Showing papers by "Moorfields Eye Hospital published in 1980"

Clinical and experimental evidence that the pattern electroretinogram (perg) is generated in more proximal retinal layers than the focal electroretinogram (ferg)

Abstract: A TV monitor was used to evoke either a pattern ERG to a contrast-reversing checkerboard (PERG), or a focal ERG to alternate increases and decreases of luminance of the blank screen within a bright surround (FERG). Both responses are small (approx 2 microV) and fast (approx 50 msec to peak) and are similar in several other properties. However, they differ in timing and respond differently to changes in contrast. Each frame of a TV picture evokes a "raster ERG," even though the screen is blank. The response is focal and specific to a small central strip of the screen. It is simpler to record than the FERG, where the whole screen is flashing. Because the FERG summation area is about 4 deg, small squares (checks) reversing in contrast produce little luminance response. In 5 of 7 cases where the PERG is unilaterally reduced, the FERGs or raster responses were not affected. Thus clinical evidence also suggests that the PERG may be a separate phenomenon to the FERG and produced at a different site. Toxic, traumatic, congenital, and degenerative diseases of the optic nerve reduce the PERG. The comparison is most easily made in unilateral disease. Ten weeks after an optic nerve insult, the PERG becomes reduced in the affected eye as if retrograde degeneration was occurring. In 27 amblyopes of various types, the PERG was reduced in 23 where orthoptic treatment had failed. In 4 patients responding to treatment, PERGs of the amblyopic eye were as large as, or larger than, those of the fellow eye. The loss is greater with smaller checks. Retinal changes do occur after age 4 but so slowly that responses in heavily occluded eyes are not reduced. An additional level in the visual pathway is thus accessible to evoked potential investigation.

Macromelanosomes in X-linked ocular albinism.

Abstract: Examination of clinically normal skin from four patients with X-linked ocular albinism of the Nettleship-Falls type by light and electron microscopy revealed the presence of macromelanosomes in some melanocytes and keratinocytes. Measuring up to 5 micron many of the abnormal melanosomes showed a concentrically laminated structure suggestive of a phasic growth pattern. Epidermis from three female carriers contained similar but fewer macromelanosomes. These findings indicate that skin biopsy could be of value not only in confirming the diagnosis of ocular albinism in affected males, but also to establish carrier status in asymptomatic females.

A comparison of acyclovir and idoxuridine as treatment for ulcerative herpetic keratitis.

Abstract: Sixty patients were treated with either acyclovir 2% ointment or idoxuridine 1% ointment 5 times a day in a stratified randomised double-blind clinical trial. The 2 antiviral agents were equally effective.

Effect of cyclosporin A on the survival of corneal grafts in rabbits.

Abstract: Cyclosporin A given to rabbits intramuscularly in a dose of 25 mg/kg/day for up to 28 days after corneal transfer results in a marked prolongation in the survival of penetrating corneal grafts compared to that in an untreated control group. Cyclosporin A 1% drops did not prolong survival of the corneal graft, but this may be related to the need for skin transfer 14 days after corneal transfer to ensure rejection, and supports the idea that the drug plays an immunosuppressive role at the time and place of sensitisation.

Diced cartilage grafts to correct enophthalmos.

Abstract: A technique is described using diced cartilage grafts to correct the volume deficit which is responsible for many of the unsatisfactory cosmetic features following enucleation.

Two distinct patterns of visual evoked response asymmetry in human albinism.

Abstract: Results are presented which confirm that in human albinos each cerebral hemisphere receives a predominantly monocular input from the contralateral eye, giving rise to an asymmetry of the visual evoked potential (VEP) to whole-field stimulation which is similar to that for stimulation of the temporal half-field in the same individual. The further finding of two distinct, and in some respects opposite, types of topographical asymmetry raises the possibility that there are two anatomically distinct variants in the retinocortical projection in human albinism, as there are in the Siamese cat.

Comparison of the ocular effects of topical etomidate and pilocarpine in rabbits

Abstract: Etomidate, (R-(+) ethyl-1-(phenylethyl) 1H-imidazole-5-carboxylate), when administered as drops to the eyes of normal New Zealand white rabbits in concentrations of 2%, 4% and 8% in arachis oil has been shown to significantly lower the intraocular pressure in these animals. The intraocular pressure was measured with the Perkins handheld applanation tonometer. The intraocular pressure reducing effect of the 2% and 4% were better than that of 1% pilocarpine; the two per cent etomidate solution reduced intraocular pressure from a pretreatment mean of 13.6mm Hg to a new mean of 7.7mm Hg after three weeks treatment, while the 4% etomidate solution lowered the intraocular pressure from a pretreatment mean of 14.4mm Hg to a new mean of 7.3mm Hg also after three weeks treatment. Pilocarpine (1%) reduced the intraocular pressure from a pretreatment mean of 13.7mm Hg to 10.7mmHg after three weeks treatment in the same group of rabbits. Etomidate (8%) solution also showed a more significant reduction of intraocular pressure than the 2% solution of pilocarpine. The eight percent etomidate reduced the pretreatment mean intraocular pressure of 14.0mm Hg to a new mean of 6.5mm Hg after three weeks treatment while 2% pilocarpine lowered a pretreatment mean of 13.9mm Hg to 9.0mm Hg after three weeks treatment in the same group of rabbits. There was a persistence of the low intraocular pressure produced by the various concentrations of etomidate in arachis oil after treatment with these drops was stopped. However, this feature was also shown by the two concentrations of pilocarpine used but not in as marked an extent as the etomidate solutions with regard to duration of effect and height of reduction of the intraocular pressure. During a three week period of topical application of drops to the rabbits eyes, the etomidate solutions were found to have no effect in the iris sphincter.

Diagnostic ultrasound in ophthalmology.

Abstract: Diagnostic ultrasound is now used routinely in the investigation of patients with opacification of the ocular media or with orbital problems. Ultrasonic frequencies within the range 5-20 MHz are generally used for ophthalmic diagnosis; at Moorftelds, we select 10 MHz for most purposes. In order to couple the high-frequency sound to the eye, a gel can be applied to the anaesthetized eye or to the closed eyelids (Bronson 1972, Ossoinig 1972). Such 'contact' methods of coupling, although convenient, do not permit the anterior structures of the eye to be well outlined. We prefer to couple the sound to the eye by means of a saline bath (Purnell 1966, Coleman et al. 1968). Three different 'pulse echo' techniques will be described, namely A-scan, B-scan and C-scan; the last technique is employed only in orbital diagnosis.

Ultrasound in ophthalmic diagnosis.

Abstract: (1980). Ultrasound in opthalmic diagnosis. Journal of Medical Engineering & Technology: Vol. 4, No. 3, pp. 125-129.

Computerized tomography in orbital lesions.

Abstract: The application of computerized tomography to orbital diagnosis was first evaluated by Ambrose et al. (I974) and by Gawler et al. (I974). Since then numerous publications have appeared detailing the technique for orbital scanning and recording the findings in specific pathological conditions such as tumours, inflammatory processes and dysthyroid exophthalmos. The presence of fat in the intraconal space acting as a natural contrast medium has made computerized tomography a very rewarding exercise in orbital diagnosis. After plain X-ray of the skull, it is the principal method of investigation of patients presenting with unilateral exophthalmos in suspected orbital disease. Other investigations ultrasound, orbital venography, carotid angiography are ancillary to it. The present apparatus in use at The National Hospital, Queen Square, is an EMI CT 5005 Body Scanner, which has been adapted for head and neck scanning and which incorporates a high resolution facility. The latter system uses only the centralS inches of the scanning aperture and, with a 5 mm collimated slice thickness, has produced the optimal scans to date (Figure l). Bone detail is particularly well shown with the high resolution method. The advantage of using a Body Scanner for orbital scanning lies in the routine availability of making scans in planes other than the axial. Coronal, oblique and saggital sections of the orbit are feasible because of the large aperture of the Body Scanner.

A long term study of low concentration guanethidine and adrenaline therapy in glaucoma

Abstract: A long term study was undertaken to evaluate the efficacy of combined guanethidine (1%) and adrenaline (0.05–0.5%) therapy in controlling intra-ocular pressure in 89 patients with chronic open angle glaucoma, in whom ocular tensions proved difficult to control on miotics and/or carbonic anhydrase inhibitors. Visual acuity, fields of vision, applanation tension, size of the pupil, anterior chamber depth and gonioscopic examination of the angle were recorded before and during treatment. The follow-up extended over a period of 12 to 42 months, the mean being 28 months. The combined therapy was found to lower the intra-ocular pressure significantly in a large number of patients and the most potent combination was guanethidine 1% and adrenaline 1/4% and the average fall of intraocular pressure with the combined therapy was around 8 mm Hg. Intolerance to the combined preparation was noticed in three patients during a period of 12–18 months with the symptoms of sore eyes, conjunctival hyperaemia and lid irritation of such severity that the treatment had to be withdrawn. Resistance to treatment developed in four patients during a period of 12–36 months and treatment had to be changed. Addition to guanethidine (1%) and adrenaline up to 1/4% to pilocarpine therapy (2–4%) in eyes with narrow angles did not result in any appreciable change of the width of the angle, the size of the pupil and the depth of the anterior chamber.

The hospital ophthalmic service.

Abstract: Over the past two or three decades the role of the hospital ophthalmic service has been changing gradually. No longer is its function largely to provide a surgical workshop for patients with cataract, squint, and medically uncontrolled glaucoma, as well as an emergency service for patients with relativelyminor, and occasionaUymajor, acute ocular disorders. Increasing emphasis is being placed on preventive ophthalmology and on the diagnosis and management of the ocular manifestations of systemic disease, the classic example being the treatment of diabetic retinopathy. Many of the significant advances that have recently occurred in ophthalmology have resulted from the greatly increased sophistication of diagnostic and therapeutic facilities. Whereas 40 years ago the ophthalmologist examined his patient with test type, loupe, and direct ophthalmoscope, he is now expected to assess several parameters of the visual functions, and to examine the eyes with slitlamp microscope (often with contact lens and gonioscope), applanation tonometer, and direct and indirect ophthalmoscope, sometimes followed by such investigations as fluorescein angiography, electrodiagnostic tests, and ultrasonography. This change in sophistication of examination has occurred against a background of a small numerical increase in the establishment of consultant ophthalmologists (about I% per annum), and a negligible change in the establishment of other non-training and training grades. An additional consequence of this increased sophistication is the expense of equipping ophthalmic units, yet it is certain that this same sophistication is at least in part responsible for the appreciable reduction in the average length of stay of inpatients that has occured in recent years and which is continuing to occur. The hospital ophthalmic service cannot be discussed in isolation, but must be considered in association with the general ophthalmic services which are staffed by ophthalmic medical practitioners (OMPs), ophthalmic opticians (OOs), and dispensing opticians (DOs). OMPs and OOs working in the general ophthalmic services are expected to test sight and to recognize variations from the normal. When such variations are encountered, the patient should be referred to a medical practitioner. An OMP may recognize