Since Gonin (1921, 1930) established the role of retinal breaks in the aetiology of retinal detachment, the closure or isolation of retinal breaks has become an essential part of all procedures for the treatment of this condition. The "prophylactic" treatment of retinal breaks is practised in many centres, but in recent years it has been shown that asymptomatic retinal breaks without detachment are a frequent finding in "normal" eyes (Halpern, I966; Byer, I967; Rutnin and Schepens, I967).About two-thirds of retinal detachments occur in myopic eyes (Duke-Elder and Dobree, I967). The present report deals with degenerative changes in the peripheral retina of asymptomatic myopic eyes, with special reference to retinal breaks. Material and methodsBiomicroscopical examination of the peripheral fundus of 332 myopic eyes was performed using the Goldmann three-mirror contact lens and the Haag-Streit goo slit lamp. The first two myopic patients appearing in the eye clinic of the Rothschild Government-Municipal Hospital, Haifa, on any receiving day during a 14-month period were included in the study provided that they fulfilled the following criteria: It was felt that the cases examined represented an unselected group of myopes, asymptomatic with regard to retinal disease.Maximum dilatation of the pupil was achieved by one or more instillations of o 5 per cent. tropicamide and io per cent. phenylephrine. The cornea was anaesthetized with 0o4 per cent. novesine.The entire peripheral fundus was examined using both fundus mirrors of the contact lens, turning the slit into the horizontal position for examination of the nasal and temporal periphery. Each eye was examined only once, 5 to I0 minutes being allotted to each examination. Only one eye was examined at each session and all the patients were invited to attend for examination of the second eye at a later date; 2I patients did not attend for examination of the fellow eye and in these cases the results of the examination of only one eye were included in the results.
Dark adapted and progressively light adapted electroretinograms (ERGs) were recorded from 34 normals and from 45 glaucoma patients. To enhance the oscillatory potentials (OP) the ERGs were highpass-filtered. The OP were characterized by two indices: their root-mean-square value and the inter-flash interval for which the maximal amplitude was obtained. In most of the glaucomatous OP, 50 of 81 eyes, both indices were abnormal, in 22 one parameter was abnormal and only in 9 were both parameters normal. In 13 of the 14 OP recorded from the opposite ('normal') eye of patients with unilateral glaucoma either one or both of the indices were abnormal. These findings indicate that the damage to the retina in glaucoma may extend more distally than the ganglion cell layer and that subclinical changes might be revealed by OP changes.
In this report we recommend the estimation of visual acuity by detection of the visual evoked potential (VEP) threshold, defined by the smallest visual angle of a constant check size that evokes potentials. This approach was implemented using a fiber-optic pattern-reversal stimulator placed at measured, increasing distances from the examined eye. Snellen visual acuity as determined in 113 subjects was correlated with the VEP detection threshold. A highly significant correlation was found between visual acuity and the threshold visual angle of check size in subjects whose vision was impaired due to opacity in ocular media. For any given visual acuity a somewhat wide range of threshold check sizes, typically 5-10 min of arc was observed. Technical difficulties that need to be overcome to improve these results are discussed.
The high incidence of retinal detachment after cataract extraction in myopic eyes is discussed in the previous paper, page 480.The study reported below was undertaken in order to establish the prevalence of degenerative changes in the vitreous and peripheral retina in myopic-aphakic eyes, with particular emphasis on those changes which might lead to the development of retinal detachment. No such study has been reported previously. Material and methodsBiomicroscopical examination of the vitreous and retina was performed on 103 aphakic eyes with axial myopia of at least -6o dioptres (83 patients). The refraction was calculated according to the formula: phakic correction = (aphakic correction -i I) X 2 (Borish, I970). The study was performed from I967 to 1972 and included all such eyes operated upon for senile cataract during this period (79 eyes), and 24 eyes of patients who had been operated on earlier and were recalled for examination. All the patients referred to in this paper were therefore also subjected to the follow-up study reported in the preceding paper, but not vice versa. Four eyes had suffered vitreous loss at the time of lens extraction.Altogether 4I eyes were examined within 3 months of cataract extraction, 38 eyes were examined between 3 and 12 months after cataract extraction, and 24 eyes were examnined I to 3 years after cataract extraction. Of the 83 patients, 32 were men and 5I were women. Eight patients were between 40 and 50 years of age, 32 were aged 51 to 6o years, 28 were aged 70 years, and I5 were aged 70 to 75 years.Maximum dilation of the pupil was achieved by one or more instillations of i per cent tropicamide and io per cent phenylephrine and the fundus was examined with Goldmann's three-mirror contact lens and the Haag-Streit slit lamp. The state of the vitreous was noted using the central part of the contact lens with the patient looking up, straight-ahead, and down. The entire fundus periphery was examined using both fundus rmirrors of the contact lens, turning the slit into the horizontal position for the examination of the nasal and temporal periphery. clumping of vitreous fibres was present in each case. Some degree of posterior vitreous detachment was present in all but one of the I03 eyes, in six eyes the posterior vitreous face was seen to be separated from the retina only in the upper part of the eye, in 47 eyes the posterior vitreous face was also detached in the posterior pole, and in 44 eyes there was total posterior vitreous detatchment with collapse. RETINAL BREAKSThere were 25 full-thickness retinal breaks in i9 of the 103 eyes examined (I8'4 per cent), including six horseshoes and I9 round breaks. Eleven of the breaks were in the equatorial region of the peripheral retina-that is, more than 2 disc diameters from the ora serrata (Rutnin, 1967) and I4 breaks were in the oral region; I4 of the 25 breaks were in the upper temporal quadrant. Eighteen breaks were up to one-quarter disc diameter in size, three were one-half disc diameter, two were one disc diameter, and two...
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