Biomedical subjects

Alex J Shortt

Publications and source records attributed to Alex J Shortt.

4 recordsLinked to original sources

PubMed2007

Limbal epithelial stem cell therapy.

Restoring vision in patients suffering from previously intractable blinding ocular surface disease has become possible with the advent of techniques for ex vivo expansion and transplantation of limbal epithelial stem cells onto the cornea. This approach represents one of the few adult stem cell therapies presently in the clinic. This article highlights several key research areas where progress will be made to specifically understand the biology and therapeutic potential of limbal epithelial stem cells, which may have an applicability to the understanding of other adult stem cell populations.

Animals↗

PubMed2006

Evidence for superior efficacy and safety of LASIK over photorefractive keratectomy for correction of myopia.

PURPOSE: To examine possible differences in efficacy and safety between LASIK and photorefractive keratectomy (PRK) for correction of myopia. DESIGN: Meta-analysis/systematic review. PARTICIPANTS: Patient data from previously reported prospective randomized controlled trials (PRCTs) and a systematic review of prospective case series in the Food and Drug Administration (FDA) clinical trials database. METHODS: A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify PRCTs comparing LASIK and PRK for correction of myopia. A meta-analysis was performed on the results of PRCTs. In parallel, a systematic review of prospective data from FDA case series of LASIK and PRK for correction of myopia was undertaken. MAIN OUTCOME MEASURES: Key efficacy outcomes (uncorrected visual acuity [UCVA] > or = 20/20, +/-0.50 diopters [D] of the target mean refractive spherical equivalent) and safety outcomes (loss of > or =2 lines of best spectacle-corrected visual acuity [BSCVA], final BSCVA > or = 20/40, and final BSCVA < 20/25 where preoperative BSCVA was > or =20/20). RESULTS: Seven PRCTs were identified comparing PRK (683 eyes) and LASIK (403 eyes) for correction of myopia. More LASIK patients achieved UCVA > or = 20/20 at 6 months (odds ratio, random effects model [95% confidence interval], 1.72 [1.14-2.58]; P = 0.009) and 12 months (1.78 [1.15-2.75], P = 0.01). Loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.69 [1.01-7.18], P = 0.05). Data from 14 LASIK (7810 eyes) and 10 PRK (4414 eyes) FDA laser approval case series showed that more LASIK patients achieved UCVA of 20/20 or better at 12 months (1.15 [1.03-1.29], P = 0.01), significantly more LASIK patients were within +/-0.50 D of target refraction at 6 months (1.38 [1.26-1.50], P<0.00001) and 12 months (1.21 [1.08-1.36], P = 0.0009) after treatment, and loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.91 [2.22-3.83], P<0.00001). CONCLUSIONS: LASIK appears to have efficacy and safety superior to those of PRK. However, the data examined are from studies conducted > or =5 years ago. It is therefore unclear how our findings relate to present-day methods and outcomes. Further trials comparing contemporary equipment and techniques are needed to reevaluate the relative merits of these procedures.

Clinical Trials as Topic↗

PubMed2004

Chronic systemic hypoxia causes intra-retinal angiogenesis.

Retinal hypoxia occurs in many conditions that cause vascular disease in the eye and is an important stimulus to new vessel formation. However, the adult retina can also become hypoxic when there is systemic hypoxaemia such as occurs in chronic lung diseases, congenital cardiac disease and residence at high altitude. Little is known about the adaptive responses of the retinal vasculature in such circumstances. Previous research in the retinopathy of prematurity model may not apply to the adult tissue given the different mechanisms controlling angiogenesis in developing and mature circulations. We tested the hypothesis that chronic systemic hypoxia leads to angiogenesis in the adult retinal circulation, in the absence of pre-existing vascular disease. Adult male Sprague-Dawley rats (n=9) were exposed to a fraction of inspired oxygen of 0.10 for 2 weeks while control animals (n=10) were exposed to room air. Stereological techniques were used to quantify the vascular volume, endothelial surface area and the total number of branch points of all blood vessels in the superficial retinal vascular plexus. The mean volume and endothelial surface area of these vessels were significantly greater in the hypoxic than in the control group. The mean number of blood vessel branch points was also significantly greater in the hypoxic group. Our findings demonstrate that chronic systemic hypoxia, in the absence of other pathological processes, causes angiogenesis in the adult rat retina and provide an in vivo model for investigating this important process in the adult retina, in particular pathways specific to this tissue.

Animals↗

PubMedDate not supplied

Pars plana lensectomy for the management of ectopia lentis in children.

BACKGROUND: Nontraumatic ectopia lentis arises from a variety of inherited disorders. It may also occur as an isolated abnormality in an otherwise healthy individual. Surgical intervention is necessary when lens subluxation causes a significant refractive error resulting in amblyopia. PATIENTS AND METHODS: We report the results of pars plana lensectomy for nontraumatic ectopia lentis in 24 eyes of 13 patients and provide data on the merits of this surgical approach. better in 17 of 22 eyes and 6/12 or better in 19 of 22 eyes. Other than contact lens-related problems, there were no perioperative or postoperative complications. CONCLUSIONS: Pars plana lensectomy is a safe, effective procedure for the management of ectopia lentis. Visual outcomes are excellent. These findings should encourage earlier surgery when indicated to prevent amblyopia and improve visual acuity.

Adolescent↗