Quantitative Analysis of Diabetic Macular Edema after Laser Photocoagulation

PURPOSE: Diabetic macular edema is one of major causes leading to visual loss and it is difficult to be quantified. We investigated a volumetric quantification of retinal thickness change before and after focal laser photocoagulation with Heidelberg Retina Tomograph (HRT). METHODS: Ten patients who were diagnosed as diabetic retinopathy with clinically significant macular edema (CSME) in only one eye and treated with focal laser photocoagulation were studied. The opposite eyes which had no CSME were studied as control group. In the eyes which had CSME, the volume above reference plane (VARP) bounded by three consecutive circle centered at the fovea (diameter 1, 2, and 3 mm) were measured. The retinal thickness of control group was also measured with the same method. We performed focal laser photocoagulation for the eyes which had CSME and measured VARP at 1, 2, and 3 months after laser treatment. RESULTS: Three months after laser treatment, the VARP of treated eyes measured in each diameter was significantly decreased, however, there was no significant difference in control group. There was no significant difference in visual acuity change between before and 3 months after laser treatment. CONCLUSION: From the above results, we concluded that HRT could be used to quantify the change of diabetic macular edema before and after laser treatment.

The Quantitative Evaluation of Optic Ne rve Head of Normal Tension Glaucoma

It is known that optic disc morphology is different between high tension glaucoma[HTG]and normal tension glaucoma[NTG]. We quantitatively evaluated optic nerve head by confocal scanning laser ophthalmoscope [CSLO]to determine if substantial morphological differences between the HTG and the NTG could be identified. 21 patients[21 eyes]in the early NTG and 32 patients[32 eyes]in the early HTG were matched for visual field defect[MD>-10dB].The optic nerve head was evaluated by Heidelberg Retina Tomograph[HRT]and 12parameters provided by HRT were compared between NTG and HTG. The mean age of patients was 56.6 +/-13.6 years in NTG and 48.9 +/-14.7 years in HTG, respectively[p>0.05].Mean MD was -5.4 +/-1.9dB in the NTG, -5.0 +/-2.5dB in the HTG, respectively[p>0.05]. Disc area was slightly lager in the NTG than in the HTG, but the difference did not reach statistical significance[p>0.05].The neuroretinal rim area was significantly larger in the NTG than in the HTG[p<0.05], whereas the mean cup depth was significantly smaller in the NTG than in the HTG[p<0.05].Among the 12 parameters, cup area, rim area, cup volume, mean cup depth, and maximum cup depth in the NTG had significant correlations with CPSD in the visual field index.These findings further support the hypothesis that there may be different mechanisms in the glaucomatous optic nerve damage.

Quantification of Diabetic Macular Edema with Heidelberg Retina Tomograph

Diabetic macular edema is a major cause of visual loss and it is difficult to be quantified.We investigated a method of assessment and volumetric quantification of diabetic macular edema with Heidelberg Retina Tomograph[HRT].Ten normal eyes of control group and 20 eyes with diabetic patients were studied.In 20 diabetic patients, 10 patients had macular edema and 10 patients had no macular edema. Macular edema was defined as any visible macular thickening within a circle centered at the fovea with 6mm in diameter. With HRT, the volumes above reference plane[VARP]bound by three consecutive circles centered at the fovea [diameter, 1, 2, and 3mm ]were measured. Measurements were repeated three times, and mean measurements were used for the analysis. Diabetic eyes with macular edema had statistically greater VARP than diabetic eyes without edema[p0.05]. The sensitivity of HRT was 90%, and the specificity was 100%. The VARP measured using HRT was found to be linearly correlated with visual acuity expressed on a logMAR scale[p<0.05]. From the above results, we concluded that HRT could identify diabetic macular edema by volumetric analysis and indicated a good relationship of volumetric changes with visual acuity.