الفهرس 
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Abstract
Study of Colour Vision and Visual Field Changes after Macular Grid Laser in Diabetic Macular Oedema
Diabetic macular oedema
Diabetic maculopathy (fovealoedema, exudates or ischemia) is the most common cause of visual impairment in diabetic patients, particularly type 2. Diffuse retinal oedema is caused by extensive capillary leakage, and localized oedema by focal leakage from micro aneurysms and dilated capillary segments. The fluid is initially located between the outer plexiform and inner nuclear layers; later it may also involve the inner plexiform and nerve fiber layers, until eventually the entire thickness of the retina becomes edematous. With further accumulation of fluid the fovea assumes a cystoid appearance (cystoid macular oedema – CMO).
Diabetic macular edema (DME) is the largest cause of visual acuity loss in diabetes (2). It affects central vision from the early stages of retinopathy, and it is the most frequent sight threatening complication of diabetic retinopathy, particularly in older type 2 diabetic patients. Its role in the process of vision loss in diabetic patients and its occurrence in the evolution of the retinal disease are being increasingly recognized.
Treatment options for DMO: laser, steroids, and anti VEGF.
The sample comprised 47 eyes of 30 patients all diabetic patients underwent a single session of argon green (514 nm) grid laser photocoagulation.
A wide range of treatment parameters used, Including:
(i) Ablation spot size (range 200 ± 50 microns).
(ii) Duration of ablation (range 0.10 - 0.25 s).
(iii) Power setting (range 40 ± 0.07 W).
(iv) Number of ablations (range 309 ± 13).
Care was taken to ensure that laser burns were not placed at the margin of, or within, the foveal avascular zone.
Only one patient required repeated grid session, and 4 eyes received intravitrealAvastin injection through the study period.
Visual acuity improved on 7 eyes with average of one line in Snellen’s acuity chart after grid laser treatment, and 40 eyes vision remained the same
Color vision was normal prior to laser and no changes noticed after laser, remained normal on Ishihara test in all patients.
Field of vision showed relative central scotomas in 12 eyes, and showed absolute central scotomas in 17eyes, and was normal in 18 eyes.
At present, despite the enthusiasm for evaluation of several novel treatments for DME including intravitreal therapies for DME (e.g., corticosteroids, and anti-VEGF drugs), laser photocoagulation remains the current standard of care and the only treatment with proven efficacy in a large-scale clinical trial for this condition Despite proven benefit in the stabilization (and occasionally the improvement) of visual acuity, The results of this study clearly show that laser photocoagulation for clinically significant DMO invariably results in a localized loss of perimetric sensitivity within the central field around 10 degrees of the fovea. The complaints of such patients confirm that the preservation of visual acuity is at the expense of field loss. The spatial position of the post-treatment localized sensitivity loss corresponded with the area of retinal ablation.
Treatment strategies for clinically significant DMO need to be developed which, as well as preserving visual acuity, avoid deleterious impact on the visual field. In the meantime, perimetry should be undertaken following laser treatment for clinically significant DMO to ensure that the patient’s ability to meet legal driving requirements are not compromised (this applies particularly to patients with fellow eye visual loss).