Author: Fatma Sema Akkan Aydoğmuş (Turkey)
Co-authors: Fatma Sema Akkan Aydoğmuş, Defne Kalaycı, Burcu Gültekin
Purpose
The aim of this study was to evaluate the efficacy of subthreshold laser therapy via Non-damaging Retinal Therapy (NRT) in patients with non-center involved diabetic macular edema (non-CI DME).
Setting/Venue
This prospective, controlled study comprised of patients with newly diagnosed non-CI DME who admitted to Ankara Numune Training and Research Hospital Eye Clinic between March 2017 and April 2019. As of April 2019, due to the hospital transfer, the examinations of the patients after this date until October 2019 were carried out at Ankara City Hospital. This study was approved by the local Ethics Committee of our instutititon. Informed consent was obtained from each patient.
Methods
The study included cases above the age of 18 who had naive non-CI DM. The best corrected visual acuity (BCVA) with log-MAR, slit-lamp and fundus examination findings, central macular thickness (CMT) and peripheral edema values from spectral domain OCT analysis were investigated at 3- monthly intervals. While NRT was performed to one group, the other group was followed at 3-monthly intervals as control without treatment sequentially. NRT was done with end-point management software of Pattern Scanning Laser (Pascal). Barely visible test spots with 200 µm and 0.015 s was set as the threshold at a non-edematous area inside the vascular arcade. The endpoint management was set to 30% and irradiation was performed to edematous area using a macular grid pattern. At each control visit, NRT was performed to the edematous parafoveal quadrant in the treatment group. If center involved DME developed in either group, intravitreal anti vascular endotelial growth factor (IV anti-VEGF) was performed and the eye was excluded from the study subsequently. Primary outcome measure was the change of retinal thickness over time and between groups. Secondary outcome measures were change in best corrected BCVA, difference in the rate of anti-VEGF requirement, and laser treatment effect on FAF imaging.
Results
A total of 75 eyes were evaluated, 36 in the treatment group and 39 in the control group. Mean follow-up period was 440.61±346,333 days and 400.56±305,567 days (P=0,75). There was no significant difference between the groups in age (P=0,271) and in terms of diabetic retinopathy severity (P=0,14). Ratio of female/male was 24/12 in the treatment group and 14/25 in the control group (P=0,008). The change in parafoveal superior, nasal and temporal quadrants over time and between groups assessed by removing the effect of gender was found significant (P<0,05). This difference seemed to be evident after the 21st month with more thinning in the treatment group. It was observed that parafoveal inferior quadrant thinned more in the treatment group compared to the control group and the difference between the groups was significant (P=0,03). The difference was evident at the 24th month, but the change between groups over time was not significant (P>0,05). CMT and BCVA changes over time and between groups were not significant (P>0,05). Rates of center-involved DME development requiring IV anti-VEGF treatment at the end of the first and second years between the groups were not different (P>0,05). No laser scar was detected in any eye in FAF imaging.
Conlusions
In conclusion, we applied NRT to some patients in eyes with non-CI DME and followed up some patients without treatment. At the end of the first and second year, we observed that BCVA was preserved in both groups. Parafoveal anatomical changes were significantly better in the treatment group. NRT alone is effective and safe in the treatment of non-CI DME at 30 months follow-up. With this method, it may be foreseen that visual acuity will be better preserved in the long term by avoiding the possible side effects of conventional laser treatment. The results of our study suggest that it would be appropriate to conduct large-scale studies examining whether the combination of IV agents and NRT treatment reduces the need for IV injection in DME involving the foveal center.
Financial Disclosure
I have no financial relationship with any company
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