Enlarging laser burns after laser ...reducing visual field
This is a real and increasing problem. Laser burns seem to start enlarging a few years after laser, and this reduces the visual field. This problem is increasing for several reasons. It make take more than 5 years after laser has finished before patients and their doctors become aware of this problem.
- diabetic control is improving so people live longer...so now we are seeing results we never saw before
- it takes years to see the result of laser, so it takes many years before we are aware laser was 'too heavy'
- laser techniques are changing..we are now lasering more lightly..we started changing 5-10 years ago.
- new lasers may help...perhaps we should all be using them? (subthreshold laser)
- better diabetic control helps prevent the problem..less laser is needed.
- But in the meantime patients who have had heavy laser will develop problems as below.
This patient (born ~1940) with type 2 diabetes had proliferative retinopathy and macular oedema, underwent many laser sessions (1996-2000). She had persistent macular oedema. In 1999, with persistent macular oedema, she had an HbA1c 8% and blood pressure ~145/90. Despite encouragement she could not achieve better control. The last laser was 2000, when the photos on the left below were taken.
In 2008, the photos on the right below were taken. At this time she notices
- loss of peripheral vision...not seeing people at the side
- 'the 'blind areas' I noticed after laser are getting larger and joining up'...her own words.
- her insulin was changed to basal bolus, her blood pressure medication changed, and she has achieved good diabetic control and is well...her sight is her main problem
As the photos show the laser burns are enlarging.
- the macular oedema only resolved after several years of good blood pressure and glucose control
- clearly in retrospect less laser would have been preferable
- if the same patient presented now with chronic macular oedema, 2-3 grid lasers, probably with an Avastin injection(s), would have been accepted as the maximum treatment for the macular oedema and more laser would not be carried out. We would endeavour to achieve very tight blood pressure, and later tight glucose control.
- unfortunately the laser burns may continue to enlarge and sight may reduce further
- Less PRP laser would be carried out...after about 4-5000 laser larger burns/each eye (15-18000 smaller lighter burns), we would now offer anti-VEGF injections.