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Biomedical subjects

W M Lyle

Publications and source records attributed to W M Lyle.

At least 19 recordsLinked to original sources
PubMed2001

Granular corneal dystrophy: slitlamp biomicroscopic appearances in three generations of patients.

PURPOSE: The purpose of this case series is to show photographically the varying clinical appearance of granular corneal dystrophy in three generations of one family and to review the genetic basis of this and related conditions. CASE SERIES: We present cases for four affected individuals along with slitlamp biomicroscopic photographs. DISCUSSION: A review of the photographs and the literature suggests that the abnormal keratoepithelin first appears in the superficial cornea as faint subepithelial opacities. With time, these become arranged in the curved lines of a vortex pattern, after which the deposits become scattered in no particular pattern and at all levels of the cornea. In this family, corneal erosions are a regular feature. Mutations of the gene coding for keratoepithelin (beta ig-h3) may give rise to variable clinical manifestations.

Adolescent↗
PubMed1997

The prevalence of selected ocular diseases and conditions.

It is useful for a clinician to know how common or rare a given ocular disease or condition is. Knowledge of a condition's prevalence provides a rough indication of how often to expect to encounter it in a clinical setting. Furthermore, knowledge of a condition's prevalence can assist in planning the health service requirements necessary to treat it. The acquisition of prevalence data from the literature, however, can be difficult and time-consuming because of the wide range of journals that have published relevant information. This article is a complication of some of the available data from the literature regarding the prevalence of many ocular diseases and conditions. It also includes a few systemic diseases with ocular involvement.

Age Distribution↗
PubMed1997

Albinism: an update and review of the literature.

BACKGROUND: Albinism can be a diagnostic challenge to the optometrist, with ocular albinism the entity most likely to be overlooked or misdiagnosed. Albinism should be suspect in a child with nystagmus. METHODS: Albinism is best diagnosed by electron microscopy of skin or hair bulbs. Measuring the flash visually evoked response (VER) is the best way to confirm the abnormal decussation of the optic nerve fibers. Transillumination of the iris can be performed to see if it lacks pigment on its posterior surface. Optometrists should also be alert for nystagmus, strabismus, lack of stereopsis, and poor fusional capacity. Most people with albinism have photophobia and reduced acuity, and many have defective hearing. RESULTS: This review describes the various kinds of albinism and summarizes associated ocular manifestations with pertinent forms of the disorder. CONCLUSIONS: Optometrists are responsible for detection of albinism and provision of optical aids and related advice to afflicted patients. These patients also need appropriate counselling and genetic studies of family members.

Albinism, Oculocutaneous↗
PubMed1996

Impact of using weighted versus unweighted measures to assess optometry faculty productivity in research.

BACKGROUND: Activities in scholarship and research are commonly self-reported in terms of the number of publications per calendar year or grant-tenure period; individuals might show widely different productivities at different times but specific data on this do not appear to be available for optometry school faculty. METHODS: Using a data base generated from a 20-year activity period at an optometry school, the impact of calculating publication rate by self-reporting or weighted scaling (linear or exponential) according to co-authorship on such publications was assessed for each individual faculty member. RESULTS: Results are presented from a faculty productivity perspective on a calendar year basis or with the faculty members matched for seniority on a year-by-year basis. CONCLUSIONS: The use of weighted scaling to productivity assessment substantially reduced the net output from the faculty in most of the 20 years assessed. The average weighted productivity was generally close to two published articles (excluding book chapters) per year, per faculty member compared to close to three articles per year per faculty member, using self-reported unweighted data.

Faculty↗
PubMed1995

Viral hepatitis: a review.

Viral hepatitis is neither a single disease condition nor is it caused by a single viral agent. Viral hepatitis can cause a wide spectrum of systemic manifestations. Here we concentrate on the five unrelated hepatitis viruses whose effect is limited almost entirely to the liver. More than 60,000 cases of viral hepatitis are reported to the U.S. Centers for Disease Control each year, although it is estimated that more than 300,000 cases actually occur. Some of the hepatitis viruses are present in all bodily fluids and, therefore, without adequate precautions, may be transmitted to either the health care provider or between patients in a clinical setting. The severity of an infection can be extremely variable among infections by the different virus types, as well as by a single virus type. Manifestations can range from the subclinical to the seriously acute to the chronic. In extreme cases, death can also result from infection, via such acute and chronic pathways as fulminant hepatitis, hepatocellular carcinoma, and cirrhosis of the liver. Because viral hepatitis is widely prevalent, can be transmissible in a clinical setting, and can have serious and long-lasting health consequences, all optometrists should be aware of some of the facts regarding viral hepatitis infections.

Acute Disease↗
PubMed1995

Medications used to prevent migraine headaches and their potential ocular adverse effects.

We present a detailed review of the medications used in the USA, Canada, and the United Kingdom for the prevention of migraine and the potential ocular adverse effects associated with the use of these medications. Those drugs that are administered for the purpose of reducing the frequency or severity of migraine attacks are classified according to whether they act on the cerebral vasculature primarily at serotonin (5-HT2) receptors (e.g., methysergide, cyproheptadine, and pizotyline), beta adrenergic (primarily beta-2) receptors (e.g., propranolol and timolol), via central nervous system (CNS) adrenergic (alpha-2) receptors (e.g., clonidine), or calcium channels (e.g., flunarizine). The roles and mechanisms of action of tricyclic antidepressants (e.g., amitriptyline) and nonsteroidal anti-inflammatory drugs (NSAIDs) in the prophylactic management of migraine are also discussed, along with possible pharmacogenetic differences in the kinetics of action of some of these drugs. The general indications, contraindications, and potential ocular and systemic adverse effects of each class of drugs is reviewed and presented along with the references to original literature on these effects.

Adrenergic alpha-Agonists↗
PubMed1994

Large sample study of the effects of phenylephrine 2.5% eyedrops on the amplitude of accommodation in man.

A single drop of phenylephrine 2.5% (MYDFRIN) was instilled into the eyes of 160 volunteers (aged 20 to 30 years) and their amplitude of accommodation assessed under standard illumination using a push-up technique without an artificial pupil. The amplitude was assessed every 5 or 10 min over a period of 90 min. Within 30 min, nearly 75% of the subjects showed a measurable change in amplitude. Overall, the amplitude declined slowly with time to realize an average 11% reduction from an average starting amplitude of 10.7 D. A large range of responses from a 30% increase to a 60% decrease in amplitude was, however, observed. Subjects with large amplitudes of accommodation were more likely to show significant decreases while some subjects with smaller amplitudes showed an apparent increase in accommodation (r2 = 0.176). The phenomenon was observed in both blue- and brown-eyed subjects and in non-contact lens wearers and soft contact lens wearers (r2 values of 0.144 to 0.265).

Accommodation, Ocular↗
PubMed1993

Role of lasers in eye care.

This review discusses the role of lasers in eye care under five headings: Absorption of laser radiation by ocular tissues. Types of lasers include: ruby, argon, gas, organic dye, krypton, Nd:YAG, excimer, and infrared. Applications of lasers for examining the eye include: laser refraction, determining visual acuity by laser fringes, measuring retinal blood flow, scanning laser ophthalmoscopy and tomography, measuring aqueous flare, ocular holography, measuring retinal absorption, measuring visually evoked potentials, and measuring corneal sensitivity. Applications of laser radiation for ocular surgery include: photocoagulation, destruction of tumors, reattaching the retina, treating glaucoma by producing an iridotomy or by trabeculoplasty or by cyclodestruction. Lasers can be used to remove surface irregularities or superficial opacities from the cornea or eyelids. Other uses are for producing a capsulotomy and for altering corneal curvature as a means of correcting ametropia. Potential adverse effects of laser radiation on the eye are summarized.

Eye Diseases↗
PubMed1993

The optometric literature: an editor's perspective.

I reviewed optometric literature trends and compared them with those of the medical literature. Several journals were surveyed and the published articles classified and counted over 5 or more years. Parallel changes seem to be occurring in the medical and optometric literature, including shorter articles, more authors per paper, and fewer case reports and anecdotal reports. It is impractical and unproductive to attempt to classify a paper as basic science or clinical science because the disciplines overlap. Fads wax and wane over cycles of about 10 years. Clinical research needs more support.

Optometry↗
PubMed1992

A review of the clinical pharmacokinetics of pilocarpine, moxisylyte (thymoxamine), and dapiprazole in the reversal of diagnostic pupillary dilation.

An alpha-adrenergic blocking drug, dapiprazole, is now marketed in eyedrop form. Dapiprazole is being promoted as an agent suitable for reversing the diagnostic mydriasis produced by tropicamide or tropicamide and phenylephrine. The mechanism of action of dapiprazole is thought to be the same as that of moxisylyte (thymoxamine). The human pharmacokinetics for these drugs are reviewed and compared to pilocarpine. Published data indicate that either dapiprazole (0.5%) or moxisylyte (0.5%) enhance recovery from the mydriasis produced by tropicamide, phenylephrine, or their combination. However, because the published studies differ substantially in the doses of these mydriatics or in the miotics actually used, it is not possible to make any firm recommendations on how many drops of these new miotics should be instilled.

Adrenergic alpha-Antagonists↗
PubMed1986

Does prior instillation of a topical anesthetic enhance the effect of tropicamide?

Preinstillation of a topical anesthetic has been reported to increase the effect of subsequently applied mydriatics. We examined the effect of instilling 1 drop of proparacaine hydrochloride (0.5%) before applying 1 drop of tropicamide (1%). The results show that preanesthesia prolongs the mydriatic and the cycloplegic effects of tropicamide in eyes with either lightly or more heavily pigmented irides.

Accommodation, Ocular↗
PubMed1986

Effect of phenylephrine on accommodation.

We studied the effect of the topical instillation of phenylephrine hydrochloride on accommodation. Factors considered were iris color and the influence of the prior application of a topical anesthetic. There has been controversy concerning the role of the sympathetic nervous system in accommodation. Our results indicate that the sympathetic nervous system does influence accommodation. Prior application of an anesthetic prolongs the effect of phenylephrine on the accommodation and on pupil diameter in eyes with either lightly or more heavily pigmented irides.

Accommodation, Ocular↗
PubMed1977

Effects of topical anesthetics on phenylephrine-induced mydriasis.

Pupil responses to phenylephrine alone and to phenylephrine preceded by a topical anesthetic were recorded by means of an infrared pupillometer. In response to phenylephrine, pupils dilated more in eyes with pale irides. Dilation was greater if a topical anesthetic was applied before the mydriatic. Benoxinate, proparacaine, and tetracaine produced approximately equal degrees of enhancement of the mydriasis. One drop of 1% phenylephrine had only a small dilating effect on an eye when the fellow eye received the phenylephrine preceded by 0.5% proparacaine.

Administration, Topical↗