[Spectrum of ophthalmologic and social rehabilitation at the Tübinger Low-Vision Clinic : a retrospective analysis for 1999-2005]. / Ophthalmologische und soziale Rehabilitation sehbehinderter Patienten : Eine retrospektive Analyse an der Tübinger Sehbehindertenambulanz von 1999-2005.

BACKGROUND: In addition to medical care, the visual and social rehabilitation of low-vision patients is of increasing importance. The aim of our study was to evaluate the actual spectrum of patients concerning diagnoses and appropriate low-vision aids at a low-vision clinic. METHODS: In a retrospective study, the medical records of 4,711 patients treated at our low-vision clinic from January 1999 to December 2005 were reviewed and analyzed. The main outcome measurements were age, ophthalmologic diagnoses, magnification requirement, and prescribed low-vision aids, as well as social and professional rehabilitation measures. To evaluate the efficiency of visual rehabilitation, reading speed was measured in a subgroup of 930 patients before and after administration of low-vision aids. RESULTS: Age-related macular degeneration was, at 40%, the most frequent diagnosis. Other main diagnoses were tapetoretinal dystrophies, optic atrophy, and diabetic retinopathy. The median magnification need was 4x. A highly significant correlation existed between the measured magnification power and the magnification factor of the prescribed low-vision aids. Visual rehabilitation was frequently sufficient with simple optical low-vision aids such as high-plus reading additions and magnifiers. Closed-circuit television systems were necessary in 26%; however, 85% of these patients had a high magnification need of more than 6 x. For distance vision, a monocular telescope was the low-vision aid prescribed most often. A high proportion of patients needed more than two low-vision aids for different application areas. Forty percent of patients needed special social and professional rehabilitation measures. In a subgroup of 930 patients, the mean reading speed was 35+/-50 words/min before the use of low-vision aids, which increased significantly to 81+/-46 words/min with the use of such aids. Therefore, the reading speed essentially doubled following the use of low-vision aids. CONCLUSION: Our results provide actual, quantitative data about the need for and success of rehabilitation for visually impaired patients. A large number of patients suffer from age-related macular degeneration. Independent from the causal ophthalmologic diagnoses, most patients benefited greatly from the rehabilitation measures provided by the low-vision service and were thus able to improve their quality of life. In the face of the increasing number of visually impaired elderly patients, rehabilitation should start as early as possible.

Effects of beta-adrenergic blockade on verapamil-responsive and verapamil-irresponsive sustained ventricular tachycardias.

To assess effects of beta-adrenergic blockade on ventricular tachycardia (VT) of various mechanisms, electrophysiology studies were performed before and after intravenous infusion of propranolol (0.2 mg/kg) in 33 patients with chronic recurrent VT, who had previously been tested with intravenous verapamil (0.15 mg/kg followed by 0.005 mg/kg/min infusion). In the verapamil-irresponsive group, 10 patients (group IA) had VT that could be initiated by programmed ventricular extrastimulation and terminated by overdrive ventricular pacing, and 11 patients (group IB) had VT that could be provoked by isoproterenol infusion (3-8 micrograms/min) but not by programmed electrical stimulation, and that could not be converted to a sustained sinus rhythm by overdrive ventricular pacing. Notably, in the group IA patients, all 10 patients had structural heart disease (coronary arteriosclerosis or idiopathic cardiomyopathy); beta-adrenergic blockade accelerated the VT rate in one patient but exerted no effects on the VT rate in the remaining 9 patients, and VT remained inducible in all 10 patients. By contrast, in the group IB patients, 7 of the 11 patients had no apparent structural heart disease; beta-adrenergic blockade completely suppressed the VT inducibility during isoproterenol infusion in all 11 patients. There were 12 patients with verapamil-responsive VT (group II). 11 of the 12 patients had no apparent structural heart disease. In these patients, the initiation of VT was related to attaining a critical range of cycle lengths during sinus, atrial-paced or ventricular-paced rhythm; beta-adrenergic blockade could only slow the VT rate without suppressing its inducibility. Of note, 14 of the total 33 patients had exercise provocable VT: two in group IA, five in group IB, and seven in group II. Thus, mechanisms of VT vary among patients, and so do their pharmacologic responses. Although reentry, catecholamine-sensitive automaticity, and triggered activity related to delayed afterdepolarizations are merely speculative, results of this study indicate that beta-adrenergic blockade is only specifically effective in a subset group (group IB) of patients with VT suggestive of catecholamine-sensitive automaticity.

[Ophthalmological rehabilitation of visually impaired children]. / Ophthalmologische Rehabilitation sehbehinderter Kinder.

BACKGROUND: There are very few studies on visually impaired children in Germany; therefore, the aim of this study was to investigate the current spectrum of diseases of visually impaired children and the care of these children in schools and kindergartens with aids and integrative support. PATIENTS AND METHODS: In a retrospective study all children (n =303) who attended the outpatient department for the visually impaired of the University Eye Hospital Tübingen in 2013 and 2014 were evaluated. The target values were ophthalmological diagnosis, best corrected visual acuity, needs for magnification, prescribed aids, measures for early support and integrative care and inclusion during schooltime. RESULTS: The most frequent diagnosis in this collective which led to visual impairment in children was optic atrophy (22.4%) followed by hereditary retinal dystrophy (18.5%), congenital nystagmus (9.9%), albinism (8.6%), retinopathy of prematurity (ROP, 7.9%), aniridia (4.6%), cerebral visual impairment (CVI, 4.3%) and severe myopia (3%). Of the children 21% suffered from multiple disabilities, 66% were visually impaired (visual acuity ≤0.3 and >0.05), 9% were severely visually impaired (visual acuity ≤0.05) and 6% were legally defined as blind (visual acuity ≤0.02). Of the schoolchildren 52% (n = 241) were able to visit a mainstream school within the framework of integrative care. For 77% of these schoolchildren integrative care was already provided by a special pedagogic institution at the time of presentation for school entry and 73% of all the schoolchildren needed magnifying aids at school: 20% used optical magnifying aids (e.g. reading stones) and 53% needed electronic magnifying aids, such as screen magnifiers or camera reading systems. CONCLUSION: Particularly for children, the use of magnifying aids for reading is essential for education in schools and 73% of the children used optical or electronic devices for reading. Of the children 52% attended a mainstream school and were additionally supported by special pedagogic counseling services.

[Accommodation ability under the aspect of refractive, demographic, and biometric parameters]. / Akkommodationsfähigkeit unter Einbeziehung refraktiver, biometrischer und demographischer Parameter.

PURPOSE: The aim of this study was to evaluate the accommodation ability in healthy phakic eyes in relation to refraction and biometric parameters in order to get comparable results for patients with the accommodative 1 CU posterior chamber lens. METHODS: The study included 120 normal eyes of 120 patients (77 males, 43 females, mean age: 40+/-18, range: 11-70 years). The inclusion criteria were spherical equivalent for distance refraction <2 D, astigmatism <1.5 D, and a best-corrected visual acuity > or =0.8. Exclusion criteria were diabetes, glaucoma, cataract, traumas, or previous surgery. Subjects were divided into six age groups at increments of 10 years. Each group consisted of 20 subjects. Measurements included subjective and objective refraction (D), the accommodation ability (D) assessed with an accommodometer, and biometric parameters using the IOLMaster. In addition, the relation of anterior chamber depth and length of the eye was calculated for analyzing the relationship of anterior eye segment and accommodation. RESULTS: The spherical equivalent for distance refraction was 0.04+/-0.6 D with a range of -1.5 to 2.0 D. There was no sex-related significant difference of accommodation range. The accommodation range (D) decreased significantly with increasing age (p<0.0001, r=-0.895). The highest decrease could be found between the ages of 30 and 50 years. In subsequent years, the decline in accommodation ability was comparatively less. In association with the anterior chamber depth and the relation of anterior chamber depth and length of the eye, the accommodation ability fell with increasing age (p<0.001). The length of the eye did not correlate with the accommodation ability (p=0.8). CONCLUSION: There is a strong relationship between accommodation ability and age. Accommodation ability decreases strongly from the 3rd to the 5th decade; after that the loss of accommodation ability is relatively lower. The increase in lens thickness during the life span can implicate a correlation between the change of anterior chamber depth in relation to the length of the eye and a decrease of accommodation ability. Our results confirm Duane's hypothesis of accommodation and age.

Reversal of left ventricular intracavitary gradient with intracavitary diastolic regurgitation in hypertrophic obstructive cardiomyopathy.

A 73 year old man presented with angina and nonsustained ventricular tachycardia. Cardiac catheterization revealed the dynamic systolic intracavitary gradient of hypertrophic obstructive cardiomyopathy. Abnormal isovolumetric relaxation resulted in the development of a diastolic gradient from the left ventricular outflow tract to the left ventricular apex accompanied by intracavitary regurgitation of contrast material from the outflow tract to the left ventricular body during left ventriculography. This case provides hemodynamic and angiographic confirmation of abnormal isovolumetric relaxation in this syndrome and insight into its mechanism.

[Requirements for low vision magnification aids in age-related macular degeneration: Data from the Tübingen low vision clinic (comparison of 2007-2011 with 1999-2005)]. / Bedarf an vergrößernden Sehhilfen bei altersbedingter Makuladegeneration: Daten der Tübinger Sehbehindertenambulanz (Vergleich der Jahre 2007 bis 2011 mit 1999 bis 2005).

BACKGROUND: The purpose of this study was to investigate if there has been a change in requirements for low vision magnification aids in recent years. PATIENTS AND METHODS: The collective data from age-related macular degeneration (AMD) patients from the Tübingen low vision clinic from the years 2007-2011 were compared with the patient collective from the years 1999-2005. Magnification needs and the prescribed magnifying aids for reading in the categories magnifying spectacles, hand-held magnifiers, monocular telescopes, electronic magnifiers and electronic reading devices were evaluated. In addition patients from 2010 and 2011 were divided into dry and neovascular AMD and the prescribed magnification aids were compared for these AMD forms. RESULTS: There was no significant change in in the prescribed magnification reading aids for AMD patients between the years 1999-2005 and 2007-2011. An electronic magnifier was prescribed most often (both collectives 43 %), followed by hand-held magnifiers (32 and 29.5 %, respectively) and magnifying spectacles (17 and 18.8 %, respectively). Also the magnifying needs and mean age of the AMD patients did not change significantly between the two periods (2007-2011 versus 1999-2005). The detailed analysis for dry and neovascular AMD for the years 2010 and 2011 showed no significant differences for the most commonly prescribed low vision aids. The prescription of low vision aids is not influenced by the AMD classification (dry or neovascular), only by the magnification needs. CONCLUSION: There is an unchanged and still high demand for rehabilitation aids of AMD patients, for dry as well as for neovascular AMD even after the introduction of anti-vascular endothelial growth factor (anti-VEGF) therapy.

Scotopic threshold response and scotopic PII in glaucoma.

PURPOSE: The value of the ERG scotopic threshold response (STR), which is known to originate in the proximal retina and of the near-threshold scotopic PII(B-wave), was studied in glaucoma. METHODS: Full-field single flashes were presented under scotopic conditions in two subject groups, a glaucoma group (n = 30) and a normal control group (n = 35). The intensity level for evoking STR was where the maximum response occurs, whereas the intensity level for evoking scotopic PII was where the response begins to appear. RESULTS: The STR is only slightly reduced in glaucoma (P = 0.046), but scotopic PII is significantly diminished (P < 0.0001). CONCLUSIONS: The relatively intact STR in glaucoma suggests that structures responsible for its generation are less damaged in glaucoma than those responsible for scotopic PII.

VEP test of the blue-sensitive pathway in glaucoma.

PURPOSE: The blue-sensitive pathway in normal subjects and in patients with primary open-angle glaucoma (POAG) was tested with the pattern visual evoked potential (VEP) method under selective adaptation. METHODS: Recording of pattern-onset VEP in response to blue (460-nm) stripes (0.88 c/deg) presented either without or with a bright yellow (570-nm) adaptation light (Maxwellian view, 33 degree diameter). Amplitude and peak times were evaluated, and the mean tritan score of the Farnsworth 100-hue test was determined. Age-matched normal subjects (n = 34) and (n = 32) patients with POAG were examined. RESULTS: The amplitude and peak time of the VEP without selective adaptation did not discriminate normal subjects from the POAG group. With selective adaptation, the amplitude was reduced (P = 0.002) and its peak time delayed (P < 0.0001) in POAG, yielding a sensitivity of 75% and a specificity of 94%. The VEP measures only under selective adaptation correlated significantly in patients with POAG with the mean perimetric defect, with the optic disc damage, and with the 100-hue test. CONCLUSIONS: Recording the blue-on-yellow VEP is a useful test in glaucoma research.

Protein quantification and electrophoresis in aqueous humor of pseudoexfoliation eyes.

PURPOSE: Pseudoexfoliation (PSX) eyes frequently show clinical signs of blood-aqueous barrier impairment. To analyze these alterations, the authors examined aqueous humor of human eyes with and without PSX. METHODS: After aqueous humor samples had been obtained during cataract or filtering glaucoma surgery, a modified Pierce-bicin choninic acid assay was used to quantify total aqueous protein concentration in 27 PSX eyes and 37 eyes without clinical signs of PSX (12 cataract eyes and 25 eyes with primary open-angle glaucoma). In addition, aqueous protein composition was analyzed by sodium dodecylsulfate polyacrylamide gel electrophoresis, silver staining, and laser densitometry in 27 PSX eyes and 59 eyes without PSX. RESULTS: Aqueous protein concentration was significantly higher in PSX (mean 0.42 +/- 0.16 mg/ml) than in normal cataract eyes (0.22 +/- 0.08 mg/ml, P < 0.0001) and in eyes with open-angle glaucoma (0.26 +/- 0.09 mg/ml, P < 0.0001, Wilcoxon-Mann-Whitney test). Electrophoresis revealed a characteristic increase of a 12.5-kDa band in 15 of 27 PSX eyes but in only 1 of 59 eyes without PSX (P < 0.00001, chi-square test). CONCLUSIONS: These results substantiate increased aqueous protein concentration and aqueous barrier impairment in PSX. The additional finding of an increased 12.5-kDa band in 56% of PSX eyes may be related to the pathogenesis of PSX in the anterior ocular segment.

Role of intravenous isoproterenol in the electrophysiologic induction of atrioventricular node reentrant tachycardia in patients with dual atrioventricular node pathways.

To assess the role of intravenous isoproterenol for the facilitation of electrophysiologic induction of atrioventricular (AV) node reentrant tachycardia, 20 patients with dual AV node pathways who lacked inducible AV node reentrant tachycardia at control study had a constant isoproterenol infusion administered and underwent repeat study. Six (30%) of 20 patients (group I) had inducible AV node reentrant tachycardia during isoproterenol infusion whereas the other 14 (70%) patients (group II) did not. Paroxysmal supraventricular tachycardia was clinically documented in all 6 group I patients compared to 3 (21%) of 14 group II patients (p = 0.002). The sensitivity and specificity of isoproterenol-facilitated induction of AV node reentrant tachycardia were 67 and 100%, respectively. The isoproterenol-facilitated induction of sustained AV node reentry was mediated by resolution of the weak link in anterograde slow pathway in 2 (33%) patients, in retrograde fast pathway in 3 (50%) and in both anterograde slow and retrograde fast pathways in 1 (17%) patient. Four group I patients were given intravenous propranolol, 0.2 mg/kg body weight, and had complete suppression of isoproterenol-facilitated induction of AV node reentry. Thus, intravenous isoproterenol is a rather sensitive and highly specific adjunct to electrophysiologic induction of AV node reentrant tachycardia in patients with dual AV node pathways but without inducible sustained AV node reentry.

Effects of beta-adrenergic stimulation on atrial latency and atrial vulnerability in patients with paroxysmal supraventricular tachycardia.

To assess the effects of beta-adrenergic stimulation on atrial latency and atrial vulnerability, the electrophysiologic properties of the atrium were studied before and during intravenous infusion of isoproterenol at 2 to 5 micrograms/min in 11 patients with paroxysmal supraventricular tachycardia exhibiting atrial latency during programmed atrial extrastimulation. In all patients, the isoproterenol infusion reduced the extent of maximum atrial latency (from 86 +/- 19 to 62 +/- 16 ms, p less than 0.001). This was accompanied by a significant shortening of both effective and functional refractory periods of the atrium (from 213 +/- 31 to 174 +/- 40 ms, p less than 0.005 and from 259 +/- 31 to 215 +/- 29 ms, p less than 0.001, respectively). The intra-atrial and interatrial conduction times were also significantly reduced (from 24 +/- 15 and 63 +/- 17 to 15 +/- 10 and 48 +/- 15 ms, p less than 0.005, respectively). In 3 patients with demonstrable atrial vulnerability, the isoproterenol infusion abolished the inducibility of repetitive atrial responses or atrial flutter, or both. Although the clinical significance of the suppressive action of beta-adrenergic stimulation on atrial vulnerability remains to be determined, the present study has demonstrated that beta-adrenergic stimulation significantly reduces atrial latency.

Electrophysiologic manifestations of the excitable gap of orthodromic atrioventricular reciprocating tachycardia demonstrated by single extrastimulation.

To assess the electrophysiologic characteristics of the excitable gap, 12 patients with orthodromic atrioventricular (AV) reciprocating tachycardia were studied. During tachycardia, 8 patients used a left-sided and 4 patients a right-sided anomalous bypass tract for retrograde conduction. QRS complex-synchronized single extrastimuli were delivered from high right atrium, right ventricular apex and coronary sinus, respectively, scanning the whole cycle length of tachycardia. An excitable gap was determined to be present if tachycardia resetting or tachycardia termination occurred. The duration of the excitable gap varied among different pacing sites and occupied 0 to 48% (mean 17 +/- 16) of basic tachycardia cycle length (240 to 480 ms, mean 327 +/- 70). Three patterns of tachycardia resetting were observed: the sum of coupling interval and return cycle being (1) less than a fully compensatory pause in 12 of 12 patients, (2) more than a fully compensatory pause in 5 of 12 patients and (3) equal to a fully compensatory pause in 2 of 12 patients, depending on extent of AV nodal conduction delay exhibited in return cycle. Tachycardia termination was possible when extrastimuli were delivered from right ventricular apex and coronary sinus but not from high right atrium, and only when basic tachycardia cycle length was greater than or equal to 290 ms in 7 of 12 patients. Tachycardia termination was accounted for by development of orthodromic conduction block in AV node in 7 of 7 patients and in bypass tract in 2 of 7 patients. Therefore, site of extra-stimulation and basic tachycardia cycle length affect electrophysiologic manifestations of excitable gap. Further, functional properties of the AV node influence patterns of tachycardia resetting and are primarily responsible for tachycardia termination during programmed single extrastimulation.

Aqueous flare following penetrating keratoplasty and in corneal graft rejection.

OBJECTIVE: Corneal allograft rejection is a major complication of penetrating keratoplasty (PK). We used the laser flare-cell meter that allows, for the first time, non-invasive quantification of aqueous flare in vivo to analyze alterations of the blood-aqueous barrier following uncomplicated PK and in acute corneal graft rejection. PATIENTS AND METHODS: Examination with the laser flare-cell meter was performed in 67 eyes of 62 patients (mean +/- SD age, 46.2 +/- 15.1 years) 12.8 +/- 13.2 months (range, 5 days to 60 months) after uncomplicated PK, in 82 normal control eyes of 82 age-and gender-matched patients (mean age, 49.0 +/- 17.1 years) and in 10 eyes of 10 patients (mean age, 51.6 +/- 15.1 years) with acute diffuse endothelial corneal graft rejection in nonherpetic eyes 15.1 +/- 12.9 months after PK. RESULTS: Compared with the normal unoperated control group (4.43 +/- 1.13 photon counts/ms), aqueous flare was significantly increased during the first 2 weeks following uncomplicated PK (14.73 +/- 8.30 photon counts/ms; P < .0001) but returned to normal levels more than 6 weeks after surgery (4.48 +/- 1.55 photon counts/ms; P > .1). In acute corneal graft rejection, aqueous flare values (17.10 +/- 6.05 photon counts/ms) increased to significantly higher levels than in eyes following uncomplicated PK and in the normal control group (P < .0001), but decreased significantly 9.5 +/- 3.3 days after treatment with systemic and topical corticosteroids (5.78 +/- 2.16; P < .0005). CONCLUSIONS: Application of the laser flare-cell meter appears promising for following up patients after PK and for detecting early corneal allograft rejection.

Quantification of aqueous flare after phacoemulsification with intraocular lens implantation in eyes with pseudoexfoliation syndrome.

BACKGROUND: Impairment of the blood-aqueous barrier is a frequent finding in eyes with pseudoexfoliation syndrome (PEX). OBJECTIVE: To perform noninvasive quantification of aqueous flare using the laser flare-cell meter to analyze blood-aqueous barrier breakdown following phacoemulsification with intraocular lens implantation in eyes with and without PEX. METHODS: After other conditions that might account for impairment of the blood-aqueous barrier were excluded, 11 eyes with PEX and 11 eyes with senile cataract without PEX were included in the study. Aqueous flare was quantitatively determined using a laser flare-cell meter preoperatively as well as 1, 3, and 5 days postoperatively. Phacoemulsification with posterior chamber intraocular lens implantation was performed by one surgeon. RESULTS: On the first postoperative day, flare values (calculated as mean+/-SD photon counts per millisecond) in eyes with PEX were higher (42.2+/-21.3) than in eyes without PEX (30.6+/-15.1) (P>.05). On days 3 and 5, postoperative flare values decreased slowly in eyes with PEX (23.9+/-7.4 and 21.2+/-5.7 photon counts per millisecond, respectively) and were significantly higher than in eyes without PEX (14.8+/-5.4 and 10.5+/-1.4 photon counts per millisecond, respectively) (P<.05). CONCLUSIONS: Breakdown of the blood-aqueous barrier is significantly more extensive in eyes with PEX and may be an important risk factor for early postoperative complications. The altered response to surgery should be considered in eyes with PEX.

An alternative technique for treatment of choledocholithiasis found at laparoscopic cholecystectomy.

OBJECTIVE: To introduce a new strategy for dealing with abnormal cholangiograms at laparoscopic cholecystectomy that makes postoperative cholangiograms possible and facilitates stone extraction by assuring access to the duct for a guide-wire-assisted endoscopic retrograde sphincterotomy. DESIGN: Retrospective review of a prospectively maintained database. PATIENTS: Twenty-four patients with abnormal cholangiograms had a percutaneously placed double-lumen catheter threaded through the cystic duct and advanced into the duodenum. RESULTS: Ten successful guide-wire-assisted endoscopic retrograde sphincterotomies were performed without complications. Eleven normal postoperative cholangiograms suggested spontaneous stone passage or false-positive intraoperative cholangiograms. There were three technical failures in the early part of the series. CONCLUSIONS: This strategy is a reasonable alternative to laparoscopic common bile duct exploration (1) when the cholangiogram is questionably positive, (2) when prolonged anesthesia (poor-risk patient) should be avoided, (3) when the equipment for laparoscopic common bile duct exploration is not available, and (4) when spontaneous stone passage seems likely. Postoperative endoscopic retrograde sphincterotomy with stone extraction is facilitated when it becomes necessary because a guide wire can be introduced through the catheter.

Quantitative assessment of the blood-aqueous barrier in human eyes with malignant or benign uveal tumors.

We assessed alterations of the blood-aqueous barrier in 43 eyes with malignant melanoma (31 choroidal and 12 ciliary body), 40 eyes with benign uveal tumors, and 199-age matched normal control eyes. Aqueous flare was quantified with the laser flare-cell meter and correlated with clinical and histopathologic findings. Aqueous flare (photon counts/ms) was significantly higher in melanoma eyes (20.91 +/- 12.40) than in eyes with benign tumors (4.26 +/- 1.55) (P < .0001) and normal control eyes (3.99 +/- 1.14) (P < .0001). In melanoma eyes, clinical and histologic findings associated with significantly increased aqueous flare values were as follows: tumor height, serous retinal detachment, tumor necrosis, lymphocytic tumor infiltration, and tumor hemorrhage. Development and growth of uveal melanomas are accompanied by marked alterations of the blood-aqueous barrier. The noninvasive laser flare-cell meter may give useful additional information about malignant and benign uveal tumors.

Quantification of aqueous melanin granules in primary pigment dispersion syndrome.

PURPOSE: Aqueous melanin granules are essential in the pathogenesis of pigment dispersion syndrome and pigmentary glaucoma. We quantified aqueous melanin granules with the laser flare-cell meter in patients with pigment dispersion syndrome, assessed the measurement reproducibility, and correlated the numbers with clinical findings. METHODS: Aqueous melanin granules were counted by means of the cell count mode of the laser flare-cell meter (KOWA FC-1000; Kowa, Tokyo, Japan) in 42 eyes of 21 patients with primary pigment dispersion syndrome under three conditions (undilated pupils, dilated pupils, after exercise). The reproducibility of the measurements was determined with the intraclass correlation coefficient. A control group of 40 age- and sex-matched eyes was also examined after pupillary dilation. The results were correlated with biomicroscopic findings in eyes with pigment dispersion syndrome (retrocorneal Krukenberg spindle, iris transillumination, pigmentation of trabecular meshwork). RESULTS: Numerous aqueous melanin granules were detected in eyes with pigment dispersion syndrome (mean, 2.9 +/- 3.7 granules/0.075 mm3) but only small numbers were counted in normal eyes (0.2 +/- 0.3, P < .001). Medical pupil dilation caused an additional increase of aqueous melanin granules in pigment dispersion syndrome (6.3 +/- 5.3, P < .001), but not undilated exercise (climbing stairs) (2.9 +/- 3.7, P > .5). The reproducibility of the measurements was very high (intraclass coefficient >0.92). The number of melanin granules correlated with the degree of Krukenberg spindle (r = .61, P = .004) and with iris transillumination (r = .69, P = .001). CONCLUSIONS: Quantification of aqueous melanin granules yields reproducible results and shows increased numbers in pigment dispersion syndrome, especially after pupillary dilation. Aqueous melanin granule quantification may be useful for evaluating eyes with pigment dispersion syndrome and for assessing treatment effects.

Blood-aqueous barrier after mechanical or nonmechanical excimer laser trephination in penetrating keratoplasty.

PURPOSE: To analyze whether nonmechanical trephination with an excimer laser influences post-operative blood-aqueous barrier breakdown after penetrating keratoplasty. METHODS: Patients undergoing penetrating keratoplasty for keratoconus or Fuchs dystrophy were prospectively randomly assigned to trephination by either excimer laser or conventional mechanical handheld motorized trephine. All surgery was performed by one surgeon, and preoperative, intraoperative, and postoperative treatment was identical in both groups. Aqueous flare was quantitatively determined postoperatively in a masked fashion by laser flare-cell meter. For statistical analysis, the nonparametric Wilcoxon-Mann-Whitney test was used. RESULTS: A total of 52 eyes of 52 patients were examined (Fuchs dystrophy, 10; keratoconus, 42). During the early postoperative period (days 3 to 9), eyes that had undergone nonmechanical excimer laser trephination (25/52) showed significantly (P < .005) lower flare values than did eyes that had undergone mechanical trephination (27/ 52). In both groups, flare values returned to normal levels by 6 weeks postoperatively. CONCLUSION: Early postoperative blood-aqueous barrier breakdown is less pronounced after penetrating keratoplasty with nonmechanical excimer laser trephination.

Physician behavioral response to a Medicare price reduction.

OBJECTIVE: To investigate at the individual practice level physician behavioral responses to the Medicare fee reductions mandated in the Omnibus Budget Reconciliation Act of 1989. Symmetric and nonsymmetric behavioral responses are modeled and investigated. DATA SOURCES: Volume index calculated from data in the Part B Medicare Annual Data (BMAD) Provider Files for 1989 and 1990. The pricing data are from the Procedure Files. STUDY DESIGN: A fixed-effects model in carrier and in specialty is employed. DATA COLLECTION: No direct data collection is required as BMAD files are used in the study. Price and volume variables are expressed as Fisher indexes of change. PRINCIPAL FINDINGS: The results show nonsymmetrical behavioral response because practices that did not face significant fee reductions do not exhibit behavioral change. By contrast, losers partially compensate for the fee reductions. For every dollar cut in their fees, physicians recoup approximately 40 cents by increasing volume. Loser behavioral responses vary by specialty. CONCLUSIONS: The presence of a volume response suggests that price control alone is not sufficient to cap rising healthcare costs. This indicates that additional or other tools must be considered if cost containment is to be attained.

The effect of stimulus size on human cortical potentials evoked by chromatic patterns.

The effect of stimulus size on the pattern onset-offset visual evoked potential elicited with stimuli of two different wavelengths is studied under intensive yellow adaptation: (1) The onset response obtained with a 460 nm pattern is of negative polarity (N1) and saturates in amplitude with a stimulus radius of 7 deg. The onset response obtained with a 550 nm pattern is of positive polarity and continues to increase up to the maximum size (32.2 deg). (2) The peak time of N1 (460 nm) decreases with increasing stimulus size, that of P1 (550 nm) remains constant. These results are discussed as reflecting either varying retinal and brain anatomy, or cone activity, color-opponent activity, or luminance contrast activity.