SUMMARY This paper describes a simplified technique for biopsy of the retina and choroid which had been used in 5 human volunteers. The biopsy was carried out in 4 immediately before enucleation of an eye for malignant melanoma and in 1 patient who was undergoing trabeculectomy for painful glaucoma associated with retinitis pigmentosa. A combination of intravenous mannitol and transient controlled systemic hypotension, induced under general anaesthesia with intravenous sodium nitroprusside, was used in 3 cases and resulted in no vitreous loss and minimal bleeding. In the 2 cases in which hypotension was not used bleeding was a definite problem, but no vitreous loss was experienced.Understanding of many types of chorioretinal pathology has long been retarded by the lack of a practical biopsy technique. Previous workers have described a full-thickness eye wall method for biopsy of the posterior segment in rabbits, monkeys, and 1 human.' A transvitreal approach to retinal biopsy has also been reported in animals.4 These methods have not been widely adopted because of the complexity of the procedure and of the universal vitreous loss reported. A simplified trans-scleral approach to chorioretinal biopsy in dogs using hypotensive anaesthesia resulted in minimal or no vitreous loss,5 so that we were encouraged to apply the procedure to 5 human volunteers. Patients and methods CASE 1A 35-year-old male presented to the neurology outpatients with a 6-week history of blurred vision in the left eye. Vision was 6/6 right, counting fingers left, and a superior field defect was noted in the left eye. On referral to the ophthalmology department a large serous detachment of the inferior retina in the left eye was noted as well as an underlying pigmented mass that had the clinical characteristics of a large melanoma of the choroid. Fluorescein angiography, 32P isotope testing, and ultrasonography all suggested a melanoma of the Correspondence to Professor 1. J. Constable, University

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