Effects of Cataract on Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Thickness on Swept Source Optical Coherence Tomography.

Purpose: To evaluate the changes in peripapillary retinal nerve fiber layer (pRNFL) thickness and macular ganglion cell-inner plexiform layer (mGC-IPL) thickness measured by swept source optical coherence tomography (SS-OCT) following cataract surgery in patients with glaucoma.

Methods: We included 42 glaucoma eyes and 42 case-matched normal eyes that underwent cataract surgery without complications. One matching set included one glaucoma eye and one case-matched normal eye. The age, sex, and cataract subtype scores were similar for each group. Before and within 3 months of surgery, we measured the pRNFL thickness and mGCIPL thickness by SS-OCT.

Results: Following cataract surgery, the image quality (IQ) of SS-OCT improved in both groups. The thickness of the pRNFL and mGC-IPL increased in the mean values and all areas, except for pRNFL from 1 to 4 o'clock in the glaucoma group and at 1 o'clock in the normal group. Posterior subcapsular cataract was related to the change in IQ following surgery. The glaucoma and normal group showed greater pRNFL thickness change due to lesser preoperative pRNFL thickness. Furthermore, the mGC-IPL thickness change was greater in the glaucoma group because of lesser preoperative mGC-IPL thickness. By contrast, the normal group demonstrated greater mGC-IPL thickness change due to higher cortical cataract scores.

Conclusions: Cataracts caused the deterioration of the IQ in SS-OCT, thereby resulting in an undermeasurement of the pRNFL and mGC-IPL thickness. Preoperative pRNFL and mGC-IPL were negatively associated with postoperative pRNFL and mGCIPL thickness change in the glaucoma and normal groups. Therefore, ophthalmologists should particularly consider the effect of cataract while diagnosing glaucoma using SS-OCT.