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| ORIGINAL ARTICLE |
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| Year : 2021 | Volume
: 29
| Issue : 1 | Page : 13-16 |
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Surgically Induced Astigmatism After Phacoemulsification with Clear Corneal 2.75 mm Incision Using Superior Approach
Angela S.D Amita MD 1, Laura A Djunaedi1, Angelo Doniho2, Andrew Adiguna Halim3
1 Departement of Ophthalmology, School of Medicine and Health Sciences, Atma Jaya Catholic University of Indonesia, Indonesia
2 Department of Ophthalmology, Faculty of Medicine Udayana University/Sanglah General Hospital, Bali, Indonesia
3 Department of Health Science, The University of Canterbury, Christchurch, New Zealand
| Date of Submission | 10-Sep-2020 |
| Date of Decision | 03-Mar-2021 |
| Date of Acceptance | 14-Apr-2021 |
| Date of Web Publication | 16-Jul-2021 |
Correspondence Address:
Angela S.D Amita
Jl. Pluit Raya 2, Department of Ophthalmology, School of Medicine and Health Sciences, Atma Jaya Catholic University of Indonesia
Indonesia
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/njo.njo_35_20
Context: Optimal postoperative vision can be achieved through a low surgically induced astigmatism (SIA), which is closely related to the site of incisions. Studies showed that temporal incision gives low SIA. However, a temporal incision is not convenient for some surgeons and in a small operating room with a limited number of assistants. These limitations can be overcome by using a superior approach. Aims: The aim of the study was to evaluate SIA after phacoemulsification with clear corneal incision using superior approach in different kinds of astigmatism as an alternative site of incision. Settings and Design: Medical records of patients who underwent cataract surgery were collected retrospectively between April and August 2017. Appropriate statistical analyses using Kruskal–Wallis, analysis of variance (ANOVA), Games-Howell test were done to assess the effect of superior approach on corneal curvature and whether it varies between different kinds of astigmatism. Results: Kruskal-Wallis test shows that there was no significant postoperative power change across different astigmatism groups (χ2 (2) = 0.805, P = 0.669). ANOVA and Games-Howell test show that oblique astigmatism had higher changes to its curvature compared with against the rule or with the rule astigmatism. Conclusions: The average SIA from the study was 0.34 diopter. Our study concludes that there is no statistically significant difference to SIA between three groups of astigmatism when they were operated using superior approach.
Keywords: Cataract, phacoemulsification, superior approach, surgically induced astigmatism
How to cite this article:
Amita AS, Djunaedi LA, Doniho A, Halim AA. Surgically Induced Astigmatism After Phacoemulsification with Clear Corneal 2.75 mm Incision Using Superior Approach. Niger J Ophthalmol 2021;29:13-6 |
Key Messages: Clear corneal incision using superior approach in phacoemulsification cataract surgery gives a low SIA in any type of astigmatism. This site of incision can be a preferred choice in a small operation room with a limited number of assistants. Besides, superior site may overcome limitations in some surgeons.
| Introduction | |  |
An excellent evaluation of corneal curvature is needed for the best result of uncorrected visual acuity after cataract surgery.[1],[2] Phacoemulsification technique can be used to minimize surgically induced astigmatism (SIA), which will produce optimal postoperative vision.[3],[4] In addition, clear corneal incision (CCI) technique can further minimize SIA that was induced by surgical sutures.[5] A previous study showed that temporal site gave a better result in minimizing SIA.[6] However, performing temporal CCI might be not suitable in all cases. In this study, we want to find out how high is the SIA after phacoemulsification cataract surgery when using a superior approach.
| Subjects and Methods | | |
Medical records of patients who underwent phacoemulsification cataract surgery with three-plane incision and superior approach between April 2017 and August 2017 at a teaching hospital were collected. The keratometry information contains dioptric power and axis of astigmatism before and from 21 to 35 days after the surgery. The same instrument was used to do the keratometry during this data collection period.
A single operator was performing all the phacoemulsification cataract surgeries with a 2.75 mm superior CCI. The patients were assigned to each of the preoperative groups of astigmatism, which are against the rule, oblique, and with the rule. This grouping of astigmatism is divided in accordance with cornea’s steepest curve. Against the rule astigmatism is eye with steepest curve lies near 180-degree meridian (150–180 and 0–30), with the rule astigmatism steepest curve located near the 90-degree meridian (60–120), and oblique astigmatism steepest curve lies between 120–150 degree and 30–60 degree. Only patients with in the bag intraocular lens (IOL) implantation using a square edge, aspheric, and foldable IOL was included. In addition, all patients in this study need to use their eye patch for 12 hours. Those with previous history of eye surgery and eye diseases were excluded.
Sample size for one-way analysis of variance (ANOVA) with P value of 0.05, 80% power, and effect size of 0.6 is 42. Statistical analysis was done using R 3.5.3 and R Studio.[7],[8] Descriptive statistics were done for the patient characteristics and their keratometry results. Change in dioptric power was assessed using Kruskal-Wallis test. Changes in axis groups of astigmatism were assessed using ANOVA and Games-Howell post hoc tests.
| Results | | |
Demographic and keratometric data in our retrospective study, which are taken from 51 patients, can be seen in [Table 1].
Kruskal-Wallis test shows that there was no significant power difference between these three groups of astigmatism (χ2 (2) = 0.805, P = 0.669). “With-the-rule” astigmatism patients tend to have lower variability of power change compared with “Against-the-rule” and “Oblique” astigmatism patients [Figure 1]. | Figure 1 Postoperative Power Mean Changes after Phacoemulsification using Superior Approach
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ANOVA test shows differences in corneal curvature between three astigmatism groups [Table 2]. Games-Howell test shows that changes in corneal curvature of postoperative astigmatism in oblique astigmatism patients were greater when compared with against the rule astigmatism patients (20.8 ± 4.2 degrees, P = 0.002) and with the rule astigmatism (25.5 ± 5, P = 0.018). However, test shows no significant difference between against the rule astigmatism and with the rule astigmatism (4.68 ± 3.1, P = 0.548).
| Discussion | | |
Getting accurate postoperative refraction will determine the success of cataract surgery.[9] One of the main factors that determine good postoperative refraction is SIA.[10] SIA is influenced by many factors, such as the type of cataract surgery, incision type, incision site, and suturing techniques.[11]
Nowadays, the two most common types of cataract surgeries are phacoemulsification and MSICS (manual small incision cataract surgery). In general, phacoemulsification surgery produces lower SIA when compared to MSICS.[4] One study suggests that MSICS induces SIA about 0.3 to 0.5 diopter (D) greater than phacoemulsification.[12] In this study, all of our patients underwent a phacoemulsification cataract surgery.
Another factor that affects SIA is the incision technique. The three-plane incision technique is considered to be quite difficult.[13] A study using optical coherence tomography showed that only 32% of patients had the expected three-plane structure, which might induce greater SIA, as the operator intended.[5] Nevertheless, when done right, this incision technique can efficiently reduce the chance of endophthalmitis owing to preventing particles from entering anterior chamber when there is a change in intraocular pressure.[14] We did three-plane incision to all of our patients.
In addition to incision techniques, Gokhale has found that temporal or superotemporal approaches would result in lower SIA when compared to superior approaches. The use of a superior approach results in a larger SIA due to gravitational force and the blinking of the eye at the incision point.[6] However, temporal approach might not be possible due to operator height related to the bed height, operator foot position, or in small operating room with limited personnel. Our study tried to overcome the gravitational force with longer eye patching time and it showed that superior incision approach that we used produces an average SIA of 0.34D, which is below the recommended keratometric shift limit (0.50D).[11]
Different locations of incision in different types of astigmatism will also affect SIA.[14] Superior incision will result in an astigmatism shift toward against the rule (ATR), while the temporal incision will cause an astigmatism shift toward with the rule (WTR).[15],[16],[17] Thus, other researchers said that superior incisions should be performed on astigmatism WTR, whereas temporal incisions should be carried out on ATR astigmatism.[18] This is because incision can decrease corneal curvature.[19] The incision is made on the site with more convex curvature, intended to balance the corneal curvature meridian and in turn reduce the SIA.[20] Our study did not show significant differences in SIA in ATR/WTR/oblique astigmatism group with the use of modified superior incisions. This might be due to the mean astigmatism of this study subjects (–0.97D), which is much smaller than the average astigmatism of the research by Masnec-Paskvalin et al. (2.00D). In addition, a smaller number of samples and smaller SIA of the operator also may affect results.
Another factor that can reduce SIA is doing incisions without suturing. The suturing process can change structures of the wound which may induce SIA. In addition, a procedure to remove the sutures itself require additional control time, giving the patient a feeling of discomfort and increasing the risk of infection.[5] Vasavada et al.[21] stated that any maneuvers carried out after operation will affect the amount of distortion in the incision site that in turn affects the integrity of the wound, leaving gaps for infection.
Some of the most recent techniques related to SIA include limbal relaxing incision that uses the principle of leveling the corneal curvature after incision. This technique resulted in an average decrease in astigmatism of 1.178D.[22] Another technique was used by Hassann et al. which obtained 1.71D in mean reduction of astigmatism after toric IOL insertion.[23] In addition, SIA can be minimized by using wound closure products such as cyanoacrylate, fibrin, or polyethylene glycol. Impermeable incisions can reduce the risk of IOL decentration and accelerate wound healing.[5]
There are various new methods to get a better uncorrected visual acuity after cataract surgery, but with limited resources we need to pick an effective and efficient method in accordance with the situation and condition we met.
| Conclusion | | |
The average SIA we have from phacoemulsification surgery with superior approach is 0.34D. This research also shows no significant difference in SIA in all groups of astigmatism.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
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[Figure 1]
[Table 1], [Table 2]
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