Repeatability of visual acuity testing using a psychometric function.

PURPOSE: To evaluate the repeatability of a new method of measurement of visual acuity by use of a psychometric function. METHODS: The visual acuity of 15 healthy adults was measured by use of a psychometric function (PFVA) and by use of a conventional method using a decimal visual acuity chart (DeVA). We performed two tests. To evaluate intra-rater reliability, a tester measured the visual acuity three times for each subject, and the intraclass correlation coefficients, ICC (1,1), were calculated for PFVA and DeVA. Next, to evaluate inter-rater reliability, three testers measured the visual acuity for one subject, and the ICC (2,1) were calculated for PFVA and DeVA. The PFVA and DeVA of five subjects with ocular diseases were also measured. RESULTS: In the evaluation of intra-rater reliability, the ICC (1,1) of the DeVA was 0.83 and the ICC (1,1) of the PFVA was 0.95. In the evaluation of inter-rater reliability, the ICC (2,1) of the DeVA was 0.88 and the ICC (2,1) of the PFVA was 0.93. In both tests the standard deviations of the PFVA were significantly lower than those of the DeVA. For four of the five subjects with ocular diseases, the PFVA was significantly improved by treatment. CONCLUSION: The repeatability of our method is better than that of the conventional method using a decimal visual acuity chart.

Detection of visual field defects in pre-perimetric glaucoma using fundus-oriented small-target perimetry.

PURPOSE: To evaluate the usefulness of automated fundus-oriented small-target perimetry in detecting glaucomatous visual field abnormalities. MATERIALS AND METHODS: One eye from each of 60 normal, 37 pre-perimetric glaucoma (PPG) and 29 early stage of primary open-angle glaucoma (POAG) persons were included. The new perimeter had two monitors, one for a campimeter and the other for the examiner's operation. A test area within the central 15° was set in the fundus image. The target size was 2.9 min in diameter, and the distance between the two adjacent targets was 60 min. The rate of negative response (RNR) among the age-matched controls, PPG and POAG were compared. The relationship between the RNR and age of the normal or standard automated perimetry (SAP) global indices in PPG and POAG was examined. The areas under the receiver-operating characteristic curve (AROC) to discriminate PPG or POAG versus normal were determined. RESULTS: The RNR increased significantly with age in normal and differed significantly (P < 0.001) among control (1.8 ± 1.3 %), PPG (9.2 ± 10.4 %) and POAG (21.2 ± 14.3 %). Significant correlation was found between the RNR and SAP global indices. The AROC was 0.89 for PPG and 0.95 for POAG. CONCLUSION: Fundus-oriented small-target perimetry is useful in detecting visual field abnormalities in PPG.

Influence of three-dimensional image viewing on visual function.

PURPOSE: A three-dimensional (3D) image viewing experiment was performed using a new 3D scenography system. The influence on visual function was investigated both in adults and in children employing both objective and subjective methods. METHODS: The subjects were 21 healthy adults (mean age ± standard deviation: 42.1 ± 10.0 years) and 21 healthy children (7.8 ± 1.5 years). The 3D image viewing time was set at 90 min for adults and 60 min for children, and the visual function was objectively evaluated using an accommodative microfluctuation analysis system both before and after 3D image viewing. In addition, subjective symptoms were surveyed employing a questionnaire both before and after viewing in the adult group to subjectively evaluate the visual function. RESULTS: No significant difference was noted in accommodative microfluctuation between the before and after viewing in either the adult or child group, nor was there a significant difference in subjective symptoms in the adult group based on the questionnaire. However, accommodative microfluctuation tended to increase after viewing in some subjects. CONCLUSIONS: Under the conditions of this study, 3D image viewing did not influence visual function, or only very slightly influenced it, if at all, but there are many unknown problems, requiring further surveys using 3D image viewing.

Functional role of hCngb3 in regulation of human cone cng channel: effect of rod monochromacy-associated mutations in hCNGB3 on channel function.

PURPOSE: The human cone photoreceptor cyclic nucleotide-gated (CNG) channel comprises alpha- and beta-subunits, which are respectively encoded by hCNGA3 and hCNGB3. The purpose was to examine the functional role of hCNGB3 in modulation of human cone CNG channels and to characterize functional consequences of rod monochromacy-associated mutations in hCNGB3 (S435F and D633G). METHODS: Macroscopic patch currents were recorded from human embryonic kidney (HEK) 293 cells expressing homomeric (hCNGA3 and hCNGB3) and heteromeric (hCNGA3/hCNGB3, hCNGA3/hCNGB3-S435F, and hCNGA3/hCNGB3-D633G) channels using inside-out patch-clamp technique. RESULTS: Both hCNGA3 homomeric and hCNGA3/hCNGB3 heteromeric channels were activated by cGMP, with half-maximally activating concentration (K(1/2)) of 11.1 +/- 1.0 and 26.2 +/- 1.9 micro M, respectively. The hCNGA3 channels appeared to be more sensitive to inhibition by extracellular Ca(2+) compared with hCNGA3/hCNGB3 channels, when assessed by the degree of outward rectification. Coexpression of either of rod monochromacy-associated mutants of hCNGB3 with hCNGA3 significantly reduced K(1/2) value for cGMP but little affected the sensitivity to extracellular Ca(2+), compared with wild-type heteromeric channels. The selectivity of hCNGA3, hCNGA3/hCNGB3, hCNGA3/hCNGB3-S435F, and hCNGA3/hCNGB3-D633G channels for monovalent cations were largely similar. Immunoprecipitation experiments showed association of hCNGA3 subunit with both of wild-type and mutant hCNGB3 subunits. CONCLUSIONS: The hCNGB3 plays an important modulatory role in the function of human cone CNG channels with respect to cGMP and extracellular Ca(2+) sensitivities. The rod monochromacy-associated S435F and D633G mutations in hCNGB3 evokes a significant increase in the apparent affinity for cGMP, which should alter cone function and thereby contribute at least partly to pathogenesis of the disease.

Imaging of (13)C-labeled glucose and sorbitol in bovine lens by (1)H-detected (13)C nuclear magnetic resonance spectroscopy.

Bovine lenses were incubated in a solution containing [1-(13)C]glucose (50 mM) for 1, 2 and 4 days. Spectroscopic images of [1-(13)C]glucose and [1-(13)C]sorbitol were constructed using (1)H-detected gradient-enhanced heteronuclear multiple-quantum coherence (GE-HMQC) in a 2.0-tesla magnetic field. Accumulations of [1-(13)C]glucose and [1-(13)C]sorbitol were mainly observed at the periphery of the lens. Their distributions corresponded to the cortex. (1)H-detected (13)C nuclear magnetic resonance (NMR) spectroscopic imaging by GE-HMQC successfully demonstrated the distribution of [1-(13)C]glucose and [1-(13)C]sorbitol at the periphery of bovine lenses.

[Localization of glucose and sorbitol in incubated bovine lenses using chemical shift imaging].

PURPOSE: To use chemical shift imaging (CSI) to measure the metabolic changes in glucose metabolites in bovine lenses incubated in tissue culture medium 199(TCM 199) with a high concentration of glucose and to evaluate the viability of this method. METHODS: We detected an accumulation of 13C-labeled glucose and sorbitol in the bovine lenses incubated in TCM 199 containing 50 mM glucose-1-13C for 1, 2, 4, or 6 days using a 2 T CSI Omega system. 1H-13C gradient-selected heteronuclear multiple-quantum coherence (GH-HMQC) in nuclear magnetic resonance (NMR), an indirect method of detecting nuclei in low sensitivity by 1H NMR, was used to observe 13C-enriched metabolites in the bovine lens in vivo. RESULTS: We found an accumulation of 13C-labeled glucose and sorbitol using the 2 T CSI Omega system. The level of glucose increased rapidly in the posterior segment of the lens as well as the anterior segment at one day after the beginning of incubation. Then it diminished gradually, and could no longer be detected on the 6th day after the start of incubation possibly because of the breakdown of the cell membrane. The levels of sorbitol increased in the anterior area and the equator of the lens one day after the beginning of incubation, and remained unchanged for 6 days. CONCLUSION: We encountered many problems especially with the imaging resolution (consequently the time for measurement was prolonged), but this approach may be useful for non-invasive monitoring of 13C-labeled compounds. We believe this method will be especially useful for detecting various metabolites in vivo.

Magnetic resonance imaging measurements of extraocular muscle path shift and posterior eyeball prolapse from the muscle cone in acquired esotropia with high myopia.

PURPOSE: To investigate extraocular muscle (EOM) path shift and prolapse of posterior eyeball from muscle cone in acquired esotropia with high myopia (AEHM), using magnetic resonance imaging. DESIGN: A case-control study. METHODS: There were 16 eyes with AEHM, 11 with high myopia (HM), 12 with moderate myopia (MM), and 11 control eyes. Extraocular muscle shift was evaluated by measuring angles formed by the line connecting orbital centroids and the line connecting each orbital centroid and each EOM centroid. The ratio of the prolapse in the posterior eyeball from the muscle cone was also measured. RESULTS: Both inferior shift of lateral rectus (LR) and nasal shift of superior rectus (SR) muscle were observed in the AEHM group, compared with HM, MM, and control groups. Neither shifted significantly in the HM group compared with control group. The prolapse ratio in AEHM group was higher than in the HM, MM, and control groups. Greater EOM shifts and eyeball prolapse were observed when the AEHM was more severe, as in esotropia fixus. CONCLUSIONS: In AEHM, a prolapsing eyeball shifts LR inferiorly and SR nasally; these findings were not observed in high myopia with neither ocular deviation nor restriction. These shifts reduce abduction and supraduction and increase infraduction and adduction in AEHM. The shifts would be predicted to create a hypoesodeviation, which is a common finding in AEHM. Both EOM shifts and superotemporal eyeball prolapse tend to be greater in esotropia fixus.

A muscle transposition procedure for abducens palsy, in which the halves of the vertical rectus muscle bellies are sutured onto the sclera.

PURPOSE: To review the results of a muscle transposition procedure in which the halves of the vertical rectus muscle bellies are sutured onto the sclera, without tenotomy of vertical recti as in Hummelsheim's procedure or surgical treatment of the lateral rectus (LR) as in Jensen's procedure. METHODS: Ten patients with abducens palsy received the procedure. We measured the ocular deviation and the field of single binocular vision, and observed the LR using magnetic resonance imaging (MRI). RESULTS: Preoperative or postoperative deviation was distributed from +27 to +58 prism diopters (PD) or orthophoria to +12 PD, respectively, in 7 patients with unilateral paresis, and +75 to +120 PD or +2 to +37 PD in 3 patients with bilateral paresis. The average correction was 42.4 PD per eye. Seven patients were able to regain the field of single binocular vision at least in the primary position. No postoperative complications were observed. MRI showed that the LR was atrophic and floppy, lacking muscle tension. CONCLUSIONS: Our procedure enabled the patients to obtain satisfactory postoperative results without treatment of the LR or tenotomy of the transposed muscles. This procedure can reduce operative damage to the eye more than Hummelsheim's or Jensen's procedure.

Common neural processing regions for dynamic and static stereopsis in human parieto-occipital cortices.

We performed functional magnetic resonance imaging to identify the neural processing regions in the parieto-occipital cortices for human dynamic and static stereopsis. The subjects were ten ophthalmologists professionally trained to do microscopic surgery. Visual stimuli for dynamic or static stereopsis were performed with solid stereograms displayed in the image guides of a binocular visual stimulation device that we developed. The dorsal occipital portion and the superior parietal lobule (i.e. dorsal parieto-occipital portion) were activated not only in static stereopsis, but also in dynamic stereopsis. The activation showed a right hemispherical dominancy. On the other hand, the temporo-occipital junction (i.e. human MT (middle temporal area) / MST (medial superior temporal area) complex) was activated in dynamic stereopsis. This demonstrates that the dorsal parieto-occipital portion is a common neural processing region for dynamic and static stereopsis.

Magnetic resonance imaging studies of the volume of the rabbit eye with intravenous mannitol.

PURPOSE: Changes in the volume of rabbit eyes after intravenous mannitol injection were studied non-invasively using 3D-magnetic resonance imaging (MRI). METHODS: Images of eight rabbit eyes were obtained using a 3D-gradient echo technique before and at 30, 60 and 90 minutes after mannitol injection at 4 g/kg. To evaluate the volume, the cross-sectional area of the eye in the central 5 slices was traced and totaled. The intraocular pressure (IOP) of five rabbits was measured before and after administration. RESULTS: The total area of the eyeball decreased significantly at 60 minutes. The total area of the anterior chamber, iris plus ciliary body decreased rapidly and then recovered. The decrease in the vitreous and the IOP was consistently significant during the 90-minute observation period. CONCLUSIONS: Consecutive MRIs enabled us to measure the changes in eye volume of the same rabbit before and after mannitol injection in a non-invasive manner.

An automated measuring system for fundus perimetry.

PURPOSE: In order to automate fundus perimetry, which is usually laborious because of the many manual operations and the frequent eye movements, we developed a new fundus perimeter with an automated measuring system using computer technology. METHODS: This fundus perimeter consists of an infrared fundus camera, a fundus-pursuit unit, and a target-display unit. Both units are personal computers operating on Windows. After presetting the measuring points on the fundus, perimetry is automatically performed. The fundus-pursuit unit recognizes and pursues the fundus reference region while calculating its coordinates in real time during perimetry. The target-display unit corrects the stimulus coordinates with data from the fundus-pursuit unit and even if eye movement occurs, automatically displays the stimulus targets at the correct retinal point that had been preset. RESULTS: Fundus perimetry can be automatically and precisely performed with this automated measuring system. It shortens the duration of the examination and frees the operator from the lengthy and laborious manual operations during perimetry. CONCLUSIONS: This automated measuring system will make fundus perimetry easier for the operator, as well as more popular for clinical use.