Biomedical subjects

Graham E Quinn

Publications and source records attributed to Graham E Quinn.

22 records · Page 2Linked to original sources

PubMed2003

A randomized trial of prescribed patching regimens for treatment of severe amblyopia in children.

OBJECTIVE: To compare full-time patching (all hours or all but 1 hour per day) to 6 hours of patching per day, as prescribed treatments for severe amblyopia in children younger than 7 years. DESIGN: Prospective, randomized multicenter clinical trial (32 sites). PARTICIPANTS: One hundred seventy-five children younger than 7 years with amblyopia in the range of 20/100 to 20/400. INTERVENTION: Randomization either to full-time patching or to 6 hours of patching per day, each combined with at least 1 hour of near-visual activities during patching. MAIN OUTCOME MEASURE: Visual acuity in the amblyopic eye after 4 months. RESULTS: Visual acuity in the amblyopic eye improved a similar amount in both groups. The improvement in the amblyopic eye acuity from baseline to 4 months averaged 4.8 lines in the 6-hour group and 4.7 lines in the full-time group (P = 0.45). CONCLUSION: Six hours of prescribed daily patching produces an improvement in visual acuity that is of similar magnitude to the improvement produced by prescribed full-time patching in treating severe amblyopia in children 3 to less than 7 years of age.

Amblyopia↗

PubMed2002

Evidence-based screening criteria for retinopathy of prematurity: natural history data from the CRYO-ROP and LIGHT-ROP studies.

BACKGROUND: The Multicenter Trial of Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) demonstrated the efficacy of treatment for threshold ROP and indicated the need for worldwide ROP screening. Previous guidelines for ROP screening have been largely based on clinical impression; we can now develop evidence-based screening recommendations. OBJECTIVE: To define the appropriate ages and retinal ophthalmoscopic signs that determine when to commence and conclude acute phase ROP screening. DESIGN: Analysis of data from 2 prospective randomized controlled trials: CRYO-ROP (January 1, 1986, to November 30, 1987) and Light Reduction in ROP (LIGHT-ROP) (July 1, 1995, to March 31, 1997). SETTING: Neonatal intensive care units in 23 study centers in the United States for CRYO-ROP and 3 centers for LIGHT-ROP. PATIENTS: Eyes were examined sequentially in 4099 infants with birth weight less than 1251 g (CRYO-ROP study) and in 361 infants with birth weight less than 1251 g and gestational age less than 31 weeks (LIGHT-ROP study). RESULTS: In 99% of infants, retinal conditions indicating a risk of poor outcome were not observed before 31 weeks' postmenstrual age or 4 weeks' chronologic age. Signs indicating that the risk of visual loss from ROP was minimal or had passed were the infant's attainment of 45 weeks' postmenstrual age without the development of prethreshold ROP or worse, progression of retinal vascularization into zone III without previous zone II ROP, and full vascularization. CONCLUSIONS: The initial eye examination should be conducted by 31 weeks' postmenstrual age or 4 weeks' chronologic age, whichever is later. Acute phase ROP screening can be discontinued when any of the 3 signs is present, indicating that the risk of visual loss from ROP is minimal or passed.

Age Factors↗

PubMed2002

Darkness and near work: myopia and its progression in third-year law students.

PURPOSE: To evaluate myopia prevalence, myopia progression, and various potential myopia risk factors in third-year law students. DESIGN: Cross-sectional study and survey. PARTICIPANTS: One hundred seventy-nine third-year law students at the University of Pennsylvania. METHODS: We administered a questionnaire to assess the prevalence of myopia, myopia progression, and risk factors, including near work, family history, and daily light/dark exposure. We conducted a screening eye examination to ascertain myopia status. Myopia was defined as the mean spherical equivalent of the two eyes of </=-0.5 diopters; myopia progression was defined by the self-reported need for a stronger eyeglass prescription during law school. MAIN OUTCOME MEASURES: (1) prevalence of myopia, (2) progression of myopia. RESULTS: Seventy-nine percent of the class participated (n = 179, two were excluded for amblyopia leaving 177 students). Fifty-eight percent were male, 75% were Caucasian, and the mean age was 27 years. Seventy-nine percent reported parental myopia. The mean amount of near work was 7.4 hours/day; mean sleep was 7.9 hours/day; mean darkness was 5.3 hours/day. Sixty-six percent of the students were myopic. Of 96 participants myopic before law school, myopia increased in 83 (86%) during law school. Among 75 students not myopic at the beginning of law school, 14 (19%) became myopic. The onset of myopia could not be determined for 6 patients. There were trends for higher myopia prevalence among those with a parental myopia history (P = 0.14) and for increased myopia progression among those reporting more daily near work (P = 0.18). Students with </=5.6 hours of daily darkness were more likely to report myopia progression than those with >5.6 hours of darkness per day (95% vs. 80%, P = 0.07). To account for possible confounding effects of risk factors with myopia progression, logistic regression with categorization of the continuous exposure variables (hours of near work, sleep, and darkness) above or below median values weakened the near work association (odds ratio 1.8, 95% confidence interval 0.5-6.7, P = 0.35) but continued to identify darkness association with daily hours of darkness (odds ratio 4.8, 95% confidence interval 1.0 >/= 23.3, P < 0.05). Among the 77 students with myopia onset before college, those with </=5.6 hours of daily darkness were more likely to progress than those with more hours of daily darkness (97% vs. 76%, P = 0.01). CONCLUSIONS: This study confirms high rates of myopia prevalence and myopia progression among law students. The strongest association, especially in those with myopia onset before college, was a relation of myopia progression during law school with less daily exposure to darkness, a potential risk factor previously identified in childhood myopia. The role of exposure to darkness in refractive development warrants additional study.

Adult↗

PubMed2002

Eye dominance in the visual cortex using functional MRI at 1.5 T: an alternative method.

PURPOSE: To develop a functional MRI method for producing eye dominance histograms in humans at 1.5 Tesla (T). METHODS: In the first set of experiments, 8 normal persons were tested. The eye dominance of each voxel within the person's visually activated primary visual cortex was determined with Student t statistics during a left eye versus right eye contrast. Eye dominance distribution was plotted, and the mean t statistic was used to describe the histogram asymmetry. In the second set of experiments, the effect of monocular optical blur and decreased luminance via filter was studied, and eye dominance distributions were similarly determined. RESULTS: The eye dominance histogram in each of the 8 normals was approximately symmetric; the average mean t value was +0.13. All 4 subjects with the right eye blurred had histograms approximately symmetric or slightly shifted toward the left eye (average mean t = +0.56), and all 4 subjects with the right eye filtered had histograms dramatically shifted toward the left eye (average mean t = +2.22). The average mean t for the group with the right eye filtered was significantly different from that of the other 2 groups (P <.0001). CONCLUSIONS: With noninvasive methods in normal persons, functional magnetic resonance imaging techniques at 1.5 T were able to characterize the distribution of eye dominance of voxels in primary visual cortex, based upon their t statistic in the left eye versus right eye contrast. The method is sensitive to filtering but relatively insensitive to visual blur. This approach may have a future use in the study of amblyopia in humans.

Adolescent↗