Topographic characteristics of the optic nerve head measured with scanning laser tomography in normal Japanese subjects.

PURPOSE: Few studies have been performed regarding the topographic information obtained with the Heidelberg retina tomograph (HRT) in normal Japanese. In this study, we examined the factors influencing optic disc parameters and hemisphere symmetry obtained with the HRT in normal Japanese subjects. METHODS: Mean values and the standard deviation range for the main HRT parameters were evaluated in 223 eyes of 223 normal Japanese subjects. The influence of age, sex, and disc size on HRT topographic data was analyzed. The superior and inferior hemisphere topographic parameters were compared. RESULTS: Disc area showed a significant difference by sex (P = 0.0493). Rim volume (r = -0.208, P = 0.019), height variation contour (r = -0.275, P = 0.001), and mean retinal nerve fiber layer (RNFL) thickness (r = -0.366, P = 0.001) declined with age. All parameters except height variation contour and mean RNFL thickness showed a clinically significant correlation with disc size (-0.159 < r < 0.719, P < 0.01). Cup parameters in the superior hemisphere were significantly greater than those in the inferior hemisphere. In contrast, rim parameters in the superior hemisphere were significantly smaller than those in the inferior hemisphere. CONCLUSIONS: Some factors, namely, sex, age, and disc size, affected the optic disc parameters in the HRT measurements. Possible parameter asymmetry between the two hemispheres should be considered in normal eyes.

[Difference of optic disc topography between a low-tension group and a high-tension group in normal-tension glaucoma patients].

PURPOSE: Glaucomatous visual field loss and optic disc damage differ by intraocular pressure (IOP) levels. In this study, we compared the optic disc topography in the high-tension group and the low-tension group in normal-tension glaucoma (NTG). METHOD: We selected NTG patients with mean deviation (MD) > or = -10.00 dB and the highest recorded IOP of < 14 mmHg or > or = 17 mmHg without glaucoma treatment. We classified NTG eyes into the following two groups: 1) a low-tension group with the highest recorded IOP of < 14 mmHg, 2) a high-tension group with the highest recorded IOP of > or = 17 mmHg. The optic disc parameters in the low-tension group eyes were compared with those in the high-tension group eyes using a Heidelberg Retina Tomograph. RESULTS: Nineteen eyes of nineteen patients were selected for each group. The cup/disc area ratio in the global sector, and the rim volume in the nasal sector of the low-tension group had deteriorated more than in the high-tension group. CONCLUSIONS: The disc topography is different between the low-tension group and the high-tension group in the nasal sector, suggesting that different pathogenetic mechanisms exist in the optic disc damage in NTG.

Specificity and sensitivity of glaucoma detection in the Japanese population using scanning laser polarimetry.

AIMS: To investigate the usefulness of the scanning laser polarimeter (GDx; GDx Nerve Fiber Analyzer) for glaucoma detection in the Japanese population, and to investigate the difference in the thickness of retinal nerve fibre layer (RNFL) between normal tension glaucoma (NTG) and primary open angle glaucoma (POAG). METHODS: 69 eyes of 69 normal subjects and 115 eyes of 115 chronic open angle glaucoma patients (60 NTG and 55 POAG patients) were studied. The thickness of RNFL was measured with GDx. An eye was diagnosed as glaucomatous, if at least one original GDx variable showed p <5%. The difference in thickness of RNFL between the NTG and POAG groups was then investigated. RESULTS: 46 normal eyes (66.7%) were diagnosed as not glaucomatous (no variables showing p <5%), and 93 glaucomatous eyes (46 NTG and 47 POAG eyes) (80.9%) were diagnosed as glaucomatous. Actual values of average thickness, ellipse average, superior average, and superior integral were significantly lower in the POAG group than those in the NTG group. CONCLUSIONS: New variables which elucidate focal RNFL defects or early changes are needed to improve the moderate detection ability found in this present study. The pattern of the change in RNFL may differ in NTG and POAG groups.

Quantification of retinal nerve fiber defects in glaucoma: three-dimensional analysis by Heidelberg retina tomograph.

PURPOSE: To describe a new method of quantifying retinal nerve fiber layer defects (NFLD) in glaucomatous eyes using the Heidelberg Retina Tomograph (HRT). METHODS: Mean tomographic images including the optic disc and peripapillary area were constructed using HRT. An image field of 15 degrees x 15 degrees or 20 degrees x 20 degrees was used for the NFLD analysis. Data on the nerve fiber layer thickness was collected and further analyzed circumferentially across the NFLD at a position 500 microm away from the optic disc margin. We studied 31 patients with early to moderate open-angle glaucoma, ie, with visual field defects appearing earlier than stage 3 of the modified Aulhorn-Greve classification. We determined the width (W), maximum depth (D), and cross-sectional area of the NFLD (A), and we identified correlations between these parameters and the visual field indices from Humphrey Visual Field tests, mean deviation (MD) and corrected pattern standard deviation (CPSD). RESULTS: NFLD parameters could be obtained from 20 of 31 eyes (65%). There was a statistically significant correlation between the D and A parameters, and between these parameters and the maximum depression threshold in the corresponding visual field. No significant correlation was found between the NFLD parameters, the global visual field indices (MD, CPSD) and the mean value of the total deviation (TD) in the corresponding hemifield visual field. CONCLUSIONS: A cross-sectional NFLD image can be obtained using HRT. Among the three NFLD parameters, maximum depth (D), and area under the surface (A) correlated well with the visual field threshold.

[The effect of phosphodiesterase type 3 inhibitor on chorio-retinal blood flow in rabbits eyes].

PURPOSE: To investigate the ocular effect of intravenous administration of a phosphodiesterase type 3 inhibitor (NSP-805) and to compare the effect of NSP-805 with that of a calcium antagonist (nicardipine hydrochloride) on chorio-retinal blood flow in anesthetized albino rabbits. METHODS: Twenty-four female albino rabbits (weighting 2.0-4.0 kg) were anesthetized with intravenous injection. NSP-805(40 micrograms/kg and 100 micrograms/kg) and nicardipine of 40 micrograms/kg were intravenously administrated to the anesthetized rabbits. Intravenously administration of 20% dimethyl sulfoxide (DMSO) was used as a vehicle. Chorio-retinal blood flow was measured with a laser Doppler flowmeter at baseline and every 20 minutes after intravenous administration for 120 minutes. Heart rates and systemic blood pressure were monitored. Baseline measurements were compared with every 10 minutes after intravenous administration. Differences between the drug groups and vehicle group were analyzed. RESULTS: After administration of a low dose of NSP--805 (40 micrograms/kg) and nicardipine (40 micrograms/kg), the chorio-retinal blood flow was significantly increased (p < 0.05). A high dose NSP-805(100 micrograms/kg) reduced systemic blood pressure significantly, but the increase of chorio-retinal blood flow was less than that at the low dose of NSP-805(40 micrograms/kg) and nicardipine (40 micrograms/kg). Chorio-retinal blood flow in the NSP 805(40 micrograms/kg) and nicardipine (40 micrograms/kg) groups was significantly increased over that in the control group (20% DMSO) (p < 0.05). CONCLUSION: The results suggest that the NSP-805 has the potential of increasing chorio-retinal blood flow in rabbit eyes.

[Serial topographic changes at the optic disc in normal-tension glaucoma viewed with scanning laser tomography].

PURPOSE: To evaluate topographic changes in normal-tension glaucoma using serial optic disc images obtained by scanning laser tomography. SUBJECTS AND METHODS: Fifty-six eyes of 30 patients with normal-tension glaucoma were imaged using the Heidelberg Retina Tomography (HRT) four or more times during follow-up periods of more than 3 years. Disc progression was determined by regression analysis of global and segmental changes in optic disc parameters. Visual field progression was determined by Humphrey Field Analyzer (HFA) program 30-2 and was compared with disc progression. RESULTS: The global parameters of the optic disc showed progression in 21 of 56 eyes(37.5%). Progression was found in 30 eyes(53.6%) at the superotemporal segment, in 24 eyes(42.9%) at the temporal segment, in 27 eyes(48.2%) at the inferotemporal segment, in 21 eyes(37.5%) at the superonasal segment, in 23 eyes(41.1%) at the nasal segment, and in 27 eyes(48.2%) at the inferonasal segment. The visual field showed progression in 19 eyes (33.9%). The progression in the optic disc parameters did not necessarily agree with that in the visual field. CONCLUSIONS: Glaucomatous disc changes over time can be determined with HRT using regression analysis.

Scanning electron microscope study of the rabbit anterior chamber angle.

The three-dimensional fine structure and the collagenous framework of the anterior chamber angle (chamber angle) of albino rabbits, which does not posses a Schlemm's canal, were examined, with or without NaOH maceration, by scanning electron microscopy. The chamber angle is ill defined because the deep ciliary cleft appears parceled by iris pillars. The collagenous framework of the pectinate ligaments and iris pillars arising from the iris root join to the collagen bundles of the trabecular sheet, and the surface of the ciliary cleft is covered by an endothelial cell layer that screens the trabecular meshwork. Round openings are apparent in the recesses of the ciliary cleft, with junctions between more superficial or deeper trabecular sheets resulting in direct communication between adjacent trabecular spaces. Openings of the angular aqueous plexus/sinus in place of Schlemm's canal were seen on the inner surface of the corneosclera after removing the trabecular meshwork. The framework of the trabecular sheet is basically formed of circumferentially arranged flat collagen bundles and reticularly diverged narrow collagen bundles extending from them. There is no shift between collagen bundles of the trabecular meshwork and the corneosclera, suggesting a frail connection between the two tissues.