Cataract is a common cause of visual impairment and one of the main causes of blindness worldwide [1]. A cataract is any opacity of the crystalline lens sufficient to cause visual impairment [2]. Opacified tissue can be due to any metabolic insult incurred by the lens, whether mechanical, chemical, and electrical, or by irradiation [3]. Most forms of cataracts progress throughout life. Opacities can form in utero during infancy and adolescence (juvenile or early onset cataract), adulthood (presenile cataract), and old age (senile cataract). There is an estimated number of people with visual impairment in excess of 161 million; 37 million are blind and 124 million suffer from low vision, in the world with 'the leading cause of blindness being cataract'.1It is the commonest cause of treatable blindness [4]. Cataracts are the main cause of curable blindness in India and worldwide. The annual incidence of cataracts in India has been estimated to be 3.8 million 2 and 1.8 million sight-restoring operations are performed yearly [5] The mainstay of management of cataracts is surgery, as medical treatment has not proved beneficial. Cataract surgery aims to provide early visual rehabilitation. The visual outcome of surgery is mainly attributed to the degree of postoperative astigmatism, which in turn depends on the type, length, and position of the incision as well as the method of wound closure. The advent of microsurgery with an operating microscope, better quality instruments, and the invention of intraocular lenses have remarkably improved the results of cataract surgery [6]. Intracapsular cataract extraction was introduced in 1753, which resulted in aphakia. Extracapsular cataract was then extracted with an intraocular lens, which corrected the aphakia, but postoperative astigmatism was significant with large incisions. The most remarkable development in cataract surgery during the 20th century was the phacoemulsification technique, introduced by Kelman in 1967.

The main advantage of this technique is the small incision, and least postoperative morbidity in terms of tissue injury, pain, inflammation, and surgically induced astigmatism. With the advent of the latest foldable intraocular lens as a deviation from the conventional rigid intraocular lens, it is possible to implant the lens through an incision as small as 2.2 mm, which helps to significantly reduce postoperative astigmatism. Assessment of corneal topographic changes using a keratometer helps correct surgically induced astigmatism with refraction [7]. Preexisting corneal astigmatism (>1.0 D has been reported to be present in 23%–47% of eyes with cataracts. 4 Toric intraocular lenses (IOLs) are widely used to treat corneal astigmatism and cataracts and are an effective and safe treatment for patients with both conditions [8, 9] Toric IOL implantation has been reported to have a corrective effect in patients with cataracts and corneal astigmatism. Therefore, it is important to minimize residual astigmatism postoperatively [8]. Today, the technology of cataract treatment has been further advanced. Clear corneal incision (CCI) phacoemulsification has become the mainstream treatment for cataracts worldwide. There are two approaches: through superior clear corneal and temporal clear corneal incisions. Therefore, in the present study, we evaluated surgically induced astigmatism after phacoemulsification with temporal and superior scleral incisions using a foldable intraocular lens.

This prospective observational study was conducted in the Department of Ophthalmology at a tertiary care center. The duration of the study was 18 months. Ethical approval was obtained from the institutional Ethical committee. Written consent was obtained from all the participants of the study after explaining the nature of the study in vernacular language.

Study Population: The study included patients diagnosed with senile cataracts who were scheduled for phacoemulsification surgery.

Sample Size: A total of 100 patients were included and randomly divided into two groups:

• Group A (n=50): Patients underwent phacoemulsification with a superior clear corneal incision.
• Group B (n=50): Patients underwent phacoemulsification with a temporal clear corneal incision.

Inclusion Criteria

1. Patients aged 40–75 years with immature or nuclear sclerosis grade 1–3 senile cataracts.
2. Both male and female patients.
3. No prior ocular surgery, trauma, or significant ocular comorbidity.
4. Patients providing written informed consent.

Exclusion Criteria

1. Age <40 or >75 years.
2. Mature or hypermature cataracts.
3. History of hypersensitivity to lignocaine, epilepsy, or inability to provide informed consent.
4. Prior intraocular surgery, trauma, or inflammation.
5. Pupil size <5 mm, or presence of ocular comorbidities including diabetic retinopathy, glaucoma, optic atrophy, keratoconus, pseudoexfoliation, uveitis, high myopia (axial length >26 mm), hyperopia (<21 mm), posterior synechiae, phacodonesis, nystagmus.
6. Patients are unwilling or unable to cooperate or provide informed consent (e.g., anxious, deaf, mute patients).

Preoperative Assessment: All participants underwent a comprehensive ophthalmic evaluation including:

1. Best Corrected Visual Acuity (BCVA)
2. Intraocular Pressure (IOP) measurement
3. Slit-lamp biomicroscopy
4. Direct ophthalmoscopy
5. Keratometry
6. A-scan biometry
7. Autorefraction

Systemic Investigations: Blood Sugar (Fasting/Random), Urine Sugar/Albumin, ECG, HBsAg, HIV (ELISA), and

Blood Pressure measurement

Surgical Technique: All surgeries were performed under peribulbar anesthesia by experienced 

surgeons using standard phacoemulsification techniques. The only variable between the two groups was the location of the clear corneal incision—superior vs temporal.

Outcome Measures:

• Primary outcomes: Surgically induced astigmatism (calculated using vector analysis of preoperative and postoperative keratometry) and postoperative visual acuity.
• Secondary outcomes: Intraoperative and postoperative complications.

Data Analysis: Data were compiled and analyzed using appropriate statistical tools. Continuous variables were compared using the student’s t-test, and categorical variables were analyzed using the chi-square test. A p-value of <0.05 was considered statistically significant.

The mean age of the patients of group A (Superior clear corneal incision) was 60.01 ± 8.47 SD years and in group B (Temporal clear corneal incision) was 58.2± 7.55 SD years. In group A, there were 30 (60%) males and 20 (40%) females, whereas in group B the males numbered 33 (66%) and females 17 (34%). Maximum patients were from the age group 66-70 yrs in Group A (Superior clear corneal incision and 46-50 yrs in Group B (Temporal clear corneal incision) depicted in Table 1.

Table 2 shows the distribution of cataract types among patients in the two study groups. Nuclear sclerosis was the most common type of cataract observed, seen in 36 patients in Group A and 40 patients in Group B, making a total of 76 cases. Posterior subcapsular cataract was the second most common type, present in 10 patients in Group A and 7 in Group B, totaling 17 cases. A combination of nuclear sclerosis and posterior subcapsular cataracts was observed in 4 patients in Group A and 3 in Group B, making up 7 cases. This distribution indicates a predominance of nuclear sclerosis in both surgical groups, with a relatively even representation of other cataract types, supporting a balanced comparison between the groups for the study's outcomes.

The best corrected visual acuity is depicted in Table 3. A critical analysis of the table shows that the Best corrected visual acuity of 6/6 was achieved in temporal clear corneal incision (Group B) surgery i.e in 28 patients (56%) as compared to superior clear corneal incision surgery (group A) i.e. in 24 patients (48%). Best corrected visual acuity of 6/9 was achieved in temporal clear corneal incision (Group B) surgery i.e. in 17 patients (34%) as compared to superior clear corneal incision surgery (group A) i.e. in 15 patients (30%). The best corrected visual acuity of 6/12 was achieved in temporal clear corneal incision (Group B) surgery i.e. in 28 patients (56%) as compared to superior clear corneal incision surgery (group A) i.e. in 24 patients (48%). Hence, in both of the above conditions temporal corneal incision (group B) has achieved better visual acuity as compared to superior clear corneal incision surgery (group A).

While comparing postoperative astigmatism in Group A and Group B as shown in Table 4, Group B (Temporal clear corneal incision) outcome is better than Group A (Superior clear corneal incision) Postoperative astigmatism of <0.50 D was achieved in 22 (44%) patients of group B whereas in group A it was seen in 7 (14%) patients only. Similarly, Postoperative astigmatism of 0.50-1D was achieved in 16 (32%) patients of group B whereas in group A it was seen in 14 (28%) patients. Mean postoperative astigmatism in Group A (Superior clear corneal incision) was 1.5D ± 0.76 D and in Group B (temporal clear corneal incision) it was 0.5 ± 0.30 D.

Cataract surgery has improved significantly from ancient methods to modern phacoemulsification. The aim was to achieve optimal postoperative visual rehabilitation with minimal dependence on corrective lenses. Surgically induced astigmatism (SIA) remains a major challenge. This can affect the visual outcomes. Research has shown that the choice of surgical incision plays an important role in minimizing the occurrence of SIA. More recently, self-sealing clear corneal incisions offer faster recovery, less inflammation, and reduced astigmatism than traditional limbal or scleral tunnel incisions [10-12]. This study evaluated 100 patients undergoing phacoemulsification via two types of clear corneal incision: superior (Group A) and temporal (Group B), with 50 patients in each group. The mean age was similar in both groups and the demographic distribution showed a slight male predominance.

The findings of this study are in agreement with those of previous studies, including Nikose et al., [13] where patient profiles were comparable. Similarly, Anders et al. found that age and preoperative astigmatism significantly influenced SIA [11]. Visual outcomes were slightly better in the temporal group. A best-corrected visual acuity (BCVA) of 6/6 was achieved in 56% of patients in Group B versus 48% in Group A. This trend persisted for other visual acuity levels, suggesting that temporal incisions offer superior refractive outcomes. Several studies in this field support our findings. Simsek et al. [14] in a similar study found significantly less SIA with temporal incisions due to reduced eyelid pressure compared to superior incisions, which tend to induce against-the-rule (ATR) astigmatism. Roman et al. [15] showed that superior incisions result in higher SIA than temporal or scleral incisions. Our study reported a mean postoperative astigmatism of 1.5 ± 0.76 D in Group A and 0.5 ± 0.30 D in Group B, indicating significantly higher SIA with superior incisions. These results are consistent with those of Simsek et al. [14] and Roman et al. [15], reinforcing the advantage offered by temporal approaches in minimizing astigmatism. Postoperative astigmatism <0.50 D was observed in 44% of Group B patients, compared to 14% in Group A. Because temporal incisions are farther away from the visual axis, they are less affected by eyelid pressure and gravity, which helps maintain stable corneal curvature and reduces the incidence of SIA [16].

 In comparison, superior incisions are more prone to induce postoperative astigmatic changes because of their proximity to the visual axis. In a large study of 812 patients, Liu et al. [16] found that temporal incisions resulted in minimal astigmatism and favorable wound healing, which supports our findings. Other studies by Barequet et al. [3] and Cillino et al. [17] concluded that temporal clear corneal incisions produced less SIA and better visual outcomes. A comparison of SIA was carried out by Latha et al. [18] for various types of incisions, and they found that the least astigmatism was produced by a temporal corneoscleral incision. This could be because of their anatomical position away from the visual axis.  Lyhne et al. [19] showed that significantly higher SIA occurred in patients with ATR astigmatism who underwent superior incisions, thus favoring temporal incisions in such cases. Bhavani MV et al. [20 observed better wound stabilization and minimal astigmatic drift with temporal incisions. Therefore, they recommended them, particularly for patients with deep-set eyes or ATR astigmatism (39). Overall, this study and other similar studies in the existing literature suggest that temporal clear corneal incisions offer better visual outcomes and significantly lower surgically induced astigmatism than superior incisions. The findings of our study support the preference for temporal approaches in phacoemulsification, especially in patients with preoperative ATR astigmatism and in those requiring rapid postoperative recovery.

This was a prospective study on astigmatic changes in 100 cataract patients who underwent phacoemulsification using two approaches: superior clear corneal incision and temporal clear corneal incision with foldable lens implantation with an incision as small as 2.2 mm which helps reduce postoperative astigmatism. Hence, we observed that the superior scleral incision is better and the temporal scleral incision is better because it causes less postoperative astigmatism. The average surgically induced astigmatism was 0.50D with temporal scleral incision as compared to superior scleral incision of 1.5D post-operatively. In patients with preoperative NIL astigmatism, a temporal scleral incision is preferred because it causes WTR astigmatism in the postoperative period, which stabilizes early postoperatively. With the comparison of temporal and superior scleral incisions, there was no significant surgically induced astigmatism amplitude but a different surgically induced astigmatism axis orientation. The discrepancy in surgically induced astigmatism is attributable to the difference in incision location. In conclusion, temporal scleral incision seems to achieve the goal of minimizing surgically induced astigmatism. The temporal scleral incision was slightly better than the superior scleral incision in minimizing surgically induced astigmatism.

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