Short-pulse Subthreshold vs Infrared Micropulse for Diabetic Macular Edema

Comparison of Short-pulse Subthreshold (532 nm) and Infrared Micropulse (810 nm) Macular Laser for Diabetic Macular Edema

When applied according to manufacturer recommendations, short-pulse system may yield more temporary reduction in edema while infrared micropulse system may yield slightly better functional outcomes.

Purpose: To assess both anatomic and functional outcomes between short-pulse continuous wavelength and infrared micropulse lasers in the treatment of DME.

Materials and Methods: A prospective interventional study from tertiary care eye hospital - King Khaled Eye Specialist Hospital (Riyadh, Saudi Arabia). Patients with center-involving diabetic macular edema were treated with subthreshold laser therapy. Patients in the micropulse group were treated with the 810-nm diode micropulse scanning laser TxCell™ (IRIDEX Corporation, Mountain View, CA, USA). Laser was applied according to manufacturer recommendations for MicroPulseTM in a confluent mode (low intensity/high density) to the entire area of the macular edema. Patients in the short-pulse group were treated with grid pattern laser with 20ms pulse PASCAL laser 532nm (TopCon Medical Laser Systems, Tokyo, Japan) with EndPoint algorithm, which was either 30% or 50% of testing burn. Main outcome measures included best-corrected visual acuity (BCVA) and foveal thickness at baseline and the last follow-up visit.

Inclusion Criteria:

• center-involving clinically significant macular edema due to diabetic retinopathy (>300 microns)
• clear ocular media
• ETDRS visual acuity >29 letters (Snellen equivalent of 20/150) or better
• treatment naïve eyes or previously treated with antiangiogenic intravitreal agent(s) more than 6 months ago to allow for long wash-out period

Exclusion Criteria:

• non-center involving diabetic macular edema
• previous retinal laser or surgery
• intravitreal steroid use
• any condition that may be associated with a risk of macular edema such as age-related macular degeneration, retinal vein occlusion, vitreomacular traction, epiretinal membrane and others.