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Oxidative effects of laser photocoagulation.
P E Jennings1, C J MacEwen, T J Fallon
1Department of Medicine and Ophthalmology, Ninewells Hospital and Medical School, Dundee, Scotland.
Free Radical Biology & Medicine
|January 1, 1991
Summary
Panretinal photocoagulation for diabetic retinopathy temporarily increases oxidative stress markers, including malondialdehyde-like material and plasma thiols. This oxidative stress may explain complications like macular edema following the treatment.
Area of Science:
- Ophthalmology
- Diabetology
- Biochemistry
Background:
- Diabetic proliferative retinopathy is a major cause of vision loss.
- Oxidative stress is implicated in diabetic retinopathy pathogenesis.
- The mechanism of action for laser photocoagulation in diabetic retinopathy remains unclear.
Purpose of the Study:
- To investigate the immediate effects of panretinal photocoagulation on oxidative stress markers in patients with diabetic retinopathy.
- To explore the potential role of free radical generation in the complications of photocoagulation treatment.
Main Methods:
- Clinical study involving 13 patients undergoing panretinal photocoagulation.
- Measurement of oxidative status in peripheral blood, including malondialdehyde-like material (MDA-LM), plasma thiols (PSH), and red cell reduced glutathione (GSH).
- Analysis of oxidative markers at baseline, 1 hour, and 2 hours post-treatment.
Main Results:
- Significant increases in MDA-LM, PSH, and GSH were observed at 1 hour post-photocoagulation (p < 0.005).
- Diene conjugates showed non-significant transient changes.
- At 2 hours, MDA-LM and PSH returned to baseline, but GSH remained significantly elevated (p < 0.005).
Conclusions:
- Panretinal photocoagulation induces a temporary increase in systemic oxidative stress.
- This transient oxidative stress may contribute to complications such as macular edema and choroidal effusions by damaging vascular endothelium.
- Further research is needed to elucidate the precise mechanisms linking oxidative stress and photocoagulation complications.