Dr.Rajesh Ramanjulu, Dr.Mahesh Shanmugam P,Dr.Aditya Barigali,Dr.Mishra Divyansh Kailashcandra
Purpose:
To evaluate the effect of photo-biomodulation on eyes with resistant or recalcitrant diabetic macular edema.
Methods:
In a prospective case series, 25 eyes of 25 patients with diabetic macular edema either refractory or recalcitrant to standard care (11 eyes for Anti-VEGF, 9 eyes for Ozurdex implant and 5 eyes for both) were treated with Photo-biomodulation.
Photo-biomodulation was done by asking the patients to see sunlight for cumulative 5 minutes using a yellow narrow band filter which allowed light of wavelength 570 nm to pass through it. They were assessed pre and post-treatment with SS-OCT, visual acuity, HVF 10-2 SITA standard and MfERG.
Results:
Mean macular thickness at baseline was 466 µ. 78 % had good response with reduction in edema (Mean 286 µ). All the patients either maintained or had a betterment on HVF 10-2 or responses on MfERG. None of the patients had detrimental effects.
Conclusion:
Photo-biomodulation is an effective treatment modality for refractory and recalcitrant diabetic macular edema.
Introduction:
Diabetic retinopathy (DR) is the leading cause of vision loss of working-age adults,1 and diabetic macular edema (DME) is the most frequent cause of vision loss related to diabetes.
Argon laser photocoagulation has been the mainstay of treatment for macular edema since the publication of the results of the Early Treatment Diabetic Retinopathy Study, which showed an approximate 50% reduction in the rate of moderate vision loss at 3 years following laser photocoagulation compared to no treatment. Recent studies from the Diabetic Retinopathy Clinical Research Network (DRCR.net) indicate that even with the guidelines of tight glycemic and blood pressure control, 12-13% of patients with foveal centred diabetic macular edema who undergo focal/grid laser lose 10 or more ETDRS letters after 2-3 years of follow-up. Additionally, with a baseline median vision of 20/50-20/63, only 36-44% of patients gained 10 or more ETDRS letters at 2-3 years of follow-up, indicating the need for improved treatment modalities.2
Within the last 5 years, the use of intravitreal corticosteroids and intravitreal anti-vascular endothelial growth factor (VEGF) agents have come into common clinical practice for the management of diabetic macular edema and several recent randomized clinical trials have shown improved effectiveness of ranibizumab compared to focal/grid laser.
While anti-VEGF therapy is often very effective, a subset of patients appear to be refractory and often require other forms of medical management, including alternative anti-VEGF therapies and/or steroids. Photo-biomodulation is an effective treatment modality for refractory and recalcitrant diabetic macular edema.3
Materials and Methods:
Prospective study which was conducted from Sep 2016 to Jan 2018. 25 eyes of 25 patients (12 males and 13 females) with diabetic macular edema, resistant or recalcitrant for standard care (11 eyes resistant to Anti-VEGF, 9 eyes to Ozurdex implant and 5 eyes for both) were included in this prospective study.
Inclusion criteria included diabetic patients with age >50 years, male or female having macular edema recalcitrant/resistant to conventional treatment. These patients were extensively investigated for systemic control and other factors influencing the response to treatment
Exclusion criteria consisted of patients with macular edema partially or completely responding to standard treatment consisting of Anti-VEGF, steroid implant or laser therapy. Systemic and other ocular conditions influencing the recurrence of macular edema and response to the conventional therapy.
Treatment protocol: The cumulative time for sunlight exposure was derived from the following method
- The light emitted from sun between 9am to 10 am was measured using SekonicL-758 DR (SekonicCorporationInc, Japan). The measured Lux units was applied at https://www.rapidtables.com/calc/light/lux-to-watt-calculator.htmla and the measured Watts was noted.
- As we needed a cumulative energy of 4 mJ, exposure for 5 mins was adequate.
- The narrow band pass filter for 577nm was sourced and tested for its adequacy at the IISc.
With this in background patients were asked to view the early sunlight (between 9am to 10am) for 5 mins.
This was done at least 5 days in a week for one complete month.The patients were the followed up for a minimum 6 months.
Patients were evaluated for macular functions using the OCTA, OCT (spectral domain), Hunphrey’s 10-2 SITA Std and MfERG, both before and 1, 3 and 6 months after the sunlight exposure and tabulated.
Results:
Mean central macular thickness at baseline was 466 µ. 76 % (19 eyes) had good response with reduction in edema (Mean reduction286 µ).
The response was independent of the duration of edema. Intra-retinal and sub-retinal fluid responded equally well. 12 eyes had near total reduction of macular edema with normalization of the foveal contour.
Recurrence of edema, a norm in these patients after conventional therapy also did well. These patients maintained normal foveal contour for a period of 6 months after stopping photo-biomodulation.
Improvement in visual acuity was also noted but not consistent in all the patients. We could see a direct correlation between the duration of the persistent edema and the visual recovery. This could be attributed to the disorganization of the inner and outer retina due to pressure effects of the cystic spaces and RPE atrophy.
All the patients either maintained or had a betterment on HVF 10-2 or responses on MfERG. None of the patients had detrimental effects.
Discusion:
In the current era where anti-VEGF therapy is considered as gold standard for treating macular edema is not short of complications. This includes retinal detachment or endophthalmitis, despite the prevalence of these complications is very low. Another peril is the non-response to these injections which in the present times leaves us with minimal options.
Macular photocoagulation or painting has been recently proposed using laser. We wanted to see the effect of such “painting” with continuous low energy light exposure in these subset of patients. We used“SUN” the best source of constant energy to the earth.
The total time duration of viewing the sunlight, was calculated by multiplying the power delivered with the duration. This was equal to the total laser enegy delivered in conventional focal laser photo-coagulation. As a rule, any alternative to laser treatment should be evaluated after two or three years’ follow up and not only during the first year. In fact, in the ETDRS study the best results were achieved at three years’ follow up, indicating that all studies should plan to evaluate its effect over DME at the three-year follow up visit.
All our patients did well and responded to photo-biomodulation
Conclusion:
Photo-biomodulation is an effective treatment modality for refractory and recalcitrant diabetic macular edema.
Bibliography:
- Lightman S, Towler HM. Diabetic retinopathy. 2003;5(2):12–21.
- J. Elman, A. Ayala, N.M. Bressler, et al.Intravitreal ranibizumab for diabetic macular edema with prompt versus deferred laser treatment: 5-year randomized trial results.
- Lazic R, Lukic M, Boras I et.al Treatment of anti-vascular endothelial growth factor-resistant diabetic macular edema with dexamethasone intravitreal implant. Retina. 2014 Apr; 34(4):719-24.
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