The effect of Nd:YAG laser posterior capsulotomy on stereoacuity.

AIMS: To assess the effect of Nd:YAG laser posterior capsulotomy in the context of unilateral posterior capsular opacification (PCO) on spatial acuity, contrast sensitivity, and stereoacuity. METHODS: This prospective study involved 60 consecutive subjects with unilateral PCO. The aforementioned parameters of visual function were assessed immediately prior and 3 weeks subsequent to unilateral posterior capsulotomy. RESULTS: In eyes that underwent laser posterior capsulotomy, the median spatial acuity (log minimum angle of resolution (MAR)) improved from 0.34 (20/44) to 0.16 (20/29) (P=<0.001, Wilcoxon test), while the median contrast sensitivity improved from 22.4 to 35.5 dB (P=<0.001, Wilcoxon test) after posterior capsulotomy. Fellow eyes exhibited negligible change in these visual parameters. The median stereoacuity improved from 240 to 60 s of arc (P=<0.001, Wilcoxon test). CONCLUSION: In the context of unilateral opacification of the posterior capsule, Nd:YAG laser posterior capsulotomy affords significant improvement in stereoacuity, apparently in excess of improvements in spatial acuity and contrast sensitivity. Routine measurement and documentation of these parameters of visual function is recommended especially when subjective visual disability appears disproportionate with impairment of spatial acuity.

Factors affecting the surgical outcome of primary exotropia.

AIMS: To identify the predictors for motor outcome and response to surgical treatment of primary exotropia. SETTING: Taunton and Somerset Hospital, Somerset, United Kingdom. STUDY TYPE: Retrospective analysis of the surgical treatment of primary exotropia performed in our department over a period of 12 years from April 1991 to May 2003. METHODS: Case-notes of the patients who had surgical treatment for primary exotropia for the specified period were identified by a hospital computer database (MDI coding). All case-notes were reviewed and the following data were recorded and used for statistical analysis: age at the time of surgery, type and severity of exotropia, presence of amblyopia, AV pattern and vertical deviation, the level of stereopsis, type of surgery, and motor and cosmetic results. The surgical outcome was determined as good motor outcome if tropia was within 10 PD of orthotropia. The response to surgery was derived from the difference between the preoperative and postoperative angle of deviation for distance per amount of muscle surgery in millimetres. RESULTS: A total of 124 cases were included in the study. Good motor outcome was achieved in 83 (67%) cases. There was a positive correlation between the preoperative angle of deviation at distance and dose response to surgery (r = 0.6 and p < 0.001) and a negative correlation between average corrected visual acuity and response (r = -0.21 and p = 0.025). There was a statistically significant negative relationship between preoperative stereopsis and response to surgery (p = 0.02). CONCLUSIONS: Surgical treatment for exotropia is effective and the dose response is correlated to the preoperative angle of deviation and average visual acuity. Poor or no preoperative stereopsis was associated with better response to surgery.

A 10 year retrospective survey of cataract surgery and endophthalmitis in a single eye unit: injectable lenses lower the incidence of endophthalmitis.

AIM: To study the incidence of endophthalmitis following cataract surgery over a 10 year period, and to examine ways in which this may be related to changes in surgical technique. METHODS: All cases of endophthalmitis occurring over a 10 year period within a single ophthalmic unit in the United Kingdom were reviewed, and possible risk factors identified. RESULTS: During the study period, as the technique of extracapsular cataract surgery was replaced by phacoemulsification, there was a commensurate reduction in the incidence of endophthalmitis. Injectable IOLs were associated with the lowest risk of postoperative endophthalmitis (0.028%). CONCLUSIONS: Injectable intraocular lenses do not make contact with the ocular surface and this may result in the observed lower rate of endophthalmitis. This, and the ease with which they can be inserted through small incisions, support their use as the first line method of lens insertion.

Ocular enlargement following infantile corneal opacification.

Congenital hereditary endothelial dystrophy (CHED) is not generally thought to be associated with other ocular abnormalities. Ultrasonography in a series of twenty eyes (ten patients) with CHED shows ocular enlargement similar to that occurring in uncomplicated axial myopia. There was an inverse relationship between the degree of enlargement and the visual acuity or visual result following penetrating keratoplasty suggesting that infantile corneal oedema sufficient to cause stimulus deprivation may result in abnormal enlargement of the globe.

Endocapsular cataract extraction.

Endocapsular (intercapsular) cataract surgery has recently gained popularity, particularly in Europe. We describe our technique of endocapsular cataract extraction and insertion of an intraocular lens and prospectively compare 93 eyes which underwent endocapsular cataract extraction with 83 which underwent a standard extracapsular procedure. There was no apparent difference between the two groups in visual outcome. Preoperative and post-operative complications were more common in the endocapsular group: posterior synechiae formation in the latter occurred in 19%. In 90% of the endocapsular cataract extractions, the lens was placed 'in the bag' at the time of surgery but at three months only 53% remained 'in the bag'. Displacement of one haptic from the capsular bag was associated with symptomatic lens decentration requiring repositioning in four eyes in the endocapsular group and two eyes in the extracapsular group.

Retinal compression folds.

Twelve cases of retinal compression folds occurring after successful retinal re-attachment surgery are reported. In all 12 eyes surgery included the use of a circumferential buckle, internal tamponade with gas or silicone oil and drainage of sub-retinal fluid. The mechanism of retinal fold formation is discussed.

Behaviour of intraocular gases.

The changes in volume of intraocular bubbles of air, sulphur hexafluoride, perfluoropropane and mixtures of these gases, were studied in human eyes, following vitrectomy for treatment of retinal detachment. The implications of these findings, for the provision of optimal internal tamponade in the treatment of retinal detachment, are discussed.