Effect of lockdown amid second wave of COVID-19 on environmental noise scenario of the megacity Delhi, India.

This paper analyzes the impact of second wave of COVID-19 lockdown on environmental noise levels of 25 sites in Delhi city and compares the noise scenario during pre-lockdown, lockdown, and post-lockdown periods. The study utilized the noise monitoring data acquired from 25 real-time ambient noise monitoring stations, installed by the Delhi Pollution Control Committee, Delhi, at various sites throughout Delhi city. A significant reduction of up to 10 and 3 dB(A) in day and night equivalent noise levels, respectively, had been observed during the lockdown period as compared to the pre-lockdown and post-lockdown periods. The study also revealed that only nine sites, including four industrial and five commercial zone sites, complied with the ambient noise standards during lockdown period, and no silence or residential zone sites complied with the ambient noise standards even during the lockdown period. A roadmap for environmental noise management and control is suggested. The study also reports the community's perception toward the change in acoustic environment of Delhi city during the lockdown period by conducting an environmental noise perception survey. The present study should be helpful in devising noise control action plans and policy interventions for environmental noise management and control in the metropolitan city Delhi, India.

To study the role of antibiotic+steroid irrigation of the middle ear in active chronic otitis media with small perforation and pulsatile discharge.

OBJECTIVE: To evaluate the usefulness of antibiotic+steroid irrigation of the middle ear in patients with otitis media with small perforation and pulsatile discharge. METHOD: A prospective, randomised, evaluator-blinded study was carried at a single tertiary care centre over eight years, looking at 100 patients with chronic suppurative otitis media involving small tympanic membrane perforations and pulsatile mucopurulent discharge. The patients were randomised and divided into two groups. In group A, the examination under microscope, with suction cleaning of the external canal, was followed by irrigation of the middle ear with antibiotic+steroid solution for up to one week, while group B was prescribed self-administration of the same drops with systemic antibiotics. The patients were followed up daily for 10 days to monitor otorrhoea relief and on a weekly basis subsequently to monitor the healing of the tympanic membrane. RESULTS: Forty-nine patients in group A had a dry ear after 3-7 days of daily suction and the irrigation of middle ear with the antibiotic+steroid solution and 44 had a healed tympanic membrane after an average three months of follow-up. Five patients with dry ear but persistent perforation underwent tympanoplasty, while only one patient with a persistent ear discharge underwent mastoid exploration. In group B, eight patients on oral antibiotics and self-administration of the same drops had dry ear while 34 had dry ear after receiving intravenous antibiotics. Thirty perforations healed spontaneously and 12 required tympanoplasty. In 8 patients, the tympano-mastoid was explored and these patients had dry, hearing ears only after surgery. CONCLUSION: Patients with chronic suppurative otitis media involving small perforations and pulsatile discharge can be managed conservatively with simple suction cleaning + middle ear irrigation with antibiotics + steroid drops.

Design and synthesis of 6,7-dimethoxyquinazoline analogs as multi-targeted ligands for α1- and AII-receptors antagonism.

Multiple-targeted ligands can have certain advantages for the management of hypertension which has multiple controls. Molecules with dual bioactivities are available in literature for treating metabolic disorders like diabetes, hypertension and hypercholesterolemia. After scrutinizing the SAR of prazosin-type α1-blockers and AII-antagonists it was planned to develop dual α1- and AII-antagonists. Five series of quinazoline derivatives were synthesized and evaluated as dual α1- and AII-antagonists on rat aortic strips for the blockade of known α1- and AII-agonist mediated contractions. Many compounds showed balanced activity on both the receptors but compound (22) was found to be the most active derivative having higher antagonistic activity on both the receptors. In the in vivo experiments the chosen compound (22) was slightly less active than prazosin but was found to be equipotent to losartan. These findings shed a new light on the structural requirements for both α1- as well as AII-receptor antagonists.

Comparative study of complete nasal packing with and without airways.

OBJECTIVE: To study and compare the effects of complete nasal packing and nasal packing with airways (uni/bilateral) on blood pressure, arterial oxygen saturation, middle ear pressure, and post-operative subjective complaints. METHODS: Ninety patients who underwent bilateral anterior nasal packing for epistaxis or following nasal surgery were divided into three equal groups by randomization. Group A received bilateral complete nasal packing, without an airway. In the other two groups, an airway designed from a poly-vinyl chloride, uncuffed endotracheal tube (number 5) was placed below the nasal pack between the inferior turbinate and septum on one (Group B) or both sides (Group C) of the nasal cavity. Patients were monitored in the ward when asleep, especially overnight, for blood pressure and SpO2 levels. RESULTS: Almost all patients in Group A had nasal obstruction with dry mouth, difficulty swallowing, and disturbed sleep. Only 33-40% patients in Groups B and C had similar complaints. Blood pressure rose > 20 mm of Hg in 20 (67%) patients in Group A, while no patients in the airway groups showed any change in blood pressure. In Group A, the average SpO2 during sleep decreased > 4% from baseline in 10 (33%) patients and negative middle ear pressure was found in 5 (17%) patients. The SpO2 and middle ear pressure was within normal limits for all patients with airway packing. CONCLUSION: Nasal packing with an airway may help to reduce post operative morbidity and reduce the risk of hypoxemia.

The effect of ABCB1 polymorphism on the pharmacokinetics of saquinavir alone and in combination with ritonavir.

This genotype panel study investigated the effect of ABCB1 polymorphism in exon 26 (C3435T), exon 21 (G2677T/A), and exon 12 (C1236T) on saquinavir pharmacokinetics and on the expression and activity of P-glycoprotein (P-gp) in peripheral blood monocytic cells (PBMCs). One hundred and fifty healthy volunteers were genotyped to identify 15 TT3435 and 15 CC3435 individuals. In these individuals, saquinavir pharmacokinetics were assessed after administration of a single oral dose of saquinavir 1,000 mg and saquinavir/ritonavir 1,000/100 mg. PBMC P-gp expression and activity were assessed in 15 and 19 subjects. The co-administration of ritonavir on study day 2 caused a significant increase in saquinavir exposure, in both TT3435 and CC3435 individuals. No correlation was observed between the ABCB1 C3435T, G2677T/A, and C1236T polymorphisms, separately and in haplotypes, with saquinavir pharmacokinetics, administered with or without ritonavir and with PBMC P-gp expression and activity. In conclusion, ABCB1 polymorphism has no pronounced effect on saquinavir exposure.

T cell subsets, epitope mapping, and HLA-restriction in patients with allergic bronchopulmonary aspergillosis.

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity lung disease characterized by Aspergillus fumigatus (Af) colonization, IgE and IgG anti-Af antibodies, pulmonary infiltrates, bronchiectasis, and pulmonary fibrosis. Little is known regarding T cell responses and their role in the pathogenesis of ABPA. To examine T cell reactivity to Af antigens, T cell clones (TCC) specific to the Asp f 1 antigen, an 18-kD protein of Af, were established from the peripheral blood of three ABPA patients. The majority of TCC isolated from ABPA patients, and specific for the Asp f 1 allergen of Af, are IL-4 producing CD4+ cells of the Th2 phenotype. Further analysis in this study revealed that the majority of TCC reacted to mainly two epitopes of Asp f 1, while the remaining TCC reacted to three additional "minor" epitopes. Blocking studies using monoclonal antibodies specific for class II HLA-D region gene products showed that most TCC, 19/21, were restricted by HLA-DR molecules, and the remaining two clones by HLA-DP molecules. The use of a panel of HLA-matched and mismatched EBV-transformed B cells as antigen presenting cells revealed that the HLA-DR restriction was mediated exclusively by either the HLA-DR2 or HLA-DR5 alleles. Genotyping of DRB1 gene products showed that class II presentation for most clones was not restricted to a single allele, representing DRB1 gene products of either HLA-DR2 or DR5. These studies offer insight into the cellular and molecular determinants which contribute to the immunopathophysiology of ABPA.

Assessing retinal ganglion cell damage.

Retinal ganglion cell (RGC) loss is the hallmark of optic neuropathies, including glaucoma, where damage to RGC axons occurs at the level of the optic nerve head. In experimental glaucoma, damage is assessed at the axon level (in the retinal nerve fibre layer and optic nerve head) or at the soma level (in the retina). In clinical glaucoma where measurements are generally limited to non-invasive techniques, structural measurements of the retinal nerve fibre layer and optic nerve head, or functional measurements with perimetry provide surrogate estimates of RGC integrity. These surrogate measurements, while clinically useful, are several levels removed from estimating actual RGC loss. Advances in imaging, labelling techniques, and transgenic medicine are making enormous strides in experimental glaucoma, providing knowledge on the pathophysiology of glaucoma, its progression and testing new therapeutic avenues. Advances are also being made in functional imaging of RGCs. Future efforts will now be directed towards translating these advances to clinical care.

Rates of glaucomatous visual field change after trabeculectomy.

BACKGROUND: Trabeculectomy is frequently performed in patients with glaucoma who are deteriorating, although its effects on rates of visual field (VF) progression are not fully understood. We studied the rate of VF progression post trabeculectomy comparing with medically treated patients matched for VF loss. METHODS: Medical records of patients who underwent trabeculectomy alone or combined with cataract extraction were reviewed. Patients with 5 or more 24-2 VF examinations post trabeculectomy were selected. The rate of mean deviation (MD) change after surgery was calculated for each patient. These patients were pairwise matched based on baseline MD with patients with glaucoma who were treated medically and had at least 5 VF tests. RESULTS: 180 surgical patients were identified and matched with 180 medically treated patients (baseline MD of -8.72 (5.24) dB and -8.71 (5.22) dB, respectively). Surgically and medically treated patients were followed for 7.4 (2.9) and 6.8 (3.1) years respectively. The MD slopes were -0.22 (0.55) dB/year and -0.08 (1.10) dB/year in the surgically and medically treated patients, respectively, and not statistically different (p=0.13, 95% CI -0.31 to 0.04). More patients in the surgical group had fast progression (rates worse than -1 dB/year) than in the medical group (17 and 7 patients, respectively, p=0.05). CONCLUSIONS: Our findings suggest that most patients who undergo trabeculectomy demonstrate relatively slow rates of VF progression postoperatively, similar to patients treated medically, although some patients can continue to progress despite adequate surgical control of intraocular pressure.

Characterization of functional trait diversity among Indian cultivated and weedy rice populations.

Weedy rice, a menace in rice growing areas globally, is biosimilar having attributes similar to cultivated and wild rice, and therefore is difficult to manage. A study was initiated to characterize the functional traits of 76 weedy rice populations and commonly grown rice cultivars from different agro-climatic zones for nine morphological, five physiological, and three phenological parameters in a field experiment under an augmented block design. Comparison between weedy and cultivated rice revealed a difference in duration (days) from panicle emergence to heading as the most variable trait and awn length as the least variable one, as evidenced from their coefficients of variation. The results of principal component analysis revealed the first three principal components to represent 47.3% of the total variation, which indicates an important role of transpiration, conductance, leaf-air temperature difference, days to panicle emergence, days to heading, flag leaf length, SPAD (soil-plant analysis development), grain weight, plant height, and panicle length to the diversity in weedy rice populations. The variations existing in weedy rice population are a major reason for its wider adaptability to varied environmental conditions and also a problem while trying to manage it.

Effects of minocycline and tetracycline on retinal ganglion cell survival after axotomy.

In the present study, we compared the in vivo neuroprotective efficacy of intraperitoneally administered tetracycline and minocycline to enhance the survival of retinal ganglion cells (RGCs) following unilateral axotomy of the adult rat optic nerve. We also examined the effects of the tetracycline drugs on the activation of retinal microglia. RGCs in retinal whole-mounts were visualized by retrograde labeling with fluorogold. The presence of activated microglia was confirmed immunohistochemically using OX-42 monoclonal antibodies. Optic nerve axotomy produced RGC death and increased activation of microglia. No significant RGC loss was seen prior to 5 days and approximately 50% and 80-90% cell loss occurred at 7 and 14 days, respectively. Examination of the effects of tetracycline and minocycline on RGC survival at 7 days post-axotomy, revealed increased numbers of RGCs in minocycline-treated animals (75% of non-axotomized control) compared with vehicle-only (52% of control) and tetracycline-treated (58% of control) animals. The densities of RGCs (RGCs/mm2+/-S.D.) for control, vehicle-, tetracycline- and minocycline-treated axotomized animals were 1996+/-81, 1029+/-186, 1158+/-190 and 1497+/-312, respectively. The neuroprotective effect of minocycline seen at 7 days was transient, since RGCs present in minocycline-treated animals at 14 days post-axotomy (281+/-43, 14% of control) were not significantly different to vehicle-treated animals (225+/-47, 11% of control). OX-42 staining of activated retinal microglia was reduced in tetracycline- and minocycline-treated axotomized animals compared with axotomized animals receiving vehicle-only. These results demonstrate that systemic administration of the second-generation tetracycline derivative, minocycline, delays the death of axotomized RGCs by a mechanism that may be associated with inhibition of microglia activation. The neuroprotective efficacy of minocycline following optic nerve axotomy was superior to that of tetracycline.

Central corneal thickness and progression of the visual field and optic disc in glaucoma.

AIMS: To determine whether central corneal thickness (CCT) is a significant predictor of visual field and optic disc progression in open angle glaucoma. METHODS: Data were obtained from a prospective study of glaucoma patients tested with static automated perimetry and confocal scanning laser tomography every 6 months. Progression was determined using a trend based approach called evidence of change (EOC) analysis in which sectoral ordinal scores based on the significance of regression coefficients of visual field pattern deviation and neuroretinal rim area over time are summed. Visual field progression was also determined using the event based glaucoma change probability (GCP) analysis using both total and pattern deviation. RESULTS: The sample contained 101 eyes of 54 patients (mean (SD) age 56.5 (9.8) years) with a mean follow up of 9.2 (0.7) years and 20.7 (2.3) sets of examinations every 6 months. Lower CCT was associated with worse baseline visual fields and lower mean IOP in the follow up. In the longitudinal analysis CCT was not correlated with the EOC scores for visual field or optic disc change. In the GCP analyses, there was a tendency for groups classified as progressing to have lower CCT compared to non-progressing groups. In a multivariate analyses accounting for IOP, the opposite was found, whereby higher CCT was associated with visual field progression. None of the independent factors were predictive of optic disc progression. CONCLUSIONS: In this cohort of patients with established glaucoma, CCT was not a useful index in the risk assessment of visual field and optic disc progression.

Clarithromycin enhances the antimalarial efficacy of mefloquine via its increased bioavailability and disrupting P. falciparum apicoplast.

AIM: Many important drugs like mefloquine are not being used because of the development of resistance and other related issues. In the present study, we aimed to control drug resistance by using combination therapy and tried to understand the mechanism involved. MATERIAL AND METHODS: We have explored in vitro interaction of clarithromycin (CLTR), and mefloquine (MQ) against Pf3D7 and PfK1 strains. Bioavailability of MQ in parasitized RBC lysate was checked in the presence/absence of CLTR using HPLC method. Further tufA mRNA/protein expression was investigated to know the effect of both drugs on apicoplast by using qPCR and Western blotting. KEY FINDINGS: MQ and CLTR inhibited growth of Pf3D7 and PfK1. CLTR showed its delayed antimalarial effect by its low IC50 values in the second cycle which indicates its effect on apicoplast. Downregulation of tufA expression on both mRNA and protein level supports this hypothesis. MQ and CLTR showed synergism/additiveness (mean ∑FICs = 0.89 and 1.26) against Pf3D7 and PfK1 respectively. It is evidenced from HPLC data that CLTR might have reduced metabolism of MQ in Plasmodium falciparum, leading to increased levels of MQ to produce enhanced antimalarial activity. The metabolism of CLTR is also reduced may be due to competitive metabolism of MQ via CYP3A4. SIGNIFICANCE: The present study reveals that broad spectrum biological activities (i.e. antimalarial and antiviral) of MQ can be saved by using suitable partner drug like CLTR. This study also shows that CLTR increases the concentration of MQ and disrupts the apicoplast.

Characterization of antiidiotypic antibodies to donor HLA that develop after liver transplantation.

Several studies have reported the development of antiidiotypic antibodies to anti-HLA alloantibodies in renal allograft transplant recipients, postulating their potential beneficial role in allograft survival. In order to evaluate the role of anti-HLA antiidiotypic antibodies in human liver transplant recipients and to differentiate them from circulating soluble donor HLA antigens, sera obtained from liver recipients, both pre- and posttransplantation, were analyzed for cytotoxicity inhibitory activity against alloantisera to mismatched donor HLA antigens. Prior to cytotoxicity inhibition assays, sera were absorbed with W6/32 coupled sepharose in order to remove circulating HLA antigens. Antiidiotypic antibodies to anti-HLA class I antibodies were detected in the sera of 7 out of 9 recipients, and antibodies to anti-HLA class II were found in the sera of 4 out of 7 recipients. Antiidiotypic antibodies were detected only during the immediate posttransplantation period. The specific inhibitory activity noted against both HLA class I and II mismatches showed no detectable preference for either HLA class or locus. Furthermore, the antiidiotypic antibodies to HLA developed in liver recipients also inhibited alloantisera to HLA-specific public epitopes or crossreactive groups (CREGS). Cytotoxicity inhibition by posttransplant sera was not mediated by circulating HLA antigens since absorption of the sera with monoclonal anti-HLA framework reagents did not change the specific inhibition of the alloantisera. In addition, the immunoglobulin fraction of the posttransplant sera retained its ability to inhibit cytotoxicity by donor-specific alloantisera. Thus these studies indicate that the development of antiidiotypic antibodies to anti-HLA is common during the immediate period following liver transplantation, even though circulating donor HLA antigens are present. The presence of circulating donor HLA antigens and the development of antiidiotypic antibodies to donor-specific anti-HLA during this period may be important for the successful adaptation of mismatched liver allografts.

Test-retest variability of frequency-doubling perimetry and conventional perimetry in glaucoma patients and normal subjects.

PURPOSE: To compare the test-retest variability characteristics of frequency-doubling perimetry, a new perimetric test, with those of conventional perimetry in glaucoma patients and normal control subjects. METHODS: The study sample contained 64 patients and 47 normal subjects aged 66.16+/-11.86 and 64.26+/-7.99 years (mean +/- SD), respectively. All subjects underwent frequency-doubling perimetry (using the threshold mode) and conventional perimetry (using program 30-2 of the Humphrey Field Analyzer; Humphrey Instruments, San Leandro, CA) in one randomly selected eye. Each test was repeated at 1-week intervals for five tests with each technique over 4 weeks. Empirical 5th and 95th percentiles of the distribution of threshold deviations at retest were determined for all combinations of single tests and mean of two tests, stratified by threshold deviation. The influence of visual field eccentricity and overall visual field loss on variability also were examined. RESULTS: Mean test time with frequency-doubling perimetry in patients and normal control subjects was 5.90 and 5.25 minutes, respectively, and with conventional perimetry was 17.20 and 14.01 minutes, respectively. In patients, there was a significant correlation between the results of the two techniques, in the full field and in quadrants, whereas in normal subjects there was no such correlation. In patients, the retest variability of conventional perimetry in locations with 20-dB loss was 120% (single tests) and 127% (mean tests) higher compared with that in locations with 0-dB loss. Comparative figures for frequency-doubling perimetry were 40% and 47%, respectively. Variability also increased more with threshold deviation in normal subjects tested with conventional perimetry. In both patients and normal subjects, variability increased with visual field eccentricity in conventional perimetry, but not in frequency-doubling perimetry. Both techniques showed an increase in variability with overall visual field damage. CONCLUSIONS: Frequency-doubling perimetry has different test-retest variability characteristics than conventional perimetry and may have potential for monitoring glaucomatous field damage.

The influence of intraocular pressure on visual field damage in patients with normal-tension and high-tension glaucoma.

There have been several reports to suggest that the type of visual field damage in open-angle glaucoma is influenced by intraocular pressure (IOP). This study was undertaken to determine the extent to which patients with normal-tension (NTG) and high-tension glaucoma (HTG) could be differentiated on the basis of some features of their visual fields. The results from 40 pairs of NTG and HTG patients were matched closely for the extent of visual field damage, pupil size, and visual acuity. Using this pooled material, the authors increased the IOP difference between the two groups in either direction, ie, by either progressively lowering the highest recorded IOP allowed for inclusion in the NTG group or by progressively increasing that required for inclusion in the HTG group. They compared the normal areas of the patients' visual fields by using simple visual field indices designed to quantify the undisturbed field. Using receiver operating characteristics (ROC) analysis, they showed that changing the inclusion criterion in the NTG group resulted in no better separation between the groups. However, when the inclusion criterion was changed in the HTG group, the two groups tended to become more separable. In this case, the degree of separation appeared to be related to the difference in the highest recorded IOP between the two groups although the separation was not complete. These findings show that pressure has a greater influence on the type of visual field damage at the higher end of the IOP spectrum encountered in open-angle glaucoma and suggest that there is no common single pathophysiologic mechanism in this disease.

Variability in patients with glaucomatous visual field damage is reduced using size V stimuli.

PURPOSE: To test the hypothesis that variability of conventional automated perimetry can be reduced using size V stimuli for patients with glaucomatous visual field damage. METHODS: Ten patients with glaucoma and five age-matched control volunteers were tested with the Humphrey Field Analyzer program 24-2 or 30-2, after which the method of constant stimuli was used to measure frequency-of-seeing curves. This was done by controlling the perimeter with a custom program run by a personal computer. At two widely separated visual field locations on the program 24-2 or 30-2 grid, stimuli were presented in 2 dB intervals to at least 10 dB on either side of the estimated program 24-2 or 30-2 threshold. This protocol was performed for each of three stimulus sizes (Goldmann sizes I, III, and V). For the patients with glaucoma, one test location was chosen in an area of normal visual field sensitivity, the other in an area of 10 to 20 dB loss. Control subjects were tested at the (3 degrees, 3 degrees) and (-21 degrees, -9 degrees) test locations. Fifteen repetitions were performed at each intensity. RESULTS: Repeated measures analysis of variance showed that variability, as measured by the standard deviation of the cumulative Gaussian function of the fitted frequency-of-seeing curves, was lowest at the abnormal sensitivity test location in the subjects with glaucoma using a size V stimulus. Differences between the results from the V to III and V to I stimuli were statistically significant (size V = 2.9 dB, III = 10.1 dB, I = 10.1 dB). The same trend in estimated standard deviations was present in tests of the area of normal sensitivity (size V = 1.1 dB, III = 1.7 dB, I = 2.0 dB) in subjects with glaucoma and for the control subjects' peripheral test locations, but not for the central location. The smaller reduction in variability between estimated standard deviations of the size I and size III stimuli was not statistically significant at any test location. CONCLUSIONS: Use of size V stimuli in conventional automated perimetry reduces variability in tests of moderately damaged and normal sensitivity test locations in subjects with glaucoma.

Comparison of conventional and pattern discrimination perimetry in a prospective study of glaucoma patients.

PURPOSE: To determine whether pattern discrimination perimetry detects progression of glaucomatous visual fields earlier than conventional static automated perimetry. METHODS: One hundred nine eyes of 109 patients with open angle glaucoma were enrolled in a longitudinal prospective study. Each patient underwent visual field examinations with conventional and pattern discrimination perimetry using the 30-2 program of the Humphrey Visual Field Analyzer (Humphrey Instruments Inc., San Leandro, CA) and a custom program for the pattern discrimination perimeter, respectively at 6-month intervals. Progression of glaucomatous visual field damage was assessed separately at each visit by predetermined criteria for conventional and pattern discrimination perimetry. The time to progression from baseline was calculated and the hemifield that showed progression first was documented for both conventional and pattern discrimination perimetry. RESULTS: Patients were followed for a mean of 5.1 years and a mean of 11.6 visits. Sixty-eight (62.3%) patients did not show progression with either technique. Of the remaining 41 patients, 15 (36.5%) showed progression with conventional perimetry alone, 9 (21.9%) with pattern discrimination perimetry alone, and 17 (41.4%) showed progression with both techniques. Of these 17 patients, 11 (64.7%) were detected earlier by conventional perimetry, and 6 (35.2%) were detected earlier by pattern discrimination perimetry. CONCLUSIONS: This study suggests that pattern discrimination perimetry is less effective than conventional perimetry in evaluating progressive glaucomatous visual field damage.

Properties of staircase procedures for estimating thresholds in automated perimetry.

The properties of the staircase procedure as applied in automated perimetry were examined. Two computer simulation models were used to vary different test- and patient-related parameters in clinical perimetry. One model was based on the KRAKEN computer simulation program; the other computer simulation was based on stimulus-response data sets from 11 normal subjects. The results were analyzed in terms of efficiency and accuracy. It was found that: (1) in general, there was an efficiency-accuracy trade-off; (2) increases in response fluctuation produced substantially greater errors in threshold estimates; (3) little or no improvements in accuracy were achieved by increasing the number of reversals; (4) the starting position of the staircase relative to the threshold influenced the efficiency of threshold determinations but not their accuracy; (5) a single-response error reduced the efficiency of staircases; (6) the position of a single-response error in a staircase sequence influenced the accuracy and efficiency of the threshold determination; and (7) more than one response error during a staircase sequence always resulted in a marked reduction in accuracy and/or efficiency. Current perimetric strategies appear to be at or near optimal levels, and therefore, strategies in the future may need to depart from a staircase-style procedure to achieve a significant increase in both accuracy and efficiency. Computer simulation studies can provide an effective means of evaluating perimetric test procedures and defining optimum strategies, which then can be verified clinically by subsequent testing in patient populations.

The effect of long-term intraocular pressure reduction on the differential light sensitivity in glaucoma suspects.

This study was undertaken to observe the effect on the differential light sensitivity in glaucoma suspects produced by a long-term reduction in intraocular pressure (IOP) with timolol maleate. The results are taken from an ongoing 6 year follow-up study of glaucoma suspects randomly selected for treatment and nontreatment. We present fine-grid meridional data, recorded every 4 months by automated perimetry, of all 46 patients (24 treated and 22 untreated) who completed the 6 year follow-up without developing localized visual field defects, acquired optic disc changes and whose IOP was not judged clinically dangerous during the follow-up. Methods of analyzing the profile sensitivity, the profile slope and the sensitivity of specific locations over the follow-up are described. The results show that the long-term fluctuation in differential light sensitivity in the two groups was not significantly different (P = 0.395) and that the sensitivity at most of the locations remained stable. The number of stable locations was not significantly different in the two groups (P = 0.412) and there was also no difference in the number of locations where the sensitivity appeared to decrease (P = 0.193) or increase (P = 0.540). Analysis of covariance showed no group difference in the profile sensitivity or the profile slope and that these variables remained stable in both groups over the 6 year period. Although the treated group maintained a consistently lower IOP than the untreated controls, our results showed that long-term pressure reduction with timolol in glaucoma suspects appeared not to influence the differential light sensitivity in the tested meridian.

Influence of fixation accuracy on threshold variability in patients with open angle glaucoma.

PURPOSE: To evaluate the contribution that fixation errors make to the overall variability of perimetric responses in patients with glaucoma. METHODS: Frequency of seeing curves were established, with and without fixation error correction, at two locations in each of 14 patients with glaucoma and good visual acuity. One location corresponded to a relatively normal region of the visual field, whereas the second corresponded to a region in which there was a sensitivity deficit. All patients had an acuity of better than 20/63 (except one whose acuity was 20/100). The locations of the first and fourth Purkinje images of a collimated infrared source were used to give a measure of eye position, during each stimulus presentation (accuracy 10 minutes of arc). RESULTS: Considerable variation was found in patient fixation accuracy. In the worst case, fixation was within 30 minutes of the target in only 7% of presentations whereas in the best, it was within this range in more than 60%. No relationship was found between accuracy of fixation and extent of loss. The gradient of the frequency of seeing curve was found to be shallow at regions of reduced sensitivity, a finding that supports the recognized relationship between variability and sensitivity deficit. A recalculation of the frequency of seeing curves, using only those responses in which the patient's fixation was within a specified range ( < 60 minutes of arc), did not show a meaningful reduction in variability at either location. CONCLUSIONS: It is concluded that fixation errors, though contributing to variability, are not the major cause of the increased variability seen at locations with reduced sensitivity.