Abstract
Purpose: :
To compare visual acuity (VA), OCT central subfieldthickness (CSF) and number of lasertreatments in eyes receiving green or yellow laser to manage diabetic macularedema (DME).
Methods: :
Eyes assigned to sham+prompt laser in aDRCR.net trial evaluating several interventions for DME were reviewed toidentify eyes managed exclusively with green or yellow laser at all treatmentencounters through 2 years of follow-up. Laser wavelength was at investigatordiscretion. ANCOVA method was used to compare change from baseline at the 1-and 2-year visits for VA and CSF between the laser wavelength groups.
Results: :
Follow-up at the first-and second-year visits was availableon 268 and 210 eyes from the initial 284 eyes in the sham+laser group,respectively, among which, 180 (67%) and 132 (63%) received laser treatmentexclusively with green wavelength by 64 investigators, while 57 (21%) and 44(21%) received exclusively yellow wavelength by 25 investigators. Only 3 investigators had patients in bothwavelength groups. Baseline VA and CSF appeared similar between eyes managedwith each laser wavelength. Mean ETDRS letter score change at 1 and 2 years was+2±13 green laser vs +5±13 yellow laser at year 1 (P = 0.05) and +2±15, vs. +7±13at year 2 (P = 0.08). At both timepoints change in CSF was similar between the wavelength groups. More lasertreatment encounters occurred during the 2 year period among eyes managed withyellow (mean 4.1) vs. green (mean 3.4, P =0.04).
Conclusions: :
Study results show a difference in visual acuity resultscomparing investigators using green laser vs. yellow laser. Because the eyes were not assigned randomly toa specific wavelength, and the group of investigators associated with eachwavelength differed, it is possible that factors other than the laserwavelength could account for the differences identified. The observation ofdifferential numbers of treatments between laser color groups is consistentwith possible confounding. While theseresults are consistent with a better treatment effect with yellow laser, arandomized study would be required to rule out confounding or chance.