Detection of the carrier state of X-linked retinoschisis.

We determined the extent of suppressive rod-cone interaction in 11 obligate carriers and eight potential carriers of X-linked retinoschisis from eight families. Despite otherwise normal ophthalmoscopic and functional testing, all of the obligate heterozygous carriers demonstrated a complete absence of normal rod-cone interaction. Of the potential heterozygous carriers, three had normal rod-cone interactions, two had no detectable interaction, and two yielded technically unsatisfactory results. This lack of rod-cone interactions allows heterozygous individuals to be identified clinically and has implications concerning the origin of this inherited disorder.

The evaluation of a humidifying device for vitreoretinal surgery.

AIM: To study the feasibility of humidifying air during vitreoretinal surgery and measure the water content of air before and after intraocular transit. METHODS: The absolute water content of air was measured in a series of six eyes undergoing fluid-air exchange during macular hole surgery. Infrared absorption spectroscopy was used to determine the water content of the air infusing and exiting each eye. After baseline measurements for each eye were recorded, a second fluid-air exchange was performed and the effect of humidifying the air infusion was documented. The humidifying device used in this study was a prototype adapted from a commercially available respiratory humidifier and enables humidified air to be delivered at a controlled temperature. RESULTS: The water content of air increased following intraocular transit, implying dehydration occurs from the intraocular surfaces. For a standard airline infusion the mean increase in water content of air egressing from an eye was 13.4 mg/l. Humidifying the air reduced the rate of water loss by nearly 90%. CONCLUSIONS: Significant water losses can occur from eyes undergoing fluid-air exchange. Humidifying the infused air can substantially reduce the dehydrating effect during an air exchange. This outcome may have a beneficial effect in reducing cataract formation and visual field defects associated with macular hole surgery.

[Color vision defect. A early sign of Sorsby retinal dystrophy?]. / Farbsinnstörung. Ein Frühzeichen bei Sorsby-Netzhautdystrophie?

In 34 asymptomatic patients from three families at 50% risk of developing Sorsby's fundus dystrophy, colour contrast sensitivity was measured. In 16 the thresholds--mainly of the tritan axis--were raised above the normal values. It is concluded that testing of colour vision is useful in detecting the abnormal genotype. Raised colour contrast sensitivity was not observed before the first fundus or fluorescein angiographic changes in two of the families, while the colour defect occurred in the absence of ophthalmoscopic abnormality in the third family. Therefore, our results support the clinical suggestion that Sorsby's fundus dystrophy is more than one disease.

Posterior vitreous detachment following cataract surgery.

OBJECTIVE: To determine the incidence of posterior vitreous detachment (PVD) in a series of patients who have undergone cataract surgery by phacoemulsification. DESIGN: Comparative case series. PARTICIPANTS: A consecutive series of 149 patients who underwent cataract surgery aged between 50 and 60 years were evaluated in this study. METHODS: Patients identified as being eligible for this study were recalled for an ophthalmic assessment, which included a dilated retinal examination. MAIN OUTCOME MEASURES: The status of the vitreous was recorded following an evaluation by slit-lamp biomicroscopy, binocular indirect ophthalmoscopy, and B-scan ultrasonography. RESULTS: A PVD was documented in 50.8% of the pseudophakic eyes as compared to 20.8% in the phakic fellow eyes. This difference was statistically significant. Furthermore, the incidence of PVD was greater in pseudophakic eyes with an axial length of 25 mm or greater compared to those eyes with an axial length of <25 mm. Neodymium: yttrium garnet (Nd:YAG) capsulotomy did not influence the prevalence of PVD.In this series of eyes, with a median follow-up interval of 77 months the incidence of pseudophakic retinal detachment (PRD) was 4%. CONCLUSIONS: The incidence of PVD in pseudophakic eyes in the 6th decade is higher than those phakic eyes, and is likely to be associated with the increased risk of PRD observed in this age group.

Inadvertent perforation of the globe during regional anaesthesia.

PURPOSE: This retrospective study was undertaken to review the clinical signs and management of patients with perforating eye injuries associated with regional anaesthesia for ophthalmic surgery. METHODS: Fifteen consecutive patients presenting with inadvertent perforation of the globe were evaluated. Eleven required vitreoretinal surgery. The indications were retinal detachment (six eyes), vitreous haemorrhage (four) and an epiretinal membrane (one eye). RESULTS: Those eyes with retinal detachments generally had a poor functional outcome in spite of the retinae being attached in five of the six eyes. The operative findings of those eyes with vitreous haemorrhage but attached retina demonstrated varying retinal tear configurations. CONCLUSIONS: Eyes with perforating injuries following intraorbital anaesthesia are at risk of developing a retinal detachment. In those eyes presenting with dense vitreous but attached retina, consideration of vitrectomy and laser photocoagulation is advised.

Macular oedema and retinal neovascularisation in juvenile diabetics.

Thirteen young diabetic patients with peripheral capillary non perfusion who presented with symptoms of mild maculopathy were reviewed retrospectively. In this group, peripheral retinal ischaemia was often overlooked and a rapidly progressive proliferative retinopathy developed. Fluorescein angiography of the peripheral retina showed capillary closure, but with preservation of arterioles and venules. In this series, half of the eyes lost vision. In seven eyes where the peripheral ischaemia was treated by pan retinal photocoagulation, the maculopathy resolved without any specific laser treatment to the macula. In young diabetics presenting with maculopathy, the peripheral retina should be examined for ischaemia, and if present, pan retinal laser photocoagulation should be performed. Focal treatment for the macular disease can be delayed until after the peripheral photocoagulation, as the maculopathy may remit.

Humidity devices in vitreoretinal surgery.

PURPOSE: To assess a humidity device used in vitreoretinal surgery. METHODS: Infrared absorption spectroscopy analysis of absolute water content (absolute humidity) was determined for a typical vitreoretinal air infusion line with and without the humidifying device. A variety of experimental laboratory conditions were utilized and designed to mimic those found in the operating room. The effect on physical parameters, such as flow rates and resistance to flow, were also determined. RESULTS: While large bore infusion (LBI) lines had a negligible effect on flow rate and resistance to flow (reduction in infusion pressure), the standard 20 G infusion line (SI) reduced flow rate and infusion pressure by approximately 25%. When used together, the humidifying device and SI reduced flow rate and infusion pressure by one third. The humidifying device was found to add 6.5 mg/L water content to the air infusion line system. Typical operating room (OR) air contains 9.5 mg/L water content, and 43.876 mg/L water content is required to saturate air at body temperature. CONCLUSION: To eliminate dehydration as a cause of intraocular morbidity, one must first saturate the infused air. If the visual field defects and other complications are eliminated, this would be good evidence for saturating infused air. As infusion pressure (flow rate) influences dehydration rate, unless saturated air is used, infusion pressure cannot be considered an independent variable in the analysis of field defects.

The vicryl tie technique for inserting a draining implant in the treatment of secondary glaucoma.

We have previously described surgical techniques for draining severe cases of secondary glaucoma by means of an artificial implant. Wherever possible these implants have been inserted in two stages. The technique involved suturing the episcleral plates of the implant to the sclera without connecting them to the chamber as the first procedure. Following this procedure the presence of the plates cause the surrounding tissue to form a thin fibrous envelope called a preformed bleb cavity. After a suitable interval of between six and eight weeks the connecting tube of the implant was inserted into the anterio chamber so as to drain aqueous into this preformed bleb cavity. This manoeuvre drastically reduced the incidence of postoperative hypotony and has proved a safe and effective technique. This communication reports an improvement on this technique in which the connecting tube of the implant is occluded by a ligature of 5-0 vicryl before inserting the tube into the anterior chamber through a fine needle puncture, at the same time as the episcleral plates of the implant are sutured to the sclera. The effect of this procedure is thus to prevent any drainage of aqueous until three to five weeks after operation when the vicryl suture material dissolves, allowing aqueous to drain into the preformed bleb system lined by a thin layer of dense fibrous tissue. This technique provides the advantages of the previous two-stage technique without the need for a second operation. The surgical technique is described together with the results of treating a series of 20 eyes with severe secondary glaucoma.

A hospital rental system for low vision aids.

Costly low vision aids are rented to patients by the Otago Hospital Board. Occupational therapists see the patients in the Low Vision Clinic and then as necessary in their homes. As a consequence accurate follow-up and analysis of the help provided by these aids is available. Patients with senile macular degeneration use telescopic reading aids for an average of 27 months after they are prescribed.

Sorsby's pseudoinflammatory macula dystrophy--Sorsby's fundus dystrophies.

The findings are presented on the updated Kempster pedigree with Sorsby's fundus dystrophy. The study confirms the features described in other families: autosomal dominant inheritance with complete penetrance, loss of central vision due to subfoveal ingrowth of new vessels, and progressive peripheral chorioretinal atrophy. By contrast to other reports the family in the current study have peripheral retinal dysfunction, a deposit of a subretinal yellow material throughout the fundus and a tritan colour defect, all prior to the loss of central vision; in some patients there was loss of central vision from atrophic disease, rather than from ingrowth of subretinal new vessels; and, there was a different temporal progression of the central subretinal neovascular complex. These features suggest the possibility of genetic heterogeneity.

Ocular fundus lesions in divers.

Retinal fluorescein angiography was used to examine the ocular fundi of 84 divers. The retinal capillary density at the fovea was low and microaneurysms and small areas of capillary nonperfusion were seen. The divers had significantly more abnormalities of the retinal pigment epithelium than a comparison group of non-divers. Furthermore, the prevalence of fundus abnormality was related to length of diving history. All observed changes were consistent with the obstruction of the retinal and choroidal circulations. Such obstruction could be due either to intravascular bubble formation during decompression, or to altered behaviour of blood constituents and blood vessels in hyperbaric conditions.

Identification of cytomegalovirus in vitreous using the polymerase chain reaction.

A presumptive clinical diagnosis of cytomegalovirus (CMV) retinitis was made in two patients presenting with atypical ophthalmologic findings. The diagnosis was confirmed by finding specific CMV DNA sequences in sampled vitreous fluid using a polymerase chain reaction (PCR) based assay. Neither of these patients yielded CMV on culture or PCR of peripheral blood leucocytes, nor was CMV present in tears or urine of either patient. Serum antibody titres were stable and did not help in establishing the diagnosis. This report suggests that CMV retinitis can occur in the absence of disseminated CMV disease.

Sorsby's fundus dystrophy. A clinical study.

A survey was undertaken of a family known to have Sorsby's fundus dystrophy. Fifty members were reviewed, and 14 were found to be affected. Many of Sorsby's original conclusions were confirmed, including the pattern of inheritance and age of visual loss. Yellow material was present at the level of Bruch's membrane early in the course of the disease. However, the earliest phenotypic marker was delayed filling of the choriocapillaris. Abnormalities of choroidal perfusion became more profound and extended centrifugally with time. The loss of central vision was commonly due to atrophy of the outer retina and choroid. Subretinal neovascularization was a rare occurrence. The homology between this dystrophy and age-related macular disease underlines the importance of the clinical findings in this family.

Pigmented lesions of the retinal pigment epithelium and familial adenomatous polyposis.

Bilateral pigmented fundus lesions were found in 65 out of 72 patients with familial adenomatous polyposis, an additional five patients having unilateral lesions. With a family history of familial adenomatous polyposis, the occurrence of multiple bilateral fundus lesions indicates the presence of the abnormal gene, as does the occurrence of oval pigmented lesions with surrounding pale haloes. The absence of pigmented fundus lesions does not exclude the abnormal genotype, while the presence of occasional pigmented spots can be found in an appreciable percentage of the population. Ocular examination would, however, appear to be valuable in screening those at risk, with a positive yield in most carriers of the gene for familial adenomatous polyposis.