|Year : 2022 | Volume
| Issue : 2 | Page : 67-69
Role of B-scan ultrasonography in preoperative evaluation of posterior segment in dense cataract: An observational study in a tertiary eye care hospital
Rajarathna Hegde, Vidya Hegde, Anupama Bappal
Department of Ophthalmology, Yenepoya Medical College, Mangalore, Karnataka, India
|Date of Submission||28-Nov-2021|
|Date of Decision||23-Feb-2022|
|Date of Acceptance||12-Mar-2022|
|Date of Web Publication||18-Jul-2022|
Department of Ophthalmology, Yenepoya Medical College, Mangalore, Karnataka
Source of Support: None, Conflict of Interest: None
Context: B-scan ultrasonography is a diagnostic tool available for use in dense cataracts that gives vital information on vitreous, retina, choroid, and sclera. Aims: This study was planned to determine the abnormalities of the posterior segment in the presence of dense cataracts using B-scan ultrasonography and to determine the sensitivity and specificity of it. Settings and Design: Observational study design. Subjects and Methods: This observational study was done in patients with dense cataracts of any age. All the study participants underwent anterior segment evaluation, vision assessment, and posterior segment evaluation using B-scan ultrasonography. After cataract surgery, fundus evaluation of these patients was done. Pearson Chi-square test was used for assessing sensitivity and specificity of B-scan ultrasonography. Results: A total of 184 eyes of 161 patients were analyzed. The mean age of the study group was 59.17 ± 10.65 years. Majority of the participants (76.4%) were from rural areas. Out of 161 participants, 23 had bilateral dense cataracts. Preoperative B-scan ultrasonography assessment in 184 eyes showed posterior vitreous detachment (n = 40), retinal detachment (n = 2), vitreous hemorrhage, posterior staphyloma, and asteroid hyalosis (n = 1 each). Sensitivity and specificity of B-scan were analyzed in 173 eyes. Pearson Chi-square test showed the sensitivity of B-scan ultrasonography to be 64.2%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 81.5%. Conclusions: The study showed that B-scan is a good tool for diagnosing posterior segment pathologies in patients with dense cataracts.
Keywords: B-scan ultrasonography, dense cataract, diagnostic tool
|How to cite this article:|
Hegde R, Hegde V, Bappal A. Role of B-scan ultrasonography in preoperative evaluation of posterior segment in dense cataract: An observational study in a tertiary eye care hospital. J Clin Ophthalmol Res 2022;10:67-9
|How to cite this URL:|
Hegde R, Hegde V, Bappal A. Role of B-scan ultrasonography in preoperative evaluation of posterior segment in dense cataract: An observational study in a tertiary eye care hospital. J Clin Ophthalmol Res [serial online] 2022 [cited 2022 Sep 26];10:67-9. Available from: https://www.jcor.in/text.asp?2022/10/2/67/351292
The most recent estimates from the World Health Organization reveal that 47.8% of global blindness is due to cataract and in the South Asia region which includes India, 51% of blindness is due to cataract. As per the National Program for Control of Blindness and Visual Impairment, the incidence of cataract in India is 0.4%–0.5%. In patients with dense or mature cataract, fundus view may be obscured or not visible at all. In these cases, B-scan ultrasonography before surgery can help in surgical planning and guiding the expectations of patients. It is an indispensable diagnostic tool. It gives vital information regarding the status of vitreous, retina, choroid, and sclera. There are few studies done to evaluate posterior segments using B-scan ultrasonography in cases of dense cataract.,, This study was done to determine the abnormalities of the posterior segment in the presence of dense cataracts using B-scan ultrasonography and also to determine the sensitivity and specificity of it.
| Subjects and Methods|| |
The study was a prospective observational type which was conducted in a tertiary hospital from November 2015 to April 2017. It was conducted after obtaining approval from the Institution Ethics Committee. Any type of cataract that obscured direct visualization of fundus, irrespective of gender and age were included in the study. Cataracts with central corneal opacities and cases where preoperative B-scan could not be done as in penetrating injuries or occult rupture were excluded. At 95% confidence interval with 10% absolute allowable error and 90% power of the study, the sample size was found to be 161. An informed consent was obtained from study participants. A detailed history was obtained. Vision assessment was done by using logarithm of minimum angle of resolution (logMAR) vision charts and anterior segment evaluation using slit-lamp biomicroscope. Intraocular pressure measurement was done using Goldmann applanation tonometer. Axial length measurement using A-scan and corneal curvature measurement using keratometer were taken for intraocular lens power calculation. Posterior segment evaluation in study participants was done by using ultrasound B-scan (MARVEL-GBK2YC1 by Appasamy associates, India). The ultrasound probe was placed over closed lids after applying a coupling gel. A combination of axial, longitudinal, and transverse B-scans along with vector A-scans was done in all patients. In transverse scan, the probe was kept at the limbus with the axis of marker circumferential at the limbus. In longitudinal scan, the marker was perpendicular to the limbus. Axial scan was done with patient fixing in primary gaze and probe centered on the cornea. The study group underwent manual Small-Incision Cataract Surgery (SICS) with posterior chamber intraocular lens (PCIOL) implantation under local anesthesia. Postoperative fundus evaluation was done either on postoperative day 2 before discharge or after 1 week at the first follow-up visit. This was done using indirect ophthalmoscope with +20 D lens or slit lamp with +78 D lens. Patients with intraoperative complications were excluded for the final analysis to determine the sensitivity and specificity of B-scan ultrasonography. Best-corrected visual acuity was assessed postoperatively using logMAR vision chart.
| Results|| |
A total of 184 eyes of 161 patients were analyzed. The mean age (in years) of the study group was 59.17 ± 10.65. The range was from 16 to 80 years. The gender distribution was 86 (53.4%) males and 75 (46.6%) females. Majority of the participants (76.4%) were from rural areas. Out of 161 participants, 23 had bilateral dense cataracts. Diabetes mellitus was present in 42 (26.1%) patients, hypertension was present in 42 (26.1%), and 7 (4.3%) patients had a history of trauma. The distribution of cataracts in the study group were– senile mature cataracts in 75 (40.8%), dense posterior subcapsular cataracts in 56 (30.4%), hypermature cataracts in 33 (17.9%), presenile dense cataracts in 9 (4.9%), traumatic cataracts in 7 (3.8%), and intumescent in 4 (2.2%). Visual acuity distribution of the study participants is as shown in [Figure 1]. Preoperative B-scan ultrasonography findings in the eyes of study group are as shown in [Table 1]. Out of the 184 eyes, manual SICS with PCIOL implantation was performed in 173 eyes, manual SICS with anterior vitrectomy and anterior chamber intraocular lens implantation in 10 eyes and manual SICS with three-port pars plana vitrectomy and scleral fixated intraocular lens implantation in one eye. [Table 2] shows the postoperative fundus findings. Out of 184 eyes, 11 eyes were excluded for the study analysis to determine the sensitivity and specificity of B-scan ultrasonography, as there was intraoperative complication in these eyes. Hence, 173 eyes were analyzed for this. Out of 173 eyes, 73 eyes were found to be normal on B-scan ultrasonography. However, postoperative fundus examination of these showed only 57 eyes to be normal, diabetic retinopathy was observed in seven eyes and nine eyes had glaucomatous cupping. Vitreous degeneration was observed in 57 eyes by ultrasonography preoperatively. However, postoperative fundus evaluation of these showed 49 eyes to be normal, five eyes with features of diabetic retinopathy and three eyes cupping. Forty eyes showed Posterior vitreous detachment (PVD) preoperatively on B-scan ultrasonography and this was observed postoperatively on fundus examination. Two eyes had retinal detachment and one eye had asteroid hyalosis preoperatively on B-scan ultrasonography that was confirmed by fundus evaluation postoperatively. In our study, ultrasonography showed a sensitivity of 64.2%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 81.5% as shown in [Table 3].
|Table 3: Results of Chi-square test for sensitivity, specificity, positive predictive value, and negative predictive value|
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| Discussion|| |
Cataracts constitute an important cause of blindness in developing countries including India and many cases have dense cataracts that preclude the visualization of fundus prior to surgery. Under such circumstances, B-scan ultrasonography can provide valuable information regarding structural abnormalities of posterior segment. This in turn helps the surgeon to provide an appropriate visual prognosis to the patient. The incidence of posterior segment pathology using B-scan ultrasonography in eyes with opaque media varies from 19.6% to 66%., Our study was intended to know the usefulness of B-scan ultrasonography in dense cataracts. We found the mean age of the study group was 59 years with majority of patients being males and from rural areas. These findings were in concordance with studies done by Shaikh et al. and Salman et al.,
The most common finding on preoperative B-scan ultrasonography in our study was posterior vitreous detachment seen in 40 eyes. Similar result was seen in a study done by Jacob et al. However, Mobin et al. in their study done on 510 patients found retinal detachment in 4% of eyes as the most common abnormal finding on B-scan preoperatively. Similarly, Qureshi and Laghari and Garg et al. had discovered retinal detachment to be the most common abnormal B-scan ultrasonography finding in 3% and 5% of patients with positive findings on B-scan. They had divided their study group into traumatic and nontraumatic groups.
Sensitivity, specificity, and predictive values can be used to quantify the result of a diagnostic test. Unlike sensitivity and specificity, predictive values vary with the prevalence of a condition within a population. Generally, a screening test should be highly sensitive, whereas a follow-up confirmatory test should be highly specific. Our study showed a good sensitivity and specificity in the evaluation of the posterior segment. A study by Parchand et al. on patients with vitreoretinal disorders reported an overall sensitivity and specificity of 92.31% and 98.31% for the identification of rhegmatogenous retinal detachment, and 96.2% and 100% for posterior vitreous detachment, whereas it was 100% for vitreous hemorrhage, preretinal bleed, and vitreous exudates. A study by Murthy and Sharma showed a sensitivity of 16% and specificity of 97.8% in detecting optic nerve head cupping in 195 eyes with dense cataracts. They found optic nerve head cupping was detected in patients with large cup: disc ratio ≥0.7:1.
Our study sample was small and we had few patients with ocular trauma. Probably, a larger sample would be ideal for determining the effectiveness of the tool.
| Conclusions|| |
The study showed B-scan to be an effective tool in detecting posterior segment pathologies, especially posterior vitreous detachment, retinal detachment, asteroid hyalosis, and posterior staphyloma in dense cataracts.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]