The history of the scientific elucidation of ocular counterrolling

The history of the elucidation of ocular counterrolling (OCR) is an interesting one. Although discovered two centuries ago, OCR has remained a contro- versial issue, even in our days. The main reason for this, is that rolling move- ments of the eyes about the line of sight are not easily detected or measured. OCR can be static, i.e. about 5 degrees counterrolling of the eyes which partly compensates for tilting of the head with respect to gravity, or it can be dynamic, that is to say a rotatory optokinetic and vestibular nystagmus. The rolling movement of the eyes about the line of sight can be seen when tilting the head of another person towards one of his shoulders. Close inspec- tion of the conjunctival vessels reveals the jerking movements of the quick phase of the rotatory nystagmus. This is what John Hunter must have seen some two hundred years ago, as he described dynamic OCR in 'The use of the oblique muscles', in a book called 'Observations on certain parts of the animal oeconomy' (1786)

Keratomycosis caused by Acremonium Recifei, treated with keratoplasty, Miconazole and Ketoconazole

A patient is discussed who developed a fungal corneal ulcer due to Acremonium (Cephalosporium) Recifei after a piece of a coconut flew into his eye while he was cracking it. Treatment consisted of keratoplasty, Miconazole as ointment and intravenously, and Ketaconazole orally. Diagnosis and treatment of fungal corneal ulcers are discussed briefly

How Accurate is Orthoptic Examination at Age One?: The Early vs. Late Strabismus Surgery Study Group

The Early vs. Late Strabismus Surgery Study Group is a group of strabismologists and orthoptists who wish to investigate whether early or late surgery is better in cases of infantile strabismus, in a controlled, multicentre, matched-pair trial: All infants will receive a standardized entry examination at age one and then be operated either before their second birthday in clinics A, or between the 32nd and 60th month of age in clinics B. The children will be evaluated at age six. After completion of the study, one child will be selected from each group, to form a pair of children with the same entry examination, who were operated early or late. Successive pairs will be generated so that finally two smaller groups with the same entry examinations are formed. These two groups can then be compared regarding degree of binocular vision, angle of squint and visual acuity of the worse eye. It was decided to perform first a pilot-study of the examination of infants age nine to 15 months, because we wanted to know to what degree of accuracy infants age one can be examined and what parts of the examination can be carried out most reliably and can therefore be used as parameters to match the pairs in the main study. 190 Children were each examined by three examiners on one day, according to a standardized examination sheet, and differences were quantified. We found that the angle of squint could be measured with reasonable precision: The largest difference between any two of the three measured angles averaged at 6.5″. The angle did not increase when the infant was examined a second or third time. Variability of the angle, vertical divergence and up-/downshoot-in-adduction could not be assessed reliably. On the other hand, restriction of abduction (in a 4-class scale) could be measured with adequate precision: in 58% there were no differences at all between the three examinations. The degree of amblyopia could be well assessed by observing the fixation pattern by means of direct fundoscopy with a fixation mark or by comparing corneal reflexes during monocular fixation. Using a 3-class scale, there were no differences at all between the three examinations of the three orthoptists in 94% of the cases. In addition, amblyopia could be accurately assessed by observing the fixation behaviour of the child with either eye, in a 5-class scale

The Variprism: A Large-Range Variable Prism for Measurement of the Angle of Squint

Prism bars and variable Herschel prisms are most commonly used today to measure the angle of squint. Both have drawbacks, however. Prism bars are too large to carry around all day and are usually limited to 40 prism diopters (PD), while variable Herschel prisms have even smaller ranges. Hans Meester and I have therefore developed, at the Netherlands Ophthalmic Research Institute, Amsterdam, a hand-held prism that is continuously variable over a large range, horizontally as well as vertically. We propose to call it the "Variprism." It consists of a small housing containing two glass elements, ie, planoconvex and planoconcave, with equal radii of the convex and concave surfaces (Fig 1). The planoconvex front element is a half globe, freely rotatable in gimbals. The planoconcave lens is situated immediately behind it

The Early vs. Late Infantile Strabismus Surgery Study: Monitoring Report

Abstract: The Early vs. Late Infantile Strabismus Surgery Study Group is a group of strabismologists and orthoptists who investigate whether early or late surgery is preferable in infantile strabismus, in a non-randomized, prospective, multi-center trial. Infants between six and 18 months of age will receive a standardized entry examination and then be operated either before their second anniversary, in clinics A, or between 32nd and 60th month of age in clinics B. The children will be evaluated at age six. After completion of the study, the two groups can then be compared regarding degree of binocular vision, angle of strabismus and visual acuity of the worse eye relative to the better one. This is the second monitoring report of the study

Robinson's computerized model of eye muscle mechanics revised.

The computerized model of static eye-muscle mechanics developed by Robinson was revised extensively and improved. An extensive literature study yielded additional information on the average diameter of the eye as related to age, on the average location of the insertions and origins of the eye muscles, and on the average cross-sectional area and length of the eye muscles

Treatment of Partly Accommodative Esotropia With a High Accommodative Convergence-Accommodation Ratio

In the June 1987 issue of the Archives, the results were published of a study by Kushner et al1 on the treatment of accommodative convergence excess, with bilateral medial rectus recessions or recessions with 14-mm posterior fixation sutures. Posterior fixation surgery was considered an unsatisfactory technique in this study, a conclusion based mainly on the frequent occurrence of overcorrections, although large undercorrections also occurred in the recession with posterior fixation suture group. Mims,2 in a letter to the editor in the September 1987 issue of the Archives, reached a similar conclusion: six overcorrections in a group of 30 patients.We think that at least some of these overcorrections were caused by adding a large, uniform-dose posterior fixation operation to a recession that, by itself, was appropriate for the angle measured at distance fixation

The Protocol for the Early vs. Late Infantile Strabismus Surgery Study

Abstract. The Early vs. Late Infantile Strabismus SurgerY Study Group is a group of strabismologists and orthoptists who investigate whether early or late surgery is preferable in infantile strabismus, in a non-randomized, prospective, multi-centre trial. Infants between 6 and 18 months of age will receive a standardized entry examination and then be operated either before their see"Ond anniversary in clinics A, or between their 32nd and 60th month of age in clinics B. The children will be evaluated at age six. After completion of the study, the two groups can then be compared regarding degree of binocular vision, angle of strabismus and visual acuity of the worse eye relative to the better

Instead of pulley bands, does retrobulbar fat keep the eye muscle bellies in place and thereby act like a pulley?

Extraocular muscle pulley bands were described by Tenon in 1805 as “faisceaux tendineux” acting as “poulies de renvoi.” The Passive and Active Pulley Hypotheses propose that these connective-tissue bands between muscle and bony orbital rim limit vertical shift of the horizontal rectus muscle belly in up- and downgaze, caused by the muscle’s tendency to assume the shortest path from origin to insertion. The band’s attachment to the muscle moves 20 mm sagittally when the eye looks from 50° left to 50° right, however, impeding vertical muscle stabilization. Sliding of the muscle in a sleeve would permit sagittal movement, but four anatomical studies could not confirm that. The band would have to be elastic: We measured it after orbital exenteration and found it to be slack, however, and once extended, very stiff. Our research group in Amsterdam suggested in 1984 that the retrobulbar fat and its enveloping connective-tissue sheets including the intermuscular membrane keep muscle bellies in place. We compared horizontal-rectus-muscle positions in up- and down-gaze using frontal CTs through the posterior pole of the eye. The bellies stayed in place while, anteriorly, the tendons bent up- and downward. We also found that the paths of horizontal rectus muscles were curved outwards in horizontal CTs. We surmised that retrobulbar pressure in the fat, resulting from four rectus muscles pulling the eyeball into the orbit, is contained by rectus muscles and connective-tissue sheets and that the resulting tension in the sheets keeps the muscles in place. Years later we repeated the CT study in a Crouzon patient whose bony orbital rim was displaced 2cm posteriorly, preventing pulley-band fixation to the bone: No vertical shift of horizontal rectus muscle bellies occurred in up- and down-gaze. Finally, we developed a mathematical finite-element model of orbit, muscles, fat and eyeball to study whether fa