Different Types Of Lenses Research Articles

Varieties of Contact Lens Fittings After Complicated Hyperopic and Myopic Laser In Situ Keratomileusis

To determine whether contact lenses with a special back surface design can improve visual acuity after complicated laser in situ keratomileusis (LASIK). Fifteen eyes (six after myopic LASIK and nine after hyperopic LASIK) of eight patients were fitted with contact lenses with a special back surface design for optical rehabilitation. Four different types of lenses (aspheric, tricurve, keratoconus, and reverse) were used selectively, depending on the abnormal eccentricity (positive and exceeding 0.5-0.7 in all preoperatively hyperopic eyes, negative in all preoperatively myopic eyes) determined by videokeratoscope and on individual conditions. The patients were followed up retrospectively for an average period of 12.3 months. Lens tolerance and corrected visual acuity were evaluated and compared with the results obtained with spectacles. Visual acuity improved in nine (60%) of 15 eyes (three eyes by more than three lines and six eyes by three lines or fewer), with an absence of halos and ghost images in four (26.7%) of 15 eyes accompanied by good contact lens tolerance and a satisfactory contact lens fit. There were no noticeable complications. Contact lens fitting after LASIK is a safe and reliable procedure for improving visual acuity and reducing complications, such as ghost images or irregular corneal surface. Depending on the eccentricity and therefore on the preoperative refraction, contact lenses with a special back surface design can minimize problems in contact lens fitting and can improve tolerance and visual results.

Occlusion Properties of Contact Lenses for the Treatment of Amblyopia

Introduction: A search of the literature has shown instances when contact lenses have been used in treatment of amblyopia. Contact lenses have been designed and marketed to give a cosmetically normal appearance to eyes that have been scarred or deformed. Purpose: The purpose of this study were to determine the efficacy occlusive contact lenses in limiting visual acuity in normal eyes and to determine if any peripheral fusion is available with different types of lenses. Participants: Ten healthy volunteers, ranging in age from 18 to 30, were recruited.

Contact lens prescribing in a specialist medical contact lens clinic based in an NHS hospital: an audit of changing practice.

To describe the range of indications for contact lenses and the types of lenses being used in an NHS hospital-based specialist medical contact lens clinic and contrast this with information from 12 years ago. A retrospective audit of 596 clinic attendances was performed in the contact lens clinic at the Western Eye Hospital between April 2002 and March 2003. The results were compared with a similar audit performed in 1991. We used the hospitals electronic records, and information on contact lens prescribing was obtained directly from the receipts generated by the contact lens department and the accounts department. We saw 392 patients with 88.5% of patients requiring 2 or less visits per year. The majority of referrals are for high myopia (28.6%) closely followed by aphakia (25.2%) and keratoconus (24.7%). This is in contrast to 1991 when 68% of referrals were for aphakia and twice as many myopes (17%) were seen as keratoconus patients (8%). A total of 560 lenses were prescribed with 68 different types of lens in use. The seven most commonly used lens types accounted for 61% of all lenses prescribed. Medical contact lens clinics provide a specialist service and also provide an important training resource for junior ophthalmologists. Safer cataract surgical techniques have had a significant impact on the case mix seen in our clinic, with the emphasis moving away from aphakic and myopic patients and toward the more challenging to fit eyes with keratoconus or postcorneal surgery.

A comparison of the use of an ATP-based bioluminescent assay and image analysis for the assessment of bacterial adhesion to standard HEMA and biomimetic soft contact lenses

The aim of this study was to investigate in vitro adhesion of clinically relevant bacteria to standard HEMA and novel biomimetic soft contact lenses (SCL) using bioluminescent ATP assay and image analysis. Unworn SCL were incubated with Pseudomonas aeruginosa, Staphylococcus epidermidis or Serratia marcescens suspended in sterile phosphate buffered saline (PBS). The level of bacterial adhesion after 1, 2, 4, 6 and 18 h, was assessed using both image analysis and a bioluminescent ATP assay. Species differences in the overall level of adhesion to the different types of lens were observed using both measurement techniques. Generally bacterial adhesion was shown to peak at 4–6 h, then decline to a much lower level by 18 h. After 4 h, adhesion of all species of bacteria to the biomimetic SCL (omafilcon A) was found to be significantly lower than to the standard HEMA SCL (polymacon) ( p<0.05, Student's t-test, n=4). Both these techniques demonstrated that novel biomimetic SCL materials exhibit significantly lower bacterial adhesion in vitro compared to standard HEMA SCL materials. SCL manufactured with these novel biomimetic materials may reduce the risk of infection.

Tolerant low-loss three-lens coupling system for 1.48-μm unstable-cavity lasers

A 1.48-/spl mu/m unstable-cavity laser is coupled into single-mode fiber using three microlenses. Reproducible coupling of very high power is demonstrated with different types of lenses (plano-convex or biconvex, with different apertures). Over 550 mW in single-mode fiber (SMF) were reproducibly reached; to our knowledge, it is the highest power coupled into an SMF from a single semiconductor laser at this wavelength. Tolerance measurements on all of the coupling elements of a three-lens system are reported for the first time; an unexpected very large tolerance an the axial displacement of the second lens was measured. Results and interpretation with the aid of Gaussian and aberration simulations are also presented.

Preventing complications in people who wear contact lenses.

The number of contact lens wearers has steadily increased over the past 10 years. Convenience, efficiency and availability of different types of lenses have made them popular. The rise in the use of contact lenses has increased the number of people at risk of contact lens-related complications. Studies have highlighted the consequences of poor contact lens care. Acanthamoeba keratitis is one of the most devastating complications of contact lens wear and can be avoided by adhering to the recommended contact lens regimen. This article reviews the literature on the complications of contact lens wear and stresses the need to educate the wearer. It examines the nurse's role in relation to health promotion and the basic principles for successful long-term contact lens wear. This information is relevant to all nurses caring for people with contact lenses and will be of particular interest to the nurse who wears contact lenses.

Astigmatism revisited: A case report

This report presents a specific case of anisometropia: the right eye showing a myopic condition with a slight amount of against-the-rule astigmatism, with the left eye with hyperopia and a large amount of with-the-rule astigmatism. The main interest in such a case is how to fit both eyes properly using the materials and techniques available. Four different types of lenses are considered. In this particular case, a bitoric lens with toroidal periphery represents the most adequate alternative to meet all the clinical standards of a good fit.

RGP manufacturing and fitting

This report presents a specific case of anisometropia: the right eye showing a myopic condition with a slight amount of against-the-rule astigmatism, with the left eye with hyperopia and a large amount of with-the-rule astigmatism. The main interest in such a case is how to fit both eyes properly using the materials and techniques available. Four different types of lenses are considered. In this particular case, a bitoric lens with toroidal periphery represents the most adequate alternative to meet all the clinical standards of a good fit.

3 years' experience with anterior chamber lenses, especially with the hook-loop lens

In the course of three years 210 intraocular lenses (Binkhorst, Schott, Worst, hook-loop lens) were implanted. The report describes the surgical technique, complications and the advantage and disadvantages of the different types of lens. The authors consider it important only to implant lenses which permit maximum postoperative mydriasis.

Retinal detachments after intraocular lens implants.

Intraocular lenses are a challenge to the retina surgeon. Forty-three eyes with pseudophakia and retinal detachment were examined. Intracapsular and extracapsular cataract extractions had been performed, and different types of lenses had been implanted. The single most important factor for the successful repair of these pseudophakic detachments was visual access to the retina.

Outline of Ocular Refraction.

This is an exceptionally interesting and valuable book, written by one who has evidently had considerable experience in all the practical details of prescribing glasses, from the initial refraction done in the office to the grinding of the lenses and the fitting of frames. The chapter on applied optics deals chiefly with the theory of glasses and contains many tables which are of value and are not often found in less practical books, such as the table giving the values of decentration of cylinders at different axes and that giving the effective powers of different types of lenses. The most stimulating chapter is that on ocular physiology, which is chiefly concerned with the relation of the muscle balance to the static and dynamic refraction. The main thesis of this is that the tonic innervation of the ocular muscles, determined by dissociation tests such as the Maddox rod, is not the