摘要:

To explore the degree to which a phoropter can induce overaccommodation (instrument myopia) and/or underaccommodation, 19 college-age subjects participated in a series of measurements of accommodation response. Accommodation responses were assessed while subjects looked through a phoropter (both with standard 19-mm viewing apertures and through 2-mm artificial pupils) and when no phoropter was present. Subjects were tested both monocularly and binocularly, and under three stimulus conditions (near target, far target, and total darkness). Even without the phoropter, subjects tended to overaccommodate for the far target. The 19-mm phoropter produced no significant overaccommodation or underaccommodation effects over and above those observed without the presence of the phoropter. The 2-mm artificial pupils produced significantly more underaccommodation for the near target. Results indicate a tendency for accommodation response to approach an intermediate resting position as the viewing situation becomes impoverished.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The effects of fovea) exposure to near maximum permissible levels of broad-band light from lamps of differing flash durations and visual angle subtense on steady-state visual evoked potentials (SSVEP's) were measured in four human volunteers. SSVEP's in response to a counterphasing checkerboard pattern were recorded with a two-phase vector voltmeter used as an analog fourier analyzer and were averaged across repeated presentation of the flash from each lamp. Two microsecond flashes of approximately 0.4° have minimal, although significant effects on early visual processing of a 2.77° diameter 6/24 (20/80) target. Five hundred microsecond flashes of equivalent size have greater effects; larger flashes (11.3,° 500 μs) produced afterimages that totally obscured the target for approximately 3.4 s and also reduced the SSVEP to near zero. Recovery of the SSVEP was subjectively correlated with afterimage duration rather than target obscuration. Therefore, single short small retinal image flashes may have minimal transient effects on photopic suprathreshold vision.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Both the equidirection (nonius) and the equidistance horopter criteria were used on a group of subjects with and without the application of a 5% overall magnifier before the right eye. For three of six subjects, shifts in the equidirection horopter induced by this afocal lens could not be predicted on the basis of the magnification properties of the lens and the assumption that corresponding points are fixed. Equidistance horopter plots showed reasonably systematic reductions in slope between the predicted and the measured values for all subjects. Irregularities in all data were accounted for by shifts in the vergence angles during the experiment.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

This study compares the effect of 10 and 30% sodium sulfacetamide on corneal sensitivity. The corneal sensitivity was measured on 11 subjects with a Cochet-Bonnet aesthesiometer without any drug, 10 and 30% sodium sulfacetamide. The results obtained for the mean corneal sensitivities (mean standard error) for the control, 10 and 30% sodium sulfacetamide were 1.07 ± 0.025, 1.09 ± 0.023, and 1.36 ± 0.10 gm/mm2, respectively. We found that there was no statistical difference between the control value and 10% sodium sulfacetamide, but the 30% produced a significant decrease in corneal sensitivity when compared to the control and 10% concentration.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Optometric examinations of 73 children with normal intelligence but with cerebral palsy revealed a higher than normal incidence of strabismus, significant refractive errors, amblyopia, nystagmus, and optic atrophy.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Clinical examination of 298 mentally retarded adults revealed a higher frequency of ocular anomalies of all types than is typical of a group of nonretarded subjects of the same age. It also became apparent that fewer of the mentally retarded had had appropriate optometric care than an equivalent nonretarded sample. The evidence indicates that correcting their ocular problems helps the retarded, yet these subjects receive less than average care.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Idiopathic cysts of the anterior uveal tract most frequently involve the epithelial layers of the ciliary body and iris. Idiopathic cysts occur less frequently in the iris stroma. Characteristically asymptomatic, most of the cases reported in the literature have been discovered during routine eye examination by slitlamp biomicroscopy as an iris elevation. Cysts of the epithelial layers rarely enlarge to cause ocular complications. Stromal cysts, although extremely rare, appear to have a greater propensity to enlarge. The visual prognosis for patients with idiopathic anterior uveal cysts is quite good. A review of the literature and examples of these disorders are presented to emphasize the clinical characteristics and management of patients with a diagnosis of idiopathic anterior uveal cyst.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

Partial recovery from amblyopia can occur in animals if the the influence from the dominant eye is removed. This report describes a human, adult amblyope who lost central vision in the dominant eye, and regained useful vision in the amblyopic eye.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The versatility of a computer-based display of the extraocular muscles is demonstrated by comparing two different assumptions as to the paths of the muscles over the globe.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID

摘要:

The time-honored practice of silver nitrate application to the eyes of newborns is compared to the use of antibiotics. Side effects, effectiveness, and clinical practicality in preventing ophthalmia neonatorum are considered. The inability of prophylactic agents to inhibit several serious pathogens that cause conjunctivitis of the newborn is a factor. Prenatal screening for venereal disease and close observation of the baby's eyes in the postpartum period are additional ways to decrease the incidence of ophthalmia neonatorum.

ISSN:0093-7002    

出版商:OVID    

年代:1984

数据来源: OVID