The developing optic nerve head in infantile idiopathic nystagmus and nystagmus associated to albinism

Abstract

Purpose: To use spectral domain hand-held optical coherence tomography (SD-HHOCT) to characterise the development of the optic nerve head (ONH) in infants between birth and seven years of age with infantile idiopathic nystagmus (IIN) and nystagmus associated to albinism, in comparison to normal controls.

Methods: 38 participants with IIN, 53 with albinism and 176 controls, aged between 0 and 7 years had optic nerves imaged using SD HH-OCT. The central B scan was identified as the point of the nerve with the deepest cup. Parameters included disk, cup and rim dimensions and peripapillary retinal thickness and retinal nerve fibre layer (RNFL) were correlated to log gestational age (logGA).

Results: There was a significant increase in disk diameter with logGA in all three groups (p<0.001) with no significant inter- group differences. Cup diameter also increased with logGA in albinism (p=0.009), but not in the IIN group. Consequently changes in cup to disk ratio with logGA were insignificant in all groups. The rim area was significantly greater in IIN than in controls (p=0.035), also showing a greater rate of increase with logGA than controls (p=0.036; IIN: r=0.615; Ctrl: r=0.230), mainly because of increase in the nasal rim. In contrast larger increase occurred in the temporal rim in albinism in relation to logGA (p=0.004). Temporal rim area was significantly thicker in albinism compared to controls (p=0.042), and increased at a faster rate (p=0.021). Nasal and temporal peripapillary retinal thickness was greater in IIN compared to controls (nasal: p=0.003; temporal: p=0.005) and increased at a faster rate (nasal: p=0.003; temporal: 0.005). In the albinism these changes were limited to temporal retinal thickness (compared to controls: p=0.015; interaction with logGA: p=0.023). Although RNFL changed with logGA there were no significant differences between the three groups.

Conclusions: We describe different patterns of the optic nerve development between the three groups. The IIN group shows greater rate of increase in neural tissue on nasal and temporal sides of the ONH with age with the greatest changes being observed for the nasal side. Only temporal neural tissue shows a significantly higher rate of thickening in the albinism group. These data show there are significant changes in the development of the optic nerve in infants with idiopathic infantile nystagmus and nystagmus associated to albinism.

Keywords: 629 optic nerve • 619 nystagmus • 556 infant vision