The Swedish Retinal Detachment Register. I. A database for epidemiological and clinical studies.

PURPOSE: To create a computer-based national register for epidemiological and clinical studies on retinal detachment (RD) for large populations over time. METHODS: A database system was developed for Microsoft Windows 95 and NT platforms to support a multi-user environment, comprising 117 fields (270 parameters). The system is equipped with statistical search programs for statistical differences and dependencies between fields and with graphical display. RESULTS: Information is structured into six subgroups: identification of patient, history of RD, preoperative ocular status, operations, recurrence, and follow-up. Lists of diagnoses, methods and surgical procedures facilitate data input. The drop-out frequency ('null') and follow-up recording are automatically monitored. Mean visual acuity is calculated using logMAR units. Data from the first 1116 patients yield a high RD incidence of 14 per 100,000 inhabitants in an urban area. Mean age at surgery for women was 62.9 years (95% confidence interval 61.54-64.35) and for men 58.3 years (95% confidence interval 57.12-59.42). Myopia was more common before the age of 50 (mean -4.16 D, 95% confidence interval -5.00 to -3.32) than at higher age (mean -0.84 D, 95% confidence interval -1.19 to -0.49). Cataract surgery had previously been performed in 30.8% of the eyes and preoperative macular detachment was present in 52.3%. CONCLUSION: This database register is a useful and powerful tool for population-based studies on epidemiological and clinical parameters of RD. Detailed analyses of retinal reattachment surgery in relation to preoperative findings can be performed in large case materials.

Changes in the direct-current electroretinogram of albino rabbits during prolonged intermittent recording.

The study investigated the pattern of the direct-current electroretinogram (ERG) of albino rabbits during prolonged intermittent recording, and whether different initial dark adaptation periods or starting the experiments at different times influenced the results. We examined 27 rabbits under general anesthesia, in three experiments, each comprising nine animals. Five series (experiments 1 and 3) or four series (experiment 2) of ten repeated light stimuli were presented to the eyes with 30 minutes of dark adaptation before experiments 1 and 3, and 90 minutes before experiment 2. The dark adaptation of experiments 1 and 2 began at 10.30 a.m. and that of experiment 3 at 3.30 p.m. The interval between consecutive series of light stimuli was 33 minutes. Stimulus intensity was 680 lux, stimulus duration 10 seconds, and the interval between stimuli 3 minutes. The mean b-wave amplitude of the ten recordings in each series of stimuli increased up to the series beginning 3.5 hours (experiments 1 and 2) or 2.5 hours (experiment 3) after the start of dark adaptation. The mean c-wave amplitude increased throughout experiments 1 and 3, and up to the series beginning 3.5 hours after the start of dark adaptation in experiment 2. The mean a-wave amplitude was more stable. It seemed irrelevant for the long-term development of the mean ERG amplitudes whether the eye was dark adapted (experiment 2) or exposed to repeated light stimuli (experiments 1 and 3) during the first part of the experiment, and whether the experiments started in the morning or in the afternoon.

Effects of prolonged uniocular dark adaptation on the direct-current electroretinogram of pigmented and albino rabbits.

The direct-current electroretinogram of seven pigmented and seven albino rabbits was recorded from both eyes for almost 4 h in response to repeated identical light stimuli. Stimulus duration was 10 s, light intensity was 6.8 x 10(2) lux, and the interval between the beginning of succeeding light stimuli was 3 min. The dark-adaptation period preceding light stimulation was 30 min for one of the eyes ('unoccluded eye') and 150 min for the contralateral eye ('occluded eye'), which was patched during the first part (117 min) of the experiment. In pigmented animals, the b- and c-wave amplitudes of the unoccluded eye slowly increased during the first part of the experiment but not significantly during the second. The a-wave amplitude was not significantly changed. After removal of the cover, the a- and b-wave amplitudes of the occluded eye immediately attained but not exceed the level of those in the unoccluded eye, irrespective of the light adaptation induced by the stimulus flashes previously presented to the unoccluded eye. (Control experiments on six pigmented rabbits confirmed that stimuli identical to those used in the main part of the study caused a light adaptation, since a decrease in a- and b-wave amplitudes occurred after the first light stimulus following an initial dark-adaptation period of 2 h for both eyes). In albino rabbits, electroretinogram responses were clearly discernible in the occluded eye also during the first part of the experiment, probably because of transillumination of the head. In other respects, the results were essentially similar to those of pigmented animals. The observation that occluded eyes did not dark adapt better, as judged by the electroretinogram responses, than contralateral eyes given repeated light adaptive stimuli may indicate the presence of a mechanism for transfer of adaptation information between the eyes.

The c-wave of the direct-current electroretinogram and the standing potential of the albino rabbit eye in response to repeated series of light stimuli with different interstimulus intervals.

The direct-current electroretinogram and the standing potential of the eye of seven albino rabbits were recorded in response to repeated light stimuli, which were presented in four consecutive series. The intervals between the beginning of succeeding stimuli were 8 minutes, 4 minutes, 2 minutes and 70 seconds (series 1, 2, 3 and 4, respectively). Stimulus duration (10 seconds) and light intensity (6.8 x 10(4) lux) were constant during the experiments. The series lasted for 36-40 minutes, and each was preceded by 30 minutes of dark adaptation. During series 1, the end amplitudes of the a-, b- and c-waves were not significantly changed compared with the initial levels. During series 2, 3 and 4, the a-, b- and c-wave amplitudes were markedly reduced immediately after the first electroretinogram recording. The a- and b-waves then recovered to a limited extent, but the c-wave was more fully restored. A slight peak in the c-wave amplitude could be discerned 16-20 minutes after the start of recording. A decrease in the standing potential was seen 50-54 seconds after the start of light stimulation during all four series, and a peak occurred 12-16 minutes after the start of recording. The similarity in behavior between the c-wave and the standing potential suggests the operation of a pigment epithelial mechanism behind the more complete recovery of the c-wave amplitude. When electroretinogram amplitudes and standing potential levels are discussed, and when one experiment is compared with another one, it is important that adaptational and stimulus conditions, as well as time course, are well controlled and clearly specified.

The c-wave of the direct-current-recorded electroretinogram and the standing potential of the albino rabbit eye in response to repeated series of light stimuli of different intensities.

In 10 experiments on five albino rabbits, the direct-current electroretinogram and the standing potential of the eye were recorded in response to repeated light stimuli (duration, 10 s; interval, 70 s), presented in four series, each consisting of 25 light flashes. Light intensities were, in order of presentation to the eyes, 3, 2, 1 and 0 log rel units (series I, II, III and IV, respectively) below the maximum output of the system. Thirty minutes of dark adaptation preceded each series. At the end of series I, the mean amplitudes of the b- and c-waves were higher and that of the a-wave relatively unchanged compared with the corresponding initial amplitudes. During series II-IV, there was a marked decrease in mean a- and b-wave amplitudes between the first and the following electroretinogram responses, and at the end of the three series, the amplitudes were still significantly reduced compared with the corresponding initial values. The mean c-wave amplitude was also markedly decreased immediately after the first electroretinogram recording, but it later recovered to a large extent. A peak in the c-wave amplitude was discerned about 14-18 minutes after the start of the recordings. A standing potential minimum during the second light stimulus was followed by a peak after about 10-13 minutes. The partially parallel behavior of the c-wave and the standing potential suggests the operation of a pigment epithelial mechanism behind the recovery of the c-wave amplitude. The final amplitudes of the b- and c-waves, and to a large extent also of the a-wave, were about the same irrespective of stimulus intensity. The adaptational processes in the rabbit appear to be more complicated than was previously thought. When electroretinogram amplitudes and standing potential levels are discussed and when one experiment is compared with another one, it is important that adaptational and stimulus conditions, as well as time course, are well controlled and clearly specified.

Evaluation of patients with obvious or suspected degenerative and dystrophic disorders of the retina, pigment epithelium and choroid. Experience from a Swedish referral center.

Between August 1, 1982, and December 31, 1988, 487 patients with clinically established or suspected diagnosis of a hereditary degenerative or dystrophic disorder of the ocular fundus or of a disorder of the optic pathways were evaluated with an extensive set of clinical and electrophysiological tests, 67% of the patients were referred from other eye departments. In order of magnitude the most frequently encountered diagnoses were: 1) 'functional' disturbances (18%), 2) disorders of the optic nerve (9%), 3) retinitis pigmentosa (8%), 4), 5) and 6) progressive cone dystrophy, disorders of the central optic pathways, and fundus flavimaculatus/Stargardt's disease (5% each), and 7) choriocapillaris atrophy (4%). Choriocapillaris atrophy affected older patients than retinitis pigmentosa (P less than 0.001). A male preponderance was observed for juvenile retinoschisis (P less than 0.005) and congenital stationary night blindness (P less than 0.05), and a female dominance in the groups of patients with 'functional' symptoms (P less than 0.01). A specific diagnosis was established in 469 patients. After exclusion of 16 patients referred because of a known hereditary disposition, 196 (43%) of the remaining 453 patients were referred under the same diagnosis as our final diagnosis, 153 (34%) under a different diagnosis and 104 (23%) without any clear diagnosis. Obviously, there is a need for regional centers specialized in these disorders.

Sulfur amino acid metabolism in cystinuria: a biochemical and clinical study of patients.

Sulfur amino acid metabolism was studied in 26 homozygotic cystinuric patients, some of whom received D-penicillamine, 2-mercaptopropionylglycine or N-acetylcysteine treatments in order to evaluate signs of cyst(e)ine deficiency. Decreased leukocyte glutathione and taurine levels, plasma cyst(e)ine and taurine concentrations and urinary inorganic sulfate, taurine, mercaptolactate and thiosulfate outputs were found in cystinuric patients, probably reflecting intracellular cyst(e)ine deficiency. An increased mercaptoacetate-cysteine mixed disulfide output was found, probably as result of a poor tubular reabsorption of this compound, as well as for cystine. Normal retinal function was recorded in all patients. During drug treatments, the excretion of most of the sulfur compounds in cystinurics was as those found in controls, probably reflecting an increased mobilization of cysteine. N-acetylcysteine treatment increased the excretion of cyst(e)ine and can thus not be recommended as stone preventive therapy in cystinuria.

Effects of intravitreal perfusion with dopamine in different concentrations on the DC electroretinogram and the standing potential of the albino rabbit eye.

The direct current electroretinogram and the standing potential were recorded from both eyes of 23 albino rabbits during intraocular perfusion of one of the eyes, which was vitrectomized, with a physiologic reference solution (PHS). PHS was then replaced by a test solution containing dopamine dissolved in PHS. The fluids were subsequently alternated (PHS-dopamine-PHS). During irrigation with 0.25-0.5 mM dopamine (11 rabbits) the c-wave amplitude was 140% higher (p less than 0.001) and during irrigation with 25 mM dopamine (6 rabbits) 85% lower (p less than 0.01) than it was during the corresponding initial perfusion with PHS. The simultaneously recorded b-wave amplitude was reduced (0.25-0.5 mM: -22%, p less than 0.001; 25 mM: -69%, p less than 0.001) and the SP level increased (0.25-0.5 mM: +2375 microV, p less than 0.01; 25 mM: +2530 microV, p less than 0.05) compared with the values obtained during the corresponding preceding irrigation with PHS. Thus the changes in the b- and c-wave amplitudes during perfusion with dopamine were dependent on the concentration of the drug. In the contralateral control eye (23 rabbits) the c-wave amplitude was 21% higher (p less than 0.001), the b-wave amplitude 14% higher (p less than 0.001) and the standing potential 1007 microV higher (p less than 0.001) during intravitreal perfusion with dopamine in the other eye than during the preceding irrigation with PHS in that eye, possibly as a result of increasing dark adaptation.

Pneumatic retinopexy in 50 patients.

Pneumatic retinopexy was introduced in our clinic in 1986. This paper reports the results from the first 50 cases. Detachments with multiple breaks within 3 clock hours and proliferative vitreoretinopathy up to grade C1 were included. This technique compares favorably to buckling procedures in selected cases. The primary success rate was 83%, and the overall success rate was 90% (pneumatic retinopexy +/- scleral buckling +/- vitrectomy).

Clear PMMA versus yellow intraocular lens material. An electrophysiologic study on pigmented rabbits regarding "the blue light hazard".

Pigmented rabbits were exposed for 3.5 h to light (retinal irradiance 60-70 mW/cm2, i.e. below the level of thermal damage) from a Xenon lamp, passing IR filters and a fiber optic system as well as a Perspex CQ (clear PMMA) IOL material in front of one of the eyes (the "PER" eye) and a yellow (blue light absorbing) filter (potential IOL material) in front of the other eye (the "YEL" eye). The difference in spectral distribution of light transmitted by the two filters may be important. Does the yellow filter offer significant protection against "the blue light hazard"? DC ERG recordings were performed before, 1 day after and 4-6 days after exposure. The c- (mainly pigment epithelium (PE)) and b-wave (neuroretina) amplitudes were measured and the cPER/cYEL as well as the bPER/bYEL ratios calculated. Both ratios were found to be reduced after exposure, for the c-wave 30-33% (p less than 0.05 - 0.001), and for the b-wave 12-20% (p less than 0.01 - 0.02). This means that both the PE and the neuroretina were injured in the PER eye, the PE more than the neuroretina. At day 4-6 the c- and b-wave ratios were found to have returned to initial levels, indicating that the damage was reversible to a large extent. Thus, the yellow filter offered a better protection than the Perspex material. There were no ophthalmoscopic fundal changes 1-2 h after exposure. After 1 day minimal changes were seen in 3/16 YEL eyes and somewhat more pronounced changes in 8/16 PER eyes, all in the central fundus. The conclusion is that in acute experiments and under the conditions applied the yellow filter protected the PE and the retina against photochemical light injury (mainly "the blue light hazard") significantly better than the Perspex material. Furthermore, the yellow filter was found to protect significantly better than a UV absorbing IOL material.

Effects of intraocular irrigation with melatonin on the c-wave of the direct current electroretinogram and on the standing potential of the eye in albino rabbits.

The direct current electroretinogram (ERG) and the standing potential (SP) were recorded from both eyes of 14 albino rabbits during intraocular perfusion of one of the eyes, which was vitrectomized, with a recently developed eye irrigation solution (PHS) produced by Pharmacia Ophthalmics. PHS was then replaced by a test solution containing melatonin dissolved in PHS (0.002 microM-200 microM). The fluids were subsequently alternated (PHS - melatonin - PHS). During uniocular irrigation with melatonin the mean c-wave amplitude and SP level of the intact control eye were increased (c-wave +24%, p less than 0.01; SP +0.65 mV, p less than 0.05) compared with the values during the initial perfusion with PHS. In contrast, the c-wave amplitude of the irrigated eye was markedly decreased in many rabbits during perfusion with melatonin compared with the initial PHS, but the mean reduction was small and not statistically significant. The mean SP level was reduced (-1.54 mV, p less than 0.001). This difference between the eyes probably depends on the route by which melatonin reaches the retinal pigment epithelium and thus whether it primarily affects the apical (as in the irrigated eye) or the basal (as in the control eye) pigment epithelial membrane. A peak in the b-wave amplitude was observed in both eyes during uniocular irrigation with melatonin when compared with the amplitude measured during the initial perfusion with PHS (irrigated eye: +27%, p less than 0.001; control eye +18%, p less than 0.002).

Effects of intraocular perfusion with two alternating irrigation solutions on the simultaneously recorded electroretinogram of albino rabbits.

The direct current electroretinogram (DC-ERG) of 15 unilaterally vitrectomized albino rabbits was studied during continuous intraocular irrigation with a recently developed solution ('PHS') produced by Pharmacia Ophthalmics. The mean amplitudes of the b- and c-waves were somewhat lower than corresponding values of previously investigated reference subjects, but not statistically different. In 11 of the 15 rabbits PHS was then replaced by the commonly used balanced salt solution (BSS). The fluids were subsequently repeatedly alternated (PHS, BSS, PHS, BSS, PHS). During irrigation with BSS the average amplitude of the b-wave was reduced to 87% (p less than 0.02) and that of the c-wave to 63% (p less than 0.001) of the levels obtained during perfusion with PHS. In two rabbits the ERG was studied about one month after vitrectomy, where PHS-irrigation was used both during surgery and for 30 min after its completion. No marked differences were observed between the treated and the untreated eyes as to the b- and c-wave amplitudes at stable stages of the recording. Thus, judged by the ERG, retinal and pigment epithelial functions were influenced unfavorably by BSS, whereas they seemed to be well preserved with PHS. From this point of view PHS appears to be an excellent irrigation solution for vitreoretinal surgery that ought to be clinically tested.

Combined effects of DL-alpha-aminoadipic acid with sodium iodate, ethyl alcohol, or light stimulation on the ERG c-wave and on the standing potential of albino rabbit eyes.

Albino rabbits were treated with intravitreal injections of DL-alpha-aminoadipic acid (alpha-AAA) into one eye (0.1 ml of a 0.15 M solution) and 0.1 ml of saline into the contralateral eye. Thirteen to fourteen hours later the DC electroretinogram (ERG) and/or the standing potential (SP) were recorded. (1) In eight of nine animals the c-wave amplitude of alpha-AAA injected eyes was increased compared with that of control eyes. Following intravenous injection of Sodium Iodate (40 mg/kg in 2% solution) the c-waves of both eyes were rapidly replaced by negative potentials. In 8 of 9 animals the amplitude reduction was more marked in alpha-AAA-treated eyes than in control eyes, but the final amplitude was higher in the former than in the latter. The SP was reduced with difference in curve form but not significantly in amplitude between the eyes. (2) In nine other rabbits iv.-injected ethyl alcohol (0.4 g/kg in 20% solution) provoked a transient increase of SP level and c-wave amplitude in control eyes and smaller but similar changes in alpha-AAA injected eyes. (3) In another five animals the SP was recorded following a step from darkness to continuous light stimulation. The light peak was less pronounced in alpha-AAA treated eyes than in control eyes.

Toxic ocular effects of two fibrinolytic drugs. An experimental electroretinographic study on albino rabbits.

The toxic effects on rabbit eyes of 2 intravitreally injected fibrinolytic substances at different concentrations were studied with repeated clinical observations and registrations of the DC ERG. The fellow, control eye of each animal was injected with saline. Urokinase (Ukidan, Serono) (13 rabbits) initially produced aqueous flare (64%), iris hyperaemia (36%) vitreous opacities (27%) and small retinal haemorrhages (18%). 2-3 months after the injection cataract (50%), vitreous opacities (25%) and retinal changes (13%) were observed. The highest dose (10 000 Ploug units) caused reduction of the ERG b-wave, as a sign of retinal toxicity. Tissue activator (D-44, Centre d'immunologie et de biologie Pierre Fabre) (10 rabbits) produced marked aqueous flare (initially 100%, after 2 weeks 50%) and pronounced, persistent vitreous opacities (25% after 2-3 months). At the late stage corneal blood vessels (38%) and cataract (38%) were also found, but only in eyes injected with the highest dose (1000 units), which was retinotoxic as judged by the ERG (reduced b- and c-waves).

Effects of intravitreally injected DL-alpha-aminoadipic acid on the c-wave of the D.C.-recorded electroretinogram in albino rabbits.

The D.C. electroretinogram of four adult albino rabbits was studied 13.5 to 15 hr after injection of 0.1 ml of 0.15M DL-alpha-aminoadipic acid (alpha-AAA) into the vitreous body of one eye. The other eye was similarly injected with saline and served as control. In the alpha-AAA--treated eye the b-wave was markedly reduced or absent and the a- and c-waves increased compared with the control eye. Sincs alpha-AAA damages the Müller cells, the results support the view that these cells are related to the generation of the b-wave and to the negative slow PIII-potential, which modifies the positive pigment epithelial component of the c-wave.

Early effects of sodium iodate on the slow off-effects, particularly the h-wave, and on the c-wave of the DC recorded electroretinogram in rabbit.

The early effects of intravenously administered sodium iodate (NaIO3) on the slow, negative 'off-effect', the h-wave, and on the slow, positive 'on-effect', the c-wave, of the DC recorded electroretinogram were studied in 8 rabbits. Both the h- and c-waves disappeared gradually after NaIO3 administration and were replaced by potentials of opposite polarity. These results strongly support the assumption that the h-wave originates in the pigment epithelium and represents the reversal of events underlying the c-wave. The slow, positive 'off-effect', the g-wave, elicited by 'dark flashes' was seen to pass into the potential replacing the h-wave after NaIO3 treatment.

Early effects of sodium iodate on the directly recorded standing potential of the eye and on the c-wave of the DC registered electroretinogram in albino rabbits.

The early effects of intravenously administered sodium iodate (NaIO3) on the directly recorded standing potential (SP) of the eye and on the c- and b-waves of the DC registered ERG were studied in 8 anaesthetized albino rabbits. In 5 of 6 animals obtaining 40 mg NaIO3/kg bwt. the SP decreased immediately following the injection, and had attained a level 3.5 - 4 mV below the original one after 1 h. The c-wave declined rapidly and 6 min after the injection it was replaced by a large cornea-negative potential. The b-wave was relatively unchanged except in one animal. In 2 rabbits treated with 30 mg NaIO3/kg btw. and in the 6th animal obtaining 40 mg NaIO3/kg bwt. an SP increase instead of a decrease was seen, and the c-wave was more slowly (about 22 min after the injection) replaced by the cornea-negative potential. The b-wave was somewhat increases. These results demonstrate the dose-related and inter-individual variability in the SP reaction to NaIO3 and are in good agreement with the well-known ultrastructural pigment epithelial injury and c-wave changes produced by this substance.

The c-wave of the human electroretinogram in central retinal artery occlusion.

The pigment epithelium-receptor complex, which is supplied from the choroidal circulation, is the main source of the c-wave of the ERG. Occlusion of the central retinal artery (OCRA), which causes serious damage to the inner retinal layers, should therefore not primarily be expected to affect the c-wave amplitude. Nevertheless, conflicting reports of increased, decreased and unchanged c-waves have appeared in the literature. In the present study on four patients with OCRA the affected eyes showed diminished b- and c-waves. On the other hand, both the a-wave and the trough between the b- and c-waves were accentuated in the diseased eyes. Experiments in progress on Cynomolgus monkeys with experimentally induced unilateral OCRA show similar results.

Studies on acute and late stages of experimental central retinal artery occlusion in the Cynomolgus monkey. I. Intensity-amplitude relations of the D.C. recorded ERG with special reference to the c-wave.

The main positive component of the c-wave of the ERG is generated by the pigment epithelium-receptor complex, which is supplied from the choroidal circulation. Occlusion of the central retinal artery (OCRA) causes serious morphological damage only to the inner retina. An effect on the c-wave is therefore not primarily to be expected. In this study on five Cynomolgus monkeys with unilateral, laser-induced OCRA the c-wave was decreased, slightly in the early stage and markedly in the late stage. A hypothetical explanation of the reduced c-wave amplitude, involving changes in potassium ion concentration, is discussed. The conflicting results in other reports may be explained by uncontrolled influence of slow c-wave amplitude oscillations, by differences between acute and late stages, and by possible surgical damage to the choroidal circulation in some cases.

Studies on acute and late stages of experimental central retinal artery occlusion in the Cynomolgus monkey. II. Influence on the cyclic changes in the amplitude of the c-wave of the ERG and in the standing potential of the eye.

The slow (2-3/h) oscillations of the c-wave amplitude and of the standing potential of the eye (SP) were studied in the Cynomolgus monkey during the acute and late stages after experimentally induced (laser photocoagulation) occlusion of the central retinal artery (OCRA). Whereas the healthy control eyes showed large cyclic variations in both the c-wave amplitude and the SP, no oscillations in the c-wave amplitude were observed in the OCRA eyes at any stage, and the SP oscillations were barely detectable in these eyes. OCRA causes morphological damage to the inner retina but not to the pigment epithelium-photoreceptor complex, which generates the positive component of the c-wave, and where the SP is also believed to originate. The findings of the present study strongly indicate that the SP and c-wave oscillations are related, and that they are either dependent on an intact inner retina or that the pigment epithelium-photoreceptor complex is functionally affected by OCRA. If not taken into consideration, the marked difference in oscillations between the OCRA eye and the healthy eye may be a major source of error when comparing c-waves from the two eyes, and it seems that some of the conflicting results reported by others can be explained in this way.