Three-dimensional mapping of peripapillary retinal layers using a spectral domain optical coherence tomography

Abstract

Purpose

To map and view the effects of age, gender, and axial length on seven individual retinal layers around the optic nerve head (ONH).

Methods

We scanned 242 healthy patients using the Spectralis spectral domain optical coherence tomography in an outpatient setting. The layers were observed on the Early Treatment Diabetic Retinopathy Study sectors using the standard Spectralis Family Acquisition Module 6.0.11.0. The center was the ONH, the inner circle (IC) was 1–3 mm away, and the outer circle (OC) was 3–6 mm away. The seven layers were retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), and retinal pigment epithelium (RPE). Additionally, we calculated the mean thickness of two combined layers: inner retinal layer (IRL) and photoreceptor layer (PL). Finally, we measured the mean of the total retinal thickness (TRT).

Results

The TRT was highest at the inferior end in the IC and at the nasal end in the OC. The RPE (p<0.001) and PL (p<0.001) were thicker in males; however, the IRL (p=0.015) was thicker in females. We found that the RNFL (p<0.001, r=0.139), GCL (p<0.001, r=0.116), IPL (p=0.016, r=0.059), INL (p<0.001, r=0.104), OPL (p=0.009, r=0.064), ONL (p<0.001, r=0.157), RPE (p=0.001, r=0.079), IRL (p<0.001, r=0.190), PL (p=0.030, r=0.053), and TRT (p<0.001, r=0.191) correlated negatively with age. The axial length significantly and negatively correlated at the GCL (p=0.003, r=0.093), IPL (p=0.020, r=0.072), INL (p=0.018, r=0.073), ONL (p<0.001, r=0.110), IRL (p=0.003, r=0.092), and TRT (p=0.003, r=0.094). We found poor reproducibility in the IC; however, this was excellent in the OC.

Conclusion

We found significant differences in layers according to age, gender, and axial length. Additionally, reproducibility can be improved by altering the algorithm to account for the ONH parameters.

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Keywords:

• retinal segmentation
• optic nerve head
• sex
• age
• gender
• interferometry

Acknowledgments

We are indebted to Mr Asif Murad for lending his expertise on the OCT machine and his contribution in data collection. Additionally, we would like to thank Mr Faisal Ahmed, Ms Samreen Jahangir, and Mr Faraz Haroon for their immense contribution in data collection. Finally, we would like to thank Dr Azfar Nafees Hanfi for his help in reviewing the fundus photographs. Without the hard work of these individuals, this manuscript would not be possible. The research was funded by the Hashmanis Foundation.

Disclosure

The authors report no conflicts of interest in this work.