Introduction
Cataract is an ocular morbidity of aging, and a leading cause of blindness [1], and cataract surgery is a cost-effective health intervention [2].
Phacoemulsification is the standard method of cataract surgery nowadays with low rates of major complications [3]. Phacoemulsification with small corneal incision with no suture, fast healing process, low astigmatism, and faster improvement of vision allows the patient to return to his daily activities within few days [4].
The surgical outcomes usually include visual outcomes, refractive outcomes, and surgical complications. In the absence of ocular comorbidity and surgical complications, the visual outcome is predicted to be excellent [5]. In a review from high-income countries showed that after cataract surgery, the quality of life improved [6]. Poor visual outcomes in a range of 11.4–44.0% were reported in many developing countries [7]. The reported reasons for such poor visual outcomes were ocular comorbidities, inaccurate biometry measurements, limited surgical skill, surgical complications, and inadequate postoperative optical correction [8].
The aim of this study was to assess the short-term outcome of phacoemulsification in a tertiary hospital and to analyze which are the factors affecting visual outcomes.
Patients and methods
This is a prospective cohort study that included 50 eyes (50 patients) with visually significant cataracts (senile cataract). All patients underwent phacoemulsification, at 6th October Military Hospital, between September 2019 and December 2020. The study protocol was approved by the Ethics Board of Al-Azhar University and was conducted in accordance with the World Medical Association Declaration of Helsinki Guidelines. A written informed consent was taken from all participants after proper explanation of the study.
Exclusion criteria
Previous ocular surgery, ocular trauma, corneal opacities, active ocular inflammation, uncontrolled glaucoma, retinal vascular diseases, age-related macular degeneration, and high errors of refraction; those with a history of systemic disease that may affect visual outcome like diabetes mellitus and collagen vascular disease were excluded from the present study.
Surgical technique
All operations were done under topical and sub-Tennon anesthesia by the same surgeon. A standard horizontal chopping technique was used with the Infiniti Vision System (Alcon Laboratories Inc., Fort Worth, Texas, USA). The OZil torsional handpiece was used through a 2.4-mm corneal incision, the wound site was superotemporal; OD and superonasal; OS (11 o’clock position of the limbus). Insertion of a single-piece intraocular lens (AcrySof; Alcon Surgical) into the bag after completing the phacoemulsification. Hydration of the wound at the end of surgery. Regimen of topical antibiotic, steroid, and nonsteroidal anti-inflammatory eye drops received postoperatively for 1 month.
Preoperative, intraoperative, and postoperative evaluation and measurements
Preoperatively, all patients underwent the following examinations: best-corrected visual acuity (BCVA) tested with logMAR (EDTRS), intraocular pressure (IOP) measurement (Goldman applanation tonometer), anterior-segment examination (slit lamp), fundus examination (indirect ophthalmoscope and slit-lamp biomicroscope with 90 D lens), keratometry (Topcon KR 800; Topcon, Tokyo, Japan), and axial length (VuPAD; Sonomed Escalon, New Hyde Park, New York, USA). B-scan ultrasonography (Sonomed Escalon) was done for patients with dense cataract and no view of the fundus. Power of intraocular lens was calculated with the SRKII formula. Measurements of anterior-chamber depth, lens thickness, and axial length were taken by the A-scan (Sonomed Escalon).
Astigmatism was calculated as the difference in K-readings between the two corneal meridians with the steeper axis as the axis of astigmatism. Surgically induced astigmatism (SIA) was calculated by using the astigmatism double-angle plot tool available on the American Society of Cataract and Refractive Surgery website (https://ascrs.org/tools/astigmatism-double-angle-plot-tool).
Postoperative follow-up at 1 day, 1 week, and 1 month; full ophthalmological examination and any complication was recorded.
Statistical analysis
Data were statistically described in terms of mean±SD. The test for the normal assumption of numerical data was done using Kolmogorov–Smirnov test. Comparison between preoperative and postoperative values was done using Wilcoxon signed-rank test for paired samples. Multivariate logistic-regression analysis was used to test for the predictors of poor visual outcome. Two-sided P values of less than 0.05 were considered statistically significant. All statistical calculations were done using computer program IBM SPSS (Statistical Package for the Social Science; IBM Corp., Armonk, New York, USA) release 22 for Microsoft Windows.
A sample size of 47 was needed for a two-sided hypothesis to detect a mean BCVA postoperatively compared with mean BCVA preoperatively in patients with senile cataract with no ocular comorbidity, if the power (1-β) was 0.9 and type-I error, a, was 0.05. The G*power program (https://www.psychologie.hhu.de/arbeitsgruppen/allgemeine-psychologie-und-arbeitspsychologie/gpower) was used for sample-size calculation.
Results
The mean age of the 50 patients was 64.86±8.48 years (SD), with 32% men and 60% right eyes.
Preoperative measurements are summarized in Table 1. The mean BCVA by log MAR was 1.079±0.66 with a range of 2.6–0.4; PL −20/50. Mean IOP was 16.88±3.193, mean corneal astigmatism was 0.94±0.57 (Table 2).
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Table 1: Preoperative data of the 50 eyes before cataract surgery
Table 2: LogMAR visual acuity, corneal astigmatism, and intraocular pressure before and after operation
Table 2 shows the change in BCVA, corneal astigmatism, and IOP between preoperative and 1-month postoperative visits, the change of corneal astigmatism measured using keratometer. For BCVA, there was an improvement that was significant (P=0.00), the change in corneal astigmatism increased significantly (P=0.02). There was a significant reduction of IOP following surgery (P=0.04).
Preoperative corneal astigmatism and at 4 weeks postoperatively was analyzed by the vector-time method. This is shown in Fig. 1. The arithmetic mean of surgically induced astigmatism (M-SIA) was 0.65±0.32 D, and the centroid of surgically induced astigmatism (C-SIA) was 0.28±0.67 D at an axis of 68° in the right-eye group. The M-SIA was 0.55±0.31 D, and the C-SIA was 0.15±0.72 D at an axis of 76° in the left-eye group (Fig. 2).
Figure 1: A double-angle plot of a 50-patient dataset for 1 month postoperatively illustrates obliquely induced astigmatism at the 68-degree meridian (OD), 76-degree meridian (OS); the incision site was slightly to the right (superotemporal, OD and superonasal, OS) to facilitate the use of the phaco handpiece. Adjusted scale for each ring: 0.50 D. Adjusted SD: 2.
Figure 2: Preoperative and postoperative with satisfactory visual outcome.
In our study, there were no intraoperative complications. At 1 month postoperatively, only five patients had the remaining complications: one patient had dilated irreactive pupil (Urrest_Zavalia syndrome), two patients had anterior-chamber reaction after topical steroid withdrawal (so reinstillation of drops started), and two patients had corneal edema.
In our study, we had preoperative variables: age, anterior-chamber depth less than 3 mm in 13 patients, lens thickness more than 4.5 mm in 26 patients, dense cataract in six patients, and patients who had postoperative complications (five patients); and we found that only dense cataract had a statistically significant effect on visual outcome after phacoemulsification as shown in Table 3.
Table 3: Logistic regression: dependent variable is postoperative best-corrected visual acuity, dichotomized as 0.3 (20/40) or worse versus 0.3 (20/40) or better (good visual outcome). Independent variables: age, complex surgery [anterior-chamber depth <3 mm; N=13 (26%), lens thickness >4.5; N=26 (52%), dense cataract; N=6 (12%)], and postoperative complications; N=5 (10%) (in total, N=50)
Discussion
Our study included 50 eyes of 50 patients (age: 45–87 years) with visually significant cataract and no ocular comorbidity. Phacoemulsification was done without operative complications. The preoperative BCVA ranging from 2.6 to 0.4 (PL −20/50), improved significantly postoperatively (P=0.00) (Table 2). One month postoperatively, 40 (80%) patients achieved satisfactory vision (BCVA ≥20/40) and 22% (11 patients) had BCVA=20/20. A similar result was reported by Alasbali et al. [9] who achieved good visual outcomes in 80% of cases, in the absence of ocular comorbidity preoperatively and no intraoperative complications. The WHO recommends that at least 80% of patients have good visual outcomes following surgery as an indication of adequate quality of service [10].
In the United Kingdom, a study from the Cataract National Dataset, 94.7% of patients without an existing ocular comorbidity reached 20/40 or better [11]. Lundström et al. [5] achieved the same vision in 98.2%. Better postoperative outcomes in countries with higher human development index could be attributed to many factors such as better screening programs, younger patients, reduced rate and effective management of complications, and comprehensive follow-up [12].
In our study, 12 patients had corneal edema first day postoperatively, which resolved 1 week after operation in 10 patients, in the other two patients, the edema did not resolve by the end of the first month (high power during phacoemulsification because of dense cataract). Yang et al. [13] in their study found gradually resolved edema around the wound within the first week postoperatively, in the absence of complications during and after operation. On the other hand, Claesson et al. [14] reported that corneal endothelial disease is a risk factor for this complication.
In our study with no ocular comorbidity or operative complications, preoperative dense cataract was the variable that affects visual outcome (Table 3). Lundström et al. [5] in their study found that ocular comorbidity and postoperative complications had a great impact on the visual outcome, also, surgical complications and conditions that required complex surgery (such as miosis, dense cataract, pseudoexfoliation, and previous vitrectomy) had a negative influence. Another study showed that preoperative visual acuity and absence of surgical complexity are related to a significant improvement in visual acuity [15].
Our results showed that mean SIA ∼0.5 D (Fig. 1), the incision was 2.4 mm and slightly to the right (11 o’clock). Similar study reported that SIA was 0.45 D, the incision was 2.83 mm [16]. In another study, the mean SIA was 0.42 with 1.8-mm temporal incision [17]. Huang et al. [18] in their study found that the mean SIA was 0.57 D 1 week postoperatively with incisions 2.0 mm, that decrease significantly at 3 months (0.36 D), corresponding to the significant decrease of corneal edema, and continued to decrease to as low as 0.18 D at 1 year postoperatively. Du et al. [19] found a positive correlation between SIA and the reduction of the endothelial cell density at the corneal incision along the first month postoperatively.
In our study, the mean IOP was 16.9 mmHg preoperatively and 15.7 mmHg postoperatively with a significant difference (P=0.043) (Table 2). Poley et al. [20] in their study found that IOP reduction was proportional to preoperative IOP, the highest preoperative IOPs decreased more. Many studies have shown a variable IOP reduction after cataract surgery [21,22].
Conclusion
This study implicates that the visual outcome of phacoemulsification, in the absence of ocular comorbidity, is satisfactory in short-term follow-up.
Limitations
Our study is limited to patients with low-to-moderate socioeconomic status, we expect better visual outcome in patients with higher socioeconomic status; younger patients with less complexity of cataract surgery.
Recommendation
Effort should be exerted during surgery to deal with ocular conditions requiring complex surgery such as dense cataract, observe, and follow up every postoperative visual progression for interventions.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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