Miyuki Fujioka

Association of retinal nerve fibre layer thickness measured by confocal scanning laser ophthalmoscopy and optical coherence tomography with disc size and axial length

Aims: To investigate the influence of age, disc size and axial length on the retinal nerve fibre layer (RNFL) thickness measurements of Heidelberg Retina Tomograph (HRT) and optical coherence tomography (OCT). Methods: A total of 162 eyes of 162 Japanese normal subjects aged between 20 and 83 were enrolled in this study. The disc area and mean RNFL thickness were measured with HRT. The disc area was also measured using the fast optic nerve scan protocol, and the average RNFL thickness was measured using the fast RNFL thickness scan mode with Stratus OCT. The correlations of age, disc area and axial length with RNFL thickness measured with HRT and OCT were analysed. The associations between axial length and disc area measured with HRT and OCT were also calculated. Results: RNFL thickness measured with the two instruments decreased with age. There was a significantly negative correlation between the mean RNFL thickness and disc area measured with HRT. The RNFL thickness measured with OCT correlated positively with the disc area measured with OCT, but not with the disc area measured with HRT. Both RNFL thickness and disc area measured with OCT were inversely correlated with axial length, whereas the two parameters measured with HRT had no association with axial length. Conclusion: In addition to the effect of ageing, the disc size affected the RNFL thickness measured with HRT, whereas the axial length influenced the RNFL thickness and disc area measured with OCT. These variables must be taken into consideration when measuring eyes with the lower or upper boundary of the normal range.

Comparison of Pentacam Scheimpflug Camera with Ultrasound Pachymetry and Noncontact Specular Microscopy in Measuring Central Corneal Thickness

Purpose: Although central corneal thickness (CCT) can be measured by several methods, interchangeability of different modalities has not been fully investigated. CCT is known to correlate with intraocular pressure (IOP). The aim of this study was to evaluate the agreement of Pentacam Scheimpflug system with noncontact specular microscopy (NCSM) and ultrasound (US) pachymetry in measuring CCT and the relation between IOP taken with Goldmann applanation tonometer (GAT) and the CCT measured with these three methods. Methods: The right eyes of 135 enrolled persons without antiglaucoma drug use (100 females and 35 males), who comprised 32 patients with primary open-angle glaucoma, 14 with ocular hypertension, 45 with primary angle-closure glaucoma, and 44 controls, were studied. Intermethod comparison of CCT was made by the 95% limits of agreement analysis according to Bland and Altman. Linear regression analysis was used to assess the relationship between IOP and CCT taken with each modality. Results: The mean CCT (±SD) taken with Scheimpflug, US, and NCSM was 559.49 ± 38.44 μ m, 553.01 ± 39.33 μ m, and 552.04 ± 42.95 μ m, respectively. The average values of CCT taken with the three instruments were not significantly different (one-factor ANOVA; p = 0.26), although the marginal mean difference between Scheimpflug and US or NCSM was statistically significant (paired t test; p = 0.0009 and 0.005, respectively). The 95% limits of agreement were 6.47 ± 43.21 μm between Scheimpflug and US, 7.45 ± 58.86 μ m between Scheimpflug and NCSM, and 0.98 ± 51.69 μ m between US and NCSM. There was a positive association between IOP and CCT measured with US or NCSM, whereas there was no correlation between IOP and CCT measured with Scheimpflug. Conclusions: Although CCT values measured with Scheimpflug, US, and NCSM are closely similar, clinicians should keep in mind that these methods are not simply interchangeable.

Quantification of retinal nerve fiber layer thickness reduction associated with a relative afferent pupillary defect in asymmetric glaucoma

Aim: The relative afferent pupillary defect (RAPD) is an important clinical sign of asymmetrical retinal ganglion cell and axonal damage. Although glaucoma essentially affects bilateral eyes, a subset of patients manifests asymmetrical glaucomatous optic neuropathy (GON), which exhibits an RPAD in the more advanced eyes. However, the degree to which axonal loss occurs before an RAPD is clinically detectable has not been substantiated. The purpose of this study is to assess the relationship between the depth of a clinically detectable RAPD and the reduction ratio of retinal nerve fiber layer (RNFL) thickness in the more advanced eyes relative to that in the contralateral less advanced eyes of patients with asymmetrical GON. Methods: Enrolled were 29 consecutive glaucoma patients with the clinically detectable RAPD. An RAPD was quantified by placing log-scaled neutral density filters over the less advanced eyes while performing the swinging flashlight test. Average RNFL thickness was determined using the Fast RNFL thickness programme of optical coherence tomography 3000. Correlation coefficient and Linear regression analyses were used in assessing the relationship between the RAPD and the ratio of RNFL thickness in the more advanced eyes relative to that in the less advanced. Results: RAPD ranged from 0.6 to 2.4 log units. The log-scaled RAPD had a statistically significantly inversed correlation with the average RNFL thickness ratio (rs = −0.729, p<0.0001). Linear regression analysis found an equation that the average RNFL thickness ratio in the more affected eyes relative to that in the less advanced (%)  = (0.827−0.169×RAPD (log units))×100 (R2 = 0.557, p<0.0001). Conclusions: When an RAPD is clinically detected, the RNFL thickness in the more advanced eyes was in average reduced to about 73% of that in the less advanced.

Comparison of mean deviation with AGIS and CIGTS scores in association with structural parameters in glaucomatous eyes.

ObjectiveTo evaluate which of the 3 clinically used visual field indices including mean deviation (MD), Advanced Glaucoma Intervention Study (AGIS) score, and Collaborative Initial Glaucoma Treatment Study (CIGTS) score are best in evaluating functional damage of glaucomatous optic neuropathy. MethodsIn 213 glaucomatous eyes, peripapillary retinal nerve fiber layer thickness (RNFLT) and optic disc configuration were measured with Stratus optical coherence tomography and Heidelberg Retina Tomograph-2, respectively. Visual field was measured with standard automated perimetry 30-2. Correlations of the structural parameters compared with the 3 VF indices using second polynomial regression were calculated. In addition, these correlations were analyzed among eyes of 3 different stages of glaucoma, as defined by MD score (early, MD≥−6 dB; moderate, −12 dB≤MD<−6 dB; advanced, MD<−12 dB). ResultsAmong structure-function relationships in all subjects, the highest correlation determination (R2) was MD with RNFLT (=0.298). CIGTS score showed better R2 than MD or AGIS score with rim area, but these values were not higher than any R2 with RNFLT. In analyses of 3 groups depending on MD, statistically significant structure-function correlations were observed only in patients with an advanced stage. ConclusionsNo clear difference was found among MD and AGIS/CIGTS scores in expressing functional damage of glaucomatous eyes. MD is suggested to be no worse than others in monitoring glaucoma in clinical setting.