TNOA Journal of Ophthalmic Science and Research

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 57  |  Issue : 2  |  Page : 105--108

Surgically induced astigmatism in manual small-incision cataract surgery: A comparative study between superotemporal and temporal scleral incisions


Machireddy R Sekharreddy, Venkatesh Sugantharaj, Shruti Prabhat Hegde 
 Department of Ophthalmology, Shri Sathya Sai Medical College and Research Institute, Sri Balaji Vidhyapeeth, Deemed to be University (SBV), Chennai, Tamil Nadu, India

Correspondence Address:
Dr. Shruti Prabhat Hegde
Associate Professor, Department of Ophthalmology, Shri Sathya Sai Medical College and Research Institute, Sri Balaji Vidhyapeeth, Deemed to be University (SBV), Ammapettai, Via Thiruporur, Chennai - 603 108, Tamil Nadu
India

Abstract

Purpose: The purpose of this study is to compare the surgically induced astigmatism between superotemporal and temporal approaches in manual small-incision cataract surgery (MSICS). Materials and Methods: This was a prospective, hospital-based, interventional study with two groups each consisting of 50 patients. Patients in Group A underwent superotemporal MSICS and those in Group B underwent temporal MSICS. Statistical analyses of the results obtained were done with the SPSS software version 20, and data sets were compared using an independent sample t-test. Results: Astigmatism induced by superotemporal incision was 0.8032 ± 0.322 D, whereas astigmatism induced by temporal incision was 0.3826 ± 0.142 D with the difference being statistically significant. Both the groups showed significant improvement in postoperative uncorrected visual acuity. Conclusions: This study showed that the temporal MSICS induces lesser astigmatism as compared to the superotemporal approach. However, unaided postoperative visual acuity was comparable and good in both the groups.



How to cite this article:
Sekharreddy MR, Sugantharaj V, Hegde SP. Surgically induced astigmatism in manual small-incision cataract surgery: A comparative study between superotemporal and temporal scleral incisions.TNOA J Ophthalmic Sci Res 2019;57:105-108


How to cite this URL:
Sekharreddy MR, Sugantharaj V, Hegde SP. Surgically induced astigmatism in manual small-incision cataract surgery: A comparative study between superotemporal and temporal scleral incisions. TNOA J Ophthalmic Sci Res [serial online] 2019 [cited 2019 Sep 17 ];57:105-108
Available from: http://www.tnoajosr.com/text.asp?2019/57/2/105/266382


Full Text



 Introduction



Cataract is the most common cause of reversible blindness, and surgery is the only intervention available till now.[1],[2] Phacoemulsification and manual small-incision cataract surgery (MSICS) are the most commonly done procedures. In our country, there is a large volume of cataract backlog, mainly among the rural and suburban population. Phacoemulsification is considered the gold-standard procedure for cataract.[3] However, MSICS has emerged as a popular procedure of choice in the surgical treatment of cataracts as it is less expensive and is as effective as phacoemulsification.[4] It may be considered a better procedure for doing mass surgeries.[5] However, MSICS comes with its own set of limitations. Surgically induced astigmatism (SIA) remains a common cause of poor postoperative visual recovery.[6] Site and size of scleral incision are the factors which influence the SIA.[7] Larger the incision size, more is the astigmatism. However, when the size is kept constant, the main determinant for the amount of SIA is the site of the scleral incision. There are three common sites where the scleral incisions are commonly made, namely, superior, superotemporal, and temporal. Out of these, superior scleral incision is commonly performed as it is easy and has the forehead support of the patient but is said to cause maximum SIA.[8] Temporal scleral incision is difficult to make due to lack of support and less area of exposure for the incision and instruments but is supposed to result in minimal SIA. This may be because most of the older patients have an against the rule (ATR) astigmatism which is nullified by the temporal scleral incision. When compared with these two, superotemporal incision is considered more advantageous. There are many studies comparing SIA between superior and temporal incisions and few studies comparing SIA between all the three incisions.[6],[9],[10],[11],[12] However, very few studies have compared superotemporal and temporal scleral incisions. In our center, we get a large number of cataract patients, and SICS is being done commonly. Therefore, we undertook this study to compare SIA between superotemporal and temporal scleral incision.

 Materials and Methods



This was a hospital-based prospective interventional study done at the Department of Ophthalmology of a Medical College Hospital. The study was done after obtaining ethical clearance from the institutional ethical committee. A total of 100 patients aged between 31 and 80 years diagnosed with presenile and senile cataract and willing to undergo cataract surgery in our institution were included in the study. Patients with hypermature cataracts, secondary cataracts due to trauma, and uveitis were excluded from the study. Patients with pseudoexfoliation syndrome, posterior synechiae, poor dilating pupils, and corneal pathologies/scarring were also excluded.

Patients were separated into two groups of 50 patients each based on the site of incision to be made. Patients who were grouped under Group A underwent MSICS with superotemporal scleral incision and patients who were grouped under Group B underwent temporal scleral incision MSICS.

An informed and written consent was obtained from the patient. A detailed history was taken regarding any systemic pathology and allergy to the drugs. Visual acuity was checked unaided for both far and near vision and with pinhole. Best-corrected visual acuity was recorded. Thorough slit-lamp examination was done to look for ocular adnexal pathology and anterior segment examination. Patient pupils were dilated with mydriatic eye drops (a combination of tropicamide 0.8% + phenylephrine 5%). Lens opacity grading was done by Lens Opacities Classification System III. Direct and indirect ophthalmoscopic examination with 78D to rule out fundus pathology was done. Systemic examination was done. Investigations such as lacrimal sac syringing and intraocular pressure measurements were done.

Preoperative keratometry readings were taken with manual keratometer (Appasamy KMS 6) and autokeratometers (Unicos-800K). Patients were started on ciprofloxacin eye drops 0.3% and flurbiprofen 0.03% from the previous day. On the day of surgery, the eye to be operated was started on tropicamide plus eye drops (tropicamide 0.8% + phenylephrine 5%).

All the 100 patients underwent MSICS and were operated by single surgeon. Under peribulbar anesthesia with lignocaine 2% with adrenaline 1:10,000 dilutions mixed with hyaluronidase 5 IU/ml, patient's eye was cleaned with betadine scrub and draped with disposable drape. Eyelid speculum was put up, and superior rectus birdling was done with 3.0 silk. Conjunctival flap was raised superotemporally for Group A patients and temporally for Group B patients, to bare the sclera. Cauterization was done to achieve hemostasis. A frown-shaped incision of 6.5 mm was made on the superotemporal and temporal sclera, respectively, 1 mm away from the limbus with a 11 size Bard-Parker blade. Sclerocorneal tunneling was made with beveled up crescent blade (2.5 mm) up to 1 mm inside the cornea. The architecture of the sclerocorneal tunnel was similar in both the groups except for the site of incision. Side port entry was made 90° away from the incision. Anterior chamber was maintained throughout the procedure with viscoelastic. Anterior capsulotomy was made with cystitome by continuous curvilinear capsulorhexis technique. Main port entry was made through the tunnel using the 2.8 mm sharp keratome, and wound was extended on both the sides with 5.2 mm keratome. Hydrodissection was performed. The nucleus was flipped into anterior chamber with dialler and delivered out by viscoexpression technique. Thorough cortical wash was given with Simcoe I and A cannula. Subincisional cortical matter was aspirated from the side port. Posterior chamber polymethyl methacrylate single-piece intraocular lens of 6 mm optic diameter was placed and dialed into the bag. After aspiration of viscoelastic anterior chamber was reformed with normal saline, and incision was thoroughly hydrated. Wound incision was checked for leakage or iris prolapse, and subconjunctival dexamethasone with gentamycin was injected. In case of temporal incision (Group B), the operating surgeon sat on the temporal side of the eye to be operated.

Postoperatively, all the patients were started with tablet ciprofloxacin 500 mg BD, tablet diclofenac 50 mg BD, and tablet ranitidine 150 mg BD. Patients were started on Ciplox-D (ciprofloxacin 0.3% with dexamethasone 0.1%) six times a day for 1 week and were tapered every week. On the 1st postoperative day, visual acuity was checked, and keratometer readings with manual and autokeratometer were taken. Patients were advised to follow-up on the postoperative day 7, 14, 21, and 45 days, and both manual and autokeratometer readings were noted on these visits. The preoperative keratometer readings were compared with the postoperative keratometer readings, and SIA was calculated with SIA calculator software 2.1 ver (All India Ophthalmic society website). The data collected in the study were coded and tabulated using SPSS statistical software version 20 (IBM, Armonk, NY, USA). The data were analyzed and are presented here in the form of rates, ratios, and percentages. Independent sample t-test was used to compare the SIA between the two groups, and P < 0.05 was considered as statistically significant.

 Results



In this study, there were 100 patients, of whom 55 were male and 45 were female patients. Among these, 47 patients underwent surgery in the right eye whereas 53 patients underwent in the left eye. The age of the patients ranged between 35 and 80 years, the details of which are depicted in [Table 1].{Table 1}

Among the participants of the study, 30 patients had a previous history of cataract surgery in the other eye and were pseudophakic. Twenty of these patients were >60 years old.

Pre- and postoperative visual acuity

The following [Table 2] and [Table 3] depict the pre and final postoperative visual acuity of the patients.{Table 2}{Table 3}

Surgically induced astigmatism

SIA calculated with the help of SIA calculator was entered into SPSS version 6 software (IBM, Armonk, NY, United States of America). The mean was calculated for both the groups. The details are given in the following [Table 4].{Table 4}

According to independent sample t-test, there was a significant difference in mean SIA between superotemporal and temporal incision. The difference was 0.4206D (t67.39=8.429, P < 0.001).

 Discussion



In this study, there was a near equal distribution with slight male preponderance among the patients getting admitted. This is easily explained by the fact that senile cataract does not show any gender predisposition. Most of the cases in this study fall in the age group of 51–60 years. This could be due to increasing awareness among the patients regarding the benefits of cataract surgery. About 10% cases were between the age group of 61 and 70 years of age. All of these patients were pseudophakic in the other eye. Thus, good visual acuity in the operated eye could be the reason for delay. The same factor has been emphasized in a recent study.[13]

In this study, both the groups had significant improvement in postoperative visual acuity. One of the factors that decide the uncorrected postoperative visual acuity is SIA.[14] However, the SIA does not have a direct bearing on the unaided postoperative visual acuity as this will depend on the preoperative magnitude and vector of astigmatism.[15] In this study, we found that superotemporal incisions had a mean SIA of 0.8032D ± 0.322, while the temporal incisions had a mean SIA of 0.3826D ± 0.142. As per the results we obtained, the SIA was less in temporal scleral incision group compared to superotemporal scleral incision group. This difference was found to be statistically significant with P < 0.001. Our results were found to be unique as compared to similar studies. The study done by Gokhale and Sawhney compared superior, superotemporal, and temporal incisions.[11] It concluded that superior incisions cause the highest SIA, whereas there is no significant difference between superotemporal and temporal incision. A study by Satyajeet Pawar and Sindal concluded that temporal incision induces less astigmatism compared to superotemporal incision, but the difference was not statistically significant as in the present study.[12]

The temporal approach for SICS has yielded excellent results in some studies and has the advantage that it induces lesser astigmatism.[16] As mentioned earlier, this is mainly because it reduces the preoperative ATR astigmatism which is more common in the elderly, who are more cataract prone and thereby provides a better uncorrected postoperative vision. However, certain points work against the temporal approach, the major disadvantage being a higher risk of bacterial endophthalmitis associated with the temporal approach.[17]

Even though SIA was significantly less in the temporal incision group, both the groups showed significant improvement in final uncorrected visual acuity. Therefore, we advocate the use of superotemporal scleral incision as it is easy to learn and train and is more cosmetically acceptable as it is covered by upper eyelid, in spite of the fact that it induces higher SIA than the temporal approach.[12] In case of large/hard nucleus, extension of incision size is permitted due to the large area of access. Thus, it has got advantages of both superior and temporal scleral incisions.

This study being a hospital-based study had its own limitations in the form of small sample size and limited follow-up. The other limitation is that we attempted to find the induced surgical astigmatism between these two approaches and did not try to use the SIA to correct preexisting astigmatism, which would have added additional useful information.

 Conclusions



This study has shown that the temporal MSICS induces lesser astigmatism as compared to the superotemporal approach. However, the unaided postoperative visual acuity is comparable and good in both groups. Thus, we recommend the superotemporal approach for manual SICS over the temporal approach considering the various advantages of the former and the disadvantages of the latter.

Financial support and sponsorship

The study was financially supported by Sri Balaji Vidyapeeth, deemed to be university.

Conflicts of interest

There are no conflicts of interest.

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