Influence of cataract on optical coherence tomography image quality and retinal thickness

Background: As optical coherence tomography ( OCT) is widely used for diagnosis and monitoring of ocular pathology, especially in the elderly people, the influence of cataract on image quality and macular retinal thickness was studied. Methods: In 29 patients scheduled for cataract surgery, preoperative and postoperative OCT scans were obtained. Cataracts were categorised as nuclear, posterior or cortical. Parameters for image quality ( signal-to-noise ratio ( SNR)) and signal strength and macular thickness were compared. A three-level expert grading scale was used to evaluate the discriminative abilities of SNR and signal strength. Results: Nuclear cataracts ( n = 12) provided better preoperative scans ( higher SNR/ signal strength) than posterior ( n = 7) and cortical ( n = 10) cataracts ( p < 0.004). Postoperatively SNR and signal strength increased significantly in all patients ( p < 0.001). The SNR was better at discriminating poor from acceptable and good scans than signal strength ( area under the receiver operating curve: 0.879 and 0.810, respectively). Postoperative macular thickness overall showed a significant increase ( p = 0.005), most evident in patients with posterior cataracts ( p = 0.028). Conclusions: OCT imaging is influenced by cataract; image quality is reduced preoperatively and macular thickness measurements are slightly increased postoperatively. In individual patients, OCT scans remain reliable for gross clinical interpretation, even in the presence of cataract.