Abstract
Purpose: :
Histopathology has proved while argon laser produces damage to both inner and outer layers of the retina, diode (810nm) laser damages only outer layer of retina. This disadvantage of conventional argon laser has prompted use of a laser that can reduce the damage by reducing the laser exposure duration i.e. micropulse laser. This property has prompted use of micropulse infrared diode laser photocoagulation to treat diabetic maculopathy and minimise the damage like enlarging chorioretinal atrophy caused by argon laser burns. We try to analyse our experience of utilising this treatment modality.
Methods: :
This is a retrospective non–randomised interventional case study. We acquired data from case notes following observation of patients with clinically significant diabetic macular oedema over variable length of time. We collected data regarding pre and post laser visual acuity, stereo fundus photographs and fluorescein angiograms where available. Change in visual acuity involving improvement or loss of snellen’s lines and clinical appearance were noted and analysed. All lasers were done by one of two practitioners.
Results: :
23 eyes of 21 patients were included in the study. Follow up was at 6 weeks and at 3 months. There were 16 male patients and 7 female patients average age was 62.7 years. All patients had fundus photography and fundus flourescein angiographies in the prelaser assessment. 21 eyes had focal and 2 eye required grid photocoagulation. Spot size ranged from 125u to 500 u. Duration was 100 to 680ms.The power used ranged from 100mw to 1400 mw. 21.5% (n=5) had repeat treatment at 6 weeks follow up. 52%(n= 12) had resolution of macular edema at 3 months. At 3–month follow up 47% (n=11) maintained pre laser visual acuity and 30%( n=7) improved by one or more snellen lines. 21%( n=5) lost one or more lines following treatment at 3–month follow up did not vary from the rest in terms of prelaser diagnosis, amount of laser treatment. This was clinically significant. No adverse laser events were noted.
Conclusions: :
We found micropulse diode laser to be a low risk and an effective treatment for clinically significant diabetic macular edema. In an ideal world a laser should affect only the deranged retina affected by macular edema and not effect normal retinal tissue. Micropulse diode laser is supposed to have therapeutic properties close to such quality. Randomized controlled trials with longer follow up are necessary involving larger number of patients to compare efficacy as against argon laser photocoagulation.
Keywords: diabetes • clinical (human) or epidemiologic studies: outcomes/complications • laser