|Year : 2020 | Volume
| Issue : 4 | Page : 1218-1225
Evaluation of corneal endothelial changes after posterior capsule rupture during phacoemulsification using specular microscope
Hoda El Sobky, Marwa Zaky, Hebatallh M. T. Nada
Department of Ophthalmology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
|Date of Submission||30-May-2020|
|Date of Decision||13-Jul-2020|
|Date of Acceptance||19-Jul-2020|
|Date of Web Publication||24-Dec-2020|
Hebatallh M. T. Nada
MSC, Faculty of Medicine, Yaseen Abdelghafar Street, Shebin Elkom
Source of Support: None, Conflict of Interest: None
Phacoemulsification cataract surgery is now the technique of choice for routine cataract extraction. However, posterior capsule rupture (PCR) during phacoemulsification cataract surgery remains an important complication because it may lead to poor visual outcome.
The aim of this study was to evaluate the effect of PCR during cataract extraction by phacoemulsification on the corneal endothelium using a specular microscope.
Patients and methods
A total of 50 patients with age range between 45 and 65 years were enrolled in this study during a period of 1 year. Anterior chamber depth measurement was done. Preoperatively, anterior chamber depth (mm) was recorded using intraocular lens master. Central corneal thickness (CCT) and the endothelial cell counts were measured using a noncontact specular microscope preoperatively and postoperatively.
We compared the preoperative details and contrasted the 1- and 3-month postoperative outcomes, including best -corrected visual acuity, endothelial cell loss, CCT, coefficient of variation, and hexagonality. We found that the majority of our patients (92%) experienced improved best-corrected visual acuity at 3 months after phacoemulsification. Our patients had an increased CCT 1 month postoperatively, with a significant rise from baseline. When polymegathism was evaluated, we observed that coefficient of variation increased significantly from baseline, and declined slightly by 3 months postoperatively. Regarding cell count density, we observed a significant decrease of cell density following the operation after 1 month and a much more decrease after 3 months.
We concluded that PCR during phacoemulsification resulted in significant corneal endothelial damage; however, it provided better visual acuity. For better outcomes, early recognition of PCR is advised, besides immediate proper management to minimize the endothelial damage.
Keywords: cataract surgery, corneal endothelium, phacoemulsification, posterior capsule rupture, specular microscopy
|How to cite this article:|
El Sobky H, Zaky M, Nada HM. Evaluation of corneal endothelial changes after posterior capsule rupture during phacoemulsification using specular microscope. Menoufia Med J 2020;33:1218-25
|How to cite this URL:|
El Sobky H, Zaky M, Nada HM. Evaluation of corneal endothelial changes after posterior capsule rupture during phacoemulsification using specular microscope. Menoufia Med J [serial online] 2020 [cited 2021 Apr 18];33:1218-25. Available from: http://www.mmj.eg.net/text.asp?2020/33/4/1218/304488
| Introduction|| |
The transparent cornea forms the anterior portion of the outer casing and has the dual function of protecting the inner contents of the eye as well as providing about two-thirds of the eyes' refractive power.
The posterior cornea, composed of Descemet membrane and endothelium, is essential for stromal dehydration, maintained through tight junctions and endothelial pump, thereby maximizing the fidelity of light passing through the cornea. Maintenance of this gradient of hydration depends on tight junctions among endothelial cells and pump function.
Corneal endothelial cells are very sensitive to trauma, which affects cell density (CD) as well as morphology. Endothelial cell loss (ECL) during surgery affects the functional capacity of the cornea to maintain transparency, with subsequent visual deterioration. Normally, the corneal tissue, which is the mainstay of postoperative clarity, essentially depends on undisturbed cell morphology and sufficient CD. In this way, postoperative corneal endothelium CD is a useful indicator of damage caused by surgical procedures.
Phacoemulsification cataract surgery is now the technique of choice for routine cataract extraction. Intraoperative complications during phacoemulsification are expected to decrease with the introduction of new surgical techniques and new instruments, thus making cataract surgery safer for the patient.
However, posterior capsule rupture (PCR) during phacoemulsification cataract surgery remains an important complication because it may lead to poor visual outcome.
PCR is a common intraoperative complication of cataract surgery and may occur at any stage of the operation including hydrodissection, phacoemulsification, irrigation, and aspiration of cortical material, and intraocular lens (IOL) implantation.
Poor visual outcomes following vitreous loss are attributed to factors such as vitreous incarceration into the surgical wound, long-standing intraocular inflammation, and high astigmatism. Incarcerated vitreous strands within the surgical wound may predispose to epithelial and fibrous ingrowth, as well as introduction of microorganisms into the eye. Furthermore, contact between vitreous strands and the corneal endothelium may lead to corneal decompensation.
Corneal edema is one among a series of cataract surgery complications. Visual impairment is progressive with development of central corneal edema. There are risk factors that promote this condition, involving long surgical time, short axial length, and previous endothelial cell malfunction. These conditions already affect the corneal endothelium to the extent that residual cell function after the surgery is insufficient for keeping the corneal transparency, hence bullous keratopathy and corneal decompensation occur. Bullous keratopathy occurs owing to damage to the corneal endothelium, where the CD diminishes to a critical level, reaching about 300–500 cells/mm2.
The corneal endothelial cell layer cannot regenerate after injury. Repair process involves enlargement of the residual cells, amitotic nucleus division, migration and Rosette phenomenon, which leads to reduction of CD, a proportional increase in mean cell size, and disruption of the normal hexagonal cell pattern.
Nowadays, specular microscope has made the evaluation of endothelium possible. Normative data regarding endothelial CD and morphology are thus important because they facilitate assessment of the functional reserve of the endothelium in individual patients.
The aim of our study was to evaluate the effect of PCR during cataract extraction by phacoemulsification using specular microscopy and the possible risk factors of increased damage.
| Patients and methods|| |
This was a prospective, cohort study that was carried out on 50 patients from Menoufia Ophthalmology Center, Menoufia University, from June 2019 toDecember 2019.
The following were the inclusion criteria:
- All patients had clear cornea
- Age ranged between 45 and 65 years
- Both sexes
- Axial length of 20–26 mm
- The pupil can be fully dilated
- The patients have low to moderate density cataract
- The patients have a PCR as an intraoperative complication during phacoemulsification
- The phacoemulsification is performed using standardized phacoemulsification technique.
Patients were excluded from the study if they had preexisting corneal diseases, for example, corneal dystrophy or scar; coexisting ocular diseases, for example, glaucoma or uveitis; systemic disease affecting ocular tissue, for example, diabetes mellitus; lens subluxation; pseudoexfoliation syndrome; previous surgery in the studied eye; or ocular trauma.
All participants were subjected to personal history, including name, age, sex, and special habits of medical importance; present history, including age of onset and duration of the disease and any previous treatments and their types, whether surgical or medical; and family history for presence of a similar condition.
The details of the procedures were explained to patients and control group. A total of 50 patients were included of both sexes, having age range between 45 and 65 years. Demographic and clinical data were collected from patients' medical records, and then followed by full ophthalmic examination.
Anterior chamber depth measurement was done preoperatively. anterior chamber depth (mm) was recorded using a noncontact specular microscope.
Specular microscopy was done to examine corneal endothelial CD and corneal thickness.
Preoperatively, the pupil was dilated with a cocktail of scopolamine 0.3%, tropicamide 1%, and phenylephrine 10%. All patients underwent local anesthesia, administered by a standard retrobulbar injection of 4 ml lidocaine 2% or a technique in which a sponge is soaked with oxybuprocaine 2%, applied to the conjunctiva near the limbus, and left in place for 10 min before surgery.
Postoperative measurements for patients with PCR undergoing surgery were taken after a month and 3 months.
The outcome measures were considered for the description and analysis of the change in the endothelial cell characteristics after surgery. The primary measured outcome was a change in corneal endothelial cell count or density (cells per square millimeter of the corneal surface). The central corneal thickness (CCT) measured in mm was the secondary outcome of measure.
Central corneal thickness
CCT was measured using the noncontact specular microscope SP-1P automated Topcon Medical Inc. (Tokyo, Japan).
Endothelial cell counts
The endothelial cell count was measured using the noncontact specular microscope SP-1P preoperative and postoperatively (three times as CCT).
The following variables were measured: (a) central endothelial cell density (ECD) defined as the number of cells per mm2 and (b) central endothelial cell size variability or the coefficient of variation (CV). This variable is defined as SD/mCS (where SD is the standard deviation of the cell size, and mCS is the mean cell size) and is expressed as a percentage.
The study protocol was approved by the medical research ethics committee, Faculty of Medicine, Menoufia University.
Informed written consent was obtained from each participant in the study after assuring confidentiality.
Statistical analysis of the data
Data were fed to the computer and analyzed using IBM SPSS software package, version 20.0. (IBM Corp., Armonk, New York, USA). Qualitative data were described using number and percent. The Kolmogorov–Smirnov test was used to verify the normality of distribution. Quantitative data were described using range (minimum and maximum), mean, SD, median, and interquartile range. Significance of the obtained results was judged at the 5% level.
The used tests were McNemar and Marginal Homogeneity Test, analysis of variance with repeated measures, Mann–Whitney test, Kruskal–Wallis test, and Wilcoxon signed ranks test.
| Results|| |
A total of 50 patients completed the study, and their age ranged between 49 and 65 years, and the mean age of the patients was 56.7 years [Table 1] and [Figure 1].
|Table 1: Distribution of the studied cases according to demographic data (n=50)|
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We compared the perioperative details and contrasted the 1- and 3-month postoperative outcomes, including best-corrected visual acuity (BCVA), EC loss, CCT, CV, and hexagonality.
We found that the majority of our patients (92%) experienced improved BCVA 3 months after phacoemulsification [Table 2].
|Table 2: Comparison between the two studied periods according to best-corrected visual acuity|
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The comparison among the three studied periods (preoperatively, 1 month postoperatively, and 3 months postoperatively) cleared that the CCT differed significantly (P < 0.01) among the different periods [Table 3] and [Figure 2].
|Table 3: Comparison among the three studied periods according to central corneal thickness|
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|Figure 2: Comparison among the three studied periods according to CCT. CCT, central corneal thickness.|
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On the comparison among the three studied periods (preoperatively, 1 month postoperatively, and 3 months postoperatively) cleared that the CD % differed significantly (P < 0.01) among the different studied periods [Table 4].
|Table 4: Comparison between the three studied periods according to cell density %|
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CV % and hexagonality % also differed significantly (P < 0.01) among the different periods of operations [Table 5] and [Figure 3], [Figure 4].
|Table 5: Comparison between the three studied periods according to coefficient of variation % and hexagonality %|
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|Figure 3: Changes of CV % over the three studied periods. CV, coefficient of variation.|
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|Figure 4: Changes of HEX % over the three studied periods. HEX, hexagonality.|
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The relationships between vitreous loss and % of loss of CD from preoperative to 1 and 3 months postoperatively differed significantly (P < 0.001) among the patients with or without vitreous loss [Table 6].
The relationships between corneal edema and % of loss of CD from preoperative to 1 and 3 months postoperatively differed significantly (P < 0.001) among the patients with or without corneal edema [Table 7].
The relationships between type of IOLand % of loss of CD from preoperative to 1 and 3 month postoperatively differed significantly (P < 0.001) among the patients [Table 8].
|Table 8: Relation between type of intraocular lens and % of loss of cell density (n=50)|
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| Discussion|| |
We found that the majority of our patients (92%) experienced improved BCVA 3 months after phacoemulsification. Most of the studies agreed on the fact that phacoemulsification induces better visual acuity. Our findings came in line with Jagani et al. who found that 95% of their patients achieved a 6/18 or higher after phacoemulsification, whereas only 24% of them could attain that acuity before the operation.
A much better BCVA was achieved by Kaur et al., where nearly 98% of their patients had over 6/18 visual acuity after phacoemulsification. Almost all studies reported a marked increase in visual acuity after phacoemulsification, indicating no PCR during operation.
Concerning CCT, our patients had an increased CCT 1 month postoperatively, with a significant rise from baseline. Of note, CCT returned to near the baseline by the third month. Deshpande et al. found a similar pattern where they observed an increased CCT when measured by the seventh day (from 509 to 528 mm) after phacoemulsification, whereas it decreased again by the 30th day (514 mm).
In addition, our results agreed with those from Bamdad et al., where they found a mean CCT of 530 mm preoperatively that increased to 541 mm on the second day after the surgery. Similarly, Perone et al. found that mean CCT increased to 8.39% of its preoperative values after 2 h of surgery, whereas it almost reached baseline by the 15th day postoperatively.
Even in uncomplicated phacoemulsification, the trend of increase and decrease in CCT applies. Simova et al. reported an increase of 20% in CCT 1 day postoperative, and this turned to decrease to reach preoperative baseline value by the end of first month.
It might be thought that the increase of CCT after phacoemulsification differs based on the preoperative mean CCT; however, Wali et al. concluded that patients with different baseline CCT (thin, normal, and thick) all followed the same pattern of upward and downward CCT postoperatively.
This change is justified by the resulting corneal edema as a result of endothelial damage by phacoemulsification. Once the corneal edema decreases, CCT returns to almost baseline values.
When polymegathism was evaluated, we observed that CV increased significant from baseline, and declined back by 3 months postoperatively, but that decrease was insignificant. Osman et al. agreed with us where they found a similar pattern; they witnessed a marked increase (from 44 to 52). They also reported the same value after 3 months postoperatively. A moderate increase (from 42 to 46) followed by remaining still after 6 weeks of surgery was also reported by Gupta and colleagues, but that increase was insignificant.
Likewise, hexagonality slightly decreased from baseline. Although this was in line with most of the studies, such reduction varied from one study to another.
Osman et al. noticed a constant marked decrease of percentage of hexagonality from baseline after 1 month (49 to 41) down to 38 after 3 months of the surgery. Similarly, in the study by Gupta et al., they found a modest and insignificant decrease from baseline (from 41 to 37 after 1 week, to 36 after 6 weeks).
In this latter study, the authors claim that both CV and percentage of hexagonality tend to return back to normal after endothelial stabilization. It is believed that the magnitude of derangement in these quantitative measurements is dependent on the presence of complications. Thus, it is logical to find some studies reporting significant differences in both measures, whereas others did not.
Regarding cell count density, we observed a significant decrease of CD following the operation after 1 month and a much more decrease after 3 months. With intraoperative vitreous loss, the mean percentage of loss was estimated to be ~17 and 18% after 1 and 3 months, respectively. Absence of vitreous loss reduced these percentages up to 9 and 10.5% after the same intervals.
Similar to our findings, findings from Jagani and colleagues followed a crescendo of cell loss percentage. They noticed a rate of loss of ~12, 16, and 17% after 1, 6 weeks, and 3 months, respectively.
On the contrary, Perone et al. disagreed with us. Despite finding a similar descending pattern, they reported lesser percentage of loss after 1 month, estimating 11%. Of note, they also depicted a 15% loss after only 4 days postoperative [13–19].
Earlier in 2010, Gogate et al. revealed a much higher percentage of cell loss following phacoemulsification, with 23 and 27% after 1 and 6 weeks postoperative, respectively. These exact high percentages are explained by their inclusion of old age groups and patients with hard cataract and ocular pathology.
These findings are attributed to the resulting ECL during surgery that affects the CD percentage and changes its level. Thus, postoperative corneal ECD can be a useful indicator of damage caused by surgical procedures.
When we analyzed the percent of cell loss based on the presence of corneal edema, we found a significant increase in this percent among the group of patients who experienced corneal edema. Gogate et al. supported this finding where corneal edema contributed to a higher percent of cell loss (23 and 27% after 1 and 6 weeks, respectively).
One more confounding factor for postoperative cell loss is the type of lens. In our study, the least percentage of cell loss occurred within bag IOL, whereas the greatest percent of cell loss was noticed when iris fixatedIOL was used. Findings from the study by Jagani et al. supported ours, as they had similar cell loss percentages, though they used bag IOL with all their cases. Similarly, Bamdad and colleagues achieved better outcomes (ECL of 11%) when used in bag lenses [9–12].
IOL implantation on the same session reduces cell loss and promotes better recovery, in addition to improving visual acuity. Sharma et al. claimed that delayed IOL implantation increases the effect of ECL leading to decreased visual acuity. Therefore, early recognition and subsequent appropriate management is mandatory for better outcomes.
Moreover, it is known that ocular biometric parameters vary with sex, age, and ethnicity, and hence are different among different populations. Furthermore, studies investigated different method of cataract surgeries, which makes the outcome inevitably different.
Previous studies used other methods to assess the immediate corneal edema and CCT such as ultrasound, pentacam, and ocular coherence tomography. However, there is a debate over the efficacy of each of those technologies in evaluating corneal endothelial measurements immediately after cataract surgery. Wong et al. proved that pentacam and ocular coherence tomography overestimate the CCT, which limit their use acutely, in comparison with ultrasound.
| Conclusion|| |
We concluded that phacoemulsification provided better visual acuity but resulted in significant corneal endothelial damage. For better outcomes, early recognition of PCR is advised, besides immediate proper management to minimize the endothelial damage resulting from corneal edema and vitreous loss.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]