|Year : 2020 | Volume
| Issue : 2 | Page : 63-69
Visual and subjective outcomes following trifocal intraocular lens implantation in Iranian cataractous patients
Farhad Nejat1, Shiva Pirhadi2, Hossein Aghamollaei3, Mostafa Naderi3, Mohamadmahdi Najafi Ghodsi4, Reza Gharebaghi1, Khosrow Jadidi3
1 Vision Health Research Center, Semnan University of Medical Sciences, Semnan, Iran
2 Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
3 Chemical Injuries Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
4 Department of Ophthalmology, Baqiyatallah University of Medical Sciences, Tehran, Iran
|Date of Submission||30-Apr-2019|
|Date of Decision||04-Nov-2019|
|Date of Acceptance||24-Mar-2020|
|Date of Web Publication||28-May-2020|
Chemical Injuries Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Mollasadra st, Tehran
Source of Support: None, Conflict of Interest: None
| Abstract|| |
BACKGROUND: The aim of this study was to evaluate visual and refractive outcomes and quality of vision after implantation of the AT LISA tri 839MP intraocular lens (IOL).
PATIENTS AND METHODS: This interventional clinical trial comprised 46 cataractous eyes of patients who underwent phacoemulsification with IOL implantation (mean age of 58.08 ± 11.01 years; range: 36–76 years old). Spherical equivalent (SE), uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), corrected intermediate visual acuity (CIVA), uncorrected near visual acuity (UNVA), and corrected near visual acuity (CNVA) were measured 1, 3, and 6 months after surgery. Contrast sensitivity (CS) was measured at 6 months. Subjective quality of vision and presence of dysphotopsia by a short questionnaire were evaluated postoperatively.
RESULTS: At 6 months, the mean visual acuity was 0.08 ± 0.11, 0.03 ± 0.08, 0.07 ± 0.09, 0.02 ± 0.08, 0.05 ± 0.09, and 0.02 ± 0.08 LogMAR for UDVA, CDVA, UIVA, CIVA, UNVA, and CNVA, respectively. The mean values of SE were − 0.4728 ± 0.32D. These variables improved over time, yet significant changes were detected in UDVA (P = 0.009) and SE (P = 0.0001). The mean CS value was 1.74 ± 0.08. The mean scores (0% = no symptoms; 100% = strong symptoms/unable to perform activities) for glare and halos were 7.07 ± 0.22% and 8.70 ± 0.23%, respectively. These items were reduced over time. Patients' level of satisfaction mean score for performing activities was 96.66%.
CONCLUSIONS: The AT LISA tri 839MP IOL provides excellent uncorrected distance, intermediate and near vision, and CS. This IOL showed a minimal level of photic phenomena and a high level of patient satisfaction.
Keywords: Contrast sensitivity, intraocular lens, satisfaction, trifocal
|How to cite this article:|
Nejat F, Pirhadi S, Aghamollaei H, Naderi M, Ghodsi MN, Gharebaghi R, Jadidi K. Visual and subjective outcomes following trifocal intraocular lens implantation in Iranian cataractous patients. Oman J Ophthalmol 2020;13:63-9
|How to cite this URL:|
Nejat F, Pirhadi S, Aghamollaei H, Naderi M, Ghodsi MN, Gharebaghi R, Jadidi K. Visual and subjective outcomes following trifocal intraocular lens implantation in Iranian cataractous patients. Oman J Ophthalmol [serial online] 2020 [cited 2021 May 18];13:63-9. Available from: https://www.ojoonline.org/text.asp?2020/13/2/63/285270
| Introduction|| |
Cataract referred to any crystalline lens opacity, regardless of its significant effect on visual acuity. To date, there are three types of age-related cataract, including cortical cataract, posterior subcapsular cataract, and nuclear cataract. Each year, 1–2 million people worldwide develop blindness secondary to cataract, and this is a general health issue among patients above 50 years of age. In Iran, cataract accounts for 50%–90% of blindness. The current treatment approach for this reversible blinding condition is implantation of intraocular lens (IOL) following cataract surgery. Ninety percent improvement in quality of vision has been reported in developed countries following this surgery.
Therefore, an approach for correction of refractive error following cataract surgery is considered as a critical issue; available options include prescribing spectacles or contact lenses as well as implantation of an IOL., Currently, the most common surgical approach worldwide is phacoemulsification with IOL implantation within the capsular bag. Although the aim of IOL implantation is to correct distance visual acuity, multifocal lenses are also designed for correction of both distance and near visual acuity following cataract surgery. These lenses could provide a clear vision for patients, which in most cases could improve their quality of life.
One of the shortcomings of monofocal intraocular lenses, as the most commonly used, is their fixed power for correction of only distance or near vision, and multifocal lenses were designed to overcome this problem. Because of pupil contraction during near tasks, the central part of theses lenses is allocated for near vision, whereas the peripheral part is for distance vision. However, in the early designs of multifocal lenses, failure to correct distance vision during pupil contraction was the main limitation, which was resolved following introduction of the new design by considering the central and peripheral parts for distance and mid-periphery for near vision correction. Recently, two companies from Germany and Belgium introduced two trifocal lenses, including AT LISA tri 839MP and Fine Vision, respectively. The designers claimed that their lenses could correct near, intermediate, and distance vision regardless of the pupil size, which is considered a great achievement. Recent studies have shown relatively acceptable visual acuities following implantation of these multifocal lenses.,,,,,, However, so far, adequate studies on their disadvantages, such as halos and glare, have not been carried out, despite providing acceptable near, intermediate, and distance vision following cataract surgery., Considering the limited number of studies on this issue and the nonuse of these types of trifocal lenses in Iran, designing a study of visual results after their implantation in Iranian patients is necessary. Therefore, the current study aimed at evaluating postoperative visual and subjective outcomes following binocular implantation of AT LISA tri 839MP lenses (Carl Zeiss Meditec AG) after phacoemulsification cataract surgery.
| Patients and Methods|| |
In this prospective nonrandomized research, 46 eyes of 23 patients were studied. All patients underwent phacoemulsification surgery with implantation of the AT LISA tri 839 MP trifocal IOL at Bina Eye Hospital, Tehran. Preoperatively, patients received essential information about the surgical procedure, trifocal IOL, spectacle independence at near, intermediate, and far distances, and neural adaptation process after this IOL implantation. They signed a consent form regarding the surgical procedure and data records for the research aims. The ethics committee of Baqiyatallah University of Medical Sciences approved this study.
Inclusion criteria consisted of patients who had vision loss due to cataract. Exclusion criteria were history of glaucoma or retinal detachment, macular degeneration or retinopathy, retinal vascular disease, history of ocular trauma, corneal disease, abnormal iris, neuro-ophthalmic disease, central nervous system disorders, previous refractive surgery, irregular corneal astigmatism, history of ocular inflammation, regular corneal astigmatism >1.25 D, age of younger than 20 years, and one eye patients.
Preoperative and postoperative examination
Preoperatively, all patients were examined with a complete ophthalmologic examination, including manifest refraction, keratometry, monocular uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA) and corrected intermediate visual acuity (CIVA) at 80 cm, uncorrected near visual acuity (UNVA) and corrected near visual acuity (CNVA) at 40 cm (visual acuities were measured under photopic conditions at approximately 85 cd/m2), Goldmann applanation tonometry, slit-lamp examination, eye fundus evaluation, corneal tomography (Pentacam HR, Oculus, Wetzlar, Germany), anterior segment OCT (Casia, SS-1000, Tomey, Nagoya, Japan), and optical biometry (IOLMaster 700, Carl Zeiss Meditec, Jena, Germany). The IOL power was calculated using SRK/T, Holladay II, and Haigis and Hoffer Q formulas. The target refraction for all eyes was Plano. In normal eyes, appropriate IOL power was selected based on the verification of all formulas. In long eyes (axial length [AL] >24), SRK/T, and in short eyes (AL < 22), Hoffer Q, was used as a suitable formula.
Patients were evaluated 1, 3, and 6 months after surgery. Manifest refraction, UDVA, CDVA, UIVA, CIVA, UNVA, CNVA, evaluation of patient satisfaction, and photic phenomena were measured at all postoperative visits. Patient satisfaction was assessed using the modified visual function (VF)-14 satisfaction questionnaire. It has been shown that this questionnaire is strongly associated with visual acuity, stereopsis, and contrast sensitivity (CS). The VF-14 test has been developed for evaluating cataractous patient's daily activities and includes 14 questions dependent on VF. Patients' responses to the questionnaire were scored from 0 (not possible) to 4 (no difficulty at all). The total score was divided by the number of answered questions and multiplied by 25 to calculate the final score. If all responses to all questions were “no difficulty at all” or “not possible,” the final result is 100 or 0, respectively. Moreover, patients were asked about incidence and discomfort percentage due to halo or glare phenomena. The questions for halo or glare incidence were: “Have you experienced any symptoms from halo/glare? If yes, how much these phenomena bother you to perform activities?” The scores were recorded according to responses: 0% (no), 25% (yes/mild), 50% (yes/moderate), 75% (yes/severe), and 100% (yes/unable to perform activities).
In addition, the binocular Mars Letter CS Test (Mars Perceptrix, Chappaqua, New York, USA) was performed at 6 months after surgery. This handheld chart includes 48 letters, 1.75-cm high, and six letters are arranged in each of the eight rows. The contrast of each letter is decreased with a constant factor of 0.04 log units. The contrast range is 0.04–1.92 log units, so that each letter represents an increase of 0.04 log units. The test is held by the optometrist at 40 cm. The mean chart luminance was 95–120 cd/m2. The test was stopped when the patient made two consecutive letter-reading mistakes.
The AT LISA tri 839 MP is a preloaded IOL, made of foldable hydrophilic acrylic, with a water content of 25% and hydrophobic surface properties. This IOL has an aspheric aberration-correcting design with an 11.0-mm overall length and a 6.0-mm optic diameter. This single-piece plate haptic lens comprises a central trifocal zone (4.34 mm) and a peripheral bifocal zone (from 4.34 to 6.0 mm) in the anterior surface. It provides a 3.33-D and 1.66-D addition for near and intermediate, respectively. It assigns 50% of light to far, 20.0% to intermediate, and 30% to near focus. The efficiency of light transmittance is 85.7% on average. The lens is available from 0.0 to + 31 in 0.50 D steps.
All surgeries were carried out by the same experienced surgeon (Kh.J), using a standard technique of sutureless phacoemulsification. Topical anesthesia was applied in most cases, yet for special patients, general anesthesia was administered. A 2.8-mm posterior limbal incision in corneal superior position was made manually. After a 5- or 5.25-mm capsulorhexis creation and phacoemulsification, the IOL was inserted in the capsular bag, using the BLUEMIXS 180 injector (Carl Zeiss Meditec, Jana, Germany) through the main incision. Postoperatively, chloramphenicol and betamethasone (SinaDarou Laboratories, Iran) drops were prescribed six and four times a day, respectively. The chloramphenicol drop was interrupted 1 week after surgery, whereas the betamethasone dosage was tapered off during 1 month. The second eye surgery was performed within 2–3 weeks after the first operation.
Data were analyzed using SPSS statistical software version 23 (SPSS, Inc., Chicago, IL, USA). All corrected and uncorrected visual acuities were converted to LogMAR values. Friedman nonparametric test was applied to compare preoperative data with postoperative visits related to 1, 3, and 6 months after surgery. Moreover, Wilcoxon nonparametric test was used to assess the differences between the two follow-up measurements. Results were presented as mean ± standard deviation (SD). In all cases, the same statistical significance level (P < 0.05) was considered.
| Results|| |
The study included 46 eyes of 23 patients. The mean age of the patients (72% women and 28% men) was 58.08 ± 11.01 years (range: 36–76 years). The mean preoperative manifest sphere, cylinder, and SE were 0.7283 ± 1.69, −0.4348 ± 0.54, and 0.5109 ± 1.67 D, respectively. The mean pupil diameter, extracted from four maps refractive, using Pentacam, was 2.77 ± 0.56 mm. The preoperative IOLMaster results, including AL, anterior chamber depth, K1, and K2, were 23.09 ± 0.94, 3.19 ± 0.43 mm, 43.75 ± 1.52, and 44.57 ± 1.58 D, respectively. The mean IOL power implanted was 21.92 D (range: 19–31.5 D). There were no intraoperative and postoperative complications. Centering of the implanted IOL was proper in all eyes. No significant capsular opacification was observed during the follow-up visits.
Refractive and visual outcomes
[Table 1] shows the preoperative sphere, cylinder, and SE values and their changes during the follow-up. A significant improvement was observed in sphere (P = 0.0001) and SE (P = 0.0001) values.
|Table 1: Descriptive and analytical data on the evolution of sphere, cylinder, and spherical equivalent variables at different follow.up times|
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Results of the related statistical analysis revealed logical improvement in near, intermediate, and distance uncorrected and corrected visual acuities during regular follow-ups, and a statistically significant difference (P = 0.0001) was noted between all follow-up measurements compared with the preoperative values. Descriptive data of measured variables follow recovery in proportional gradient, and significant differences were discovered in a different period of time. The descriptive and analytical data of the aforementioned variables are summarized in [Table 2]. Furthermore, changes in variables between 1st- and 3rd-month follow-ups as well as between 3rd- and 6th-month follow-ups, postoperatively, were evaluated [Table 3]. Comparing 1st- and 3rd-month postoperative results, other than a significant difference in UDVA, no significant difference was noted among the variables. Whereby, UDVA on the 3rd postoperative month (0.08 ± 0.11 LogMAR) was significantly better than the 1st postoperative month (0.1208 ± 0.12442 LogMAR; P = 0.009).
|Table 2: Descriptive and analytic data on changes in uncorrected distance visual acuity, corrected distance visual acuity, uncorrected intermediate visual acuity, binocular corrected intermediate visual acuity, uncorrected near visual acuity, and binocular corrected near visual acuity variables at different postoperative times|
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|Table 3: Comparison of changes in halo, glare, and satisfaction variables at the 1st, 3rd, and 6th months postoperatively|
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Sphere and SE showed a significant reduction between 1 and 3 months (sphere: P = 0.001, SE: P = 0.001), yet no significant reduction was observed between 3 and 6 months (sphere: P = 0.660, SE: P = 0.584). The mean cylinder reduced over time, yet no statistically significant change was observed in this value at 1- (P = 0.816), 3- (P = 0.666), or 6-month follow-up (P = 1.000) [Table 3]. At 6 months, 76% and 95% of eyes had an SE value within −0.5–0.00 D and −1.00–0.00 D, respectively.
Photic phenomena, satisfaction questionnaire, and contrast sensitivity outcomes
[Table 4] shows the results derived from statistical analysis related to a measure of the VF-14 questionnaire regarding postoperative halo and glare on the 1st, 2nd, and 6th months postoperatively. A gradual decline was revealed in halo and glare, and at 6 months postoperatively, it reached 8.7% and 7.07%, respectively. This decline was statistically significant for halo (P = 0.017), and a comparison of results regarding halo and glare between the 1st and 3rd months, as well as the 3rd and 6th months, revealed a significant difference in the former period of time [Table 4]. The mean score of the patients' satisfaction questionnaire was 96.6% at 6 months postoperatively, and the level of satisfaction of patients in postoperative follow-up had a statistically significant increase. The CS test was performed at 6 months postoperatively, and the mean of this test was 1.74 ± 0.08 in LogMAR.
|Table 4: Comparison of changes in uncorrected distance visual acuity, corrected distance visual acuity, uncorrected intermediate visual acuity, binocular corrected intermediate visual acuity, uncorrected near visual acuity, binocular corrected near visual acuity, sphere, astigmatism, spherical equivalent, halo, glare, and satisfaction at two time period of 1st and 3rd month as well as 3rd and 6th month postoperatively|
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Intraocular lens power calculation formulas
[Table 5] shows a comparison of different formulas for calculating patients' IOL power. The mean error or ME was calculated as the difference between patients' spherical error (SE) at 6 months postoperatively and the predicted SE of each formula (actual postoperative refraction-predicted refraction). Furthermore, the mean absolute error (MAE), which is the absolute value of the ME, is calculated for each formula. The negative ME shows that the postoperative SE is more myopic than expected (more myopic than intended). As indicated, the MAE of the Hoffer Q formula was lower than the rest of the formulas.
|Table 5: Comparison of formulas' error for calculating intraocular lens power|
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| Discussion|| |
Nowadays, in modern societies, the increase in visual demand at different distances and the independence of spectacles is increasing in patients with presbyopia or cataract. In order to meet this need, multifocal IOLs are designed by a variety of designers, and independent of the type of design, their main purpose is to provide the highest degree of independence of spectacles in patients. The main types of these lenses include refractive, diffractive, refractive diffractive, and accommodative IOLs, each with advantages and disadvantages, yet they can all provide good visual acuity for patients at near and distance. However, reaching proper intermediate vision, which is important for daily activities (such as working with computers, cooking, and playing music), is not satisfactory in a large number of patients.
One of the approaches for creating an intermediate vision was the design of trifocal IOLs. The AT LISA tri 839MP (Carl Zeiss Meditec AG), a new diffractive IOL with a trifocal design, has been studied by several published studies,,,, and has yielded satisfactory results, yet lens responsiveness may vary in different societies. This is the first study that evaluated the visual and subjective outcomes of Iranian patients following implanting this trifocal IOL.
The SE outcomes and 3-month monocular visual acuities after implantation of the AT LISA tri 839MP IOL related to previous studies are summarized in [Table 6].
|Table 6: Reported spherical equivalent outcomes and monocular visual acuities 3 months postoperatively following implantation of AT LISA tri 839MP lens in various studies|
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In the current study, the mean SE at 3 months postoperatively was −0.45 D ± 0.36 D. Seventy-six percent and 86% of the eyes were in the range of −0.50–0.00 D and 1.00–0.00 D, respectively. Although these results provide good predictability, the SE value obtained in the current study was larger than other studies. The UDVA parameter of the patients, at 3 months postoperatively, reached 0.08 ± 0.11 LogMAR, which is similar to the results obtained by other studies, indicating the best outcomes for distant vision without correction.,, In the current study, the values of UIVA and UNVA were 0.09 ± 0.08 and 0.06 ± 0.08 LogMAR, which is identical to that of Kretz et al.
Of course, the best results for UIVA and UNVA are related to Bilbao-Calabuig's study, which were 0.00 ± 0.17 and 0.07 ± 0.10 LogMAR, respectively. The differences in studies can be due to the difference in their sample size, the age of the patients, and method of measurement of visual acuity. In spite of these differences, two previous studies, as well as the current study have reported good results for each of the three distances: near, intermediate, and distance vision simultaneously. The current authors believe that the results that are simultaneously obtained for these three distances are suitable for achieving high levels of independence of spectacles for daily activities. In the current study, 96% of patients achieved independence of spectacles at all three distances, and only one patient needed spectacles for distant vision.
The IOLs that can produce more than one focal point, due to the split of incident light between the focal points, result in out of focus images. This can affect the quality of vision in patients and reduce their CS and the appearance of dysphotopic phenomena, such as halo and glare. In this study, the researchers asked patients about the halo and glare, and percentage of their perceived annoyance due to these phenomena, in order to determine decreasing or incremental trends of these phenomena in subsequent follow-ups. Their response was graded as follows: 0% (no), 25% (yes/mild), 50% (yes/moderate), 75% (yes/severe), and 100% (yes/unable to perform activities). The results showed that the response of most patients (19 out of 23 patients) regarding perceived halo and glare was no, and the rest, with the experience of halo and glare, reported mild discomfort. Law et al. and Mendicute et al. found a progressive decline in relation to these phenomena, which was confirmed by the current study. This improvement seems to be justified with smooth microphase technology (the lack of sharp angles on the lens surface) used in this trifocal IOL, as well as the neural-adaption process that occurs for patients over time. There are several reasons for halo and glare after multifocal IOL implantation such as dry eye, pupil size, angle kappa, aberrations, surgical technique, capsule size, and postoperative lens decentration. In our study, as mentioned in the exclusion criteria, we excluded unsuitable cases for IOL implantation. Hence, it seems that halo and glare observed in our study are related to design and structure of IOL. Although the design of this lens has improved significantly, there is still a need to optimize their structure to minimize these complications.
This research conducted the Mars CS test on the 6th-month postoperative follow-up, which revealed 1.74 ± 0.08 LogMAR. The reported mean of this CS test for people with normal vision and mean age of 58.9 years was 1.76. This shows that the achieved CS rate in the current study is very good. The percentage of patients' satisfaction rate was assessed using a VF-14 questionnaire. The results indicated a high percentage of patient satisfaction and their satisfaction had an increasing trend over time.
A comparison was also done between consecutive follow-up times (1st and 3rd months as well as 3rd and 6th months). Statistical analysis showed that the improvement of variables, including UDVA, sphere, SE, and the occurrence of halo and glare between the 1st- and 3rd-month follow-ups, had a significant difference, and none of the variables had a significant statistical difference between 3rd- and 6th-month follow-ups. It seems that stability was achieved at least 3 months, postoperatively, and any interference in a patient's condition before 3 months postoperatively should be avoided.
In this study, different formulas used to determine patients' IOL power were evaluated, and MAE of each formula was calculated. The error of the Haigis formula was the least in comparison to the rest of the formulas. It seems that the use of this formula can determine IOL power more accurately. Therefore, the authors suggest the application of this formula by surgeons to determine proper IOL power, preoperatively.
| Conclusions|| |
The AT LISA tri 839MP trifocal IOL provides excellent visual outputs for patients following cataract surgery, and the ability to predict postoperative refraction is also appropriate. A combination of appropriate vision at different distances, high level of the spectacle independence, low incidence of halo and glare, and high percentage of patients' satisfaction showed that this lens has a very good response among Iranian patients. Finally, if the patient is properly selected according to the inclusion and exclusion criteria of the study, accurately consulted preoperatively, and the IOL power is correctly calculated before surgery, satisfactory results could be achieved. However, the selective population is a limitation of this study because, for this IOL implantation, we have to select cases that are healthy for eye examination and without any systemic disease.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]