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L B Young

Publications and source records attributed to L B Young.

7 recordsLinked to original sources
PubMed2003

Correlation of a scanning laser derived oedema index and visual function following grid laser treatment for diabetic macular oedema.

AIM: To correlate change of an oedema index derived by scanning laser tomography with change of visual function in patients undergoing grid laser photocoagulation for clinically significant diabetic macular oedema (DMO). METHODS: The sample comprised 24 diabetic patients with retinal thickening within 500 micro m of the fovea. Inclusion criteria included a logMAR visual acuity of 0.25, or better. Patients were assessed twice before a single session of grid laser treatment and within 1 week of, and at 1, 2, 4, and 12 weeks after, treatment. At each visit, patients underwent logMAR visual acuity, conventional and short wavelength automated perimetry (SWAP), and scanning laser tomography. Each visual function parameter was correlated with the mean oedema index. The mean oedema index represented the z-profile signal width divided by the maximum reflectance intensity (arbitrary units). A Pearson correlation coefficient (Bonferroni corrected) was undertaken on the data set of each patient. RESULTS: 13 patients exhibited significant correlation of the mean oedema index and at least one measure of visual function for the 10 degrees x 10 degrees scan field while 10 patients correlated for the 20 degrees x 20 degrees scan field. Seven patients demonstrated correlation for both scan fields. Laser photocoagulation typically resulted in an immediate loss of perimetric sensitivity whereas the oedema index changed over a period of weeks. Localised oedema did not impact upon visual acuity or letter contrast sensitivity when situated extrafoveally. CONCLUSIONS: Correlation of change of the oedema index and of visual function following grid laser photocoagulation was not found in all patients. An absence of correlation can be explained by the localised distribution of DMO in this sample of patients, as well as by differences in the time course of change of the oedema index and visual function. The study has objectively documented change in the magnitude and distribution of DMO following grid laser treatment and has established the relation of this change to the change in visual function.

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PubMed1998

Short-wavelength sensitive visual field loss in patients with clinically significant diabetic macular oedema.

The aim of the study was to compare the sensitivity of short-wavelength and conventional automated static threshold perimetry for the psychophysical detection of abnormality in patients with clinically significant diabetic macular oedema. The sample comprised 24 patients with clinically significant diabetic macular oedema (mean age 59.75 years, range 45-75 years). One eye of each patient was selected. Exclusion criteria included the presence of lenticular opacity. The sensitivity of the macular visual field of each patient was determined with programme 10-2 of the Humphrey Field Analyser on two occasions, using both short-wavelength and conventional stimulus parameters; the results of the second session were analysed to minimise learning effects. A pointwise horizontal hemifield asymmetry analysis was derived for short-wavelength perimetry (thereby negating the influence of pre-receptoral absorption); the pointwise pattern deviation probability plot was analysed for conventional perimetry. Abnormality was defined as 3 or more contiguous stimulus locations with negative asymmetries (short-wavelength) or reduced sensitivity values (conventional) that resulted in a statistical probability level of p less than 0.05. The fields of 8 patients were abnormal as assessed by conventional perimetry while all were classified as abnormal using short-wavelength perimetry. In the 8 patients who exhibited both abnormal conventional and abnormal short-wavelength perimetry results, the extent of field loss was generally greater using short-wavelength perimetry. The position of the localised field loss (i.e. as distinct from field loss that was generalised across the visual field) assessed by short-wavelength perimetry corresponded with the clinical mapping of the area of diabetic macular oedema but the extent of this loss was generally greater than that suggested by clinical assessment. Short-wavelength automated perimetry offers improved sensitivity for the psychophysical detection of clinically significant diabetic macular oedema.

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PubMed1998

Influence of laser photocoagulation for clinically significant diabetic macular oedema (DMO) on short-wavelength and conventional automated perimetry.

The aim of the study was to determine the effect of laser photocoagulation for clinically significant diabetic macular oedema (DMO) on macular visual function as assessed by conventional and short-wavelength automated static threshold perimetry. The sample comprised 24 patients who required laser photocoagulation for clinically significant DMO (mean age 59.75 years, range 45-75 years). One eye of each patient was selected for the study. Patients underwent conventional and short-wavelength perimetry using programme 10-2 of the Humphrey Field Analyser on two separate occasions prior to treatment and subsequently within 1 week of, and at 1, 2, 4 and 12 weeks after, treatment. The pointwise pattern deviation plot was analysed for conventional perimetry and a pointwise horizontal and vertical hemifield asymmetry analysis was derived for short-wavelength perimetry (thereby negating the influence of pre-receptoral absorption). The extent of sensitivity loss was determined by counting the number of stimulus locations with statistical probability levels of p less than 0.05. Group mean log minimum angle of resolution (logMAR) visual acuity was largely unchanged over the course of the study. Conventional perimetry showed an increase in the group mean number of abnormal contiguous stimulus locations from 2.4 (SD 4.3, range 0-14) immediately prior to treatment, to 12.4 (SD 7.8, range 0-30) within 1 week of treatment; at 3 months post-treatment, the group mean number of abnormal contiguous stimulus locations was 8.1 (SD 6.5, range 0-20). A similar but less pronounced change was found for short-wavelength perimetry. The spatial position of the post-treatment localised sensitivity loss corresponded with the area of retinal photocoagulation. Despite proven benefit in the stabilisation of visual acuity, laser photocoagulation for clinically significant DMO invariably results in a localised loss of perimetric sensitivity within 10 degrees eccentricity of the fovea. Evidence for the value of laser therapy for clinically significant DMO must be re-examined.

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PubMed1979

Metal binding by intestinal mucus.

Electron probe microanalysis offers distinct advantages for the study of intestinal mucus. This technique permits analysis of metal binding in situ, requires only a small amount of tissue, allows several experiments to be performed with one animal, and can resolve variations in binding that may occur in different portions of the intestine. We have used electron probe microanalysis to examine the metal binding capacity of intestinal mucus in situ. We have exposed portions of excised intestine to various concentrations of several metals, rapidly frozen the tissue and freeze dried it. After anhydrous embedding, thick sections were cut and analyzed on silicon discs or carbon coated copper grids. Qualitative analysis shows two distinctive patterns of distribution. The results of this work show clearly that at least three divalent cations are bound by mucus, that mucus exhibits different affinities for different metals, and that binding of metals is not uniform throughout mucus.

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PubMed1975

Biogenesis of intranuclear lead-protein inclusions in mouse kidney.

A single dose of lead (5 mug/g body weight), given as lead acetate by intracardiac injection, produces, within 8 hours, characteristic fibrillar intranuclear and intracytoplasmic inclusions in proximal tubular epithelial cells in mouse kidneys; after a dose of 40 mug/g body weight, such inclusion appeared within 6 hours. Their development was completely prevented by cycloheximide (one or more intraperitoneal injections of 20 mug/g body weight). The development of intranuclear inclusions was also noted in tubular epithelial cells explanted from normal mice and grown in vitro for 15 hours in a medium containing 20 mug lead/ml. Thus, the development of the characteristic fibrillar inclusion bodies depends upon de novo synthesis of inclusion body protein, induced by lead.

Animals↗
PubMedDate not supplied

Pregnancy after vitrectomy for proliferative diabetic retinopathy.

A 26-year-old female with insulin-dependent diabetes of 16 years duration had a vitrectomy for a dense non-resolving vitreous haemorrhage. Two months later she became pregnant. She delivered a healthy baby and despite the known adverse effects of pregnancy on retinopathy no deterioration occurred in visual acuity or in retinal appearance.

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