Purpose: To evaluate the integrity of the photoreceptor inner segment and outer segment (IS/OS) junction using spectral-domain optical coherence tomography (SD OCT) in patients with diabetic macular edema and to correlate the relationship between the integrity of the IS/OS junction and visual acuity. Design: Observational, prospective study. Materials and Methods: Forty eyes of 22 diabetic patients having diabetic macular edema. The authors performed spectral-domain optical coherence tomography in all eyes before treatment, 1month and 6 months after treatment. Central subfield thickness was defined as the average retinal thickness of the central 1-mm scanned area. The length of disruption of the inner and outer segments of the photoreceptors in the fovea were measured and graded according to their length as follows: Grade 0: Intact IS/OS line (no disruption at all), grade 1: Mild disruption (<400 μm). Grade 2: Moderate disruption (>400 μm but <1400 μm), Grade 3: Severe disruption (>1400 μm )or completely lost. Results: At the baseline, there was no correlation between the visual acuity (VA) and grade of defect (r = 0.214, P-value = 0.190). After 1 month and 6 months of treatment, there was a correlation between the VA and the grade of the defect (r = 0.538, P-value < 0.001) (r =0.603, P-value < 0.001), respectively. There was no significant association between the improvement in the IS/OS and final VA (P-value < 0.385). The mean change in VA from base line to 1 month in those who showed improvement in the defect was better than those in the nonimproved group (P-value = 0.001), and the mean change in the VA values from base line to 6 months in the improved group was better than those in the non improved group (P-value = 0.001). Conclusions: SD OCT showed that the integrity of the inner and outer segments of the photoreceptors was correlated with best-corrected visual acuity only 1 and 6 month after treatment, but not before treatment, so the correlation was not absolute.

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Purpose: To evaluate the efficacy of ranibizumab (1 mg) for the treatment of refractory diabetic macular edema (DME). Materials and Methods: This prospective, consecutive, non-comparative case series included 24 eyes with refractory DME. Patients were included in the study independently of the size of the leakage area, retinal thickness, visual acuity (VA), age, metabolic control and type of diabetes mellitus. Exclusion criteria included presence of a hard exudate at the fovea, macular edema secondary to causes other than diabetic maculopathy, signs of vitreomacular traction clinically or by optical coherence tomography (OCT), proliferative diabetic retinopathy requiring treatment, history of glaucoma or ocular hypertension and macular ischemia. Patients who had intraocular/periocular steroid/antivascular endothelial growth factor injections within 6 months of the enrollment or significant media opacities were excluded. After a written informed consent was obtained, all patients were treated with three intravitreal injections, 1 month apart, of 0.1 mL (1 mg) injection of ranibizumab. Changes of retinal thickness and VA, as measured by the Snellen chart and converted to decimal equivalents, were evaluated. Results: A total of 24 eyes of 24 patients (nine females and 15 males) with non-proliferative diabetic retinopathy (12 patients; 50%) or quiescent diabetic retinopathy (12 patients; 50%) were included in the study. Their mean age and standard deviation (SD) was 45.5 ± 13.1 years (range: 27-71 years). All patients completed 6 months of follow-up. No injection-related side-effects, either locally or systemically, were observed during the follow-up period. All included patients were subjected to at least one method of treatment for DME. At baseline, the mean VA ±SD was 0.015 ± 0.008; after 1 month from the first injection, the mean VA increased to 0.019 ± 0.008 (significant increase, P = 0.0013). The VA remained the same after the second and the third injections. Six months after the third injection, the mean VA ± SD was 0.018 ± 0.009 (significant increase, P = 0.0013). The mean central retinal thickness ± SD by OCT was 526.7 ± 243.4μ at baseline. Four weeks post-operatively, a significant decrease of mean retinal thickness ± SD to 429.7 ± 187.8μ was observed. Eight weeks after the injection, the mean macular retinal thickness ± SD had further decreased to 352.2 ± 142.5μ, which is a significant difference (P = 0.001) compared with the baseline thickness. After 12 weeks, the mean retinal thickness ± SD further decreased to 333.7 ± 114.5μ (P = 0.001). Conclusion: The intravitreal injection of 1 mg of ranibizumab provides a new treatment strategy for refractory DME, which offers patients a true perspective of visual recovery. Further prospective and randomized studies will be needed to better determine which patients benefit the most and how often and in which concentration the drug should be administered.

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