Ординатура / Офтальмология / Английские материалы / Pickwell's Binocular Vision Anomalies 5th edition_Evans_2007

APPENDICES

A12.1 also gives the places in this book where more information on these topics can be found.

Final assessment

Once preregistration optometry students have demonstrated all the core competencies in practice, they will have to pass a final assessment. This examination has four sections: Routine, Ocular Disease and Abnormality, Clinical Decision Making, and Contact Lenses. All these sections except the last will require a knowledge and understanding of binocular vision anomalies. The sections of this book that will be particularly useful in revising for these examinations are listed in Table A12.2, and specific tips on the cover test and motility test are given below the table.

Table A12.2 College of Optometrists preregistration final assessment

APPENDICES

■failing to detect eye movements. To make it easier to see small eye movements during cover testing, make sure that you have a good light directed towards the patient’s face (but not uncomfortable for the patient), you are close enough to the patient and the patient has opened their eyes wide enough for you to see any eye movements.

Detecting abnormalities on motility testing

Again, ask your supervisor to ‘test’ you on any patients they examine who have an abnormality on motility testing, and on a few patients with no abnormalities to check your technique. Common errors are:

■not using a pen torch

■having the pen torch too close to the patient

■moving the pen torch too fast

■moving the pen torch too far so that the view of one eye is obscured, for example by the nose. Watch the corneal reflections of the pen torch to guard against this

■becoming confused over inconsistent patient reports about diplopia. It is best to form an opinion on what you see first, then ask the patient about diplopia. If the patient reports diplopia in positions where you did not see an underaction or overaction, check by cover testing in peripheral gaze. If the results are still confusing, do other tests (e.g. algorithms, Hess screen; Ch. 17)

■when cover testing in peripheral gaze, make sure that you fully cover the eye, remembering that it is looking away from the primary position

■cover testing in peripheral gaze is difficult but gives valuable information so should be carried out in the examination. Therefore, make sure that you practise this before the examination.

Diploma in Orthoptics (Dip Orth) of the College of

Optometrists

I co-authored the syllabus for the Dip Orth. It is recommended that candidates for this diploma are familiar with all sections of this book. The first step is to request the Dip Orth syllabus from the College of Optometrists. This lists, for each module of the Diploma, a recommended reading list that specifies the sections of this book that are appropriate for each module. More information on the Diploma in Orthoptics examination and clinical portfolio, including examples, can be found in other publications (Evans 2004a–j).

Fellowship of the Royal College of Ophthalmologists

GLOSSARY

Related words or phrases that are cross-referenced and described elsewhere in the Glossary are given in bold. The abbreviation ‘cf.’ is used to highlight related terms. Commonly used abbreviations for words or phrases are included in italics in brackets. Most terms in the Glossary are described in detail elsewhere in the book and the relevant page numbers can be found in the Index.

A-pattern A binocular anomaly characterized by, relatively speaking, excessive divergence on downward gaze and/or excessive convergence on upward gaze. Synonyms: A-phenomenon, A-syndrome.

Abduction When an eye moves in a temporalward direction.

Abnormal correspondence See retinal correspondence.

Abnormal retinal correspondence See retinal correspondence.

Absolute hypermetropia Hypermetropia for which accommodation cannot compensate.

AC/A ratio The accommodative-convergence to accommodation ratio. See accommodation.

Accidental alternator A rarely used term to describe the majority of cases of alternating strabismus where one eye usually fixates. cf. essential alternator.

Accommodation Alteration in the dioptric power of the eye to enable it to focus at different distances. Accommodation is linked to convergence and the amount of convergence that occurs reflexly in response to a change in accommodation is called the accommodative convergence. The amplitude of accommodation (Amp. Acc.) is a measure of the closest point at which a person can focus and is measured in dioptres (D), with any significant spectacle correction in place.

Accommodative esotropia A strabismus in which accommodation has a major influence on the deviation, through accommodative convergence. Accommodative esotropia is characterized by a significant degree of hypermetropia and/or a high AC/A ratio.

GLOSSARY

Adduction When an eye moves in a nasalward direction.

Agonist A muscle receiving primary innervation to contract, so as to move the eye into a new direction of gaze.

Aligning prism (A.P.) The prismatic correction required to eliminate a fixation disparity. This term has been recommended as a replacement for associated heterophoria. If no prism is required, the appropriate symbol is an X with a vertical and/or horizontal line through it (Bennett & Rabbetts 1989, p 211).

Alternating deorsumduction A type of dissociated vertical deviation where either eye deviates downward under cover. Synonym: alternating hypophoria (see also kataphoria).

Alternating strabismus A strabismus where, at a given distance, either eye is sometimes used for fixation.

Alternating sursumduction A type of dissociated vertical deviation where either eye deviates upwards under cover. Synonym: alternating hyperphoria (see also anaphoria).

Amblyopia (amb.) Visual acuity worse than 6/9 that is not due to refraction errors, ophthalmoscopically detectable anomalies of the fundus or pathology of the visual pathway (Nelson 1988a). In Chapter 13, a broader definition is proposed: a visual loss resulting from an impediment or disturbance to the normal development of vision. In Chapter 13 subtypes of amblyopia are also defined.

Amblyoscope See synoptophore.

Anaglyph The creation of binocularly fusible, usually stereoscopic, images using stimuli of complementary colours that are viewed through coloured filters (usually red and green). Sometimes, the term tranaglyph seems to be used synonymously with anaglyph.

Anaphoria Sometimes anaphoria is used as a synonym of alternating sursumduction (Millodot 1993). Alternatively, the term anaphoria is defined differently as a type of gaze palsy in which the eyes have limited ability for depression, so that both eyes turn upwards in the absence of a fixation stimulus (Bennett & Rabbetts 1989, p 219).

Angle alpha The angle between the visual axis (which passes through the object of regard and fovea) and the optical axis (which passes through the optical centres of the refracting surfaces of the eye). The visual axis usually lies nasal to the optical axis on the plane of the cornea (a positive angle alpha).

Angle gamma The angle between the optical axis and the fixation axis (which passes through the object of regard and the centre of rotation of the eye).

Angle kappa The angle between the optical axis and the line of sight

(which passes through the object of regard and centre of the entrance 368 pupil).

GLOSSARY

Angle lambda The angle between the pupillary axis (which passes through the centre of the entrance pupil and is normal to the corneal

GLOSSARY

optometry aims to enhance visual information processing in individuals who may not appear to have a specific ocular or vision defect. The philosophy of behavioural optometry has been criticized because of the high proportion of patients who are treated and for the inadequacy of supporting research.

Bielschowsky’s head tilt test A test to determine which of the inferior or superior extraocular muscles is paretic.

Bielschowsky’s phenomenon A phenomenon that occurs in dissociated vertical deviation (DVD). If one eye is occluded and a neutral density filter bar is placed before the fixating eye, as the filter density is increased there comes a point when the eye behind the cover moves down. This phenomenon can be used to test for DVD.

Binocular instability A heterophoric condition in which the alignment of the visual axes, at a given fixation distance, is unstable. The condition is characterized by an unstable heterophoria and low fusional reserves.

Binocular lock The visual input that is common to both eyes and thus helps to maintain fusion.

Binocular vision (BV ) The ability to use the two eyes together simultaneously. In normal binocular single vision sensory and motor fusion result in a single percept and stereopsis.

GLOSSARY

Contrast sensitivity function (CSF ) This provides an evaluation of the detection of objects of varying spatial frequencies and of variable contrast. This is a more complete assessment of vision than standard visual acuity measurement, which only measures the spatial resolution of high contrast targets.

Convergence (con.) A turning in of the visual axes, usually to maintain fixation upon an object as it moves towards the observer. Convergence is