Julio DeLeon-Ortega

Optical coherence tomography of the retina and optic nerve – a review

Optical coherence tomography (OCT) is a rapid non‐contact method that allows in vivo imaging of the retina, optic nerve head and retinal nerve fibre layer (RNFL). Since its introduction in Ophthalmology approximately a decade ago, the use of this technology has disseminated into the clinical practice. OCT has proven to be a useful ancillary tool for assessing retinal diseases because of its capability to provide cross‐sectional images of the retina, and also to perform quantitative analysis of retinal morphology. In glaucoma, the OCT represents one of the methods capable of documenting and analysing optic disc and RNFL morphology in attempt to diagnose and monitor glaucomatous optic neuropathy. Recently, the spectral domain OCT became available, a new technique that allowed major improvements particularly regarding image acquisition speed and image resolution. Future studies will address how these major technological advances will impact the use of the OCT in research and clinical practice.

Frequency doubling technology perimetry in non-arteritic ischaemic optic neuropathy with altitudinal defects.

Aim: To determine if frequency doubling technology perimetry (FDT) is more sensitive to optic nerve injury in non-arteritic ischaemic optic neuropathy (NAION) than standard automated perimetry (SAP). Methods: Charts from 18 patients (20 eyes) with NAION with altitudinal defects who underwent a complete neuro-ophthalmic examination, SAP, and FDT were reviewed. The extent of damage as determined by SAP, FDT, and clinical estimation of the regional extent of optic disc pallor was compared. 10 subjects (20 eyes) with normal ocular examinations and full appearing optic nerve heads were included as a control group. Results: FDT demonstrated more extensive visual field defects in the relatively intact hemifield on SAP (proportion of locations at 5% or worse in the total deviation plot was 8.7% (SD 6.2%) for SAP and 38.3% (39.5%) for FDT p<0.0027). 16 of 20 eyes with altitudinal NAION demonstrated diffuse optic disc pallor. 11 of these eyes with diffuse pallor demonstrated significant defects in both hemifields using FDT, while only two eyes demonstrated diffuse damage using SAP. Correspondence between the extent of optic disc pallor and the extent of visual scotoma was higher for FDT (85%) than with SAP (40%). Conclusion: FDT appears more sensitive to axonal injury reflected by the extent of optic disc pallor in altitudinal NAION than SAP and in some patients reveals visual dysfunction in the hemifield that appeared relatively uninvolved when evaluated using SAP.

Selective perimetry in glaucoma diagnosis.

Purpose of review Selective perimetry evaluates visual function by using visual stimuli that attempt to target specific subpopulations of retinal ganglion cells, which is designed to improve sensitivity to detect glaucomatous functional loss. This paper reviews recent studies that have assessed the characteristics of new strategies/programs of selective perimetry. Recent findings Selective perimetry is usually compared against an existing standard technique – standard automated perimetry. Recent studies did not consider standard automated perimetry results as part of inclusion/exclusion criteria, avoiding selection bias and permitting fair comparisons between perimetry techniques. Furthermore, the Swedish Interactive Threshold Algorithm is replacing Full-Threshold as the standard automated perimetry gold-standard strategy, and comparisons of the diagnostic performance of function-specific perimetry may be influenced by which standard automated perimetry technique is used as the reference. These factors may impact our perception about the role of selective perimetry in glaucoma management. Summary The lack of a perfect gold-standard diagnostic test for glaucoma limits the interpretation of results from cross-sectional studies evaluating visual field tests. Nevertheless, evidence suggests that visual dysfunction in eyes with early glaucoma varies significantly between individuals and no single technique is superior to the others in all patients. A multimodal functional assessment may be more effective in detecting/quantifying visual impairment associated with early glaucoma.