Macular Photocoagulation Study (MPS)

Macular Photocoagulation Study (MPS)

A Series of Randomized, Controlled Clinical Trials

Purpose: To evaluate laser treatment of choroidal neovascularization through three sets of randomized, controlled clinical trials.

  1. Argon Study: To study the efficacy of argon blue-green laser photocoagulation in the treatment of extrafoveal CNV in the prevention or delay of central vision loss in three underlying conditions (AMD, POH, and INVM; each with separate trials).
  2. Kryton Study: To determine whether krypton red laser photocoagulation of CNVs within the parafoveal area is beneficial in the prevention or delay of visual acuity in patients with three underlying conditions (AMD, POH, and INVM; each with separate trials).
  3. Foveal Study: To determine whether laser photocoagulation is beneficial in the prevention or delay of further visual acuity loss in patient with new or recurrent CNV under the center of the FAZ. Two separate trials carried out, one for each type of lesion.

Description:

In each RCT of each MPS group, focal laser photocoagulation was compared to observation without treatment

-        Visual symptoms attributable to macular lesion (e.g. decreased VA, Amsler grid distortion)

-        Visible, well-demarcated hyperfluorescence consistent with classic CNV on FA

-        Eligibility criteria for each condition:

o   AMD: >50 years old, drusen in macula in >1 eye

o   POH: >18 years old, one characteristic histo spot in >1 eye

o   INVM: >18 years old, no evidence of AMD, POH, angioid streaks, high myopia, DR, or other identifiable cause of CNV

-        Additional eligibility criteria for each study:

o   Argon Study: Clinical serous RD with diffuse area of leakage and discrete extrafoveal CNV, VA>20/100 in study eye

o   Krypton Study: CNV with blood/pigment extending into the CNV; posterior border of CNV extend as close as 1 micron to FAZ center; VA>20/400

o   Foveal Study: AMD patients only. FA showing leaking CNV extending under center of FAZ, or CNV consisting of old laser treatment scar and contiguous leaking CNV within 150 microns from center of FAZ. New, never-treated subfoveal lesions <4 DA in size; recurrent lesions <6 DA in size. VA<20/40 and >20/230.

Results:

  1. Argon Study: All trials (AMD, POH, INVM) halted early due to dramatic reduction in severe VA loss with argon laser treatment
  2. Krypton Study:
    1. Beneficial effect for krypton red laser treatment in eyes with AMD, most pronounced in normotensive patients (not apparent among pts with HTN).
    2. POH patients with significant benefit from krypton red laser
    3. Results in INVM patients were intermediate between AMD and POH.
  3. Foveal Study:
    1. Generally, eyes with AMD and subfoveal CNV benefitted from laser
    2. Initially, laser-treated eyes had immediately lost more vision than observed eyes; this loss was similar to the untreated group at 12 months

Conclusions:

  1. For patients with well-demarcated classic CNV from AMD, POH, or INVM, treatment with laser photocoagulation, performed according to MPS guidelines, had better visual prognosis
  2. Likewise, patients with extrafoveal and juxtafoveal CNV from AMD, POH, or INVM had better visual prognosis with laser photocoagulation.
  3. Eyes with AMD and subfoveal CNV:
    1. Eyes with smaller lesion and worse initial VA had greater and earlier benefits of laser treatment
    2. Eyes with large subfoveal CNV lesions and good initial VA are not good candidates for focal laser photocoagulation