|Year : 2020 | Volume
| Issue : 4 | Page : 365-370
Optical coherence tomography patterns of diabetic macular edema and their correlation with visual acuity
Omar M Ali1, Mohammad S Saad1, Hazem A M. Hazem1, Mariam N Dawood2
1 Department of Ophthalmology, Faculty of Medicine, Assiut University, Assiut, Egypt
2 El Ramad Hospital, Assiut City, Egypt
|Date of Submission||21-Dec-2019|
|Date of Decision||22-Dec-2019|
|Date of Acceptance||22-Jan-2020|
|Date of Web Publication||20-Nov-2020|
Mariam N Dawood
El Ramad Hospital, Assiut City
Source of Support: None, Conflict of Interest: None
The aim was to identify and evaluate the patterns of diabetic macular edema (DME) currently known by optical coherence tomography (OCT) and correlation of these patterns with visual acuity.
Patients and methods
OCT scans were done for 60 eyes of 36 patients with diabetes. OCT is used to define the pattern of DME and measure the central macular thickness (CMT). Analysis of data was done to evaluate the relationship between retinal thickness and visual acuity and prevalence of each different morphological subtype and investigate the presence of relationship between different patterns and visual acuity.
Our OCT-based classification was as follows: group 1 had diffuse macular edema without cysts (35%), group 2 had cystoid macular edema (CME) (26.67%), group 3 had CME with serous retinal detachment (SRD) (16.67%), group 4 had SRD with diffuse thickening (8.33%), and group 5 had tractional macular edema (13.33%). Eyes with sponge-like retinal swelling had the best-corrected visual acuity. Best-corrected visual acuity in eyes with CME and CME with SRD was significantly worse. Eyes with CME, CME with serous sensory detachment, and tractional had CMT significantly larger than eyes with diffuse retinal thickening. There was a reverse correlation between best-corrected visual acuity and CMT at the fovea in eyes with diffuse thickening alone, whereas the correlation was not significant in eyes associated with CME or serous sensory detachment.
Our study affirmed that OCT is very useful in routine assessment of DME and in detecting vitreoretinal traction and SRD undetectable on biomicroscopy.
Keywords: diabetic macular edema, macular thickness, optical coherence tomography, visual acuity
|How to cite this article:|
Ali OM, Saad MS, M. Hazem HA, Dawood MN. Optical coherence tomography patterns of diabetic macular edema and their correlation with visual acuity. J Curr Med Res Pract 2020;5:365-70
|How to cite this URL:|
Ali OM, Saad MS, M. Hazem HA, Dawood MN. Optical coherence tomography patterns of diabetic macular edema and their correlation with visual acuity. J Curr Med Res Pract [serial online] 2020 [cited 2020 Dec 1];5:365-70. Available from: http://www.jcmrp.eg.net/text.asp?2020/5/4/365/301043
| Introduction|| |
Diabetic macular edema (DME) is the greatest cause of loss of visual acuity in diabetes. Studying the history of DME shows that 24% of eyes with DME will lose at least three lines of vision within 3 years. DME may occur at any stage of diabetic retinopathy (DR), either mild, moderate, or severe nonproliferative DR, or at progressed stages of DR.
Collection of subretinal and intraretinal fluid in the inner and outer plexiform layers is owing to dysfunction of outer and inner retinal barriers. Vascular endothelial growth factor plays the main role in disrupting the function of the inner blood retinal barrier.
In recent times, optical coherence tomography (OCT) had greatly altered the diagnosis and follow-up of DME. Most patients can accept OCT, as it is noninvasive. It gives dependable and objective cross-sectional images of the retina and the vitreoretinal interface and permits quantitative measurements of the thickness of the retina,.
According to OCT, four categories of DME were found:
- Diffuse DME (DRT): thickening of retina and light reflection weakening.
- Cystoid macular edema (CME): there is cystoid dark cavity.
- Serous sensory detachment DME [serous retinal detachment (SRD)].
- Vitreomacular interface abnormalities: there are incomplete or complete posterior vitreous detachment and ERM formation or vitreomacular traction or both.
| Patients and Methods|| |
This is a prospective observational study. OCT scans were done for 60 eyes of 36 diabetic patients in Assiut Diagnostic Eye centers (El Nour, EL Forsan, Tiba) during a period of 10 months (from May 2016 to March 2017).
Patients with diabetes mellitus with evidence of any stage DR clinically and with evidence of a macular edema involving center of the macula clinically or angiographically were included.
The following were the exclusion criteria:
- Eyes with marked media opacities were excluded (cataract, intravitreal hemorrhage, and corneal opacity).
- Eyes with diseases that affect vision such as ischemic maculopathy, glaucoma, retinal detachment, and optic nerve diseases.
- Other causes of macular edema such as age-related macular degeneration, retinal venous occlusion, hereditary disorders, and inflammatory eye diseases.
- Pregnant women and patients with renal disease.
Methods of ocular examination
- History taking included the following:
- Type and diabetes duration.
- Treatment (insulin, oral hypoglycemic, or combined).
- Detailed visual complaints.
- Past ocular history (disease, surgery, laser photocoagulation, and intravitreal injection).
- Other associated systemic diseases.
- An informed consent was obtained for each patient.
- Ocular examination:
Detailed ophthalmic examination was performed as follows:
- Best-corrected visual acuity (BCVA), by Snellen's chart and converted to logMAR using visual acuity conversion tables.
- Examination by slit lamp.
- Examination of fundus and macula: by slit lamp with the +90 D lens.
- Color fundus photography.
- Fundus fluorescein angiography: to document DR stage and define the type of leakage (focal or diffuse), its site, size, and relation to the fovea, either center involved or not.
- OCT: OCT was done using the optical coherence tomography scanner (DRI OCT Triton, Swept source OCT) made in Japan.
OCT is used for the following:
- To define the pattern of DME either:
- Noncystoid sponge-like diffuse retinal thinking (DRT).
- DRT with CME.
- CME with SRD.
- DRT with SRD.
- Tractional macular edema: any previous pattern plus either posterior hyaloid traction or epiretinal membrane or both.
- To measure the central macular thickness (CMT).
Optical coherence tomography scanning was done for all patients as follows
The pupils have been dilated using 1.0% tropicamide and 2.5% phenylephrine (cyclopherine; Kahira Pharm, Kahira Pharmaceuticals: Cairo, Egypt). The patient data were introduced to the computer. Twelve consecutive line scans were done at equally spaced angular orientations in a radial spoke pattern focused on the fovea. The scan length is 6 or 9 mm.
Retinal thickness data were shown in two ways: a quantitative and a false color topographic display. The macula was divided into nine ETDRS-type regions, including a central disc of 500-μm diameter, and an inner and outer rings, each splitted into four quadrants, with outer radii of 1 and 2 disc diameters, respectively. Each of the nine regions has average retinal thickness.
In the false color display, thickness of the macula was changed to a false color value within 2 disc diameter from the center. The brighter colors indicate increased retinal thickness.
Computer program SPSS 'version 21' (SPSS Inc., Chicago, Illinois, USA), was used to collect and analyze data. Data were expressed as number, percentage, mean, and SD. Man Whitney U Test was used to determine significance for numeric variables, and also analysis of variance test was used. χ2-test was used to determine significance for categorical variable and Pearson's correlation to determine significance between variables in the same group. The level of significance was set as follows:
P > 0.05, no significant.
*P < 0.05, mild significant.
**P < 0.001, moderate significance.
***P < 0.0001, highly significance.
The study was approved and monitored by the Medical Ethics Committee, Assiut Faculty of Medicine, IRB#17100858.
The investigators explained the steps and value of the research to all eligible participants. Those who agreed to be included in the study signed a fully informed consent form.
| Results|| |
The study was done on 60 eyes of 36 patients with a mean age of 57.30 ± 10.48 years (range: 32–83.0 years) [Table 1].
All patients were between 32 and 83 years of age, with 16 (44.44%) patients in 60–69 years, nine (25%) patients in 50–59 years, six (16%) patients in 40–49 years, three (8.33%) patients in 70–79 years, one (2.77%) patient in 30–39 years, and one (2.77%) patient in more than 80 years [Table 2] and [Table 3].
We classified DME by OCT into five groups:
- Group 1, in which the eyes had noncystoid sponge-like DRT, with intraretinal reflectivity reduction and extended areas of lower reflectivity in the outer retina without CME or SRD. This group included 21 (35%) eyes.
- Group 2, in which the eyes had CME defined by the presence of cystic spaces in the retina which appeared as round or oval low reflectivity areas, with highly reflective septa separating the cystic cavities. This group included 16 (26.67%) eyes.
- Group 3, in which the eyes had CME and SRD in the same eye. SRD is collection of fluid under fovea and a well-defined outer border of the detached retina without traction. This group included 10 (16.67%) eyes.
- Group 4, in which the eyes had DRT with SRD in the same eye. This group included five (8.33%) eyes.
- Group 5, in which eyes had tractional macular edema. This traction is either posterior hyaloid traction or epiretinal membrane traction or both. This group included eight (13.33%) eyes [Figure 1], [Figure 2], [Figure 3] and [Table 4], [Table 5], [Table 6].
|Table 4: Central macular thickness by optical coherence tomography and best-corrected visual acuity by logMAR best-corrected visual acuity logMAR in this study|
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|Table 5: Central macular thickness in optical coherence tomography patterns of diabetic macular edema study groups|
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|Table 6: Best-corrected visual acuity logMAR in optical coherence tomography patterns of diabetic macular edema study groups|
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|Figure 1: Diabetic macular edema by optical coherence tomography. (a) Diffuse retinal thickening; (b) cystoid macular edema; (c) cystoid macular edema with serous retinal detachment; (d) serous retinal detachment with diffuse retinal thickening; (e) tractional macular edema by epiretinal membrane; (f) tractional macular edema with vitreomacular interface abnormality.|
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|Figure 2: Best-corrected visual acuity logMAR in optical coherence tomography patterns of diabetic macular edema.|
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|Figure 3: Central macular thickness in optical coherence tomography patterns of diabetic macular edema.|
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| Discussion|| |
The mean age of all patients was 57.30 ± 10.48 years in our study. The large number of patients were in the age group 60–69 years (44.44% of patients). Sander et al. found the mean age of the patients was 57 years (range: 28–71 years), whereas Kang et al. found the mean age of patients was 59.9 years (range: 31–86 years).
In this study, of the 36 patients, 20 (55.5%) were males and 16 (44.4%) were females. In the study by Golubovic-Arsovska, 55.8% of patients were females, whereas 44.2% were males. Klien et al., in the Wisconsin Epidemiologic Study of Diabetic Retinopathy, found that increased incidence of DME associated with female sex.
The duration of diabetes mellitus of the patients in our study ranged from 5 to 30 years. Overall, 77.77% of patients had diabetes for 15 years and more. Mean duration was 16.19 years. Kang et al. found the average duration of diabetes in patients having clinically significant maculae edema (CSME) was 15.09 ± 7.49 years, and also TH Chou et al. found the mean duration of DM with CSME is 11.2 ± 5.5 years, whereas the study by Zhang et al. showed that diabetic maculopathy often occurred within 10 years of diabetes duration, and its severity and incidence increased year by year.
In this study, five OCT-based classification were discussed: group 1 included eyes with diffuse macular edema without cysts (35%). This may represent the swollen Müller cells and Henle's fiber layer. Group 2 included eyes with CME (26.67%), which represents retinal edema persistence and Müller cells necrosis described histopathologically. Group 3 included eyes with CME with SRD (16.67%). SRD is characterized by accumulation of fluid accumulation subretinal with distinct posterior border of detached retina. This appears as a high reflective line attached to the retinal pigment epithelium in the peripheral margin of the subretinal lenticular space by OCT.
Group 4 included eyes with SRD with diffuse thickening (8.33%). Group 5 included eyes with tractional macular edema (13.33%) This traction is either posterior hyaloid traction or epiretinal membrane traction or both.
Otani et al. described three patterns of OCT: sponge-like swelling (88%), retinal edema with cystic spaces (47%), and retinal edema with subfoveal fluid accumulation (15%). A classification by Kang et al. was reported type 1 thickening with homogenous optical reflectivity (55.2%), type 2 thickening with markedly decreased optical reflectivity in the outer retinal layers (30.3%), and type 3A, with detachment of fovea without traction (14.5%), and type 3B, with detachment of fovea with obvious vitreofoveal traction (2.8%).
Kim et al. sat out another classification: DRT (97%), CME (55%), and SRD (2.9%), whereas Murakami et al. classification was CME (CME type: 16%), SRD (SRD type: 16.8%), and absence of either CME or SRD (diffuse type: 67.2%).
The prevalence of SRD in eyes with DME in this study either combined with diffuse macular edema or with CME was 25%. This was reported by Otani et al. as 15%, Kang et al. as (14.5%) and Kim et al. as (9.9%), but it was reported by Catier et al. as 26% which is near to what was reported in our study. It was thought that SRD is caused by breaking down of the retinal-blood barrier at the level of the retinal capillaries and the retinal pigment epithelium. Fluid and proteins are released, and the anatomical features limit protein and water movement out of retina. The draining vascular system and the retinal pigment epithelium are unable to handle the water load.
A relationship between some morphologic patterns of DME and worse visual acuity was found in our study. The visual acuity was significantly the best in group 1 (diffuse macular edema without cysts). On the contrary, BCVA in eyes with CME and CME with SRD was significantly worse.
A study by Yamamoto et al. assumed that eyes with diabetic CME have worse visual acuity than eyes with diffuse retinal swelling with no cysts. Moreover, the study by Kang et al. found that best visual acuity was in eyes with thickening with homogeneous optical reflectivity.
Electron microscope found intracytoplasmic swelling of Muller cells and secondary neuronal degeneration in eyes with CME and so may have less visual acuity than those with diffuse macular edema. Recently, Sun et al. have also discovered that the inner retinal layer disturbance in the 1-mm foveal area leads to worse VA.
The mean central foveal thickness of: group 1 (diffuse macular edema without cysts) was 337.92 ± 71.58, group 2 (CME) was 408.94 ± 68.36, group 3 (CME with SRD) was 453.10 ± 98.83 while Otani et al. have found that the mean foveal thickness was 424.6 ± 18 μm in eyes with diffuse macular edema, and 527.6 ± 18 μm in eyes with CME. Yang et al. reported a mean foveal thickness of 255.6 μm in eyes with CSME, and 174.6 μm in eyes without CSME. Yamamoto et al. recorded that the mean foveal thickness became 252.7 μm in eyes with diffuse macular edema, and 537.1 μm in eyes with CME.
The current study revealed a reverse correlation between best-corrected VA and CMT of the fovea in patients with diffuse thickening alone, whereas the correlation was not significant in eyes associated with CME or SRD. These results were comparable to previous studies, which showed modest correlation between OCT measured CMT and VA. Kim et al. found that the more the increase in retinal thickness, whatever the pattern, the worse the VA, and Otani et al. found that the central foveal thickness and the BCVA revealed an intermediate negative correlation, whatever the tomographic features, whereas Murakami et al. concluded that CME type had mean VA significantly worse than with the SRD type or diffuse type but found that thickening of fovea was significantly correlated with bad VA in eyes with diffuse macular edema or with CME but not in eyes with SRD.
Recently, Shin et al. assumed that integrity of foveal photoreceptor layer was related intimately with the final VA in DME.
| Conclusion|| |
OCT has the advantage that it gives quantitative measurements, beside the qualitative assessment done with biomicroscopy or fluorescein angiography. Our study affirmed that OCT is very useful in routine assessment of DME either before or after therapy and in detecting vitreoretinal traction and SRD undetectable on biomicroscopy.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]