PubMed · 14785921
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J D GAMBLE. 1950-10-15. Points in practical optics.. https://pubmed.ncbi.nlm.nih.gov/14785921/
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BACKGROUND: Vertical strabismus can be modulated by the viewing distance. We report on 19 patients with this disorder. METHODS: The following squint angles were measured by the alternate prism and cover test at a viewing distance of 5 m. At 0.3 m, measurements were taken with and without an addition of 3.0 D to the corrected refraction. Cases of a dissociated vertical deviation were excluded. Fifteen patients underwent surgery. They were reexamined 3 months later. RESULTS: At a viewing distance of 5 m, the vertical deviation ranged from 0 degrees to 16 degrees (median 7 degrees ). At 0.3 m, the deviation increased by 2 degrees -15 degrees (median 7 degrees ) in 15 patients and decreased by 3.5 degrees -8 degrees (median 4.5 degrees ) in 4 patients. Eleven patients had a strabismus sursoadductorius and one had a strabismus deorsoadductorius. Eye muscle surgery reduced both the vertical deviation for distance fixation to 0 degrees -14 degrees (median 2 degrees ) and the difference between the deviations for distance and proximal fixation to 1 degrees -6 degrees (median 3 degrees ). CONCLUSIONS: In certain cases, vertical strabismus can be modulated by convergence and accommodation. This condition is frequently associated with an incomitance of the vertical deviation in side gaze. The baseline deviation can be reduced by appropriate eye muscle surgery. In cases of vertical accommodative vergence, bifocal glasses can be helpful.
BACKGROUND, MATERIAL AND METHODS: Down's syndrome is the most common cause of mental retardation with an incidence of about 1.5/1000 live births. Life expectancy and quality of life have improved substantially for this group over the last decades. The aim of this paper is to give an updated short survey of ocular changes present in Down's syndrome based on current international literature and the clinical experience of the authors. RESULTS AND INTERPRETATION: Ocular problems are common, mostly refractive errors, poor accommodation, strabismus, cataract, and keratoconus. Accommodation deficit is present in a majority of individuals with Down's syndrome, also in children and young people. Bifocal or progressive glasses should therefore be prescribed liberally. Because of the high frequency of ocular pathology, all individuals with Down's syndrome should be enrolled in a continuous visual screening programme from birth. We suggest the following screening guidelines: first examination at one month of age, then at one year of age, at 2-3 years of age, at 5-6 years of age (school start), and thereafter every five years. In case of positive findings (e.g. refractive errors, poor accommodation, strabismus) the frequency of examination should be increased and determined individually by the responsible ophthalmologist.
PURPOSE: To determine the individual variability of the dark-adapted pupil diameter over 2 testing sessions using a standardized dark-adaptation protocol. SETTING: Texas Tech University Health Sciences Center, Lubbock, Texas, USA. METHODS: In this prospective observational cohort study, 40 volunteers with no history of ocular disease, surgery, or injury other than requirement for refractive correction were included. The right eye was tested. A standardized dark-adaptation protocol was used that controlled for accommodation and patient alertness. Infrared, still digital photographs were taken after 5 and 10 minutes of dark adaptation and analyzed independently by 2 investigators using digital-image software. Two test sessions were performed 1 to 7 days apart. Lifestyle factors such as sleep, diet, and exercise were not controlled. RESULTS: The mean subject age was 31.5 years (range 20 to 49 years). There were 20 men; 27 subjects wore correction for myopia, and 13 wore no correction. The mean interval between test sessions was 2 days (range 1 to 7 days). The mean difference and 95% confidence intervals for pupil diameter difference between sessions were as follows: 5-minute readings, +0.032 mm (-0.030 to +0.094); 10-minute readings, -0.006 mm (-0.059 to +0.047); mean of 5- and 10-minute readings, +0.013 mm (-0.038 to +0.064). Using the paired t test, the pupil diameter did not differ significantly between sessions in 5-minute dark adaptation (P =.2980), 10-minute dark adaptation (P =.8263), or the mean (P =.6049). CONCLUSION: Using a consistent dark-adaptation protocol that controlled for alertness, individuals aged 20 to 49 years showed no significant variation in dark-adapted pupil diameter when tested twice in 1 week.