexis was performed with 26 gauge bent needle. Entry wound for phaco probe was made with keratome. Cortical cleaving hydrodissection was done to ensure complete rotation of nucleus. 50 eyes were subjected to torsional phacoemulsification system and rest 50 eyes were operated upon by linear phacoemulsification system. Nuclear fractis was done by direct chop technique. Coaxial irrigation and aspiration of remaining cortex was done with BSS solution. The foldable PCIOL was inserted using the injector apparatus from main incision site in the 24 Del J Ophthalmol 2014;25(1)

Corneal endothelial cell loss in phacoemulsification capsular bag in posterior chamber after maintaining the anterior chamber with viscosurgical adhesive device. The remaining viscoelastic was aspirated out by using coaxial irrigation and aspiration hand piece. Hydration at the side ports with balanced salt solution (BSS) performed. No suture was taken in clear corneal wound. 20 mg Gentamicin and 4mg Dexamethasone was injected subconjunctivally after completion of surgery. Eyes were patched for 12 hours in which local anesthesia were given while the eyes were patched for 4 hours in which topical anesthesia were given. Postoperatively steroid eye drop was given eight times a day for a week and then tapered accordingly along with cycloplegic eye drop three times for one week was advised. Patients were examined on postoperative days 1, 7, and 30. The postoperative best corrected visual acuity (BCVA) was documented. The central corneal thickness and the central endothelial cell count were measured using a non-contact special microscope automatic digital (Tomey: EM3000) on postoperative days 1, 7 and 30. Results Demographics The 100 eyes in this prospective randomized study were from 100 patients who underwent uneventful cataract surgery. Out of 100 patients, fifty patients (50%) underwent torsional phaco and fifty patients (50%) underwent linear phaco. Mean age ± standard deviation of patients in torsional group was 61.56 ± 6.66 years and linear group was 60.40 ± 6.29 years. Out of 50 patients in torsional group, twenty five (50%) were males and twenty five (50%) were females. Out of 50 patients in linear group, twenty three (46%) were males and twenty seven (54%) were females (graph 1). Thirty eight patients (76%) had nuclear sclerosis (NS) grade 2 and twelve patients (24%) had NS grade 3 out of total fifty patients in torsional phaco group. Out of fifty patients in linear group, thirty four (68%) had NS grade 2 and sixteen (32%) had NS grade 3 (graph 2). Graph 2: Distribution according to nuclear sclerosis Outcome During a follow up period of September 2011 and September 2013, the baseline mean UCVA in torsional group was 0.76 ± 0.20 Log MAR which improved to mean UCVA of 0.16 ± 0.10 LogMAR, 0.13 ± 0.10LogMAR and 0.12 ± 0.10 Log MAR on postoperative days 1, 7 and 30 [p<0.001] whereas baseline mean UCVA in linear group was 0.74 ± 0.22LogMAR which improved to mean UCVA of 0.20 ± 0.12LogMAR, 0.17±0.09LogMAR and 0.16 ± 0.09LogMAR on postoperative days 1, 7 and 30 [p <0.001]. Although there was no statistical difference between baseline UCVA in torsional group (0.76 ± 0.20 Log MAR) and baseline UCVA in linear group (0.74 ± 0.22 Log MAR) [ p = 0.743] but, the percentage change of mean UCVA from baseline was 78.8% in torsional group and 72.3% in linear group. [p=0.039] on postoperative day 1 and 83.07% in torsional group and 75.2% in linear group. [p=0.024] on postop day 7, both the results showing statistically significant difference in improvement in UCVA between the two groups with better results in torsional group. However, on postoperative day 30, the percentage change of mean UCVA from baseline was 83.9% in torsional group and 78.6 % in linear group [p = 0.070] which is insignificant difference (graph 3). Group 1: Torsional phacoemulsification Group 2: Linear phacoemulsification Graph 3: Comparison of UCVA Graph 1: Gender Ratio of study group There was significant improvement in mean BCVA in both torsional and linear groups. Mean baseline BCVA in torsional group was 0.60 ± 0.23 Log MAR which improved to 0.00 ± 0.03LogMAR on postoperative day 30 representing 99.5 ± 3.5% improvement. Mean baseline BVCA in linear group was 0.59 ± 0.20 Log MAR which improved to 0.06 ± 0.09 Log MAR on postoperative day 30 representing 90.2 ± 17.7% improvement. There was significant difference in improvement in BCVA between the two groups with torsional group proving to be better [p = 0.001] (graph 4). 25

Sawhney A et al ISSN 0972-0200 During the follow up period, mean baseline corneal ECD in torsional group was 2684.28 ± 187.15 cells/mm 2 which had fallen to 2588.96 ± 177.31 cells / mm 2, 2515.66 ± 186.10 cells/ mm 2 and 2465.86 ± 191.44cells/mm 2 on postoperative days 1, 7 and 30 representing 3.5%, 6.3% and 8.1% loss of ECD on the respective follow up days. In linear group, baseline mean corneal ECD was 2724.04 ± 238.48 cells/mm 2 which had fallen to 2584.26 ± 260.67 cells/mm 2, 2454.74 ± 243.60 cells/mm 2 and 2429.88 ± 248.48 cells/mm 2 on postoperative days 1,7 and 30 representing 5.1%, 9.8% and 10.78% loss of corneal ECD on the respective follow up days. The percentage change of mean corneal ECD from baseline was 3.5% in torsional group and 5.1% in linear group [p = 0.026] on postoperative day 1, 6.3% in torsional group and 9.8% in linear group. [p < 0.001] on postoperative day 7, 8.1% in torsional group and 10.78% in linear group. [p = 0.001] on postoperative day 30 (graph 5). Graph 5: Comparison of percentage (%) change in CD from baseline between the two groups on postoperative days 1,7,30. Graph 4: Comparison of BCVA Discussion This study reported that corneal endothelial cell loss was significantly less in patients who underwent torsional phaco as compared to those who underwent linear phaco. Results also indicate that improvement in mean BCVA on postoperative day 30 as compared to baseline mean BCVA is significantly more in torsional group as compared to linear group. In our study, mean BCVA at postoperative day 30 was 0.00 Log MAR (mean SD = 0.03) and baseline BCVA was 0.60 Log MAR in torsional group, whereas, linear group had mean BCVA at postoperative day 30 of 0.06 Log MAR (mean SD = 0.09) and baseline BCVA of 0.59 Log MAR. This result showed that mean BCVA at final follow up was statistically and significantly better than baseline BCVA in both the groups [ Torsional p <0.001 and Linear p <0.001]. This result also showed that there was statistically significant difference in BCVA at postoperative day 30 between torsional and linear groups [p = 0.001]. Results of BCVA in our study were similar to results reported in study done by Rekas et al in 2009. Rekas et al found mean BCVA at postoperative day 30 to be 0.06 Log MAR and baseline BCVA to be 0.53 Log MAR in torsional group whereas in linear group mean BCVA at day 30 was 0.07 Log MAR and baseline BCVA was 0.51 Log MAR. Hence mean BCVA at final follow up was statistically and significantly better than baseline BCVA even in this study, however there was no statistically significant difference noted between torsional and linear groups in this study. 10 The mean cell density (CD) loss from baseline was 3.5% in torsional group and 5.1% in linear group on postop day 1 [p=0.026], 6.3% in torsional group and 9.8% in linear group on postoperative day 7 [p<0.001], and, 8.1% in torsional group and 10.78% in linear 26 Del J Ophthalmol 2014;25(1)

Corneal endothelial cell loss in phacoemulsification group on postop day 30 [p=0.001]. There was statistically significant difference in CD on all follow up days between the two groups. The results of endothelial cell density in our study were similar to study done by Lui et al in 2007, which reported mean CD loss at postoperative day 7 from baseline of 10.4% in torsional group and 17.6% in linear group, and, mean CD loss at postoperative day 30 from baseline was 12.5% in torsional group and 19.1% in linear group. Hence even this study reported statistically significant difference in CD on postoperative days 7, 30 between the two groups. 11 The mean loss of corneal endothelial cells was statistically significantly less in torsional phacoemulsification than linear phacoemulsification. Financial & competing interest disclosure The authors do not have any competing interests in any product/ procedure mentioned in this study. The authors do not have any fi nancial interests in any product / procedure mentioned in this study. References 1. Kelman, C.D.: Phacoemulsification and aspiration. Am. J. Ophthalmol 1967; 64: 23-35. 2. Wirbelauer Ch, Anders N, Pham DT, Wollensak J. Corneal endothelial cell changes in pseudoexfoliation syndrome after cataract surgery. Arch Ophthalmology 1998; 116:145-9. 3. Bourne WM, Kaufman HE. Endothelial damage associated with intraocular lenses. Am J Ophthalmol 1976; 81:482-5. 4. Nucci P. Normal endothelial cell density range in childhood. Arch Ophthalmol 1990; 108:247-8. 5. Liesegang TJ. The response of the corneal endothelium to intraocular surgery. Refractive and Corneal Surg 1991; 7:81-6. 6. Tuft SJ, Coster DJ. The corneal endothelium. Eye 1990; 4:389-424. 7. Allen D. Efficient surgery with a new torsional phaco mode. Presented at Annual Meeting of the American Society of Cataract and Refractive Surgery; March 17-22, 2006; San Francisco. 8. Aguilera F. Comparing outcomes of linear phaco technology vs. torsional phaco technology in the emulsification of cataracts. Presented at Annual Meeting of the American Society of Cataract and Refractive Surgery; March 17-22, 2006; San Francisco. 9. Cionni R. Torsional to longitudinal phacoemulsification comparison. Presented at Annual Meeting of the American Society of Cataract and Refractive Surgery; March 17-22, 2006; San Francisco. 10. Rekas M, Montes-Mico R, Krix-Jachym K, Klus A, Stankiewicz A, Ferrer-Blasco T. Comparison of torsional and longitudinal modes using phacoemulsification parameters. J Cataract Refract Surg 2009; 35:1719-24. 11. Liu Y, Zeng M, Liu X, Luo L, Yuan Z, Xia Y, Zeng Y. Torsional mode versus conventional ultrasound mode phacoemulsification: randomized comparative clinical study. J Cataract Refract Surg 2007; 33:287-92. 27