The use of lasers to treat diabetic retinopathy is an invasive and destructive 

procedure and it is essential to obtain informed consent for each new 

treatment course as for any surgical procedure.

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6.1 Definition

NVD are defined as any abnormal collection of leaking vessels occurring on 

the optic disc or within one disc diameter of the optic disc. They may be 

distinguished from collateral vessels by the presence of dye leakage on 

fluorescent angiography.

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6.2 Treatment

Treatment of NVD (and NVE, see section 7) is by pan-retinal laser photo-

coagulation (PRP). The risk of severe visual loss in high risk patients is 

reduced by 50% at 2 and 5 years by this therapy and by up to 70% in 

moderate risk patients. PRP should be given with fully informed consent 

(see below under counselling) and can be tailored to the nature fo the 

NVD in order to minimize effects on the visual field.

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6.2.1 Early NVD

Newly developing flat ‘early’ new vessel usually respond well to a basic 

PRP comprising 15000-2000, 200-500 micron laser burns applied pre- and 

post-equatorially outside the vascular arcades (Figure 23a, b). Lesions 

should normally be applied leaving lesion-wide (ie 200-500 micron) 

intervals throughout the fundus to preserve visual field. Some practitioners 

prefer routinely to use a smaller spot size such as 200 micron but a 

correspondingly larger number of burns is required to achieve an effect. 

In addition, spot size will vary with the lens used (see above). Sufficient 

energy should be applied to achieve ‘blanching’ (ie. a greyish white lesion) 

of the retina without producing visible necrosis. The amount of energy 

required will vary for each patient and also at different retinal locations 

in the same eye depending on factors such as retinal thickness, oedema 

and degree of melanisation of the retinal pigment epithelium (the main 

energy absorbing tissue in this procedure).

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Figure 23 NVD (long arrow) and NVE (short arrows) before a) and after b) treatment with panretinal photocoagulation. 

6.2.2 Established NVD

‘ Established’ new vessels are those which have developed into mature 

branching and/or arcade formations, but are still ‘flat’ ie they lie on the 

retinal surface, and have not led to haemorrhage. Established NVD may 

require a full PRP (>2000 laser burns) applied over more than one session. 

The precise number of burns will depend on the response to treatment 

which should be monitored at 2-3 weekly intervals.

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6.2.3 Florid NVD

NVD in young adolescents may progress rapidly to extensive sheets of 

vessels occupying a wide region of the peripapillary retina (Figure 15). 

Such vessels require urgent, aggressive management which should 

comprise a full PRP applied in a single session if possible. Laser lesions 

should be appropriately ‘ heavy ‘ in florid retinopathy. 

Further laser should be applied at weekly intervals until regression of 

vessels is achieved. If the neovascularization cannot be controlled, 

vitrectomy with endolaser may be required (see below).

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6.2.4 Stable NVD

NVD respond to PROP either by regressing completely (especially in 

older subjects and if treated early) or by ‘maturing’ into non-leaking 

smaller vascular formations which do not progress. These can be 

described as ‘ stable’ NVD which require observation and monitoring, 

if necessary with fluorescent angiography, but probably do not require 

further photocoagulation.

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6.2.5 Non-responding NVD

In a proportion of patients, NVD fail to regress and/or mature into an 

inactive stable state. Inadequate laser therapy is a frequent cause, 

often due to poor patient compliance with the PRP procedure. This 

may be improved by performing the laser with local (retrobulbar) or 

general anaesthetic. In the latter case, the laser may be applied via 

the indirect ophthalmoscope with good effect and a larger burn size. 

Older photocoagulation systems such as Xenon arc may also be useful 

in treating wider confluent areas of retina. Even if fully treed as 

described above, certain patients still fail to respond. Re-treating 

treated areas of the retina may then be performed, usually however 

at the expense of the visual field. This will affect the patient’s 

fitness to drive and appropriate counselling is essential. Recourse to 

vitrectomy may be necessary if the neovascularization cannot be 

controlled (see below).

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6.2.6 Forward NVD

Patient may present with untreated ‘forward’ NVD or the NVD may 

project into the vitreous cavity during the course of treatment as a 

result of posterior vitreous detachment (PVD). In the absence of 

vitreous haemorrhage forward NVD should be treated urgently with a 

full PRP with the proviso that an overly aggressive PRP may induce 

too rapid a regression of he forward vessels and cause vitreous 

bleeding. In such circumstances vitrectomy and intra-operative 

endolaser therapy is likely to be the treatment of choice (see below).

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6.2.7 NVD with vitreous haemorrhage

Treatment of NVD in the presence of small collection of subhyaloid 

or intra-gel blood should be aimed at performing a basic PRP (2000 

laser burns, 500 micron) followed by careful application of further 

brief laser applications (200-300 laser burns per session) until 

regression of the NVD is achieved. However, this may not be 

successful and vitrectomy with endolaser may be required. 

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