THE EFFECT OF YELLOW WAVELENGTH LASER PHOTOCOAGULATION ON CORNEAL HIGH-ORDER ABERRATIONS AND ANTERIOR SEGMENT PARAMETERS

This study aims to assess the effects of 577 nm yellow wavelength laser photocoagulation (Easyret™ 577nm Pattern Laser, Lumibird Medical, Cournon d'Auvergne Cedex, France) on corneal higher-order aberrations (HOA) and anterior segment parameters using a Scheimpflug corneal topography device (Sirius, CSO, Florence, Italy), despite the low corneal absorption of this wavelength, due to potential indirect effects such as heat dissipation or mechanical contact.

University of Health Science, Haseki Training and Research Hospital, Istanbul, Türkiye

This prospective study included 42 eyes from 23 patients who underwent laser treatment. Indications for laser therapy included diabetic retinopathy (82.6%), macular telangiectasia (4.3%), Coats disease (4.3%), and retinal vein occlusion (8.7%). Simulated keratometry (SimK), K1, K2, iridocorneal angle (ICA), horizontal anterior chamber diameter (HACD), anterior chamber volume (ACV), corneal volume (CV), and HOAs were evaluated before and after laser sessions using a topography device.

The study included 42 eyes from 23 patients (mean age: 56.43±12.11 years, 15 females/8 males). The average number of spots per session was 2451.25±1826.31, with a spot diameter of 331.5±125.7 µm, spot power of 581.14±150.97 mW, and spot duration of 0.028±0.005 s, with a mean number of laser sessions of 2.4±1.3. The median interval between two visits was 21 days (range: 7 days-1 month). SimK values were 43.60±1.70 D before treatment and 43.57±1.70 D after treatment (p=0.55), while K1 was 43.18±1.70 D and 43.16±1.68 D (p=0.73), and K2 was 44.03±1.77 D and 43.99±1.78 D (p=0.45). HACD values were 11.74±1.20 µm before treatment and 11.80±1.77 µm after treatment (p=0.77); ACV was 133.14±35.45 µm before treatment and 131.45±34.30 µm after treatment (p=0.41); CV was 58.59±3.62 µm before treatment and 58.68±3.21 µm after treatment (p=0.78). HOA values were 0.459±0.69 µm before treatment and 0.332±0.25 µm after treatment (p=0.23); spherical aberration was 0.110±0.05 µm and 0.112±0.04 µm (p=0.85); coma was 0.223±0.24 µm and 0.178±0.13 µm (p=0.25); trefoil was 0.238±0.42 µm and 0.149±0.22 µm (p=0.09); quadrifoil was 0.133±0.23 µm and 0.093±0.11 µm (p=0.22); secondary astigmatism was 0.611±0.73 µm and 0.491±0.38 µm (p=0.22). However, the ICA values decreased from 41.90±8.77 degrees before treatment to 38.83±10.70 degrees after treatment (p = 0.002).

Yellow wavelength laser photocoagulation demonstrated no significant impact on corneal aberrations, supporting its safety profile in preserving corneal integrity. The slight narrowing observed in the iridocorneal angle is likely due to the use of a direct contact lens during treatment rather than the laser itself. Overall, the 577 nm yellow laser proves to be a safe and effective option for retinal disease management, presenting minimal risk for anterior segment complications and underscoring its suitability for repeated use in clinical practice.