Roth Contact Lens Complications

Etiology, Pathogenesis, Prevention, Therapy
1. Auflage 2003
ISBN: 978-3-13-257811-1
Verlag: Thieme
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 224 Seiten, ePub

Reihe: Thieme

A widely popular option for vision correction, contact lenses are also useful for the treatment of many serious optical disorders. Like any therapeutic tool, however, they have both positive and negative effects, and a variety of complications can result from their use. Diagnosing and treating these complications and injuries - which sometimes mimic eye diseases - can be complex. Drawing on more than 25 years of knowledge and experience, Contact Lens Complications is the first text to provide a practical, comprehensive overview of the eye injuries caused by wearing contact lenses. This book is filled with hundreds of outstanding, full-color illustrations of problems associated with contact lenses, including eyelid lesions, eye tears, hygiene complications, and lens accidents. You will learn how to confidently manage these problems and effectively distinguish them from common ophthalmic diseases. Additionally, the book covers: treatment guidelines; patient examination and counseling; types of contact lenses available today; common lens fitting and wearing problems; and much more! More than 450 exquisite color photographs and illustrations to facilitate quick injury/disease diagnosis Meticulous, step-by-step techniques for eye examination Easy-to-understand terminology, even to those new to contact lens patient care Clear and concise disease prevention guidelines Practical patient management tips Contact Lens Complications gives medical professionals factual, clear, current information on the injuries and complications caused by wearing contact lenses. Essential for anyone involved in vision care, this authoritative and eminently practical work is certain to become a key resource in the field.

Hans-Walter Roth

Zielgruppe

Ärzte

Autoren/Hrsg.

Roth, Hans-Walter

Fachgebiete

• Medizin | Veterinärmedizin Medizin | Public Health | Pharmazie | Zahnmedizin Klinische und Innere Medizin Augenheilkunde, Optometrie

Inhaltsverzeichnis

1 Problems Caused by Contact Lenses
2 Patient Counseling and Examination
3 Pathologic Findings
4 Visual Impairment
5 Causes of Contact Lens Damage
6 Alterations of Contact Lenses
7 Primary Fitting and Wearing Problems
8 Eye Injuries in Contact Lens Wearers
9 Frequency of Contact Lens Complications
10 Treatment of Contact Lens Complications

Leseproben

2 Patient Counseling and Examination

Patient Counseling

History Taking

Examination

General

Lid

Conjunctiva

Cornea

Inner Eye

Intraocular Pressure

Refractive Error and Visual Acuity

Binocular Vision

Inspection of Contact Lenses

Inspection of Contact Lens Cases

Documentation of Findings

Follow-up

Patient Counseling

All patients need thorough counseling and instruction before they choose the type of contact lenses they will wear and as they begin to wear them. The major issues to be addressed are listed in Table 5. The choice of contact lens is not simply a matter of finding the type that gives the best cosmetic result, as patients may at first assume, but requires consideration of patient-specific risks and other factors, particularly the patient's living and working environment. Despite recent advances in soft-lens technology, hard lenses are still better tolerated over the long term, though hydrophilic lenses may be better suited to the patient's lifestyle and desired manner of wearing. For patients who plan to wear contact lenses only occasionally, soft lenses are preferable; those who plan to wear contact lenses instead of spectacles over the long term are better served with hard lenses. Patients should be informed, however, that switching from hard contact lenses back to spectacles may be difficult. Long-term wearing of hard contact lenses can cause irregular astigmatism, leading to diminished visual acuity and increased glare; this is the so-called spectacle blur phenomenon. It often takes several months after the cessation of contact lens wear for these symptoms to resolve so that vision with spectacles is as good as before.

Lens care products are to be regarded as medications, and due attention should be paid to their storage, stability, and expiration dates. Every contact lens wearer should be adequately instructed about their use, effects, and potential complications. The proper choice of lens care system depends not only on the type of lens, but also on the type and rate of deposition on the lens surface, which varies from patient to patient. Those for whom lens care is difficult, such as patients with arthritis, should use only one cleaning agent, if possible. Those with particularly sensitive eyes should use hydrogen peroxide. Careful consideration should be given to the possible use of an additional cleaning solution, or of enzyme tablets.

The ever-decreasing cost of contact lenses and the introduction of disposable lenses have misled many wearers to imagine that contact lens optics is a routine matter, and that their purchase and use are a retail business like any other. Yet the fitting of contact lenses actually demands the highest expertise of the ophthalmologist and optician. Additionally, their physical specification and manufacture are an intricate technical process, at whose end the lenses can be safely handed over to the patient only when all of the problems discussed above have been resolved, unnecessary risks avoided, and possible contraindications ruled out. Finally, the prescriber of contact lenses must be certain that the patient can care for them properly and knows the problems that may arise with improper use.

Table 5 Patient education

General reasons for wearing contact lenses Pros and cons of contact lenses . spectacles Problems in switching between contact lenses and spectacles Problems in the workplace Limited wearing time Lens handling, insertion, removal Lens cleaning Lens disinfection Frequency of replacement of short-term lenses Contact lenses and use of medication Contact lenses in patients with chronic illnesses Follow-up examinations by the fitter or ophthalmologist What to do in an emergency

History Taking

The patient's past medical history and review of systems may indicate the presence of an acute or chronic illness that would increase the risk of wearing contact lenses. Such illnesses, a history of major trauma, and the chronic use of medications of certain types may contraindicate wear. The use of oral contraceptives, pregnancy, and breastfeeding are also limiting factors. The patient should be asked about prior ocular injuries, infections, other diseases, and the prior use of eye drops.

If the data are available, the physician should also note any changes over time of the patient's spectacle prescription, which may indicate a progression of the refractive error. Finally, the patient should be asked whether contact lenses were previously prescribed or worn, with what result, and why a previous fitting was unsuccessful, if this was the case.

Examination

General

The tasks of the ophthalmologist include ocular examination before contact lens fitting, monitoring for potential problems in the initial adaptation phase, and regular follow-up thereafter. The routine ophthalmological examination of the contact lens wearer is the same as that of any other patient; its most important elements are listed in Table 6. Yet a few special considerations deserve mention in this section.

Most problems due to contact lenses develop slowly and become manifest only after a variable interval. It is thus desirable to document the findings regularly with any of the numerous photographic and video systems now available for clinical use, with which the data may be digitally stored and statistically processed.

The improved safety of modern synthetic materials and lens care products has greatly lessened the risks associated with contact lenses, but wearers must nonetheless be followed up regularly for the prevention of ocular damage, and particularly of slow, cumulative damage over the long term.

Table 6 Initial visit or annual follow-up examination of the contact lens patient

General medical history, ocular history Lids Conjunctiva Cornea Sclera Anterior chamber Pupillary mobility Crystalline lens Vitreous body Fundus Visual fields Refractive correction (objective, subjective) Visual acuity Binocular vision Corneal diameter Corneal thickness Corneal topography Tear flow Intraocular pressure (in all patients over age 40 and those with progressive myopia, suspected glaucoma, or a positive family history)

Ocular examination before, during, and after contact lens fitting thus serves not only for the immediate detection of acute complications, but also for the early detection of incipient long-term complications, which may affect either the anatomy or the physiology of the eye. We therefore recommend adherence to the classical sequence of the routine ophthalmological examination: visual acuity, motility, lids, conjunctiva, cornea, anterior and posterior chambers, retina, and intraocular pressure.

Not only the eyes, but also the contact lenses should be examined. Any abnormalities of lens position, surface depositions, staining, defects, and changes in parameters should be noted. Microbiological tests may reveal poor lens hygiene and an elevated risk of infection. One should also try to determine whether the patient has a proper understanding of lens care. Dirty hands or a dirty lens case indicate that this is not so.

Lid

Inadequate opening or closure of the eyelids, excessive blinking, or blepharospasm will be immediately visible to the examiner without special equipment. Ordinary daylight is best for examination of the lids. A check for symmetry readily reveals any monocular abnormality, such as ptosis.

The normal interpalpebral space is almond-shaped and of equal height on the two sides. The lids snugly overlie the globe and point directly upward (lower lid) and downward (upper lid). The nasal canthus makes a sharp corner, while the temporal canthus is rounded. The lacrimal puncta are fully immersed in the lacrimal menisci.

The skin of the eyelids is very thin and elastic, and care must be taken to avoid injuring it when spreading the lids apart to insert contact lenses, particularly in infants and toddlers. Children's lids are soft and smooth, those of elderly persons baggy and wrinkled.

Pathological changes of the lids are often the first sign of an adverse reaction to the lens itself, or to lens disinfectants or cleaners. The skin between the lashes should be examined carefully with a slit lamp under high magnification to detect early reddening and scaling. These findings mandate discontinuation of the contact lenses, as they are predictive of toxic keratopathy, which does not appear till much later. Particular vigilance is required in patients with a history of squamous blepharitis, which predisposes to such problems and is thus a relative contraindication to the wearing of contact lenses.

Conjunctiva

The conjunctiva, an elastic, highly vascularized tissue lying in an exposed position between the globe and the lids, responds to all forms of irritation from within or without by vasodilatation, which is visible as conjunctival hyperemia (injection). This most common abnormal finding associated with contact lens problems often provides the key to their detection and differential...

Über Autor(innen)

Hans-Walter Roth