Abstract
Purpose:
To evaluate whether panretinal photocoagulation (PRP) affects retinal nerve fiber layer (RNFL) thickness and visual field sensitivity.
Methods:
Prospective study of approximately 6 months duration involving 34 eyes in the PRP treatment group and 30 eyes in the control group followed with spectral domain optical coherence tomography (SD-OCT) and Humphrey visual field (HVF) 24-2.
Results:
Treatment group [SD-OCT RNFL average thickness difference +1.69 um +/- 6.56 SD (p=0.16), HVF mean deviation difference +0.52 +/- 2.30 SD (p=0.23)]. Control group [SD-OCT RNFL average thickness difference -0.59 um +/- 5.75 SD (p=0.60), HVF mean deviation difference -0.27 +/- 2.82 SD (p=0.68)]. Treatment subgroup without prior PRP [SD-OCT RNFL average thickness difference +4.83 um +/- 4.39 SD (p=0.003), HVF mean deviation difference +1.21 +/- 2.45 SD (p=0.13)]. Control subgroup without prior PRP [SD-OCT RNFL average thickness difference +1.23 um +/- 5.72 SD (p=0.45), HVF mean deviation difference +0.18 +/- 3.49 SD (p=0.87)]. Treatment subgroup <= 3 months follow-up (SD-OCT RNFL average thickness difference +2.52 um +/- 4.07 SD (p=0.01), HVF mean deviation difference +0.83 +/- 2.59 SD (p=0.17)]. Treatment subgroup > 3 months follow-up (SD-OCT RNFL average thickness difference +0.19 um +/- 7.77 SD (p=0.91), HVF mean deviation difference +0.10 +/- 2.21 SD (p=0.85)].
Conclusions:
PRP treatment may initially cause RNFL thickening. SD-OCT RNFL thickening was statistically significant in the treatment subgroup without prior PRP and during the initial 3 months after PRP treatment. With time, the increase diminished and was not statistically significant in the > 3 months follow-up subgroup. The effects of PRP treatment on HVF mean deviation were not statistically significant. PRP treatment seemed to improve retinal sensitivity as HVF mean deviation improved initially but with time this improvement became negligible. The use of SD-OCT RNFL and HVF to diagnose and manage glaucoma with concomitant diabetic retinopathy requiring PRP should be done cautiously in order to avoid mistreatment.
Keywords: 629 optic nerve •
758 visual fields