Dye laser treatment in proliferative diabetic retinopathy and maculopathy

Abstract

The aim of this study was to compare the efficacy of various dye laser wavelengths in different forms of retinopathies. The study material consisted of 292 eyes of 210 diabetic retinopathy patients treated with dye laser photocoagulation between 1990 and 1992. All the patients were followed for at least 6 months after photocoagulation. Non-proliferative changes (maculopathy and/or preproliferative retinopathy) were present in 135 (46.3%) and proliferative retinopathy in 157 (53.7%) of the eyes undergoing photocoagulation. Of the 157 eyes with proliferative retinopathy, 60 (20.5%) had disc neovascularization, 71 (24.3%) had retinal neovascularization and 26 (8.9%) had retinitis proliferans. Yellow dye laser (580 nm) was applied in 92 (31.5%) eyes, red dye laser (630 nm) in 120 (41.1%) eyes and both yellow and red dye lasers in 80 (27.4%) eyes. There was no significant difference between the different wavelength groups with regard to visual acuity changes before and after treatment (p < 0.01). Overall, the visual acuity was maintained in 56.2% and improved in 25.0% of the eyes. After panretinal photocoagulation, disc neovascularization regressed partially or completely in 47 (78.3%) of the eyes. There was no significant difference among the various laser wavelengths with regard to treatment efficacy judged by the disappearance or regression of disc neovascularization (p < 0.01). All retinal neovascularizations regressed completely with laser treatment, but in 7 eyes (9.9%) new retinal neovascularizations in previously untreated areas developed. Dye laser has not resulted in any complications. It requires lower power settings compared to argon laser and thus facilitates photocoagulation. Another advantage of dye laser is the ability to use yellow and red wavelengths sequentially.

Comparing Two Techniques of Panretinal Photocoagulation on Visual Acuity on Patients with Proliferative Diabetic Retinopathy

“…Blankenship (25) found worsening of two or more rows, 24% after CPRP and 8% after PPRP, and McDonald (20) found worsening of 25% after PRP. Other groups of authors found bettering of VA from 8% to 89% depending on results evaluation (31)(32)(33)(34)(35)(36). Their results are hardly comparable with the present study because they treated patients with differ-ent DR grade (16,36,37,38), and they did not use the same laser techniques (16,28), more laser treatment (25,29,30,32,35,36,38) with larger groups of patients (16,22,24,30,32).…”

Comparing Two Techniques of Panretinal Photocoagulation on Visual Acuity on Patients with Proliferative Diabetic Retinopathy

“…Blankenship (25) found worsening of two or more rows, 24% after CPRP and 8% after PPRP, and McDonald (20) found worsening of 25% after PRP. Other groups of authors found bettering of VA from 8% to 89% depending on results evaluation (31)(32)(33)(34)(35)(36). Their results are hardly comparable with the present study because they treated patients with differ-ent DR grade (16,36,37,38), and they did not use the same laser techniques (16,28), more laser treatment (25,29,30,32,35,36,38) with larger groups of patients (16,22,24,30,32).…”

Therapeutic Window of Retinal Photocoagulation With Green (532-nm) and Yellow (577-nm) Lasers

“…The observed logarithmic dependence of therapeutic window on pulse duration is consistent with previous measurements with frequency-doubled Nd:YAG, 12 argon, 13 and diode (810-nm) 14 lasers. The slightly lower thresholds of coagulation with yellow wavelength than with green wavelength has been previously described with dye laser 2,5,25 and could be attributed to decreased intraocular scattering. Lesions were placed in the visual streak, which functions similarly to the human macula.…”

“…However, the ongoing trial assessing relative clinical effi cacy of these particular wavelengths is welcomed to supplement past observations of wavelength-independence in effi cacy. 5,[32][33][34][35] Additional oxyhemoglobin-mediated light absorption occurs in the holangiotic, vascularized human inner retina compared to the merangiotic, avascular inner rabbit retina. Equivalence in clinically observed rupture complication rate should be scrutinized as use of 577-nm wavelength becomes more common.…”

19th EURETINA Congress Keynote Lecture: Diabetic Retinopathy Today

“…Other types of lasers than argon green (352 nm), including orange dye (600 nm) laser [45], red (630 nm) and yellow (580 nm) dye lasers [46], diode (810 nm) laser [47], and double-frequency Nd:YAG laser (532 nm) [48], were proved to have an efficiency similar to conventional PRP. Conversely, physics and physicians made their best to develop "nondamaging" devices, capable to deliver selective laser treatment to the retinal pigment epithelium, sparing the neurosensory retina [49].…”

Comparing Two Techniques of Panretinal Photocoagulation on Visual Acuity on Patients with Proliferative Diabetic Retinopathy

“…Blankenship (25) found worsening of two or more rows, 24% after CPRP and 8% after PPRP, and McDonald (20) found worsening of 25% after PRP. Other groups of authors found bettering of VA from 8% to 89% depending on results evaluation (31)(32)(33)(34)(35)(36). Their results are hardly comparable with the present study because they treated patients with differ-ent DR grade (16,36,37,38), and they did not use the same laser techniques (16,28), more laser treatment (25,29,30,32,35,36,38) with larger groups of patients (16,22,24,30,32).…”

Therapeutic Window of Retinal Photocoagulation With Green (532-nm) and Yellow (577-nm) Lasers

“…The observed logarithmic dependence of therapeutic window on pulse duration is consistent with previous measurements with frequency-doubled Nd:YAG, 12 argon, 13 and diode (810-nm) 14 lasers. The slightly lower thresholds of coagulation with yellow wavelength than with green wavelength has been previously described with dye laser 2,5,25 and could be attributed to decreased intraocular scattering. Lesions were placed in the visual streak, which functions similarly to the human macula.…”

“…However, the ongoing trial assessing relative clinical effi cacy of these particular wavelengths is welcomed to supplement past observations of wavelength-independence in effi cacy. 5,[32][33][34][35] Additional oxyhemoglobin-mediated light absorption occurs in the holangiotic, vascularized human inner retina compared to the merangiotic, avascular inner rabbit retina. Equivalence in clinically observed rupture complication rate should be scrutinized as use of 577-nm wavelength becomes more common.…”

19th EURETINA Congress Keynote Lecture: Diabetic Retinopathy Today

“…Other types of lasers than argon green (352 nm), including orange dye (600 nm) laser [45], red (630 nm) and yellow (580 nm) dye lasers [46], diode (810 nm) laser [47], and double-frequency Nd:YAG laser (532 nm) [48], were proved to have an efficiency similar to conventional PRP. Conversely, physics and physicians made their best to develop "nondamaging" devices, capable to deliver selective laser treatment to the retinal pigment epithelium, sparing the neurosensory retina [49].…”

Comparing Two Techniques of Panretinal Photocoagulation on Visual Acuity on Patients with Proliferative Diabetic Retinopathy

“…Blankenship (25) found worsening of two or more rows, 24% after CPRP and 8% after PPRP, and McDonald (20) found worsening of 25% after PRP. Other groups of authors found bettering of VA from 8% to 89% depending on results evaluation (31)(32)(33)(34)(35)(36). Their results are hardly comparable with the present study because they treated patients with differ-ent DR grade (16,36,37,38), and they did not use the same laser techniques (16,28), more laser treatment (25,29,30,32,35,36,38) with larger groups of patients (16,22,24,30,32).…”

Therapeutic Window of Retinal Photocoagulation With Green (532-nm) and Yellow (577-nm) Lasers

“…The observed logarithmic dependence of therapeutic window on pulse duration is consistent with previous measurements with frequency-doubled Nd:YAG, 12 argon, 13 and diode (810-nm) 14 lasers. The slightly lower thresholds of coagulation with yellow wavelength than with green wavelength has been previously described with dye laser 2,5,25 and could be attributed to decreased intraocular scattering. Lesions were placed in the visual streak, which functions similarly to the human macula.…”

“…However, the ongoing trial assessing relative clinical effi cacy of these particular wavelengths is welcomed to supplement past observations of wavelength-independence in effi cacy. 5,[32][33][34][35] Additional oxyhemoglobin-mediated light absorption occurs in the holangiotic, vascularized human inner retina compared to the merangiotic, avascular inner rabbit retina. Equivalence in clinically observed rupture complication rate should be scrutinized as use of 577-nm wavelength becomes more common.…”

19th EURETINA Congress Keynote Lecture: Diabetic Retinopathy Today

“…Other types of lasers than argon green (352 nm), including orange dye (600 nm) laser [45], red (630 nm) and yellow (580 nm) dye lasers [46], diode (810 nm) laser [47], and double-frequency Nd:YAG laser (532 nm) [48], were proved to have an efficiency similar to conventional PRP. Conversely, physics and physicians made their best to develop "nondamaging" devices, capable to deliver selective laser treatment to the retinal pigment epithelium, sparing the neurosensory retina [49].…”