The binocular accommodative response in uncorrected ametropia.

PURPOSE: To measure the changes in astigmatism and in the degree of anisometropia when ametropes respond to accommodative stimulation. METHODS: The accommodative responses of ametropes were binocularly measured with an improved photorefractometer (PR-1100), which objectively measured binocular refraction in all meridians simultaneously, when a visual fixation target was shown in natural space at 5 and 0.5 m. RESULTS: (1) Changes of astigmatism and anisometropia occur during binocular accommodation. (2) Changes of astigmatism mainly result from lag of accommodation in the horizontal meridian. (3) Changes of anisometropia result from the effort to focus. (4) The interaction of both eyes is suggested as the cause of the changes of astigmatism and anisometropia with accommodation. (5) In the majority of strong anisometropes (nonoverlapping group in this paper), the magnitude of anisometropia decreases (approaching isometropia) with accommodation. CONCLUSION: Changes in astigmatism and anisometropia can occur during accommodation, and these interactions of both eyes with accommodation may contribute to the development and maintenance of binocular function.

Effect of tetra-peptide isolated from interleukin 1 (IL-1) on corneal epithelial wound healing in the rabbit.

To develop a new method for wound healing in case of injured corneal epithelium, the effects of the tetrapeptide (Val-Leu-Leu-Lys), showing the consensus sequence between human interleukin (IL)-1alpha and bovine parotid protein (parotin) on epithelial cell proliferation and elongation were analysed in vitro cell culture experiments on epithelial cells obtained from rabbit cornea. The peptide showed dose-dependent stimulatory effects on epithelial cell proliferation and elongation at 10-100 microg ml(-1)compared with the control experiments. Furthermore, the peptide also exhibited a significant wound healing activity for the epithelial cells in an in situ experiment using mechanically injured rabbit cornea, while the higher concentration of the peptide (100 microg ml(-1)) showed greater efficient results than a previously known agent, sodium hyaluronate (0.3%). In addition, no pyrogenic activity of this peptide was detected by the previously established pyrogenicity test using rabbits. These results suggest that the tetrapeptide (Val-Leu-Leu-Lys) is a promising agent for wound healing in the case of injured corneal epithelium.

The Influence of Corneal Thickness and Curvature on the Difference Between Intraocular Pressure Measurements Obtained with a Non-contact Tonometer and Those with a Goldmann Applanation Tonometer.

Purpose: The influence of corneal thickness and curvature on the difference between intraocular pressure (IOP) measurements obtained with a non-contact tonometer (NCT) and those with a Goldmann applanation tonometer (GAT) was studied.Methods: The corneal thickness and curvature were obtained in 230 eyes of 115 subjects. The correlation between them and ratios of measurement with NCT to that with GAT ([NCT/GAT]) were examined.Results: [NCT/GAT] and corneal thickness showed a significant positive correlation (r = 0.556, P <.01), but, the correlation between [NCT/GAT] and the radius of corneal curvature was not statistically significant (r = -0.035, P =.30).Conclusion: The thick cornea has more influence on the measurement with NCT than GAT, because IOP is measured with NCT over a wider applanation area. The corneas with steeper curvature also cause higher corneal rigidity and produce more overestimation of NCT measurement, while they have stronger capillary attraction of the precorneal tear film for the GAT tip and also produce overestimation of GAT measurement. As a result, [NCT/GAT] was believed to be not influenced by the corneal curvature.

[The influence of corneal thickness and curvature on the difference between intraocular pressure measurements obtained with a non-contact tonometer and those with a Goldmann applanation tonometer].

PURPOSE: The influence of corneal thickness and curvature on the difference between intraocular pressure (IOP) measurements obtained with a non-contact tonometer (NCT) and those with a Goldmann applanation tonometer (GAT) was studied. METHODS: The corneal thickness and curvature were obtained in 230 eyes of 115 subjects. The correlation between them and ratios of measurement with NCT to that with GAT ([NCT/GAT]) were examined. RESULTS: [NCT/GAT] and corneal thickness showed a significant positive correlation (r = 0.556, p < 0.01), but, the correlation between [NCT/GAT] and the radius of corneal curvature was not statistically significant (r = -0.035, p = 0.30). CONCLUSION: The thick cornea has more influence on the measurement with NCT than GAT, because IOP is measured with NCT over a wider applanation area. The corneas with steeper curvature also cause higher corneal rigidity and produce more overestimation of NCT measurement, while they have stronger capillary attraction of the precorneal tear film for the GAT tip and also produce overestimation of GAT measurement. As a result, [NCT/GAT] was believed to be not influenced by the corneal curvature.

Accommodation causes with-the-rule astigmatism in emmetropes.

PURPOSE: To measure the changes in astigmatism when bilateral emmetropes accommodate. METHODS: Bilateral emmetropes accommodative responses were measured with an improved photorefractometer PR-1100, which measured binocular refraction in all meridians simultaneously as a fixation target was shown in natural space. RESULTS: The accommodative responses in the vertical meridian are greater than those in the horizontal meridian. In the horizontal meridian, the accommodative responses are less than the accommodative stimulus. CONCLUSIONS: When accommodating the majority of bilateral emmetropes show with-the-rule astigmatism and lag of accommodation in the horizontal meridian.

Determination of corneal gel dynamics.

From observations of the dynamics of light scattered by the cornea, intensity autocorrelation functions that revealed two independent diffusion coefficients, D (fast) = 2.4 +/- 0.2 x 10(-7) cm2/s and D (slow) = 9.4 +/- 1.3 x 10(-9) cm2/s, were obtained. The diffusion coefficients were found to be statistically independent of the position and depth on the lateral surface of the cornea from which the scattered light was sampled. The slow diffusion coefficients obtained from light sampled from within cross-sections of the cornea were, however, measurably different. Diffusion coefficients obtained independently from observations of the kinetics of corneal swelling for comparison were found to be several orders of magnitude greater than those obtained from light scattering. The large disparity in the diffusion coefficients obtained from the two independent methods invoked the possibility that the lamellar layers within the cornea behave as individual gel sheets. Irrespective of this additional hypothesis, divergent behavior in the measured total scattered light intensities and diffusion coefficients upon varying external conditions, such as temperature or pressure (stretching), was observed. Namely, a slowing down of the dynamic modes accompanied by increased "static" scattered light intensities was observed. Although the slowing down of the dynamic modes is possibly indicative of the reduced affinity of protein binding to the gel matrix that "softens" the gel, the divergent behavior in the scattered light intensities and diffusion coefficients is, however, more characteristic of a phase transition. In addition, the divergent behavior in the scattered light intensities and diffusion coefficients was reversible up to a critical temperature (approximately 50 degrees C) or stretching (approximately 16%).

[High-speed recording of fluorescein fundus angiography using an argon laser as the illumination source].

We constructed a new fluorescein fundus angiography system using a speedy and sensitive fundus camera and an argon laser apparatus as the illumination source. The system consists of a fluorescein fundus camera, a high-speed camera, a digital recorder, an argon laser apparatus, and a cathode ray tube(CRT)monitor. The frame speed was 200 frames/s. It was possible to record high speed fluorescein angiography with lower illumination by using an argon laser as the illumination source. This system allowed us to measure the rate of blood flow in the retinal vessels because it easily detected the dye front in the retinal vessels.

[Biocompatibility of polyvinylalcohol gel as a vitreous substitute].

Polyvinylacohol (PVA) gel cross linked by gamma irradiation was assessed as a possible vitreous substitute. In our previous, reports, elevation of intraocular pressure and inflammatory changes in the vitreous cavity after operation were observed in some of the experimental animals. Four types of PVA gel (sol) were produced by a newly refined method. We improved the gel systhesis process to remove the monomer and contamination. Colored rabbits were used for this experiment. Vitreous replacement was performed after vitrectomy. This was followed clinically by ophthalmoscopy, tonometry, fundus photography, electroretinogram, chemotaxis, and laser-flare-cell-metering. Histopathological examination by light microscopy was performed after 3 months. PVA gel has good biocompatibility in the vitreous cavity, and gel with a network similar to that of the vitreous body showed the best biocompatibility. Although it is necessary to investigate the biocompatibility over the long term and to evaluate the tamponade effect, PVA gel will be a bood candidate for a vitreous substitute.

[Optical characteristics of the human eye].

The optical characteristics of the eyeball are caused by its non-coaxial system. We show that the refraction changes throughout an individual's life. Results were obtained by a longitudinal study for ten years on patients (from 3-year-old to 58-year-old, 254 eyes of 127 persons) with only ametropia. We also did a longitudinal study for two years of healthy 3-year-old children (54 eyes of 27). However, we could not define the factors which control the refraction change. We examined the alteration of refraction induced by examination circumstances such as the size, shape, direction of fixation targets, and brightness of the room. Only minimizing size caused an increase of deviation range of astigmatism axis with miosis. Concerning a moving target from 5 m to 0.5 m, anisometropic eyes with the retinal conjugate point nearer to the target tended to track the target more closely than isometropic eyes.

Design concept and construction of a hybrid lamellar keratoprosthesis.

A novel hybrid lamellar keratoprosthesis composed of epithelium and stroma was developed. Artificial extracellular matrices were constituted of photocrosslinkable copolymers of N,N-dimethylacrylamide and 2-(7-coumaroxy)ethyl methacrylate; a copolymer with a high content of coumarin (A) was used as a basement membrane (BM) for the epithelium, and a copolymer with a low content (B) was used for entrapment of keratocytes. The lamellar keratoprosthesis was constructed as follows: First, a viscous buffer solution containing water-soluble copolymer (B), collagen, and keratocytes derived from rabbit was prepared. Then, a cast film of copolymer (A) was tightly placed onto the mixed solution. Ultraviolet light irradiation leading to intermolecular dimerization of coumarin groups resulted in the formation of a transparent keratocyte-entrapped hydrogel that was layered with an artificial BM. Epithelial cells were seeded on the BM. Further culturing produced the lamellar keratoprosthesis, within which both kinds of cells proliferated well. The preliminary study on two week implantation of the lamellar keratoprosthesis in rabbits provided quite promising results; adverse tissue reactions, such as corneal opacity and neovascularization, were not observed.

[A portable automatic infrared refractor].

In order to measure refractive errors in infants who cannot be measured by the conventional refractor, we have devised a portable automatic infrared refractor. This device has four unique advantages. The first is that an examiner can measure refractive states at any position. The second is an auto-start system. The third is that this device enables the patient to look at an external fixation object through the half-mirror of the handipiece. The fourth is its portability. From the measurements on 44 infant subjects, a good correlation between this device and the conventional refractor was obtained. The specifications are: minimal pupil diameter, 2.9 mm; measurement range: spherical power +/- 20 D, cylindrical power +/- 7 D. We believe that this device has wide applicability in clinical examination. For example, we can use this device for measurements of refractive states during cataract surgery.

Association of hyperimmunoglobulinaemia D syndrome with erythema elevatum diutinum.

Hyperimmunoglobulinaemia D and periodic fever syndrome was observed in a female patient with erythema elevatum diutinum. The association of this skin disease with hyperimmunoglobulinaemia D may indicate a pathogenetic relationship. The skin lesions responded to dapsone therapy.

Visual-evoked potentials elicited by laser speckle patterns. Studies on the characteristics and assessment of visual function in patients with ocular media opacities.

Visual-evoked potentials (VEPs) were recorded using a laser speckle pattern. Stimulation with a speckle pattern was elicited either by pattern appearance-disappearance or by pattern shift. The VEPs obtained by this method were similar in properties to the previous pattern VEPs that were obtained either by pattern appearance-disappearance or by pattern reversal. Patients in whom dense and diffuse ocular media opacity defied measurement by the interferometric visual acuity method were studied to test if the speckle pattern generated by diffusion from lens opacity itself could act as a stimulus for obtaining VEPs. It is concluded that the present method enables one to obtain a reliable VEP and to assess the visual function of the retino-cortical system, even in patients with mature cataracts.