Abstract
Purpose::
To evaluate whether increased central retinal thickness (CRT) in clinically significant diabetic macular edema (CSDME) responds differently to modified grid laser photocoagulation in the setting of focal vs. diffuse parafoveal thickening as defined by optical coherence tomography (OCT) criteria.
Methods::
A retrospective review was conducted on patient charts identified by codes for focal macular laser photocoagulation procedures performed from January 2004 through May 2006. OCT, demographic, and clinical data was recorded for 28 consecutive eyes with CSDME and at least borderline elevated CRT (>225 microns) for whom baseline and 3-5 month follow-up OCT data are available.
Results::
The mean CRT decreased from 351 to 315 microns (36 micron change) with a relatively stable visual acuity (20/62 baseline vs. 20/58 f/u). Subgroup analysis of patients with CSDME and diffuse edema (15 of 28 eyes) by OCT criteria (>300 microns in all parafoveal quadrants) revealed an mean CRT decrease of 50 microns (382 to 332 microns) and stable visual acuity (20/77 baseline vs. 20/78 f/u). The subgroup with CSDME and more focal edema by OCT criteria (13 of 28 eyes) had a mean CRT decrease of 20 microns (314 to 295 microns) and improved visual acuity from 20/51 to 20/45.
Conclusions::
Modified grid laser photocoagulation is effective in reducing central retinal thickness (CRT) associated with clinically-significant diabetic macular edema (CSDME). This effect appears to be significant regardless of the extent of parafoveal involvement. Visual acuity may be more likely to improve in those eyes without parafoveal edema >300 microns in all 4 quadrants, but more data is likely necessary to determine the predictive utility of these OCT criteria because the degree of initial central thickening may also correlate with anticipated improvements in CRT and visual acuity.
Keywords: diabetic retinopathy • laser • edema