Panretinal Photocoagulation for Diabetic Retinopathy With PASCAL Laser

Overview

This study will investigate the clinical efficacy and safety of the PASCAL laser (PAttern SCAn Laser) for diabetic retinopathy. Patients with proliferative or severe nonproliferative retinopathy will be treated with panretinal photocoagulation utilizing different treatment strategies. The investigators believe that using "lower" laser parameters, the clinical response may be equivalent with less adverse effects.

Full Title of Study: “Panretinal Photocoagulation for Diabetic Retinopathy With PASCAL Laser – an Anatomic and Functional Evaluation of Different Treatment Strategies”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: Single (Participant)
  • Study Primary Completion Date: March 2012

Interventions

  • Procedure: Panretinal photocoagulation
    • Panretinal photocoagulation utilizing 100ms pulse duration, moderate intensity burns, in a single-shot fashion
  • Procedure: Panretinal photocoagulation
    • Panretinal photocoagulation utilizing 20ms pulse duration, moderate intensity burns, in a multiple-shot fashion
  • Procedure: Panretinal photocoagulation
    • Panretinal photocoagulation utilizing 20ms pulse duration, barely visible intensity burns, in a multiple-shot fashion

Arms, Groups and Cohorts

  • Active Comparator: 100ms single-shot
    • Panretinal photocoagulation utilizing 100ms pulse duration, moderate intensity burns, in a single-shot fashion
  • Experimental: 20ms multiple-shot
    • Panretinal photocoagulation utilizing 20ms pulse duration, moderate intensity burns, in a multiple-shot fashion
  • Experimental: 20ms multiple-shot, barely visible
    • Panretinal photocoagulation utilizing 20ms pulse duration, barely visible intensity burns, in a multiple-shot fashion

Clinical Trial Outcome Measures

Primary Measures

  • Incidence of severe visual loss after 1 year
    • Time Frame: 1 year
    • Severe visual loss is defined as visual acuity worse or equal to 5/200 in two consecutive visits (DRS/ETDRS primary outcome)

Secondary Measures

  • Clinical involution of retinal new vessels
    • Time Frame: 1 year
    • Clinical involution of retinal new vessels will be evaluated with retinography and fluorescein angiography
  • Nerve fiber layer thickness
    • Time Frame: 1 year
    • Nerve fiber layer thickness will be evaluated with Spectral Domain OCT
  • Retinal sensitivity
    • Time Frame: 1 year
    • Retinal sensitivity will be evaluated with Humphrey computerized perimetry and FDT (Frequency Doubling Technology)

Participating in This Clinical Trial

Inclusion Criteria

  • proliferative or severe nonproliferative diabetic retinopathy (type 1 or type 2) – best corrected visual acuity of 20/50 or better – capability to read and follow instructions – capability to sign the consignment term Exclusion Criteria:

  • best corrected visual acuity worse than 20/50 – significant macular edema responsible for visual acuity lower than 20/50 – media opacities (includes vitreous hemorrhage in the visual axis, but not a reabsorbing inferior vitreous hemorrhage) – previous laser treatment (PRP, focal or macular grid) – glaucoma (confirmed or suspicious) – other diseases of the retina and optic nerve – previous ocular surgery in the last 6 months – impossibility to obtain good quality images of retinography, angiography or OCT

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Federal University of São Paulo
  • Provider of Information About this Clinical Study
    • Renato Magalhães Passos, Doctor at the Ophthalmology Department of UNIFESP
  • Overall Contact(s)
    • Renato M Passos, MD, 55 11 50852043, renatompassos@yahoo.com.br

References

Modi D, Chiranand P, Akduman L. Efficacy of patterned scan laser in treatment of macular edema and retinal neovascularization. Clin Ophthalmol. 2009;3:465-70. doi: 10.2147/opth.s6486. Epub 2009 Aug 20.

Muqit MM, Gray JC, Marcellino GR, Henson DB, Young LB, Patton N, Charles SJ, Turner GS, Dick AD, Stanga PE. In vivo laser-tissue interactions and healing responses from 20- vs 100-millisecond pulse Pascal photocoagulation burns. Arch Ophthalmol. 2010 Apr;128(4):448-55. doi: 10.1001/archophthalmol.2010.36.

Muqit MM, Marcellino GR, Henson DB, Young LB, Patton N, Charles SJ, Turner GS, Stanga PE. Single-session vs multiple-session pattern scanning laser panretinal photocoagulation in proliferative diabetic retinopathy: The Manchester Pascal Study. Arch Ophthalmol. 2010 May;128(5):525-33. doi: 10.1001/archophthalmol.2010.60.

Nagpal M, Marlecha S, Nagpal K. Comparison of laser photocoagulation for diabetic retinopathy using 532-nm standard laser versus multispot pattern scan laser. Retina. 2010 Mar;30(3):452-8. doi: 10.1097/IAE.0b013e3181c70127.

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