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Biomedical subjects

R G Pigion

Publications and source records attributed to R G Pigion.

6 recordsLinked to original sources
PubMed1985

Fatigue of accommodation: changes in accommodation after visual work.

The present study was designed to determine whether classical accommodation theory or dual-innervation accommodation theory best explains the visual fatigue effects of prolonged visual work. The accommodation responses of 20 young male adults were measured, using a laser optometer, while they viewed a near target (30 cm), a far target (6 m), or in total darkness. Measurements were made before and after 1-h fatigue sessions, during which subjects either read monocularly presented slides of text at near or far distances, or remained in darkness. There were no significant changes in near or far target static accommodation as a result of any of the fatigue sessions. Dark focus accommodation shifted inward after the near target viewing task and after prolonged dark viewing. The results are discussed in terms of their implications for research in accommodative fatigue, and their relation to other current research.

Accommodation, Ocular↗
PubMed1984

Overaccommodation, underaccommodation, and the clinical phoropter: a study of instrument myopia and related effects.

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.

Accommodation, Ocular↗
PubMed1983

Use of a ready signal in accommodation assessment.

The usual procedure in making laser optometer measurements of accommodation is to precede each trial with a ready signal. Given previous findings that stress, arousal, attention, etc., can influence accommodation and related phenomena, the question arises as to whether such a ready signal might induce some form of orientation response reflected in alterations of accommodation. Dark focus (DF) accommodation (accommodation in total darkness) was assessed in 26 young adults (13 males and 13 females) under two conditions, one of which involved the use of a ready signal and the other did not. Analyses showed that the presence or absence of the ready signal had no differential impact on accommodation.

Accommodation, Ocular↗