Convergence accommodation to convergence CA/C ratio: convergence versus divergence.

Aim: To determine whether the convergence accommodation to convergence (CA/C) ratio during divergence with base-in (BI) prisms is of a similar or different magnitude to that measured during convergence with base-out (BO) prisms.

Methods: Eighteen participants with normal binocular single vision were recruited. The participants viewed a pseudo-Gaussian target, which consisted of a light emitting diode (LED) behind a diffusing screen at 40 cm.

Non-linearity of the response accommodative convergence to accommodation ratio.

Purpose: Previous studies have reported variation in stimulus accommodative convergence to accommodation (AC/A) ratio across differing accommodative stimuli. Response AC/A ratio was assessed across 4 accommodative demands to determine if these differences could be due to accommodative inaccuracies to stimuli.

Methods: Twenty-three student participants aged 18 to 26 years (mean age 20.

Depth of suppression in anisometropic amblyopia (with or without microtropia).

Background And Purpose: There are conflicting reports concerning the relationship between depth of suppression and level of amblyopia in strabismics. Little attention has been given to anisometropes. This study examines the density of suppression in anisometropic amblyopes, with or without microtropia, and investigates whether there is a relationship with level of amblyopia.

The response AC/A ratio: differences between inducing and relaxing accommodation at different distances of fixation.

Purpose: To determine if there is a difference between the response AC/A ratios when measured using the gradient method at near and distance fixation with plus and minus lenses respectively in young adults with normal binocular single vision.

Methods: A repeated measures design was used. The accommodative response of the right eye was measured objectively using the Shin-Nippon SRW-5000 autorefractor (Grand Seiko Company, Fukuyama, Japan) (open view) at 33 cm with and without plus lenses (2DS or 3DS) and at 3.

The effect of testing distance on the bielschowsky head tilt test.

Aims: The Bielschowsky Head Tilt Test (BHTT) is a commonly used test in Orthoptic practice and is used mainly to differentiate between a long standing Superior Oblique and Superior Rectus palsy. No consistent test distance is recommended in the literature and therefore the aim of this study was to determine whether test distance had an effect upon the measurements obtained.

Method: Thirteen participants were recruited.

Comparison of the visual effects of Fresnel prisms in normal and amblyopic eyes.

Purpose: To assess the effects of Fresnel prisms on visual acuity and peak contrast sensitivity in the amblyopic and sound eyes of participants with amblyopia and to determine whether these functions were affected by Fresnel prisms to a different degree than those of controls.

Methods: The LogMAR visual acuity and peak contrast sensitivity of 10 unilateral amblyopic participants (mean age, 22.6 years) and 9 controls (mean age, 26.

Stereoacuity is affected by induced phoria but returns toward baseline during vergence adaptation.

Purpose: In normal binocular single vision adaptation to an induced deviation occurs over a period of several minutes. This study investigates the effect on stereoacuity during vergence adaptation.

Methods: Stereoacuity, using the Frisby near stereotest, was measured in 20 participants aged 20.

Tilt and reading speed.

Purpose: To measure the effect of head tilt on reading rate and to determine whether a difference existed between the body or the text being tilted.

Methods: The Wilkins Rate of Reading Test was used to measure rate of reading in a population of normal readers. In the first part of the study, rate of reading with a head tilt of 15 degrees and 30 degrees was measured; in the second part of the study, rate of reading with a body tilt of 45 degrees and 90 degrees or a text tilt of 45 degrees and 90 degrees was measured.

Is the Cardiff Acuity Test effective in detecting refractive errors in children?

Purpose: Refractive error is a common cause of reduced visual acuity in young children. This reduced vision should be detected as soon as possible to avoid development of squinting and educational disadvantage. The Bailey-Lovie Chart (BLC) is based on the logarithm of the minimal angle of resolution (logarithm of the minimum angle of resolution logMAR) and is widely accepted as the clinical standard for visual acuity testing.

Visual side-effects from transdermal scopolamine (hyoscine).

Transdermal scopolamine may be used to reduce drooling in children with disabilities. Side-effects include dilated pupils and a reduction in the near point of accommodation (the closest point at which clear vision is possible). Two male children with epilepsy, one with spinal dysraphism (aged 7y 6mo) and one with cerebral palsy (aged 5y 8mo), who have undergone treatment for drooling with transdermal scopolamine are described.

Heroin and diplopia.

Aims: To describe the eye misalignments that occur during heroin use and heroin detoxification and to give an overview of the management of persisting diplopia (double vision) which results from eye misalignment.

Methods: A literature review using Medline and the search terms strabismus, heroin and substance withdrawal syndrome is presented. General management of cases presenting to the ophthalmologist and orthoptist with acute acquired concomitant esotropia is described.

Binocular sighting ocular dominance changes with different angles of horizontal gaze.

Background And Purpose: Ocular dominance testing is generally carried out in the primary position. A change of eye dominance when viewing in the contralateral field of horizontal gaze has recently been reported. The purpose of this study was to determine whether this occurs with other tests of eye dominance.

Vertical vergence adaptation does improve with practice.

Purpose: To investigate the effect of repeated testing on adaptation to a 2 Delta vertical prism in subjects with normal binocular single vision.

Methods: Subjects were required to have good visual acuity and normal binocular single vision. The residual deviation was measured after a 1-min period of adaptation to a 2 Delta vertical prism using a modified Maddox Rod technique.