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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 110  |  Issue : 3  |  Page : 83-88

Evaluation of anterior segment changes using ultrasound biomicroscopy following phacoemulsification and implantation of one-piece and three-piece intraocular lenses in high myopia


Department of Ophthalmology, Banha University, Banha, Egypt

Date of Submission12-Dec-2016
Date of Acceptance22-Aug-2017
Date of Web Publication6-Nov-2017

Correspondence Address:
Ayser Abd El-Hameed Fayed
Department of Ophthalmology, Banha University, Banha, 13511
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ejos.ejos_29_17

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  Abstract 

Aim
The aim of this research was to study the performance of the implanted one-piece and three-piece intraocular lenses (IOLs) in relation to the enlarged diameters of the capsular bags of the highly myopic eyes.
Patients and methods
Patients were randomly divided into two groups: group A included 15 eyes that underwent phacoemulsification with implantation of one-piece IOLs, and group B included 15 eyes that underwent phacoemulsification with implantation of three-piece IOLs. All patients included in this study were high myopes with axial length greater than 26.5 mm. All eyes were planned for clear lens extraction or cataract extraction.
Results
In group A, a statistically significant negative correlation was found between the diameters of the capsular bags and the diameters of the implanted one-piece IOLs. The correlation coefficient (r) is −0.56. In group B, a statistically significant positive correlation was found between the diameters of the capsular bags and the diameters of the implanted three-piece IOLs. The correlation coefficient (r) is 0.86.
Conclusion
The study of this correlation is to help in answering an important question − that is, does one diameter IOL fit all capsular bags? The statistical analyses in both groups point to a statistically significant correlation between the diameters of the capsular bags and the diameters of the implanted IOLs in both groups A and B, which demonstrates the absence of fitting of both sorts of IOLs in relation to the enlarged capsular bags of the highly myopic eyes − i.e. it focuses on the divergence between the size of the IOLs and that of the capsular bag.

Keywords: capsular bag, intraocular lens, myopia, ultrasound biomicroscopy, white to white distance


How to cite this article:
Samy RM, Fayed AA, Aboulnasr TT, Abdoh YF. Evaluation of anterior segment changes using ultrasound biomicroscopy following phacoemulsification and implantation of one-piece and three-piece intraocular lenses in high myopia. J Egypt Ophthalmol Soc 2017;110:83-8

How to cite this URL:
Samy RM, Fayed AA, Aboulnasr TT, Abdoh YF. Evaluation of anterior segment changes using ultrasound biomicroscopy following phacoemulsification and implantation of one-piece and three-piece intraocular lenses in high myopia. J Egypt Ophthalmol Soc [serial online] 2017 [cited 2017 Dec 18];110:83-8. Available from: http://www.jeos.eg.net/text.asp?2017/110/3/83/217697


  Introduction Top


Ultrasound is an indispensable tool in medical imaging and has an important role in ophthalmologic diagnoses. Conventional B-scan examinations produce two-dimensional cross-sectional views of the eye and orbit. This method of imaging is the most important examination technique for intraocular lesions, particularly in the presence of anterior segment opacities; however, there are limitations to conventional ultrasound [1].

Ultrasound biomicroscopy (UBM) gives images in living eyes without affecting the internal relationship of the imaged structures. It provides information that was unobtainable by other noninvasive approaches. It now allows structural details of the angle, visualization of the area posterior to the iris and ciliary body, and quantification of precisely anatomic relations among the anterior segment structures [2].

UBM provides a unique method to test the intraocular lens (IOL) location and its relationship to adjacent ocular structures. Moreover, UBM provides reproducible measurements of the distances between the IOL and these structures. It produces short wavelengths that provide higher resolution and accurate measurement but at the expense of penetration [3].

Most IOL companies manufacture a given IOL model with one overall diameter for implantation in the capsular bag, considering a certain uniformity of the capsular bags receiving these IOLs. The dimension of the crystalline lens is not the same in all eyes; however, a single IOL diameter may not ideally fit all capsular bags. In addition to individual variation, axial length and age are also well-known factors in determining crystalline lens diameter. This variability in the size of the capsular bag can be a cause of postoperative IOL complications including decentration, tilt, and refractive instability [4].

Postoperative refraction deviations may develop through the postoperative axial movement of the optic, tilt, and/or decentration of the IOL [5],[6].

In a myopic eye with a larger capsular bag, the use of the same IOL size could lead to an insufficient capsular tension, resulting in asymmetrical IOL fixation, capsular fold, and an increased likelihood of posterior capsule opacification (PCO) [7].

This situation leads to a number of questions: what is the anatomical position of the IOL and capsular bag in different-sized eyes implanted with IOLs of the same diameter? Could increasing IOL diameters, as a function of the increasing axial length of the eye, improve the anatomical and functional results of bag implantation? Could experimentation improve the adaptability of such an IOL system? [4].


  Patients and methods Top


Patients were randomly divided into two groups: group A and group B. Group A included 15 eyes that underwent phacoemulsification with implantation of one-piece IOLs (corneal IOLs; Alcone Laboratoire, Inc., Fortworth, Texas, USA, optic diameter=6.00 mm, overall diameter=12.00 mm). The mean age was 47.07±22.03 years.

Group B included 15 eyes that underwent phacoemulsification with implantation of three-piece IOLs (acrySof IOLs; Alcone Laboratoire, Inc., Fortworth, Texas, USA, optic diameter=6.00 mm, overall diameter=13.00 mm). The mean age was 42.47±15.72 years.

All patients included in this study were high myopes, with axial length greater than 26.5 mm. The spherical equivalent in all patients was more than −6 D. They were patients who planned for clear lens extraction or cataract extraction with no other ocular pathology.

The patients were recruited from the outpatient clinic of the Ophthalmology Department of Benha University Hospitals in the period December 2008 to January 2010.

The Institutional Review Board of the College of Medicine, University of Banha, approved the study protocol, and informed consent was obtained by all patients who agreed upon inclusion.

Exclusion criteria

Any ocular pathology (other than cataract), including corneal opacities, history of previous ocular surgery, lens subluxation and pseudoexfoliation syndrome, any surgical complications, such as ruptured posterior capsule, cases that had sutured wounds, and cases that did not show implantation of IOLs in the capsular bag during the postoperative follow-up.

The preoperative examination for all patients included full medical history, refraction whenever possible, best corrected visual acuity, IOP measurement by applanation tonometry, and slit lamp examination for conjunctiva, cornea, anterior chamber, iris, and lens. Fundus examination was performed by an indirect opthalmoscope, whereas ultrasonography was restored to access fundus in opaque media. Ultrasonic measurement of the axial length of the eye, A-scan biometry for IOL power calculation in which the SRK-T formula was used to calculate the IOL power as the targeted postoperative refraction was 1D, UBM was done for the patients. Preoperative ultrasound biomicroscopic measurement using UBM model (DICON, UBM plus, Model 45; Paradigm® Medical Industries Inc., Salt Lake City, UT) included central anterior chamber depth (ACD) − distance between the center of the posterior corneal surface (corneal endothelium) and the anterior lens capsule − and angle opening distance 500 µm from the scleral spur [anterior opening distance (AOD) 500 µm] − which is the degree of anterior chamber angle opening. It was measured in the four quadrants of the angle (nasal, temporal, superior, and inferior quadrants) and trabecular iris angle (TIA), which was also measured in the four quadrants of the angle (nasal, temporal, superior, and inferior quadrants).

Postoperative ultrasound biomicroscopy

Postoperative UBM was done just as preoperative UBM with the same methods, using calipers included in the equipment software. The following parameters were measured to be compared with the corresponding preoperative values.

ACD, angle opening distance of 500 µm from the scleral spur (AOD 500 µm), TIA, and diameters of the capsular bag were measured from the equatorial edge of the capsular bag. Diameters of the implanted IOL were measured from the end of one haptic to the end of the other haptic, and white to white distance was measured from the outer aspect of the corneal junction from one side to the opposite side.

The obtained measurements were then statistically analyzed and correlated together in each group of patients in order to be used in the study of the relationship between the diameters of the capsular bags of the highly myopic eyes and the diameters of the implanted IOLs (including one-piece and three-piece IOLs).

Comparison of quantitative variables between the two groups was done using Student’s t-test. Comparison between preoperative and postoperative data was done using paired t-test for comparing categorical data. χ2-Test was performed. The association between two variables was done using correlation coefficient. A P value less than 0.05 was considered statistically significant. P value less than 0.001 was considered highly statistically significant. P value more than 0.05 was considered statistically nonsignificant. All statistical calculations were done using statistical package for the social sciences version 16 (SPSS; SPSS Inc., Chicago, Illinois, USA) program.


  Results Top


This study was conducted on 30 eyes of 18 patients who are high myopes. The patients were divided into two groups: group A included the patients who underwent implantation of one-piece IOLs and group B included the patients who underwent implantation of three-piece IOLs. Detailed statistical analysis of each of the measured parameters was done by comparing the preoperative values with the postoperative values. The mean increase in ACD was 1.1 mm, ∼32% deeper than before surgery, represented in [Table 1] and [Figure 1]. AOD 500µm significantly increased postoperatively in four cardinal quadrants of the globe, with a highly significant correlation ([Table 2]).
Table 1 Values of anterior chamber depth (in mm) in the study population throughout follow-up on comparing between the preoperative and postoperative values

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Figure 1 An example of the difference in ACD between preoperative (a) and postoperative (b).

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Table 2 Values of temporal anterior opening distance (in mm) in the study population throughout follow-up on comparing between the preoperative and postoperative values

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Postoperatively, the diameters of the capsular bags and those of the implanted IOLs were measured in either group and then the measured values were statistically analyzed and correlated together ([Table 3],[Table 4],[Table 5] and [Figure 2]a, [Figure 2]b). The measured values of the capsular bag diameter in groups A and B were not statistically different, whereas comparing CBD in relation to the implanted IOL diameter in group A a statistically significant negative correlation was found between the diameters of the capsular bags and the diameters of the implanted one-piece IOLs. The correlation coefficient (r) is −0.56 ([Table 5] and [Figure 3]a). In group B, a statistically significant positive correlation was found between the diameters of the capsular bags and the diameters of the implanted three-piece IOLs. The correlation coefficient (r) is 0.86 ([Table 5] and [Figure 3]b).
Table 3 Range and mean±SD of capsular bag diameter in mm among the study groups

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Table 4 Range and mean±SD of intraocular lens diameter in mm among the study groups intraocular lens diameter

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Table 5 Correlation between capsular bag and intraocular lens diameters in the study groups A and B

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Figure 2 (a) UBM view showing sulcus to sulcus imaging of a three-piece IOL implanted in the bag. (b) The same UBM view in [Figure 1] after placing the segment measuring caliper on the image to measure the capsular bag diameter (red line) and IOL diameter (green line).

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Figure 3 (a) UBM view of the implanted 3-piece IOL in group (B), IOL diameter is 10.41 mm (green) & CBD is 11.66 mm (red). (b) UBM view of the implanted 3-piece IOL in group (B), IOL diameter is 10.15 mm (green) & CBD is 11.68 mm (red).

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In both groups, a statistically significant positive correlation was found between the capsular bag diameter and the white to white distance ([Table 6]).
Table 6 Correlation between capsular bag diameters and white to white distance in the study groups A and B

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  Discussion Top


An important aim of this thesis is to identify and quantify the changes in the anterior segment configuration of the highly myopic eyes after clear corneal incision phacoemulsification and foldable IOL implantation, by means of UBM. Thus, UBM was performed to measure the anterior segment parameters both preoperatively and at the first and third postoperative months.

In our study, the mean postoperative ACD was 4.48±0.42 mm at the first postoperative month, and was 4.45±0.44 mm at the third postoperative month, compared with the mean preoperative ACD of 3.36±0.49 mm. Therefore, the mean difference in ACD was 1.1 mm, ∼32% deeper than before surgery, which is highly statistically significant (P<0.001).

Similarly, AOD 500 µm significantly increased postoperatively in four cardinal quadrants of the globe, which was highly significant. As for the TIA, the present study revealed that the difference between preoperative and postoperative months was highly statistically significant.

The above-mentioned results of the present study are supported by similar results reported by other studies [8],[9],[10],[11].

The present review was an endeavor in answering a critical question − that is, does one diameter IOL fit all capsular bags? For this purpose, two different IOL types with different overall diameters were used in this study and the selected patients were high myopes with axial length greater than 26.5 mm. The spherical equivalent in all patients was greater than −6 D. The diameters of the implanted IOLs and those of the capsular bags were measured in all eyes and then statistically analyzed and correlated together in each group.

In group A in which one-piece IOLs (with overall diameter of 12 mm) were implanted, the mean diameter of the implanted one-piece IOLs was 10.01 mm. The correlation between the measured IOL and capsular bag diameters in this group was found to be statistically significant (P<0.05). Moreover, this correlation was found to be negative (r=−0.56).

This means that from the statistical point of view the larger the capsular bag diameter, the smaller the IOL diameter.

In group B in which three-piece IOLs (with overall diameter of 13 mm) were implanted, the mean diameter of the implanted three-piece IOLs was 10.4 mm. The correlation in this group between the measured IOL and capsular bag diameters was additionally highly statistically significant (P<0.001). It is a positive correlation in which the correlation coefficient (r) is 0.86. Therefore, from the statistical point of view the larger the capsular bag diameter, the larger the IOL diameter.

On looking at the estimations of the measured diameters of the implanted one-piece and three-piece IOLs, a statistically significant difference was found between the two IOL types (P<0.05).

The statistical analyses in both groups point to a statistically significant correlation between the diameters of the capsular bags and the diameters of the implanted IOLs in both groups A and B, which demonstrates the absence of fitting of both sorts of IOLs in relation to the enlarged capsular bags of the highly myopic eyes − i.e. it focuses on the divergence between the size of the IOLs and that of the capsular bag.

Additionally, on comparing the two IOL types together, the three-piece IOLs appear to show better anatomical fitting in the capsular bags than the one-piece IOLs. This is attributed to the negative correlation found in group A between the diameters of the capsular bags and those of the one-piece IOLs in contrast to the positive correlation found in group B between the diameters of the capsular bags and those of the three-piece IOLs and is also attributed to the statistically significant difference found between groups A and B regarding the measured values of the IOL diameters.

On the premise results found out by this thesis speak to an endeavor to answer an important question mentioned above, that is, does one diameter IOL fit all capsular bags? Actually the answer of this question is not known yet and even the studies attempting to answer it are still very few.

In 2009, an experimental study was performed by Sourdille [4] to analyze 25 eyes in which phacoemulsification was done and the capsular bags were implanted with different IOLs of different diameters (including one-piece and three-piece designs), and then the modifications that were induced in the shape and size of the capsular bags were measured with the aid of high-frequency ultrasound. Three of the implanted three-piece IOL models consistently enlarged and ovalized the capsular bags, frequently causing central capsular folds, and these IOLs also moved the bag into a retrociliary position. On the other hand, the one-piece IOLs implanted in this study caused no fold and no ovalization of the capsular bags, concluding that an IOL manufactured with only one diameter did not anatomically fit all capsular bags.He also concluded that the concept behind the lens, which states that longer eyes receive larger IOL diameters and shorter eyes receive shorter IOL diameters, improves the anatomical situation and may avoid unexpected refractive results. These findings were clinically affirmed in another late prospective randomized bilateral clinical study [5].

All the above-mentioned results point to the importance of the adaptability of the IOL diameter to the different bag sizes and the correlations of the IOL diameter with the dioptric power, and the axial length of the eye should result in better capsular bag fitting. Moreover, the difference in the capsular bag size of the highly ammetropic eyes may result in unpredicatable IOL position with inaccurate refractive outcome.

The measured values in this thesis were used to calculate a stepwise multiple regression analysis, which was computed with capsular bag diameter as the dependent variable. This formula used the white to white distance of the eye to calculate the CBD. It is as follows:

Capsular bag diameter=1.023×white to white distance−0.839.

This formula represents an attempt to find an accurate method for predicting the capsular bag diameter.


  Conclusion Top


The statistical analyses performed in this study point to a lack of fitting of both types of IOLs in relation to the enlarged capsular bags. It also shows that three-piece IOLs appear to be better anatomically fitting in the capsular bags than the one-piece IOLs.

Does one-diameter IOL fit all capsular bags? is an important question that needs many future studies with large number of high ammetropia and different design of IOL to be answered correctly.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Pavlin CJ, Harasiewicz K, Sherar MD, Foster FS. Clinical use of ultrasound biomicroscpy. Ophthalmol 1991; 98:287–295.  Back to cited text no. 1
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2.
Pavlin CJ, Foster FS. Basic consideration (chapter 1).Ultrasound biomicroscopy of the eye. 1st ed. New York: Springer Verlag 1995. 3–60.  Back to cited text no. 2
    
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Jimenez-Alfaro I, Gracia-Feijio J, Perez-Santonja JJ, Cuina R. Ultrasound biomicroscopy of ZSAL-4 anterior chamber phakic intraocular lens for high myopia. J Cataract Refract Surg 2001; 27:1567–1573.  Back to cited text no. 3
    
4.
Sourdille P, Modesti M, Werner L. Measurement of the capsular bag before and after implantation. L’Ophthalmographe 2009; 29:9–11. retrieved from http://www.croma.pl/files//ophthalmographe.pdf  Back to cited text no. 4
    
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Vass C, Menapace R, Schmetterer K, Findl O, Rainer G, Steineck I. Prediction of pseudophakic capsular bag diameter based on biometric variables. J Cataract Refract Surg 1999; 10:1376–1381.  Back to cited text no. 5
    
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Koeppl C, Findl O, Kriechbaum K, Sacu S, Drexler D. Change in IOL position and capsular bag size with an angulated intraocular lens early after cataract surgery. J Cataract Refractive Surg 2005; 31:348–353.  Back to cited text no. 6
    
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Georgopoulos M. Can variable IOL diameter result in improved fitting influence on IOL axial position, centration and incidence of PCO? Ophthalmol Time Europe 2009. Available at: http://www.osnsupersite.com  Back to cited text no. 7
    
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Frederico AS, Sebastiao C. Ultrasound biomicroscopy study of anterior segment changes after phacoemulsification and foldable intraocular lens implantation. Am J Ophthalmol 2003; 110:1799-1806.  Back to cited text no. 8
    
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Kurimoto Y, Park M, Skaue H, Kondo T. Changes in the anterior chamber configuration after small incision cataract surgery with posterior chamber intraocular lens implantation. Am J Ophthalmol 1997; 124:775–780.  Back to cited text no. 9
    
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Guo XP, Gao Y, Chen G, Liu XL. A quantitative study of anterior chamber angel with ultrasound biomicroscopy after cataract surgery with phacoemulsification and foldable intraocular lenses implantation. Zhonghua Yan KeZaZhi 2004; 40:94–96.  Back to cited text no. 10
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Zhang S, Tang X, Wang TC. Study of anterior chamber configuration with panoramic ultrasound biomicroscopy after cataract surgery with phacoemulsification and foldable intraocular lenses implantation. Zhonghua Yan KeZaZhi 2008; 44:301–305.  Back to cited text no. 11
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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