V. Dragomirescu

Photographic Documentation of Disturbances of the Lens Transparency during Ageing with a Scheimpflug Camera System

Due to its limited depth of focus, the conventional slitlamp photography is not suitable for the documentation of a total lens section which depends on a sufficient depth of focus. By applying the Scheimpflug principle it is, however, possible to demonstrate the optical section through the lens as a slit image which is nearly undistorted and shows sufficient depth of focus. An integrated instrument based on the Scheimpflug principle has been developed, and the present paper demonstrates its importance for clinical and experimental use. After densitometric evaluation, these photos enable to obtain hard data on normal and pathologically changed lenses. Different densitometric methods may be employed for the evaluation. Experiences with the equipment from running clinical test series are reported.

Improved Biometry of the Anterior Eye Segment

In this paper, a method is presented to evaluate the true values of several optical parameters of the anterior eye segment. These are: the thicknesses of the cornea and lens, the depth of the anterior chamber and the anterior and posterior curvatures of the cornea and lens. First, a photo is taken of each patients eye with a Topcon SL-45 Scheimpflug camera. There are two effects distorting the photo. As the film plane and the object plane are perpendicular to each other, the imaging scale is not constant over the photo, a phenomenon which is called the camera distortion. As the light passes through different refractive media on its way from the inner structures of the eye to the camera, the rays of light are refracted, which is called the refractive distortion of the eye. Following these distortions, the proportions on the photo do not correspond to those in the human eye. The intention of this paper is to calculate the true optical parameters of the anterior eye segment. The seeming optical parameters are taken from the photo and the path of light from a point in the film plane through the camera and the refracting surfaces into the eye is constructed by ray tracing. A set of representative points calculated according to ray tracing provides a basis to evaluate the true optical parameters. This work is done using a Basic program, that accepts the seeming parameters from the photo as input values and provides the true values as output. The adjectives seeming and true added to the optical parameters indicate a value correlating with a distorted photo and a value that was corrected by the theory. The two terms were chosen by mnemonic reasons, although another pair of adjectives such as distorted and corrected might have been of higher precision. For an average adult human eye the optical parameters from the photo were compared with the calculated ones. A phantom eye with well-known optical parameters was constructed and photos were taken from this eye to verify the calculations.

Biometry of the Anterior Eye Segment by Scheimpflug Photography

Scheimpflug photos of 262 cataract patients, classified according to various forms of opacifications characteristic for senile cataracts were evaluated by biometric methods. The measured values on cornea thickness, depth of anterior chamber, lens thickness, and radii of curvatures of cornea and anterior lens surface show that a correlation between some of the parameters and certain forms of opacities must be assumed.

Photo-Cell Device for Slit-Beam Adjustment to the Optical Axis of the Eye in Scheimpflug Photography

In the photographic documentation of lens findings according to Scheim-pflug’s principle, a good reproducibility of the camera adjustment to the patient’s eye is prerequisite for quantitative densitom

In vivo Lens Fluorescence Photography

We are reporting a new, objective and quantitative method for monitoring age-related molecular changes in the human ocular lens in vivo, as expressed by increases in at least two (nontryptophan) fluor

Long-term follow-up examination of experimental cataracts in rats by scheimpflug photography and densitometry

Development of experimental cataract can be objectively monitored in rats by application of Scheimpflug photography with the SL 45 Topcon camera and subsequent densitometric image analysis. The method has been used to study naphthalene cataract in Brown-Norway rats (BN-CPB), as well as diabetic cataract induced by streptozotocin injection in Sprague-Dawley rats. The values obtained by linear microdensitometric image analysis allowed precise characterization of the opacification with respect to size, topography, and time progress so that statistical evaluation of the efficacy of certain drugs in prevention or delay of experimental cataracts was possible.

Monitoring lens transparency during in vitro incubation by Scheimpflug photography and densitometric image analysis

Dragomirescu et al. [1983] described a 2-chamber flow system for the incubation of lenses with an inserted photometer to measure changes in lens transparency. Mester et al. [1984] applied the method to simulate conditions occurring during vitrectomy, which occasionally leads to reversible lens opacification. Using Scheimpflug photography (a modified SL 45 Topcon camera) instead of the transmission measurements of incubated lenses has the advantage that disorders in lens transparency can be exactly localized and the sensitivity is much higher than the photometer readings. Application of Scheimpflug photography required a modification of the incubation chamber. The application of the experimental set-up was demonstrated with pig lenses under various incubation conditions. The results obtained by densitometric image analysis of Scheimpflug photos were compared with transmission measurements by photometer.

Evaluation of the Ocular Safety of Verapamil

The ophthalmic examination of patients with hypertrophic cardiomyopathy treated with high doses of verapamil over a considerable period of time showed no evidence of a side effect of the drug, thus pr

Light Scattering in the Human Lens in Childhood and Adolescence

The age-related increase in normal light scattering in the adult human lens has frequently been documented with Scheimpflug imaging techniques. There are only insufficient data on lens light scattering, however, from the first 2 decades of human life. After having obtained informed consent from their parents, the anterior eye segments of 26 children of both genders were documented with a Topcon SL-45 Scheimpflug camera on Kodak Tmax 400 ASA black-and-white film in 3 meridians. The age of the children, who had either a normal visual acuity or best corrected visual acuity, ranged from 4 to 18 years. Thirty minutes prior to photography, maximal mydriasis was induced by 3-fold instillation of Mydriaticum Roche®. Parallel to the Scheimpflug photographic documentation, all eyes were subjected to a basic ophthalmological examination. All images obtained were evaluated with microdensitometry as described earlier. The density data in young children demonstrate that there is very little light scattering in the central lens parts and only a faint zone of discontinuity apart from the 2 signals caused by the anterior and posterior capsules. Starting at the age of 14–15 years, the first separations occur in the zones of discontinuity, thus the first age-correlated increase in light scattering. The data obtained demonstrate that the development of light scattering in the young lens differs from that in the adult lens. Our results point to the assumption that the development of protein light scattering in the lens correlates with physical life-time of the individual and not with the period of life in different species with various life expectancies.

Experimental Fluorescein Findings in Rat Eyes after Retinal Laser Coagulation

A fluorescence angiographical and histological study has been carried out using rat eyes treated with different laser intensities, as an attempt to compare the effect of a single spot with multiple sp