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Study of the Effect of Grid Laser Photocoagulation on Contrast Sensitivity in Patients with Diabetic Macular Odema

Introduction: 
Contrast sensitivity is an important aspect of visual function and 
is even more important for ordinary daily tasks than visual acuity. 
Contrast sensitivity function may be deteriorated to a significant 
level in diabetic retinopathy, especially in diabetic macular edema. 
Diabetic macular edema is a microvascular complication of diabetes 
mellitus defined as retinal thickening resulting from the accumulation of 
fluid in the retina. When it is associated with hard exudates, both retinal 
damage and permanent visual loss will occur. 
Diabetic macular Odema is one of the major causes for moderate 
vision loss in diabetic patients. Laser photocoagulation is the treatment 
modality for DME either focal or grid laser is done which reduces the 
odema thus improving the vision and contrast sensitivity. The objective 
of this study was to determine the impact of macular laser 
photocoagulation as the standard treatment of clinically significant 
macular edema on contrast sensitivity. 
AIM OF THE STUDY 
PRIMARY OBJECTIVE 
1. To assess the improvement in contrast sensitivity with 
Pelli Robson chart after grid laser 
2. To quantify assessment of macular thickness by OCT. 
SECONDARY OBJECTIVE 
To assess the improvement in visual acuity with ETDRS chart 
after grid laser. 
MATERIALS AND METHODS 
This study was intended to evaluate the efficacy of grid laser 
photo coagulation on contrast sensitivity in patients with CSME which 
was carried out in the department of Retina services of RIOGOH, 
Chennai from June 2010 to June 2011. All the patients who were 
referred to retina clinic with Diabetic CSME were screened and selected 
for the study. 
CONCLUSION 
Contrast sensitivity is an important aspect of visual function and 
is even more important for ordinary daily tasks than visual acuity. Loss 
of Contrast sensitivity is more important and disturbing for the patient 
than is the loss of visual acuity 
Visual acuity was recorded by ETDRS chart due to the fallacies 
associated in Snellen shart. The Contrast sensitivity was recorded by 
Pelli Robson’s chart was sensitive and reproducible. 
Grid laser photocoagulation in CSME helps in improving the 
contrast sensitivity and stabilizes the visual acuity. 
The changes in contrast sensitivity and visual acuity are 
independent of each other.