Aims-To determine whether unilateral cataract causes a pathological Pulfrich's phenomenon. Methods-29 subjects with unilateral cataract and contralateral pseudophakia were assessed on their ability to perceive the Pulfrich phenomenon. Using a computer generated pendulum image, and graded neutral density filters, a series of forced choice trials were performed in which the subject was required to describe the direction of any apparent pendulum rotation. A pathological Pulfrich eVect was said to occur when apparent rotation was perceived in the presence of a zero strength neutral density filter. The size of any pathological Pulfrich eVect which was present was quantified by neutralising the perceived pendulum rotation with neutral density filters of varying strength placed before the better seeing eye. Results-20 out of 29 subjects were able to perceive apparent pendulum rotation when uniocular filtering was performed. In the group (n=12) which was tested both before and after cataract extraction with intraocular lens implantation, a statistically significant pathological Pulfrich effect was demonstrated preoperatively, compared with a group of normal control subjects. This eVect was abolished after cataract extraction (p=0.009). The median size of the eVect was equivalent to a 0.25 log unit neutral density filter over the non-cataractous eye. The subjects who were unable to perceive the Pulfrich phenomenon at all had a significantly greater diVerence in the visual acuity of each eye (p=0.045) and significantly worse stereoacuity than those who were able to perceive the eVect (p=0.002). Conclusions-Unilateral cataract can cause a pathological Pulfrich phenomenon. This finding may explain why some patients with unilateral cataract complain of visual symptoms that are not easily accounted for in terms of visual acuity, contrast sensitivity, or stereoacuity.

Aims-To examine the postoperative stability of inferior rectus recession, with particular reference to the incidence of progressive overcorrection. Methods-The results of consecutive patients undergoing inferior rectus recession over a 3 year period were reviewed. Results-21 patients underwent inferior rectus recession, using an adjustable suture technique in all but three cases. In 16 patients additional vertical muscle surgery was performed at the time of the inferior rectus recession. All patients were followed for a minimum of 3 months postoperatively, with a mean follow up of 9.3 months. At the final postoperative visit 11 patients were well aligned, eight were undercorrected, and two were overcorrected. In five of the eight undercorrected cases, the residual deviation was the result of postoperative drift in the direction of the preoperative deviation, following an initially good alignment. Review of the results failed to reveal any factor predictive for this postoperative drift. Conclusion-The risk of postoperative overcorrection following inferior rectus recession should be considered, but in this study, undercorrection occurred more frequently than overcorrection. The possible reasons for overcorrection and undercorrection are discussed.

No abstract

Acute dacryocystitis is a rare complication of infectious mononucleosis with only three previous reports in the English literature. We present two further children with acute dacryocystitis and clinical and laboratory features of Epstein-Barr Virus related infectious mononucleosis. Both were treated with systemic antibiotics and one child additionally required surgical drainage of a lacrimal sac abscess. Both children made a complete recovery without any lacrimal symptoms. Acute dacryocystitis is uncommon in children without a history of congenital nasolacrimal duct obstruction, and an underlying systemic condition such as infectious mononucleosis should be suspected. In such patients, dacryocystitis can be expected to resolve without symptoms of nasolacrimal duct obstruction and dacryocystorhinostomy is seldom required.