Caroline Faucher

Spasm of the near reflex triggered by disruption of normal binocular vision.

A 26-year-old healthy female was referred by her optometrist to the binocular vision clinic of our institution for the investigation of an accommodative spasm occurring during monocular conditions. Corrected binocular visual acuity was 20/20 (6/6), with normal pupils and good ocular alignment. When the fellow eye was covered, visual acuity was <20/200 (6/60) in each eye, miosis was present in both eyes, and the occluded eye was in esodeviation, indicating a spasm of the near reflex. The spasm disappeared when a translucent occluder was used instead of an opaque black occluder. Further investigation permitted us to establish that dioptric and nondioptric blur, as well as reduced light transmission, also triggered the spasm of the near reflex, but only for specific power, opacity, or density. Cycloplegia did not eliminate the spasm. Comparisons are made with the single other similar case found in the literature. Assumptions are made as to the possible causes of that intermittent spasm.

Modulation of the scotopic electroretinogram and oscillatory potentials with systemic hyperoxia and hypercapnia in humans

Purpose. Systemic hyperoxia reduces blood flow to the retina while systemic hypercapnia has the opposite effect. However, the effect this modification in blood flow has on neuroretinal function in humans has not been documented yet. The purpose of this study was to evaluate the effect of pure oxygen and carbogen breathing on scotopic electroretinograms (ERGs) and oscillatory potentials (OPs) in humans. Methods. Thirty-five healthy adults volunteered for this study. The ERGs and OPs were recorded: 1) during room air breathing, 2) after a period of pure oxygen (O 2) or carbogen breathing, 3) in room air just after the flow of gas was interrupted, and 4) 10 minutes after the end of the gas administration. Results. The amplitude and latency of the a- and b-waves were not altered during systemic hyperoxia. The amplitude of OP3 increased during hyperoxia while the amplitude of the other OPs was not altered. The latency of all OPs remained stable throughout the O 2 session. Ten minutes after the end of pure O 2 breathing, the a- and b-wave latencies were delayed. No change was found in the amplitude of the a-wave during the carbogen session that increased the end-tidal carbon dioxide by 7.1%, whereas the b-wave was reduced ten minutes after the end of carbogen breathing. The amplitude of OP5 was reduced during carbogen breathing, as well as 10 minutes later. The amplitude of all other OPs, as well as the latencies of all ERG and OP components remained stable throughout the carbogen session. Conclusions. Breathing pure O 2 or carbogen did not compromise retinal function in any major way, likely due to adequate retinal and choroidal regulatory mechanisms. Further investigations are required to better delineate the impact and temporal characteristics of such physiological challenges on retinal function.

Optometrists' clinical reasoning made explicit: a qualitative study.

Purpose Because the clinical reasoning processes engaged in by practicing optometrists have not previous been investigated, until now, there has been no way of knowing whether models of clinical reasoning from other health professions can be transposed to optometry. The purpose of this study has therefore been twofold: making explicit the clinical reasoning processes of optometrists at both the “competent” and “expert” levels and comparing these processes to highlight the characteristics of clinical reasoning expertise. Methods Four competent-level optometrists and four expert-level optometrists participated in this qualitative study. Each optometrist performed a complete optometric examination on a preselected patient. Each of these examinations was recorded on a DVD video and followed by a feedback session, also captured on a DVD video. The feedback session was conducted using techniques inspired by a form of interview called the “explicitation interview,” aiming to describe optometrists’ mental actions and the time sequence of these actions throughout the examination. Results The results indicate that optometrists’ clinical reasoning is patient centered and includes both analytical and nonanalytical modes of reasoning. When compared with a competent-level optometrist, an expert-level optometrist is more patient centered, formulates an earlier mental representation of the patient’s clinical situation (including diagnosis formulation), plans examinations more thoroughly, is able to analyze and reflect during cognitively demanding tasks, and draws up his or her care management plan throughout the entire examination. Conclusions The verbalization of optometrists’ clinical reasoning processes represents a first step toward a better understanding of this competency. The impact of this research on optometric education is discussed. The results open doors to further research in the field, for example, toward defining the stages of clinical reasoning development among optometry students and professionals.

Assessing clinical reasoning in optometry using the script concordance test

Clinical reasoning is central to any health profession but its development among learners is difficult to assess. Over the last few decades, the script concordance test (SCT) has been developed to solve this dilemma and has been used in many health professions; however, no study has been published on the use of the script concordance test in optometry. The purpose of this study was to develop and validate a script concordance test for the field of optometry.

Hyper-response of OP3 to systemic hyperoxia in the dark-adapted retina

Purpose:  We have demonstrated that the third wavelet (OP3) of the scotopic flash oscillatory potential (OP) complex shows a hyper‐response during experimentally‐induced systemic hyperoxia. The objective of the present study was to further evaluate and detail the time course of this enhanced retinal response.