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Biomedical subjects

F C Hollows

Publications and source records attributed to F C Hollows.

At least 19 recordsLinked to original sources
PubMed2006

Visual-evoked response, pattern electroretinogram, and psychophysical magnocellular thresholds in glaucoma, optic atrophy, and dyslexia.

PURPOSE: The purpose of this study is to compare visual-evoked response (VEP) pattern electroretinogram (PERG) and psychophysical thresholds to the same stimulus, designed to be optimal for the magnocellular system, in suspects and patients with early glaucoma, patients with optic nerve disease, dyslexic children, and age-matched controls. METHODS: Stimuli were low spatial frequency sinusoidal luminance profile gratings abruptly phase reversing at 7.14 Hz. Electrophysiological recordings were made at 50%, 30%, 20%, 10%, and 5% contrast. Threshold was the lowest contrast evoking a clear response at the stimulus frequency. Three independent judges scored the traces. Psychophysical thresholds were obtained by ascending and descending method of limits. VEPs and PERGs to International Society for Clinical Electrophysiology of Vision (ISCEV) standards and to increasing spatial frequencies were obtained as parvocellular specific controls. Patients were diagnosed independently by the referring professionals. RESULTS: Parvocellular-specific responses were normal, except in cases with explicable visual acuity loss. The judges scores correlated highly (> 0.9). VEPs and PERGs correlated highly and each correlated less well with psychophysics in normals, glaucoma, and dyslexia but the opposite occurred in optic nerve disease. VEPs had the lowest normal values and least variance (all adults < 5%, children < 10%, PERGs < 20%). In glaucoma, VEP magnocellular deficits occurred in 85% of recently diagnosed positive cases, 48% of high-risk suspects, 39% of low-risk suspects, and ocular hypertensives. Approximately 28% of dyslexics had VEP magnocellular deficits. PERG losses were less frequent. There was a clear dichotomy and low correlations between psychophysics and electrophysiology both within and between groups. Psychophysical threshold elevations were absent in all glaucoma groups, often large in optic atrophy and small (2.5%) but highly significant in dyslexia. CONCLUSION: Contrast thresholds to magnocellular-specific stimuli are consistent in cortex and retina. VEPs are more reliable. Psychophysics seems to tap different mechanisms. VEPs are very sensitive to early glaucoma. The lack of VEP loss in dyslexia suggests the other losses are artifactual. Further research is needed to see if stimuli even more like the frequency-doubling technology are more useful clinically.

Adult↗
PubMed1995

Flash and pattern electroretinogram changes with optic atrophy and glaucoma.

We investigated recent reports that, contrary to common belief, glaucoma can affect flash as well as pattern electroretinograms. An extensive flash and pattern electroretinogram test protocol was used in a large sample of glaucoma patients and age-matched controls who were either visually normal or had other optic nerve diseases. All electroretinogram parameters were reduced and delayed in normal people > 55 years of age. The effect did not increase in later decades. In patients aged < or = 55 years, flash electroretinograms showed mild reductions and delays from optic atrophy alone. Glaucomatous ERG changes were larger and increased with disease severity. Pattern electroretinograms and oscillatory potentials were almost equally reduced in optic atrophy and all degrees of glaucoma. Mildly affected patients > 55 years of age had similar electroretinogram change to age-matched normals in most conditions. Advanced glaucoma patients showed similar differences from normal irrespective of age. This suggests that direct diagnostic application of these results to older patients will be difficult, that the ERG changes in glaucoma cannot be attributed simply to optic atrophy and that additional widespread outer retinal damage occurs in glaucoma.

Age Factors↗
PubMed1992

High dose intravitreal ganciclovir in the treatment of cytomegalovirus retinitis.

OBJECTIVE: To assess the role of intravitreal administration of high doses of ganciclovir as a supplement and alternative to intravenous administration in the treatment of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS). DESIGN: A retrospective study of visual outcome, relapse and complications of intravenous and high dose intravitreal administration of ganciclovir alone and in combination. METHOD: Twenty-three patients with AIDS and CMV retinitis (37 eyes) were examined by the authors and notes, fundal drawings and photographs reviewed. Initially patients were treated with intravenous ganciclovir alone and given supplementary intravitreal therapy for relapse or vision-threatening retinitis; however, later patients were managed with combination maintenance ganciclovir or maintenance intravitreal treatment alone. RESULTS: Relapse and loss of vision occurred frequently in patients treated with intravenous ganciclovir alone or in combination with intermittent intravitreal therapy. Eyes managed with maintenance high dose intravitreal ganciclovir alone or in combination with intravenous treatment did not relapse or lose vision. The most important complication of intravenous administration of ganciclovir was neutropenia (73% of patients), whereas that of intravitreal therapy was endophthalmitis (three eyes). CONCLUSION: High dose ganciclovir given intravitreally effectively suppressed CMV retinitis and preserved vision without adverse systemic effects or deterioration of quality of life.

AIDS-Related Opportunistic Infections↗
PubMed1989

Pharmaceutical production and intraocular lens implantation: technology appropriate to the Third World.

Eritrea, in the Horn of Africa, suffers the serious health problems and obstacles to the provision of adequate health care that typify Third World countries. Yet, despite the compounding effect of war, the Eritreans' pharmaceutical facility meets 40% of their capsule and tablet requirements, and all their intravenous fluid demands. If intravenous fluid production is possible in this environment, as it is, then the authors contend that routine microscopic intraocular surgery (including intraocular lens implantation) should be as well. The establishment of an Eritrean facility capable of such surgery is recorded. The authors believe this type of surgery should be seriously considered in any attempt to deal with the problem of Third World cataract blindness.

Cataract Extraction↗
PubMed1988

Uremic optic neuropathy.

Vision loss progressing over several days, reduced pupil reactions to light, and swollen optic nerves were the clinical features in six patients with severe renal disease manifested by uremia, anemia, and (in four patients) moderately or severely elevated blood pressure. In two patients pale edema of the optic nerve head extended into the macula. One patient with renal transplant rejection was in the early phases of cryptococcal meningitis that went undiagnosed for two weeks. Medical management with hemodialysis was followed by improvement of vision in four patients. In one patient, resumption of oral corticosteroid therapy was followed by improvement in vision. The patient whose vision improved the most rapidly was managed by prompt use of both dialysis and oral corticosteroid therapy. The patient with cryptococcal meningitis did not recover vision.

Adolescent↗
PubMed1988

Scleral reinforcement in the treatment of pathologic myopia.

Pathologic myopia is a relatively common blinding condition for which current treatment is limited and controversial. Macular changes and vision loss proceed from the development of a posterior staphyloma. A scleral reinforcement technique has been used in seven eyes of six patients. The procedure is technically uncomplicated and safe.

Adolescent↗
PubMed1988

Avoidable blindness.

Explore the source record for details and available documents.

Anti-Bacterial Agents↗
PubMed1988

Sling markers in scleral reinforcement surgery.

Scleral reinforcement surgery requires a long-term controlled study to establish its efficacy in arresting the blinding complications of pathologic myopia. Only those cases with proven scleral sling reinforcement of the posterior pole should be included in such a study. Tantalum graft markers allow postoperative verification of sling position, and the exclusion of those cases with inappropriately placed reinforcement grafts.

Constriction↗
PubMed1984

Pterygium and ultraviolet radiation: a positive correlation.

Pterygium has long been believed to be an environmental disease, Ultraviolet (UV) radiation playing a major role in its development. In examination of more than 100 000 Aborigines and non-Aborigines in rural Australia a strong positive correlation between climatic UV radiation and pterygium prevalence was found, providing further evidence of a causal relationship. In addition interesting differences were found in prevalence in the different racial groups and between the sexes. These differences may be explained by differences in lifestyle.

Adolescent↗
PubMed1983

Respiratory disease amongst Aborigines in the Pilbara.

Aboriginal communities have a high prevalence of upper and lower respiratory tract disease. One thousand two hundred and eighty seven West Australian Aborigines and 265 non-Aborigines were examined. Twenty nine per cent of Aborigines had lower respiratory tract abnormalities. Amongst 635 Aboriginal children less than 15 years of age, 23% had lower respiratory tract signs--four times the prevalence in 174 non-Aborigines. Twenty six per cent of Aborigines under 10 years of age had signs of otitis media, compared to 3% amongst non-Aborigines. Two hundred and thirty eight (53%) of Aboriginal children less than 10 years of age had nasal discharge, compared to 1.6% of the non-Aboriginal children.

Adolescent↗
PubMed1981

Systemic factors in patients with low-tension glaucoma.

Nineteen patients (38 eyes) with low-tension glaucoma were compared with 53 subjects (106 eyes) with ocular hypertension. Comparable for age and sex, the 2 groups were assessed with respect to haematological and biochemical criteria, physical activity, and medical history. Statistical analyses of the differences between the 2 groups highlighted the importance of diastolic ophthalmodynamometry levels, prediagnosis exercise habits, cardiovascular disease status, and possibly systolic blood pressure. Patients with low-tension glaucoma suffered a higher prevalence of multiple abnormalities of these systemic factors than did their ocular hypertensive counterparts. There were no significant differences between the 2 groups with respect to the many other factors examined.

Adult↗