Abstract
Purpose: :
To identify the diagnostic tests of visual function and structure which best reflect the status of patients with LHON mutations before, during, and after vision loss, and to determine which are most ideal to reflect change.
Methods: :
12 patients with LHON mutations (6 with mt 11778, 4 with mt 3460, 2 w mt 14484) were assessed. All had fundus photos, threshold visual fields, and peripapillary RNFL measurements with OCT and/or GDx. In addition, the most recent 6 had SD OCT ganglion cell complex (GCC- iVue Optovue) and MAIA microperimetry (MP, CenterVue) assessments. 5 were followed from carrier to affected state. Of these, a 15 yo male with mt 11778 was evaluated monthly but not treated; a 27 yo with mt 11778 was treated with EPI-743 (Edison Pharmaceuticals) after converting in one eye and evaluated monthly. Treatment (Tx) was initiated when VA of fellow eye was still 20/20, GCC and MAIA MP were normal.
Results: :
In 3 patients with sufficient data, an increase in thickness of the RNFL of 10-20u with both the GDx and/or OCT occurred prior to the onset of both symptoms and VA loss by 1-2 months. The earliest thickness increase occurred within the inferior temporal bundles. Profound loss of the RNFL occurred 3-4 months later. However, the initial reduction could either represent improvement/normalization or the first stage of profound loss. The GCC did not increase in thickness in tandem with the RNFL; reversal of eventual thinning of GCC has not been observed. Dense paracentral field loss with MP occurred prior to VA reduction and prior to GCC reduction. Serial MP appeared superior to standard fields, especially when fixation became less stable due to a drop in VA. This was also the case in the second eye of the patient treated with 743. An asymptomatic 7 yo old with mt 3460 and normal VA, had marked bilateral loss of the RNFL and GCC not attributable to any other etiologies.
Conclusions: :
Increases in RNFL are often the first indication of LHON conversion **, and may support Tx before symptoms and VA loss. However, one cannot differentiate recovery vs conversion via RNFL. In contrast to RNFL, the GCC may be used as an indicator of disease progression at any stage. GCC loss under Tx suggests progression. Functional loss (on MP) occurs prior to GCC loss and may be reversible with Tx.** Barboni P, et al. Natural history of Leber's hereditary optic neuropathy: longitudinal analysis of the retinal nerve fiber layer by optical coherence tomography. Ophthalmology. 2010 Mar;117(3):623-7. Epub 2010 Jan 19.
Keywords: neuro-ophthalmology: optic nerve • imaging/image analysis: clinical • ganglion cells