Biomedical subjects

J W Grierson

Publications and source records attributed to J W Grierson.

3 recordsLinked to original sources

PubMed2005

Health and wellbeing of HIV-positive Australians: findings from the third national HIV Futures Survey.

The aim of this paper is to characterize the health and well being of people living with HIV/AIDS (PLWHA) in Australia. The HIV Futures 3 Survey was a self-complete anonymous questionnaire distributed through multiple sites. Data were collected on health, clinical and social variables. There were 894 responses, 6% of the known HIV-positive population. Respondents were aged between 20 and 77; 79% were homosexual men. In all, 58% reported a viral load of <500 copies/mL, and 81% a CD4 count of over 250 cells/microL. In all, 38% reported another major health condition, and 26% a mental health condition. A total of 72% were using antiretroviral therapy. About 48% were in a regular relationship, and 42% of regular partners were HIV-positive. In all, 55% had stopped working because of HIV and 31% were living in poverty. While the overall picture for PLWHA in Australia is optimistic, there remain clear patterns of health and social disadvantage that require ongoing policy vigilance and service provision.

Adult↗

PubMed2000

The lids influence on corneal shape.

BACKGROUND: The lids are in contact to the corneal surface in normal viewing. Refractive surgery, however, is performed with a speculum in place and thus the lids are not in contact with the cornea. PURPOSE: To investigate central corneal shape with and without the lids touching the corneal surface. METHODS: The technique consists of exporting the point cloud of the topography scanner into computer software that recreates the corneal surface. The technique of surface modeling was used to form central corneal elevation height difference maps of four normal eyes with and without lid contact to the corneal surface. RESULTS: Surface modeling demonstrated the trend that the lids influence the corneal shape. CONCLUSION: The lids distort corneal shape.

Cornea↗

PubMedDate not supplied

A mathematical model for laser in situ keratomileusis and photorefractive keratectomy.

PURPOSE: The purpose of ablation refractive surgery is to remove the refractive error from the inherently asymmetric aspheric cornea. Although the technique is gaining wide acceptance and popularity, some patients are left with irregular corneas. Our objective was to develop a methodology to analyze corneal shape, reduce the shape to arcs, modify the local arc value to the desired new arc value, and render a new continuous Euclidean surface without discontinuity. METHODS: The method to reconstruct the corneal surface consists of importing scanner output elevation data points into a computer-aided design (CAD) application to form the surface model. The corneal arc measurements are derived at 5 degrees increments and centered about the Gauss point of symmetry. Each arc is manipulated to adjust the corresponding arc on the proposed corneal surface to reflect the new arc value, correcting for the refractive error. The method determines the amount of corneal tilt and ablation depth at a given diameter required for the refractive error with a smooth transition zone to the base cornea. RESULTS: The case example is a patient who began with a spherical refraction of -8.75 D and after LASIK was emmetropic, but had irregular astigmatism and 20/30 best spectacle-corrected Snellen visual acuity. The proposed mathematical model compares the achieved surface shape to the mathematically planned surface contour. An enhancement procedure to remove the LASIK-induced corneal irregularity was designed. CONCLUSION: A mathematical technique to plan myopic ablative surgery to make the corneal surface regular and symmetric is proposed.

Adult↗