Abstract
Purpose:
To assess the long term effectiveness of subthreshold focal laser photocoagulation treatment (SRFLPT) in managing CSME in patients with NIDDM Type 2, by following visual acuity and changes in central retinal volume as measured by OCT.
Methods:
Two year data were collected from the 142 patients (216 eyes) with ETDRS defined CSME enrolled in our study. ETDRS visual acuity, SD-OCT volume (central 6X6mm), F/A and ICG were obtained at 24 months to follow up on our previously reported results. ICG findings were used again to identify focal leakage from larger retinal microaneurysms and these were then individually treated with direct bare threshold (light blanching) focal laser application. Reduced invisible sub-threshold grid laser photocoagulation was used to treat areas of diffuse capillary leakage determined by F/A findings. The settings of the laser treatment were not changed : spot size of 100µm and a duration of 20msec. Central macular volume was monitored by the Heidelberg SD-OCT.
Results:
At the end of our 2 year follow-up period, the average total fluence was 2650 ±150 J/cm2. 9 patients were lost to follow-up. Visual acuity continued to improve on average 4.6±3.9 ETDRS letters after 24 months (<0.05). Similar to our one -year results, the macular volume improved to 7.6±1.1mm3 from our baseline of 8.6±5.5mm3. 19% of the patients (27) exhibited a gain of more than 10 letters, when 9% (13 eyes) lost 15 or more letters.
Conclusions:
Our study suggests that clinical improvement of eyes with CSME continues for 24 months when using SRFLPT. Minimizing the total energy used in each session, results in a reduction of the collateral damage and inflammation while still achieving an effective treatment of the macular edema as indicated by our two years results regarding vision and total retinal thickening. However, CSME laser treatment defined by the ETDRS remains still the gold standard. Continued long term follow-up and a larger controlled randomized trial is necessary to better assess the effectiveness of this treatment.
Keywords: 499 diabetic retinopathy •
578 laser •
585 macula/fovea