Diagnostic Accuracy of B-scan ultrasonography In Diagnosis of Diabetic Macular Edema in Al Najaf Al Ashraf City

Abstract

Background: Diabetic retinopathy, one of the most frequent complications of diabetes. Diabetic macular edema is the largest
cause of visual acuity loss in diabetic patients. Optical coherence tomography imaging is analogous to B-scan ultrasound imaging,
except that it uses infrared light reflections instead of ultrasound, well tolerated by patients, that provides new insights about
morphological changes of the retina in diabetic retinopathy and diabetic macular edema. Objective: identify diagnostic accuracy of
B-scan ultrasonography in diagnosis of diabetic macular edema. Patients and Methods: One hundred seventeenth patients (150
eyes) were enrolled consecutively into the study. Age , address, time of onset of diabetes, medical history, surgical and drug history
was taken, full ophthalmological examinations including best corrected visual acuity, anterior segment examination to exclude
abnormalities that obscure visual axis like corneal opacity, cataract .After dilatation of pupil with 1% tropicamide (MYDRIACYL)
and using Volk lens (78D ,90D) and slit lamp biomicroscopy for vitreous examination to exclude abnormalities like vitreous
hemorrhage and vitritis and fundus examination to show the signs of diabetic maculopathy and severity of diabetic macular edema
(DME). Then imaging performed to the patients firstly by Optical coherence tomography (TOPCON) and specifically the
perifoveal and peripheral areas and B-scan ultrasonography (TOMY) which is performed by professional expert ophthalmologist.
Results: A mean age of 56.1 ± 10.7 years. Majority of the patients aged 50 years or more. Males were 48 represented 41% of the
studied group while the remaining 59 % were females. A total of 150 affected eyes among the 117 patients, OD were 81 (54%) and
OS were 69 (46%).The mean macular thickness according to the OCT was 368.7 ± 79.3 µm with no statistically significant
difference between OD and OS where the mean macular thickness was 368.8 ± 76.8 and 367.9 ± 82.8, respectively.
The distribution of the studied group according to the macular thickness using a cut point of 300 µm. majority of the eyes
119/150(79.3%) had a macular thickness of > 300 µm and only 31 eyes (20.7%) had macular thickness of < 300 µm.
By B-scan examination, macular edema was found in 85 eyes while 65 eyes had no ME, furthermore, DME was more frequent in
OD than OS. By using cut point of macular thickness of 290 µm, the sensitivity, specificity and accuracy were 59%, 100% and
61%, respectively. When using a cut point of 300 µm, there was change validity tests of B-scan, sensitivity was 68.9%, and
specificity was 90.3% and accuracy was73.3%. By using a cut point of 320 µm the sensitivity, specificity and accuracy was were
84%, 82% and 83%, respectively, (Table 3.5). These values were not much different when cut point of 340 µm used to be 89%,
81% and 85%. Conclusion and recommendation: The best cut point that give good sensitivity, specificity and accuracy were 340
µm and since the majority of patients had a macular edema of more than 300 µm ,B scan ultrasonography can be used as an
alternative tools in evaluating diabetic macular edema especially regarding the cost , availability and the invisibility of fundus due
to optical opacities