Biomedical subjects

G Baikoff

Publications and source records attributed to G Baikoff.

At least 19 recordsLinked to original sources

PubMed2005

[Multifocal phakic intraocular lens implant to correct presbyopia].

INTRODUCTION: Presbyopic surgery is considered as the new frontier in refractive surgery. Different solutions are proposed: myopization of one eye, insertion of an accommodative crystalline lens, scleral surgery, the effects of which are still unknown, and finally multifocal phakic implants. We therefore decided to undertake a prospective study under the Huriet law to determine its efficacy and specify the conditions required for an anterior chamber multifocal phakic implant. MATERIAL AND METHOD: Fifty-five eyes of 33 patients received an anterior chamber foldable multifocal phakic implant. Twenty-one females and 12 males underwent surgery. Initial refraction was between -5D and +5D. The implant's single addition was +2.50. Recuperating a distant uncorrected visual acuity of 0.6 or better and near uncorrected vision of Parinaud 3 or better can be considered a very good postoperative result. RESULTS: Average follow-up was 42.6+/-18 weeks. Mean postoperative refraction was -0.12+/-0.51 D. Mean postoperative uncorrected visual acuity was 0.78+/-0.20. Postoperative uncorrected visual acuity was Parinaud 2.3+/-0.6. Eighty-four percent of eyes operated on recuperated 0.6 or better without correction and Parinaud 3 or better without correction. Lenses in four eyes were explanted for different reasons, essentially optical, and no severe anatomical complications were observed. CONCLUSIONS: Placing an anterior chamber multifocal phakic implant to correct presbyopia is an effective technique with good predictability and has the advantage of being reversible in case of intolerance, optical parasite effects or undesired complications. Considering the particularity of this surgery, it is imperative to respect very strict inclusion criteria: anterior chamber depth equal to or above 3.1 mm, open angle, endothelial cell count equal to or above 2000 cells/mm2, absence of an incipient cataract or the slightest evidence of macular alteration.

Female↗

PubMed2005

[Refractive phakic IOLs: three different models and contact with the crystalline lens. An AC-OCT study].

Three patients received three different models of phakic implants. With the usual slit-lamp examination method, we were not able to establish whether there was contact between the implants and the natural crystalline lens. Using the anterior chamber optical coherence tomography scanner (AC-OCT), we were able to demonstrate that there was direct contact between the natural crystalline lens and the three different phakic implants. A dynamic study of these contacts was carried out during accommodation. These observations show that examination of the anterior segment with the optical coherence tomography scanner is essential in refractive surgery.

Accommodation, Ocular↗

PubMed2005

[Evaluation of capsular block syndrome with an anterior segment OCT].

A year after routine phacoemulsification and insertion of a soft posterior chamber IOL, a 59-year-old woman developed progressive moderate myopia. A syndrome of late capsular block was diagnosed following biomicroscopic examination, which was treated by Nd YAG laser posterior capsulotomy. The myopia disappeared immediately. This observation was illustrated with optical coherence tomography (OCT) developed for the anterior segment. After capsulotomy, the IOL moved backwards by 448 microm, which corresponds exactly to a--1D induced myopia.

Anterior Eye Segment↗

PubMed2005

[Analysis of the eye's anterior segment with optical coherence tomography. Static and dynamic study].

PURPOSE: To study the biometric modifications of the anterior segment depending on accommodation and age. To try and define their possible applications in certain fields of anterior segment surgery, in particular in refractive implants. MATERIAL AND METHOD: Anterior chamber biometry can be very easily studied with 1310-nm wavelength optical coherence tomography. The equipment has a fixation target that can be focused and defocused with negative lenses in order to stimulate natural accommodation. The human anterior chamber was therefore studied during accommodation. We studied 104 eyes of 56 patients aged between 7 and 82 years. Refraction was between +5D and - 5D. A single operator carried out all the measurements. The anterior chamber's horizontal diameter, the anterior chamber's depth, the horizontal pupil diameter and the horizontal radius of curvature of the crystalline lens' anterior pole were measured unaccommodated or after stimulating accommodation. RESULTS: The different static or dynamic measurements were compared to ametropia, age and accommodation. At rest, the average AC diameter was 12.33 mm, the average AC depth was 3.11 mm and the average pupil diameter was 4.26 mm. On average, for 1 D of accommodation, the crystalline lens anterior pole moved forward by 30 microm. There was a 0.3-mm reduction in its radius of curvature and a 0.15-mm reduction in pupil diameter. Several other measurements are illustrated on graphs. CONCLUSIONS: The AC OCT is a user-friendly instrument to evaluate the anterior segment and explore the anterior chamber (cornea, iris, crystalline lens, irido-corneal angle). The 1310-nm light wavelength is blocked by pigments preventing exploration behind the iris. However, the AC OCT is capable of providing good-quality images and a better visualization of the anatomical relationships of the anterior segment, even behind an opaque cornea.

Adaptation, Physiological↗

PubMed2005

[An in vivo OCT study of human natural accommodation in a 19-year-old albino].

Modifications of the anterior segment during accommodation of the eye under examination cannot be studied in a simple and direct way with anterior segment imaging techniques such as Scheimpflug photography, A Scan, B Scan, and UBM. With this equipment, it is necessary to stimulate the fellow eye in order to observe the variations of the analyzed eye. The techniques using ultrasound equipment can only be used with contact systems or with water baths that will modify the anatomical dimensions or the pressure of the anterior segment. With the Scheimpflug photographic technique, geometrical reconstructions are necessary and cannot be used in certain axes. Optical coherence tomography provides the advantage of producing non-contact images of the anterior segment in static and dynamic conditions that are then easy to use. The target of the optical system can be focused and unfocused with negative or positive lenses, thus reproducing the conditions of natural accommodation. With a normal subject, the morphological modifications of the crystalline lens behind the iris screen cannot be studied because the infrared light source used is blocked by the pigment epithelium. The absence of this pigment in an albino subject allowed us to study the modifications of the crystalline lens and the ciliary body during accommodation. In this study, we were able to definitely confirm all the modifications of the anterior segment as described by von Helmholtz in 1855, who, at the time, used very rudimentary optical procedures based on the reflections of a flame on the surface of the crystalline lens.

Accommodation, Ocular↗

PubMed2005

[Pigment dispersion and Artisan implants: crystalline lens rise as a safety criterion].

PURPOSE: To validate the theoretical notion of a crystalline lens rise as a safety criterion for ARTISAN implants in order to prevent the development of pigment dispersion in the implanted eye. MATERIAL AND METHOD: Crystalline lens rise is defined by the distance between the crystalline lens's anterior pole and the horizontal plane joining the opposite iridocorneal recesses. We analyzed the biometric measurements of 87 eyes with an Artisan implant. A comparative analysis of the crystalline lens rise was carried out on the nine eyes having developed pigment dispersion and 78 eyes with no problems. Among the modern anterior segment imaging devices (Artemis, Scheimpflug photography, optical coherence tomography, radiology exploration, magnetic resonance imaging, TDM), an anterior chamber optical coherence tomography (AC-OCT) prototype was used. RESULTS: This working hypothesis was confirmed by this study: the crystalline lens rise must be considered as a new safety criterion for implanting Artisan phakic lenses. Indeed, the higher the crystalline lens's rise, the greater the risk of developing pigment dispersion in the pupil area. This complication is more frequent in hyperopes than in myopes. We can consider that there is little or no risk of pigment dispersion if the rise is below 600 microm; however, at 600 microm or greater, there is a 67% rate of pupillary pigment dispersion. In certain cases, when the implant was loosely fixed, there was no traction on the iris root. This is a complication that can be avoided or delayed. CONCLUSIONS: The crystalline lens rise must be part of new safety criteria to be taken into consideration when inserting an Artisan implant. This notion must also be applied to other types of phakic implants. The distance remaining between the crystalline lens rise and a 600-micromm theoretical safety level allows one to calculate a safety time interval.

Adolescent↗

PubMed2000