Can myopia worsen after laser photocoagulation on one eye?

Myopia Worsening After Laser Photocoagulation

Yes, it is common for patients to experience worsening of myopia after laser photocoagulation in one eye, particularly when the procedure is performed for choroidal neovascularization (CNV) associated with pathologic myopia.

Mechanism and Evidence

Laser photocoagulation can affect myopia through several mechanisms:

1. Scar Expansion

   • Progressive enlargement of atrophic laser scars is a well-documented phenomenon after laser photocoagulation for myopic CNV
   • In a study of 19 eyes with degenerative myopia, 68% showed spontaneous progressive enlargement of the atrophic photocoagulation scar, which worsened visual acuity 1

2. Biomechanical Changes

   • Laser treatment alters the structural integrity of the retina and choroid
   • These changes can affect the biomechanics of the eye, potentially influencing axial length and refractive error

3. Refractive Outcomes

   • The Cochrane review on laser photocoagulation for CNV in pathologic myopia noted that enlargement of atrophic laser scars could be a potentially vision-threatening long-term complication 2
   • This scar expansion can contribute to increased myopia and visual deterioration

Comparison with Other Conditions

Interestingly, the effect of laser photocoagulation on refractive error varies by condition:

• Retinopathy of Prematurity (ROP): Laser treatment actually results in less myopia compared to cryotherapy. A study found myopia in only 40% of laser-treated eyes versus 92% in cryotherapy-treated eyes 3

• Pathologic Myopia with CNV: Laser treatment often results in worsening myopia due to scar expansion and structural changes 1, 2

Management Considerations

For patients experiencing worsening myopia after laser photocoagulation:

• Regular Monitoring: Follow refractive changes closely with serial measurements

• Optical Correction: Update spectacle or contact lens prescriptions as needed

• Contact Lens Options:

  • Rigid gas-permeable (RGP) lenses may be beneficial for irregular astigmatism that can develop 4
  • Scleral lenses are effective for severe irregular astigmatism 4

• Topography/Tomography: Essential for assessing any induced irregular astigmatism 4

Important Caveats

1. Distinguish from Natural Progression: High myopia can progress naturally over time, independent of laser treatment

2. Alternative Treatments: Modern treatments for myopic CNV (such as anti-VEGF therapy) have largely replaced laser photocoagulation due to better visual outcomes

3. Bilateral Assessment: Compare with the untreated eye to determine if myopia progression is related to the laser treatment or represents natural disease progression

4. Patient Education: Inform patients about the possibility of myopia progression following laser treatment, especially in pathologic myopia cases

Conclusion

The perception that myopia has worsened after laser photocoagulation is often valid and supported by clinical evidence. This is particularly true for treatments targeting CNV in pathologic myopia, where progressive enlargement of laser scars can contribute to increasing myopia and visual deterioration.