Diffuse and localised visual field defects to automated perimetry in primary open angle glaucoma

Age-related changes in the peripheral retinal nerve fiber layer thickness

Purpose

This pilot cross-sectional study aimed to determine age-related changes of the retinal nerve fiber layer (RNFL) thickness in retinal periphery by swept-source optical coherence tomography-based analysis.

Methods

Forty eyes of 40 healthy subjects were studied in three age groups, group 1 (20–40 years, n=15), group 2 (41–60 years, n=14), and group 3 (≥61 years, n=11). Wide-angle swept-source optical coherence tomography scans, including the optic disc and macula, were montaged with the nasal peripheral optical coherence tomography images acquired with a contralateral gaze. The peripapillary and peripheral RNFL thickness values were obtained for nasal and temporal sides. The ratio of peripheral-to-peripapillary RNFL thickness was also calculated for these sectors.

Results

We detected a significantly thinner RNFL in older than younger subjects at a distance of 6 mm from the optic disc on nasal and temporal sides (P<0.001). An age-related reduction in peripheral-to-peripapillary RNFL thickness ratios (P<0.001 and P<0.02 for nasal and temporal sides, respectively) was also detected.

Conclusion

The age-related decline should be taken into consideration when determining the glaucoma-related alterations in peripheral RNFL thickness. Continued analysis in patients with ocular hypertension and glaucoma should help determine whether RNFL in the periphery with lower nerve tissue reserve might be more susceptible to injury, whether injury to the peripheral RNFL might be easier to detect, and/or whether analysis of the peripheral RNFL thickness could improve clinical diagnosis and follow-up of glaucoma.

Relevance of the site of injury of glaucoma to neuroprotective strategies

Glaucomatous optic neuropathy is a chronic progressive disease associated with characteristic changes in the morphology of the optic disk, pattern of visual field, and death of retinal ganglion cells. Neuroprotection is a potential treatment for glaucomatous optic neuropathy which acts independently of lowering intraocular pressure. Neuroprotective strategies differ in their site of action, and it is important to correlate this with the location at which the glaucomatous injury occurs. This article describes a hypothetical scheme for determining the site of progression of glaucomatous optic neuropathy and discusses the implications of this model for evaluating studies of neuroprotection.