Extensive argon laser photocoagulation in the treatment of proliferative diabetic retinopathy.

Abstract

SUMMARY A group of 20 patients (28 eyes) with proliferative retinopathy who required extensive argon laser photocoagulation to induce regression of new vessels is presented. The mean number of burns applied to each eye was 7225, with a maximum of 11513. These were delivered in a mean of nine sessions over a mean period of 22.9 months. Twenty-five eyes (89%) had a final visual acuity of 6/18 or better. The remaining three eyes (11%) had severely reduced vision attributable to complications of proliferative diabetic retinopathy (traction retinal detachment involving the macula in two eyes and ischaemic maculopathy and a persistent vitreous haemorrhage in the third). Large amounts of confluent argon laser photocoagulation may be necessary for the elimination of new vessels in some patients, and it is our view that laser photocoagulation should be continued until regression of new vessels occurs. This is compatible with the retention of functional vision and good visual acuity.Proliferative diabetic retinopathy is characterised by neovascularisation at the optic disc or in the peripheral retina. Recurrent vitreous haemorrhage and its sequelae and traction retinal detachment cause visual loss. It is the commonest cause of blindness between the ages of 30 and 65 years.' Several controlled trials have proved the benefit of photocoagulation in the treatment of proliferative diabetic retinopathy.2 The largest of these was the Diabetic Retinopathy Study (DRS), which showed that a single session of photocoagulation reduced the incidence of severe visual loss (defined as a visual acuity of less than 5/200) in treated eyes.2 The beneficial effect of photocoagulation is associated with the regression of retinopathy risk factors (RRF), particularly new vessels on the disc (NVD).' The question whether additional treatment is beneficial was not addressed by these trials, but it is widespread clinical practice to apply further laser photocoagulation until regression of new vessels occurs. How many burns can be applied? We present a group of 20 patients (28 eyes) who were included in the study because their disc new vessels required an excess of 5000 burns to induce regression, an end point which had not been achieved with lesser numbers of burns.Correspondence to Mr R V Pearson. FRCS. 197Patients and methodsThe appointment records of patients attending the Diabetic Clinic at Moorfields Eye Hospital were analysed with the outpatient computer. The case notes of those attending regularly for treatment over the last year were examined. Patients who had received more than 5000 argon laser burns to at least one eye were identified. Patients who had further photocoagulation pending, or who had received xenon arc photocoagulation or direct treatment to disc new vessels, were excluded from the study. Information was extracted from the notes regarding age, duration of diabetes, treatment of diabetes, visual acuity, indication for photocoagulation, presence of maculopathy and its treatment, clarity of media, number of burns, number of treat...

Intravitreal bevacizumab (avastin) for proliferative diabetic retinopathy: 6-months follow-up

“…20,21,33,34 However, substantial regression of new vessels may take weeks after completion of PRP, and in up to one-third of cases, new vessels continue to grow despite initial PRP. 21,34 In these cases, vitreous haemorrhage may induce visual loss and prevent complete laser.…”

“…18,19 Long intervals between PRP sessions and the variable amount of time required for a favourable response may increase the incidence of complications due to the progression of PDR. 18,20 In fact, a single episode of PRP or shorter intervals between PRP episodes, although desirable in severe PDR and when the patient must travel long distances for treatment, are often associated with acute visual disturbances due to exudative choroidal detachment, retinal detachment, and macular oedema. [21][22][23][24] The purpose of this retrospective study was to evaluate the effectiveness of intravitreal bevacizumab on RN in patients with PDR as a base for future studies in which bevacizumab may be used as an adjuvant treatment to PRP for PDR.…”

Pascal panretinal laser ablation and regression analysis in proliferative diabetic retinopathy: Manchester Pascal Study Report 4

“…Our results for 20-ms PRP treatment show results similar to this study; however, Reddy and co-workers used krypton red and/or cryotherapy as supplemental treatment modalities. In a study of eyes with NVD only, Aylward and co-workers 20 reported 64% complete regression using conventional (200-500 mm) 100-ms PRP treatment; however, a mean of 7225 laser shots were required (range 5279-11 513 burns) and this resulted in confluent laser scarring. The application of confluent PRP is outwith the current Royal College of Ophthalmologists recommended laser treatment guidelines.…”

A proposed new classification for diabetic retinopathy: The concept of primary and secondary vitreopathy

“…In addition to the above, PRP induces posterior vitreous detachment in 50% cases and in the large majority this is eventless. A small percentage of these cases may show vitreous bleeding or even TRD during completion of PRP if it is too aggressive and spaced closely 40. We therefore understand that in the large majority of cases (77% in our series) a balance is established between the beneficial effect of laser on retina and the damaging effect of diabetic vitreopathy.…”