Optic Nerve Head Topography of Retinitis Pigmentosa

1. Chin-Tzu Kuo¹
2. Ching-Yao Tsai^1,2
3. Li-Lin Kuo^1,2
4. Ya-Chung Hsiao¹
5. Shiow-Wen Liou^1,3
6. Lin-Chung Woung^1,3

¹Department of Ophthalmology, Taipei City Hospital, Taipei, Taiwan
²Community Medicine Research Center and Institute of Public Health, National Yang-Ming University, Taipei, Taiwan
³Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan

Purpose: To evaluate and compare the optic nerve head characteristics of patients using Heidelberg retina tomography II (HRT II) with retinitis pigmentosa (RP) and to those of normal controls.

Methods: Prospective and comparative clinical study.

Results: A total of 12 patients (24 eyes) with RP were enrolled. The ratio between cup and disc area was larger in the RP eyes than in the control eyes (0.412 ± 0.147 vs. 0.250 ± 0.155, P=0.023). The linear cup/disc ratio also revealed similar results (0.632 ± 0.119 vs. 0.465 ± 0.189, P=0.034). In the components relating to the RNFL, the rim area (1.069 ± 0.225 mm2 vs. 1.472 ± 0.329 mm², P=0.005), rim volume (0.182 ± 0.106 mm³ vs. 0.361 ± 0.091 mm³, P＜0.001), height variation contour (0.262 ± 0.080 vs. 0.391 ± 0.107, P=0.007), mean RNFL thickness (0.155 ± 0.090 mm vs. 0.254 ± 0.072 mm, P=0.008), and RNFL cross-sectional area (0.734 ± 0.410 mm² vs. 1.251 ± 0.282 mm², P=0.001) were significantly smaller or thinner in the RP eyes than in the control eyes.

Conclusions: It the first document using laser-based optic disc imaging of morphological features of the optic nerve head in RP eyes. The changes in optic cup morphology in RP show similarities to those seen in glaucomatous optic neuropathy. This may provide further evidence that it is the interplay of degenerative factors with the biomechanical properties of the optic nerve head that results in the development of both glaucomatous and RP optic neuropathy.