Menoufia Medical Journal

ORIGINAL ARTICLE
Year
: 2014  |  Volume : 27  |  Issue : 1  |  Page : 174--177

Optical coherence tomography as a prognostic tool for visual improvement after management of diabetic macular edema


Faried M. Wagdy, Abdel Rahman E Sarhan, Osama A. Elmorsy, Marwa A Zaky Galal, Moustafa K. Nassar 
 Department of Ophthalmology, Faculty of Medicine, Menoufia University, Al-Menoufia, Egypt

Correspondence Address:
Marwa A Zaky Galal
MSc, Department of Ophthalmology, Faculty of Medicine, Menoufia University, Shebin El-Kom, Al-Menoufia, 11160
Egypt

Abstract

Objectives The aim of the study was to evaluate the role of optical coherence tomography (OCT) as a prognostic tool for visual improvement after management of diabetic macular edema (DME). Background OCT provides an easy quantitative assessment of the relationship between DME and visual acuity. Patients and methods Fifty eyes affected with DME were treated and followed up for 6 months. The main outcome measures were best corrected visual acuity (BCVA) and central macular thickness (CMT) in addition to photoreceptor integrity changes, which were measured using OCT at 1 month and 6 months after treatment. Result After treatment of DME, follow-up at 1 month revealed that the mean CMT was significantly higher among patients in the panretinal photocoagulation (PRP) + intravitreal triamcinolone acetonide (IVTA) + grid group compared with the patients in the grid + PRP group (P = 0.001), focal + PRP group (P = 0.01), and focal management group (P = 0.008). The mean BCVA was significantly lower among patients in the grid + IVTA group compared with patients in the grid + PRP group (P = 0.03), focal + PRP group (P = 0.02), and focal treatment group (P = 0.008). After 6 months of treatment, there was no significant difference between the mean values of CMT (P = 0.46) or BCVA (P = 0.07) with respect to different ways of management. With respect to the photoreceptor integrity at 1 month follow-up, the mean CMT was significantly lower in the intact (P = 0.001) and disrupted (P = 0.01) groups compared with that in the absent photoreceptor integrity group, whereas the mean BCVA was significantly higher in the intact group than in the absent (P = 0.001) and disrupted (P = 0.001) photoreceptor integrity groups. At 6 months, the mean CMT of the absent photoreceptor integrity group was significantly higher than that of the intact group (P = 0.03), and the mean BCVA was significantly higher in the intact group than that in the disrupted photoreceptor integrity group (P = 0.01). Conclusion CMT measured using OCT and the status of photoreceptor layer significantly provide an objective guideline for predicting the visual improvement in eyes with DME after treatment.



How to cite this article:
Wagdy FM, Sarhan AE, Elmorsy OA, Zaky Galal MA, Nassar MK. Optical coherence tomography as a prognostic tool for visual improvement after management of diabetic macular edema.Menoufia Med J 2014;27:174-177


How to cite this URL:
Wagdy FM, Sarhan AE, Elmorsy OA, Zaky Galal MA, Nassar MK. Optical coherence tomography as a prognostic tool for visual improvement after management of diabetic macular edema. Menoufia Med J [serial online] 2014 [cited 2021 May 12 ];27:174-177
Available from: http://www.mmj.eg.net/text.asp?2014/27/1/174/132794


Full Text

 Introduction



Optical coherence tomography (OCT) is an accurate tool for early diagnosis, analysis, and monitoring of diabetic retinopathy, with high repeatability and resolution. It allows not only the qualitative diagnosis of diabetic macular edema (DME) but also the quantitative assessment of DME [1].

OCT is particularly valuable in analyzing vitreomacular relationship and detecting serous detachment that is not detectable with biomicroscopy [2].

OCT features of DME were classified into four patterns: diffuse retinal thickening, cystoid macular edema, serous retinal detachment, and vitreomacular interface abnormalities [3]. OCT provides easy measurement of objective macular thickness and quantitative assessment of the relationship between DME and visual acuity (VA) [4].

Laser treatment for diabetic retinopathy is still the gold standard in the treatment of focal and diffuse DME and proliferative diabetic retinopathy (PDR). When treated properly, the 5-year risk for blindness is reduced by 90% in patients with PDR, and the risk for visual loss from macular edema is reduced by 50% [5].

Intravitreal injection such as intravitreal triamcinolone acetonide (IVTA) injection or antivascular endothelial growth factor such as pegaptanib Macugen (American biotechnology company, Foster City, California, USA.), bevacizumab Avastin, and ranibizumab Lucentis (Genentech/Roche enentech, Inc. South San Francisco, California, United States) are increasingly used to treat patients with macular edema resulting from a variety of conditions such as diabetes, pseudophakia, and idiopathic cystoid macular edema [6].

Pharmacologic inhibition of vascular endothelial growth factor has been suggested as a promising treatment strategy for DME [7].

 Patients and methods



This study included 50 patients with DME aged between 30 and 65 years (28 male patients and 22 female patients). The study included both insulin-dependent (one patient) and noninsulin-dependent (49 patients) patients; 30 patients with non-PDR and 20 with PDR. The duration of diabetes ranged from 11 to 20 years. Patients with any type of DME detected by clinical examination either in association with non-PDR or PDR were included in the study, whereas patients with advanced cataract, significant corneal opacities, prior vitreoretinal surgeries, retinal diseases other than diabetic retinopathy, ocular hypertension or glaucoma, and major ocular surgery, including cataract extraction within 6 months before the study, were excluded.

All patients were examined with respect to the measurement of best corrected visual acuity (BCVA) using the Landolt broken ring chart that converted it to decimal from the VA notation table, and fundus fluorescein angiography was performed at presentation.

Spectral domain OCT was used, Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany), for all patients. Two examination modalities were used: 'macular cube' and 'line scan'. A macular cube generates a cube of data through a 6-mm 2 grid (6.0 × 6.0 mm). Retinal thickness was then displayed as a two-dimensional color-coded map of retinal thickness in the posterior pole, with brighter colors indicating the areas of increased retinal thickness, and as a numeric average of nine early treatment diabetic retinopathy study (ETDRS) type area for quantitative evaluation.

OCT was performed at presentation, 1 month, and 6 months, and central macular thickness (CMT) was measured automatically using an OCT retinal mapping software. The photoreceptor layer was analyzed as either present with a completely visible inner segment/outer segment (IS/OS) or disrupted IS/OS or even absence of the IS/OS.

Management of DME was carried out either with argon laser photocoagulation, focal or grid, or with IVTA Kenacort (Bristol-Myers Squibb, New York City, USA) 40 mg, 4 mg in 0.1 ml/injection in the operation theater under strict asepsis.

Patients were examined at 1 month and 6 months with respect to BCVA, CMT, and photoreceptor integrity.

Results were collected, tabulated, and statistically analyzed using an IBM compatible personal computer with the SPSS statistical package version 20 (SPSS Inc., Chicago, Illinois, USA).

Pearson's correlation was used to express the correlation between two normally distributed variables, whereas Spearman's correlation was used to express the correlation between not normally distributed variables. A P value of less than 0.05 was considered statistically significant.

 Results



This study included 50 patients: 28 (56.0%) male and 22 (44.0%) female. The mean age among the studied group was 53.16 years and the mean duration of diabetes was 12.62 years.

The mean CMT among the studied group at presentation was 324.46 ± 106.36 μm and the mean BCVA (in decimal) was 0.21 ± 0.12.

Management of DME was carried out, and at 1 month the mean CMT was significantly higher among patients in the panretinal photocoagulation (PRP) + IVTA + grid group compared with patients in the grid+PRP group (P = 0.001), focal + PRP group (P = 0.01), and focal management group (P = 0.008). The mean VA was significantly lower among patients in the grid + IVTA group compared with patients in the grid + PRP group (P=0.03), focal + PRP group (P = 0.02), and focal treatment group (P = 0.008) [Table 1].{Table 1}

After 6 months, there was no significant difference between the mean values of CMT (P = 0.46) or VA (P = 0.07) with respect to different ways of management [Table 2].{Table 2}

The mean CMT was significantly lower in the intact (P = 0.001) and disrupted (P = 0.01) groups compared with the absent photoreceptor integrity group, whereas the mean VA was significantly higher in the intact group compared with the absent (P = 0.001) and disrupted (P = 0.00) photoreceptor integrity groups at 1-month follow-up [Table 3]. At 6 months the mean CMT in the absent photoreceptor integrity group was significantly higher than that in the intact group (P = 0.03), and the mean VA was significantly higher in the intact group than that in the disrupted photoreceptor integrity group (P = 0.01) [Table 4].{Table 3}{Table 4}

 Discussion



This study shows that there was a significant negative correlation between the mean values of CMT and VA with respect to the management at 1 month among the studied groups.

This was similar to the study by Sutter et al. [8], who reported that IVTA was effective in improving VA and reducing DME and was also in agreement with the study by Soliman et al. [9], who found that 1-month macular laser treatment was critical for establishing the outcome of macular laser treatment in DME.

The present study shows that there was no significant correlation between the mean values of VA, CMT, and the management modality at 6 months follow-up.

The same findings were obtained by Schmid et al. [10], who showed that there was no significant change in VA, although OCT revealed a significant change in retinal thickness during 6 months follow-up period after treatment of DME using macular grid laser.

This was in contrast to the study by Gillies et al. [11], who suggested that the beneficial effect of IVTA in eyes with DME persists up to 5 years.

This study shows that the mean CMT at 6 months in the absent photoreceptor integrity group was significantly higher than that in the intact group, whereas the mean VA was significantly higher in the intact group than that in the disrupted photoreceptor integrity group.

This was in agreement with the study by Maheshwary et al. [12], who considered the rupture of the IS/OS junction as an important predictor of VA in patients with DME.

In addition, these results agreed with the study by Hannouche et al. [13], who concluded that the photoreceptor integrity was correlated with the CMT. Patients with continuous photoreceptor integrity showed lower CMT and significantly better BCVA (P < 0.001) than patients with disrupted photoreceptor integrity; also, patients with disrupted photoreceptor integrity showed higher CMT (P < 0.001) and worse VA.

Otani et al. [14] also reported that the integrity of these structures was more related to the BCVA than CMT, as it is more directly related to visual function.

This was in agreement with the study by Blumenkranz et al. [15] and Deαk et al. [16], who suggested a strong and reliable correlation between the measurements of the outer photoreceptor layer and VA. In addition, Shin et al. [17] showed that VA was closely associated with the IS/OS integrity, whereas CMT had no significant correlation with photoreceptor integrity in patients with DME.

 Conclusion



Early diagnosis of DME is vital to the preservation of VA. OCT is a promising new imaging technique that can improve the diagnosis and clinical management in patients with DME.

CMT and integrity of the photoreceptor IS/OS layer are significant predictors of VA in patients with DM, which may help to predict the outcome after treatment and to choose the best treatment modality.

 Acknowledgements



Conflicts of interest

None declared.

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