Abstract
Purpose::
The purpose of this study was to propose a new method of quantifying and categorizing the degree of optic nerve hypoplasia based on optic disc area, retinal nerve fiber layer thickness, and visual field sensitivity
Methods::
26 patients (43 eyes) were identified with a diagnosis of optic nerve hypoplasia based on the clinical and photographic appearance of the optic nerve. 74 normal eyes and 43 eyes judged to have clinically hypoplastic nerves had perimetry, optic nerve photographs, OCT of the retinal nerve fiber layer thickness (fast RNFL scan) and optic disc area (fast disc scan).
Results::
Based on OCT optic disc area alone, 35/43 eyes (81%) were smaller than the lower 5% of normal (<1.73mm2). Based on sectoral or average RNFL abnormal thinning and small disc area, 31/43 eyes (72%) were abnormal; of these, 25/31 (81%) also had an abnormal visual field.
Conclusions::
Optic nerve hypoplasia should be considered as a spectrum of pathology ranging from mild (small nerve with normal retinal nerve fiber layer thickness and normal visual field) to severe (small disc area with abnormally thin retinal nerve fiber layer and visual field loss). The degree of pathology in a given eye can be best estimated by knowing the area of the scleral opening, the retinal nerve fiber layer thickness (assumed to be proportional to axon number) and the visual field sensitivity.
Keywords: neuro-ophthalmology: optic nerve • neuro-ophthalmology: diagnosis • nerve fiber layer