Macular edema is the major cause of visual acuity impairment in diabetic patients, and laser photocoagulation has been effective in reducing severe vision loss caused by CSME.
19 22 Macular edema is currently diagnosed and investigated by fundus biomicroscopy, stereo fundus photography, and more recently by OCT. OCT has been claimed as a novel “standard ” method for quantifying and monitoring macular edema, even diabetic macular edema.
23 24 Our OCT findings confirmed that retinal thickness progressively increases from the nonedema group toward the CSME group, as previously reported.
25 26 The functional impact of diabetic macular edema is currently quantified by visual acuity, even if this parameter represents just one (and not necessarily the most relevant) of the aspects of macular function.
27 28 29 Micoperimetry is able to quantify macular sensitivity (and fixation) in an exact, fundus-related fashion, thus adding detailed information about the degree and pattern of macular function alteration.
30 Microperimetry has been successfully used in the diagnosis and follow-up of different macular disorders, including age-related macular degeneration, myopic maculopathy, macular dystrophies, and diabetic macular edema.
4 5 6 7 8 11 30 31 32 33 Our microperimetry findings showed that macular sensitivity significantly decreases when diabetic macular edema develops and that macular sensitivity deteriorates in eyes at more severe stages of macular edema
(Fig. 6) .
5 30 We also observed a statistically significant correlation between retinal sensitivity and thickness, in the CSME group only. In the same group, retinal sensitivity decreased in the superior and temporal macular OCT fields (2 and 3) more than in the nasal one (field 5). Wolf et al.
34 emphasized that the temporal part of the macula is characterized by lower capillary density and thus is the first one to become ischemic. Remky et al.
35 demonstrated that the alteration of the perifoveal network are related to selective disturbances of visual function as measured by blue-on-yellow perimetry. Although we have not described the angiographic features of our subjects, all our patients with macular edema (NCSME and CSME groups) had macular leakage, but no signs of significant ischemic alterations. Thus, macular ischemia may not be the key factor explaining decreasing macular sensitivity in eyes affected by macular edema.