|Year : 2015 | Volume
| Issue : 2 | Page : 67-73
Comparison between effects of Ringer's and Ringer's lactate irrigating solutions on corneal endothelium during phacoemulsfication
Hossam T Al-Sharkawy MD
Department of Ophthalmology, Faculty of Medicine, Mansoura University, Mansoura, Egypt
|Date of Submission||02-Feb-2015|
|Date of Acceptance||15-May-2015|
|Date of Web Publication||23-Jul-2015|
Hossam T Al-Sharkawy
Ophthalmology Centre, Faculty of Medicine, Mansoura University, Mansoura 35516
Source of Support: None, Conflict of Interest: None
The aim of this study was to compare the effect of phacoemulsification on the corneal endothelium using Ringer's and Ringer's lactate as the intraocular irrigating solution.
Mansoura Ophthalmic Centre, Faculty of Medicine, Mansoura University, Egypt.
Prospective randomized comparative study.
Materials and methods
A total of 102 eyes of 102 patients with senile cataract were randomized to have phacoemulsification with foldable intraocular lens implantation performed using Ringer's (group 1) or Ringer's lactate (group 2) as the intraocular irrigating solution. Specular microscopy was done preoperatively, 1 week and 3 months postoperatively to evaluate endothelial cell density (ECD), coefficient of variation (CV), and central corneal thickness. Data were analyzed using the t-test, the Mann-Whitney U-test, and the Pearson correlation coefficient.
Mean ECD was 2532 cells/mm 2 preoperatively, 2345 cells/mm 2 1 week, and 2284 cells/mm 2 3 months postoperatively in group 1, and 2526, 2374, and 2322 cells/mm 2 , respectively, in group 2. There was a statistically significant difference between preoperative ECD and each of 1 week and 3 months postoperative ECD in each group. No significant difference was found between 1-week mean ECD reduction in group 1 (7.35%) and group 2 (6.05%) or between 3-month mean ECD reduction in group 1 (9.69%) and group 2 (8.07%).
Ringer's and Ringer's lactate solutions are associated with minimal changes in corneal ECD, morphology, and function during uncomplicated phacoemulsification with foldable intraocular lens implantation in patients with normal endothelial cell counts. There is no clinically significant difference in endothelial cell preservation and polymegathism and corneal swelling between Ringer's and Ringer's lactate solutions.
Keywords: Corneal endothelium, phacoemulsfication, Ringer′s
|How to cite this article:|
Al-Sharkawy HT. Comparison between effects of Ringer's and Ringer's lactate irrigating solutions on corneal endothelium during phacoemulsfication. J Egypt Ophthalmol Soc 2015;108:67-73
|How to cite this URL:|
Al-Sharkawy HT. Comparison between effects of Ringer's and Ringer's lactate irrigating solutions on corneal endothelium during phacoemulsfication. J Egypt Ophthalmol Soc [serial online] 2015 [cited 2020 Jun 5];108:67-73. Available from: http://www.jeos.eg.net/text.asp?2015/108/2/67/161394
| Introduction|| |
The corneal endothelium consists of a monolayer of cells on the posterior corneal surface that has limited regeneratory capability after injury. The normal thickness and transparency of the cornea are maintained by a barrier function and the active fluid pump of corneal endothelial cells . The natural loss of human endothelial cells is ∼0.6% each year . Intraocular manipulation, such as that during phacoemulsification cataract surgery, causes fluid and lens fragment turbulence that can lead to endothelial cell damage .
With the development of sophisticated intraocular surgical techniques, there is an increasing need for commercially available intraocular irrigating solutions that can maintain the integrity of the corneal endothelium and other intraocular tissues even when used in a large volume and for a long time period .
Solutions initially used for cataract surgery were salt solution, Ringer's solution, and plasmalyte 148. Subsequently, in 1960, more physiological solutions with ionic composition, pH, and osmorality similar to aqueous humour were developed and received the name of balanced salt solution (BSS) . In 1973, a third generation of irrigation solution, named BSS Plus, was developed after studies by Edelhauser and colleagues , who verified that the addition of glutathione, glucose, and bicarbonate to the irrigation solution would contribute to endothelial cell function and survival in vitro. The high cost of BSS Plus limits its widespread acceptability and usage. In contrast, despite the fact that Ringer's lactate lacks several essential constituents necessary for endothelial functioning and protection, it remains the most widely used irrigating fluid in our part of the world due to its low cost .
| Aim of the work|| |
Two intraocular irrigating solutions are commonly used in Egypt, Ringer's and Ringer's lactate solutions. The aim of this study is to evaluate and compare the effects of these two solutions on corneal endothelial cell density (ECD) and size variation and corneal thickness after phacoemulsification and implantation of foldable intraocular lens (IOL).
| Materials and methods|| |
This prospective randomized study comprised 102 eyes of 102 patients with uncomplicated age-related cataract scheduled to undergo phacoemulsification with IOL implantation at the Mansoura Ophthalmic Centre, Faculty of Medicine, Mansoura University, Egypt between October 2011 and September 2012. They were 39 males (38.24%) and 63 females (61.77%) and their age ranged from 42 to 78 years with a mean age of 60.27 ± 8.08 years. The Ethics Committee of the Faculty of Medicine, Mansoura University, approved the study protocol and written informed consent was obtained from each patient. Patients with coexisting corneal pathologies, an endothelial cell count of less than 1500 cells/mm 3 , glaucoma, diabetes mellitus, uveitis, trauma, brown cataract, or prior intraocular surgery were excluded from the study. All patients underwent complete conventional preoperative examinations that included best corrected visual acuity, biomicroscopy, tonometry, funduscopy under pupillary dilatation, and IOL power calculation. Central corneal thickness (CCT) and corneal endothelium were examined with a noncontact specular microscope (Tomey EM - 3000, Nishi-ku, Nagoya, Japan). Three photographs were taken per eye at each examination, and the mean of measurements was calculated. The CCT, ECD, and coefficient of variation (CV) were measured in all cases. CV was automatically calculated by dividing the SD of the cell areas measured in each specular micrograph by the mean cell area and is expressed as a percentage. This index provided a measurement of the cell size variability (polymegathism), which is independent of cell area and density [Figure 1].
Before surgery, the patients were randomized into two groups, group 1 received Ringer's and group 2 received Ringer's lactate as an irrigating solution during surgery. Ringer's solution used was isotonic and had ionic composition of sodium (Na + ): 147.5 mEq/l, potassium (K + ): 4.0 mEq/l, calcium (Ca 2+ ): 4.5 mEq/l, chloride (Cl - ): 156 mEq/l, and total osmolarity of 309.75 mOsmol/l, whereas Ringer's lactate had ionic composition of sodium (Na + ): 130 mEq/l, potassium (K + ): 4.0 mEq/l, calcium (Ca 2+ ): 2.7 mEq/l, chloride (Cl - ): 108.7 mEq/l, bicarbonate (as lactate): 28 mEq/l, and total osmolarity of 273 mOsmol/l.
Tropicamide with phenylnephrine eye drops was used for preoperative pupillary dilatation. A single surgeon performed all surgeries under retrobulbar anesthesia using a standardized surgical technique. The patient was draped. A 3.2-mm two-plane superior clear corneal incision was made with a metal blade. Healon was injected to maintain the depth of the anterior chamber. Two limbal paracentesis incisions of 1 mm were made in the clear cornea 180° apart using a beveled 1-mm knife. A bent 26-G needle was used to initiate a small nick in the anterior capsule and capsulorhexis was completed using forceps. Thorough multiquadrant cortical cleaving hydrodissection was performed. The nucleus was emulsified with an Oertli Instrumente AG (Switzerland, Switzerland) phacomachine, using four-quadrants divide and conquer technique.
The parameters used during different stages of surgery were a power of 40-60%, a vacuum of 20-260 mmHg, and an aspiration flow rate of 25-30 ml/min. The bottle height was raised to a maximum of 110 cm from a minimum of 90 cm during fragment removal. Care was taken to perform phacoemulsification at the posterior plane. Bimanual irrigation/aspiration was performed for cortex removal. After expanding the capsular bag with Healon, a foldable hydrophilic acrylic IOL (Barret, 6 mm optic, 13 mm overall diameter with preloaded injector) was implanted in the bag. The residual viscoelastic was removed with bimanual irrigation/aspiration. The surgical procedure was concluded after hydration of the wound edges to seal the incisions. No sutures were required in any case. Subconjunctival injection consisting of 0.5 ml gentamycin (40 mg/ml) and 0.5 ml dexamethasone (4 mg/ml) was given. The volume of fluid used from commencement of sculpting to the end of viscoelastic removal after IOL implantation and the effective phaco time (average ultrasound power×average ultrasound time/100) were noted for each case. The postoperative regime was also standardized in both groups, and patients were prescribed tobramycin+dexamethasone eye drops and moxifloxacin 0.5% eye drops six times daily in reducing frequency for 4 weeks.
Postoperatively, the patient was examined at 1 week and after 3 months. At each follow-up visit, specular microscopy was done to measure the CCT and to examine the central corneal endothelium. The main outcome measures were the change in CCT from the baseline preoperative value, percentage loss of ECD, and change in the CV from preoperative values. The change in CCT in microns was calculated by noting the difference between CCT at the 1-week and 3-month follow-up visits and the preoperative CCT. The percentage decrease in central corneal ECD at 1 week and 3 months postoperatively was expressed as: (preoperative central corneal ECD−postoperative central corneal ECD) × 100/preoperative central corneal ECD. The change in the CV was calculated as the difference between CV at 1-week and 3-month follow-up and the preoperative CV.
Observed data were presented as means and SD and statistical analysis was performed using a statistical software package SPSS (version 15.0; SPSS Inc., Chicago, Illinois, USA) for Windows. The data were analyzed using the Student t-test to compare quantitative data populations with normal distributions, whereas the Mann-Whitney U-test was used for populations with non-normal distributions and correlations were investigated using the Pearson correlation coefficient. A P value of 0.05 or less was considered statistically significant.
| Results|| |
Of the 102 eyes enrolled in the study, phacoemulsification was not completed because of intraoperative complications in two eyes, one from each group, and these were excluded from the study. The results were obtained from 100 eyes of 99 patients, 50 eyes in each group.
As shown in [Table 1], patients of group 1 who received Ringer's as an intraoperative irrigating solution were 21 males (42%) and 29 females (58%) and their mean age was 60.98 ± 7.56 years with a range from 44 to 78 years, whereas patients of group 2, who received Ringer's lactate as an intraoperative irrigating solution, were 18 males (36%) and 32 females (64%) and their mean age was 59.52 ± 8.53 years with a range from 42 to 75 years. There was no statistically significant difference in age between the two groups (P = 0.383). Mean preoperative CCT in group 1 was 508.16 ± 37.69 μm with a range from 414 to 591 μm, whereas mean preoperative CCT in group 2 was 512.71 ± 33.28 μm with a range from 454 to 601 μm. The difference between the two groups in preoperative CCT was not statistically significant (P = 0.526). Mean preoperative central ECD in group 1 was 2531.46 ± 239.72 cells/mm 2 with a range from 1726 to 3031 cells/mm 2 , whereas the mean value in group 2 was 2526.42 ± 260.52 cells/mm 2 with a range from 1807 to 3187 cells/mm 2 and the difference between the two groups was not statistically significant (P = 0.920). Mean preoperative coefficient of variation (CV) in group 1 was 40.28 ± 5.79% with a range from 30 to 64%, whereas the mean value in group 2 was 39.90 ± 5.58% with a range from 29 to 54% and the difference between the two groups was also statistically nonsignificant (P = 0.766).
The mean volume of intraoperative irrigating fluid in group 1 was 211.67 ± 69.98 ml with a range from 130 to 300 ml, and in group 2 it was 200.80 ± 103.72 ml with a range from 100 to 400 ml, but the difference between the two groups was not statistically significant (P = 0.810). The mean effective phaco time in group 1 was 46.33 ± 23.58 s with a range from 14 to 86 s, and in group 2 it was 44.27 ± 25.09 s with a range from 10 to 92 s, and the difference was also statistically nonsignificant (P = 0.856).
[Table 2] shows CCT, ECD, and CV preoperatively, 1 week, and 3 months postoperatively in both groups. There were statistically significant differences between the preoperative values and each of the postoperative values in both groups as shown in [Table 3]. However, there was no significant correlation between ECD and CCT at any stage (preoperative: P = 0.443; 1 week: P = 0.937; and 3 months: P = 0.564).
|Table 2: Central corneal thickness, endothelial cell density, and coefficient of variation preoperatively, 1 week, and 3 months postoperatively in the two groups|
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|Table 3: Change in central corneal thickness, endothelial cell loss, and change in coefficient of variation 1 week and 3 months postoperatively and their significance in the two groups|
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[Table 3] shows change in CCT, endothelial cell loss (ECL), and change in coefficient of variation (CV) 1 week and 3 months postoperatively and their significance in the two groups. At 1 week postoperatively, the mean central ECL in group 1 was 7.35 ± 8.26% with a range from 0.29 to 28.77%, whereas in group 2 it was 6.05 ± 7.52% with a range from 0.11 to 31.50%, but the difference between the two groups was not statistically significant (P = 0.311). The coefficient of variation (CV) increased in group 1 by a mean of 4.36 ± 4.88% with a range from 0 to 24%, and in group 2 by a mean of 4.38 ± 5.58% with a range from 0 to 29%, and the difference was also not statistically significant (P = 0.751). The CCT increased in group 1 by a mean of 15.98 ± 21.19 μm with a range from 0 to 108 μm, and in group 2 by a mean of 14.70 ± 24.25 μm with a range from 0 to 111 μm, and the difference was also statistically nonsignificant (P = 0.186). There was no significant correlation between ECL and either the volume of intraoperative irrigating fluid (P = 0.067 and 0.084 in groups 1 and 2, respectively), or the effective phaco time (P = 0.209 and 0.400 in groups 1 and 2, respectively).
Three months postoperatively, the mean central ECL in group 1 was 9.69 ± 9.06% with a range from 0.41 to 37.41%, whereas in group 2 it was 8.07 ± 8.58% with a range from 0.34 to 33.18%, and the difference between the two groups was not statistically significant (P = 0.285). The coefficient of variation (CV) increased from the preoperative value in group 1 by a mean of 1.42 ± 1.70% with a range from 0 to 7%, and in group 2 by a mean of 2.04 ± 2.80% with a range from 0 to 12%, and the difference between the two groups was also not statistically significant (P = 0.468). The CCT increased in group 1 by a mean of 2.06 ± 3.48 μm with a range from 0 to 25 μm, and in group 2 by a mean of 2.56 ± 4.74 μm with a range from 0 to 28 μm, and the difference between the two groups was also statistically nonsignificant (P = 0.734). There was also no significant correlation between ECL and either the volume of intraoperative irrigating fluid (P = 0.597 and 0.343 in groups 1 and 2, respectively), or the effective phaco time (P = 0.636 and 0.336 in groups 1 and 2, respectively).
| Discussion|| |
The corneal endothelium continuously dehydrates the stroma and is therefore responsible for its transparency . Endothelial alterations are considered important parameters of surgical trauma and are also essential for estimating the safety of surgical techniques. ECD decreases at a greater rate after cataract surgery than it does in healthy, previously unoperated corneas . Corneal distortion, irrigation solution turbulence, instrument-related mechanical trauma, nuclear fragments, IOL contact, and free oxygen radicals can cause corneal damage during cataract surgery .
The toxicity of irrigating solutions on corneal endothelium is well known . Corneal endothelial safety is the guideline for developing intraocular irrigating solutions . Edelhauser and colleagues , showed that the composition of the irrigating solution is more important to endothelial survival than irrigation time. Past studies have shown that the best intraocular irrigating solution for corneal endothelial protection is one that has a composition similar to aqueous humor, with the same ionic composition, the same buffer, and the addition of an antioxidant . Presently, BSS Plus is one of the irrigating solutions most used in intraocular surgery. It contains the essential ions, glucose as an energy source, bicarbonate similar to the buffer in the aqueous humor, and the antioxidant glutathione. This irrigating solution can provide protection to the corneal endothelium . However, its high cost limits its use. This study compared Ringer's and Ringer's lactate solutions because of their widespread use and cost-effectiveness regarding the influence on corneal ECL and corneal thickness after phacoemulsification and implantation of foldable IOL.
Ringer lactate contains potassium, calcium, and lactate ions, which maintain corneal endothelial cells for long periods. Calcium is essential for protecting the endothelial cell functions . However, Ringer lactate is hypotonic and slightly acidic (osmolality 280 mmol, pH 6.0) as compared with BSS (osmolality 302 mmol, pH 7.4) and aqueous (osmolality 302 mmol, pH 7.4). It lacks a buffer system and energy source for the endothelium. In addition to potassium, calcium, and lactate, BSS contains magnesium (essential for the Mg-ATPase endothelial pump) and an acetate citrate buffer system. It is only slightly hypotonic to the aqueous fluid and has an alkaline pH. Previous studies have shown that BSS is superior to Ringer lactate, although not as ideal as BSS Plus .
The minimal average decrease in postoperative cell density in the current study indicates that both Ringer's and Ringer's lactate solutions (7.35 and 6.05% loss at 1 week and 9.69 and 8.07% loss after 3 months, respectively) performed very well at maintaining endothelial cells. Although Ringer's lactate solution was associated with less ECL than Ringer's solution both at 1 week and 3 months postoperatively, the difference between the two solutions was not significant either in ECL or in coefficient of variation (polymegathism) change whose mean was 4.36% with Ringer's and 4.38% with Ringer's lactate solution at 1 week and 1.42% with Ringer's and 2.04% with Ringer's lactate solution 3 months, postoperatively. Cellular loss is associated with increased polymegathism as adjacent nondividing cells migrate and enlarge to fill the void; polymegathism then normalizes as sizes equalize with time.
Corneal thickness increases when the pump and barrier functions of the endothelium are compromised. Measuring CCT helps gauge the extent of the surgically induced endothelial trauma. There was a significant increase in mean CCT at 1 week postoperatively with both Ringer's and Ringer's lactate solutions (15.98 and 14.70 μm, respectively) with no significant difference between the two solutions, but CCT returned to near-preoperative values at 3 months postoperatively. There was no significant correlation between ECL and either the volume of intraoperative irrigating fluid or the effective phaco time in both groups. These results are comparable with those of Kiss et al.  who evaluated the protective effect on corneal endothelial cells of a low-cost (Ocucoat and Ringer's solutions) and an expensive (Viscoat and BSS Plus) combination and found a mean change in CCT of +8.7 ± 12.4 and +7.9 ± 9.0 μm at 1 week and +1.5 ± 5.3 and −0.4 ± 5.5 μm after 3 months in the low-cost and expensive combination, respectively, with no statistically significant difference. They also found a mean ECL of -4.0 ± 12.6% in the low-cost and −0.3 ± 8.5% in the expensive group and a mean change in CV of +1 ± 0.05% in the low-cost and −2 ± 0.05% in the expensive group 3 months postoperatively. They reported no significant between-group difference in endothelial cell counts or morphology.
The results also agree with those of Lucena et al.  who found no statistically significant difference between ECD reduction in group lactated Ringer 13.1 ± 2.0% and BSS Plus 9.2 ± 1.9% at day 60 or in any study visit. There was no statistically significant difference between CV increase in group lactated Ringer 23.0 ± 3.0% and BSS Plus 20.2 ± 4.0% at day 60 or in any study visit. CCT was significantly increased (P < 0.05) at 1, 8, 15, and 30 days postoperatively, returning to baseline at 60 days in both groups. There was no significant difference in CCT increase in both groups at any visit. Interestingly, there were statistically significant correlations between ECD loss and phacoemulsification time and ECD loss and irrigation solution volume in the Ringer group, but not in the BSS Plus group. Puckett et al.  also reported similar endothelial preservation with the use of BSS Plus or Lactated Ringer's as irrigating solutions but for atraumatic extracapsular cataract extraction surgery.
On the other hand, Joussen et al.  reported that corneas irrigated with BSS Plus during phacoemulsification were less swollen than corneas irrigated with Ringer's solution on the first postoperative day. Another study, by Vasavada et al. , also reported the same finding, although in this Indian study, standard BSS was used.
The results of the current study also confirm the findings of other investigators that ECD is not correlated with CCT on a long-term basis ,. These data showed that CCT returned to preoperative values after 60 days, despite the endothelial loss, in agreement with data reported by Cheng et al.  and Glasser et al. , who showed that the functional reserve of a normal endothelium can maintain corneal thickness despite the significant reductions of cell density occurring with age or after intraocular surgery. The thickness of the cornea increases immediately after surgery, when the pump and the barrier functions of the endothelium are compromised, and therefore the measurement of corneal thickness reveals the extent of the surgically induced endothelial injury. At 1-2 months after surgery, endothelial cell count remains irreversibly changed, but cell function is usually re-established, and there is a proportional increase in endothelial cell size and reduction in corneal pachymetry to preoperative values .
It is important to point out that this study included uncomplicated cases performed with a mean of less than 46 s of phacoemulsification time and with a mean of less than 210 ml volume of irrigating fluid and all patients had a preoperative ECD within the normal range. Given the much higher cost of BSS Plus compared with Ringer's and Ringer's lactate solutions, the use of the latter two solutions may provide an economic benefit on the cost of minimally traumatic cataract surgery. In contrast, for cataract operations that may require a higher volume of irrigation solution or longer phacoemulsification time, such as dislocated lens, dense cataracts, and in eyes with a lower endothelial cell count, BSS Plus may contribute to lower ECL.
| Conclusion|| |
Ringer's and Ringer's lactate solutions are associated with minimal changes in corneal ECD, morphology, and function during uncomplicated phacoemulsification with foldable IOL implantation in patients with normal endothelial cell counts. There is no clinically significant difference in endothelial cell preservation and polymegathism and corneal swelling between Ringer's and Ringer's lactate solutions.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]