Biomedical subjects

D Poinoosawmy

Publications and source records attributed to D Poinoosawmy.

At least 19 recordsLinked to original sources

PubMed2003

The phenotype of normal tension glaucoma patients with and without OPA1 polymorphisms.

AIM: Polymorphisms in OPA1, the gene responsible for autosomal dominant optic atrophy, were recently found to be strongly associated with normal tension glaucoma (NTG). The aim of this study was to determine whether OPA1 polymorphisms affect the phenotype of NTG patients. METHODS: A retrospective analysis was performed of 108 well characterised NTG patients who had been genotyped for OPA1 variations, and who had previously undergone automated perimetry and Heidelberg retina tomography (HRT). 25 NTG patients had the at-risk OPA1 genotype (IVS 8 +4 C/T; +32 T/C) and 83 NTG patients did not. Differences between groups were sought in a wide range of structural, psychophysical, and demographic factors. These included sex, age at diagnosis, family history of glaucoma, history of ischaemic risk factors and vasospasm, laterality of glaucoma, presenting and highest diurnal intraocular pressure (IOP), initial cup-disc (CD) ratio, baseline visual field global indices, and optic disc parameters as measured by HRT. For a subgroup of patients with at least 5 years of follow up and 10 visual field tests, pointwise linear regression analysis (PROGRESSOR for Windows software) was applied to the visual field series. RESULTS: There was no significant difference in the two groups with respect to sex, age at diagnosis, family history of glaucoma, history of ischaemic risk factors and vasospasm, or laterality of glaucoma. The comparison of IOP, CD ratio and visual field global indices, MD and CPSD in the two groups showed no significant difference. There were no differences in the mean values for any of the HRT parameters analysed. For the subgroup of patients with at least 5 years of follow up, there was also no significant difference in the number of patients with progressing locations, the mean number of progressing locations per subject, the mean slope of the progressing locations or the mean slope for whole visual field. CONCLUSIONS: The absence of phenotypic differences in normal tension glaucoma patients with and without the OPA1 polymorphisms IVS 8 +4 C/T; +32 T/C suggest that these OPA1 polymorphisms do not underlie any major phenotypic diversity in these patients.

Age of Onset↗

PubMed2002

Effect of treatment by medicine or surgery on intraocular pressure and pulsatile ocular blood flow in normal-pressure glaucoma.

PURPOSE: To study the effect of trabeculectomy and monotherapy with topical betaxolol, brimonidine and latanoprost on intraocular pressure (IOP) and pulsatile ocular blood flow (POBF) in patients with normal-pressure glaucoma (NPG). METHODS: In this retrospective study NPG patients attending the glaucoma research unit at Moorfields Eye Hospital were reviewed. Patients treated by surgery or topical medication (betaxolol, brimonidine or latanoprost) who had pre- and post-treatment IOP and POBF measurements were studied. For those patients who were having treatment to both eyes, one eye was selected at random for analysis. RESULTS: A total of 147 patients were reviewed. Forty-three eyes were receiving betaxolol 0.5%, 58 eyes latanoprost 0.005%, 23 eyes brimonidine 0.2% and 23 eyes had undergone trabeculectomy surgery. There were more female than male patients in all four groups, and the groups were similar with regards age. Pre-treatment IOP and POBF values were similar among the groups ( P=0.27, P=0.08 respectively). Post-treatment IOP values tended to be lower than pre-treatment values for all four groups. All groups had an increased POBF except for betaxolol, where POBF decreased. CONCLUSION: Patients treated by trabeculectomy and those receiving topical latanoprost and brimonidine had lower IOP and higher POBF following treatment. The betaxolol-treated group, despite a slight decrease in IOP, had a decreased POBF. Lowering IOP by treatment may not necessarily be associated with an increase in POBF.

Administration, Topical↗

PubMed2001

The ability of the GDx nerve fibre analyser neural network to diagnose glaucoma.

PURPOSE: To evaluate the neural network used by the GDx in a group of normal subjects, patients with ocular hypertension (OHT) and patients with normal-pressure glaucoma (NPG). METHODS: The GDx neural network produces a "number" that indicates the likelihood that glaucoma is present. This number was compared in three groups representing different stages of health and disease, namely, normal controls (n = 101), OHT (n = 102) and NPG (105). The GDx number's ability to differentiate between normal and glaucoma individuals was then investigated. We also studied the relationship between the GDx number and retinal nerve fibre layer (RNFL) average thickness and visual field status to examine how well the GDx number reflects disease severity. RESULTS: The GDx number was significantly different among the groups (P < 0.01); it was highest in NPG and lowest in normal controls. The GDx number differentiated between glaucoma and normal with sensitivity of 92.3% and specificity of 96%. When combined with the parameter of RNFL average thickness, sensitivity and specificity were 88.5% and 100% respectively. In NPG a significant correlation was found between the GDx number and RNFL average thickness(rho = -0.88, P < 0.001) and visual field mean deviation (rho = -0.64, P < 0.001). CONCLUSION: The GDx number is able to differentiate between groups of normal, OHT and NPG subjects. Its close relationship with RNFL average thickness and visual field status in glaucoma indicates that it is able to reflect disease severity. Furthermore, its measured ability to distinguish between normal individuals and those with glaucoma demonstrates potential for use in glaucoma diagnosis.

Adult↗

PubMed2000

Longitudinal nerve fibre layer thickness change in normal-pressure glaucoma.

PURPOSE: To investigate longitudinal retinal nerve fibre layer (RNFL) thickness change in patients with normal-pressure glaucoma (NPG) and to assess how this may be related to visual fields. METHODS: NPG patients and normal subjects who had had serial GDx nerve fibre layer Analyzer II imaging and Humphrey visual fields performed at least 18 months apart were selected for study. These measurements were compared between groups at baseline and at subsequent follow-up, for change over time. RESULTS: Seventy-five NPG patients and 35 normal subjects were studied. Significant differences in RNFL thickness were found between NPG patients and normal controls at baseline (P < or = 0.001). Over the same time, there was greater RNFL thinning in NPG patients than in normal subjects (P < or = 0.0001). RNFL thinning in NPG was negatively correlated with visual field log MD at baseline (P < 0.001) and change in MD over time (P < 0.001). CONCLUSION: Reduction of RNFL thickness over time was significantly greater in NPG patients than in normal subjects, indicating that NPG patients' RNFL had thinned at a faster rate. NPG patients with initially better visual fields had a greater reduction in RNFL thickness than did those with initially more advanced visual field defects, suggesting that more RNFL change may be observed when glaucoma is at an earlier stage. There was a direct relationship between RNFL thinning and visual field deterioration.

Aged↗

PubMed2000

Mapping the visual field to the optic disc in normal tension glaucoma eyes.

PURPOSE: To establish the anatomical relationship between visual field test points in the Humphrey 24-2 test pattern and regions of the optic nerve head (ONH) DESIGN: Cross-sectional study. PARTICIPANTS: Glaucoma patients and suspects from the Normal Tension Glaucoma Clinic at Moorfields Eye Hospital. METHODS: Sixty-nine retinal nerve fiber layer (RNFL) photographs with well-defined RNFL defects and/or prominent bundles were digitized. An appropriately scaled Humphrey 24-2 visual field grid and an ONH reference circle, divided into 30 degrees sectors, were generated digitally. These were superimposed onto the RNFL images. The relationship of visual field test points to the circumference of the ONH was estimated by noting the proximity of test points to RNFL defects and/or prominent bundles. The position of the ONH in relation to the fovea was also noted. MAIN OUTCOME MEASURES: The sector at the ONH corresponding to each visual field test point, the position of the ONH in relation to the fovea, and the effect of the latter on the former. RESULTS: A median 22 (range, 4-58), of a possible 69, ONH positions were assigned to each visual field test point. The standard deviation of estimations was 7.2 degrees. The position of the ONH was 15.5 degrees (standard deviation 0.9 degrees ) nasal and 1.9 degrees (standard deviation 1.0 degrees ) above the fovea. The location of the ONH had a significant effect on the corresponding position at the ONH for 28 of 52 visual field test points. CONCLUSIONS: A clinically useful map that relates visual field test points to regions of the ONH has been produced. The map will aid clinical evaluation of glaucoma patients and suspects, as well as form the basis for investigations of the relationship between retinal light sensitivity and ONH structure.

Cross-Sectional Studies↗

PubMed2000

Glaucomatous optic disc changes in the contralateral eye of unilateral normal pressure glaucoma patients.

OBJECTIVE: To evaluate the optic disc for structural abnormalities in the contralateral eye of unilateral normal pressure glaucoma patients. DESIGN: Cross-sectional study. PARTICIPANTS: Fifty-three unilateral normal pressure glaucoma patients. TESTING: Optic disc imaging with the Heidelberg Retina Tomograph (HRT). MAIN OUTCOME MEASURES: Optic disc structural parameters. RESULTS: Of the contralateral (normal visual field) eyes, 79.2% were found to have an abnormal optic disc by HRT analysis. Of the glaucomatous (abnormal visual field) eyes, 94.3% were found to have an abnormal disc. The patterns of disc abnormality were defined as marked or moderate diffuse thinning of the neuroretinal rim (NRR) or broad or narrow focal thinning of the NRR. The most common pattern in the contralateral eyes was moderate diffuse thinning of the NRR (45.2%). The most frequently abnormal segments were the nasal superior (73. 8%) followed by the nasal inferior and the global NRR parameter (both 54.8%). CONCLUSIONS: A high frequency of NRR thinning was found in the contralateral (normal visual field) eyes of unilateral normal pressure glaucoma patients by HRT analysis. Knowing whether these abnormalities predict future progression to the development of visual field abnormality must wait until longitudinal studies are completed. If a disc abnormality is shown to predict future field loss, then early identification will allow early treatment.

Aged↗

PubMed1999

Severity and stability of glaucoma: patient perception compared with objective measurement.

OBJECTIVE: To elucidate the relationship between the subjective assessment in patients with glaucoma of (1) the severity of their visual loss, and (2) any deterioration in their visual function and their objective visual fields as measured by computed perimetry. DESIGN: First, patients completed a questionnaire relating to perceived visual disability and underwent binocular visual field testing. Second, a separate group of patients answered a question about perceived visual deterioration: their monocular visual field tests were analyzed retrospectively by pointwise linear regression to establish stability or deterioration. SETTING: The Glaucoma Service of a specialist eye hospital, which is a tertiary referral center and serves the local community. SUBJECTS: One hundred twenty-three patients with glaucoma including 62 for the severity arm of the study and 61 for the progression arm. MAIN OUTCOME MEASURES: Questionnaire responses, Esterman binocular disability score, and objective visual field deterioration. RESULTS: Questions strongly associated with Esterman binocular disability scores related to bumping into things, problems with stairs, and finding things that have been dropped. There was a strong association between perceived visual deterioration and measured bilateral visual field deterioration (P<.01). CONCLUSIONS: There is a strong association between some types of perceived visual disability and the severity of binocular field loss. A patient who notices gradual visual deterioration is twice as likely to have bilateral visual field deterioration as not. The findings in this sample of patients with mild-to-moderate glaucoma challenge the belief that glaucoma is an insidious process in which the symptoms do not appear until the end stage of the disease.

Diagnostic Techniques, Ophthalmological↗

PubMed1999

Detection of optic disc change with the Heidelberg retina tomograph before confirmed visual field change in ocular hypertensives converting to early glaucoma.

AIM: To determine whether analysis of sequential optic disc images obtained with the Heidelberg retina tomograph (HRT) is able to demonstrate optic disc change before the development of reproducible field defects in a group of ocular hypertensive (OHT) patients converting to early glaucoma. METHODS: Two groups were analysed: (1) 13 eyes of 13 OHT patients who subsequently developed reproducible field defects (converters); and (2) 13 eyes of 11 normal control subjects. Two sequential optic disc images were obtained using the HRT (median separation between images was 12 months for the converters and 13 months for the normals). The second image in the converter group was obtained before confirmed visual field loss. The optic disc variables were analysed both globally and segmentally using HRT software version 1.11. The Wilcoxon signed rank test was used to determine if there were any significant differences between the variables of the two image sets. RESULTS: Significant optic disc change was demonstrated in the group of converters: (1) global variables: the cup area increased by 9.7%, the C/D area ratio increased by 10.5%, and the rim area decreased by 6.9%; (2) segmental variables: the superonasal cup area increased by 11.0%, the superonasal C/D area ratio increased 11.7%, and the inferonasal cup volume increased by 28.4%. The temporal rim volume decreased by 15.6%, the inferotemporal rim volume decreased by 23.6%, and the rim area in the superonasal and superotemporal segments decreased by 6.6% and 6.9% respectively. CONCLUSION: Analysis of sequential optic disc images on the HRT allowed the detection of glaucomatous change before confirmed visual field change in a group of OHT patients converting to early glaucoma.

Aged↗

PubMed1999

Inter- and intraobserver variation in the analysis of optic disc images: comparison of the Heidelberg retina tomograph and computer assisted planimetry.

AIMS: The development of imaging and measurement techniques has brought the prospect of greater objectivity in the measurement of optic disc features, and therefore better agreement between observers. The purpose of this study was to quantify and compare the variation between observers using two measurement devices. METHODS: Optic disc photographs and images from the Heidelberg retina tomograph (HRT) of 30 eyes of 30 subjects were presented to six observers for analysis, and to one observer on five separate occasions. Agreement between observers was studied by comparing the analysis of each observer with the median result of the other five, and expressed as the mean difference and standard deviation of differences between the observer and the median. Inter- and intraobserver variation was calculated as a coefficient of variation (mean SD/mean x 100). RESULTS: For planimetry, agreement between observers was dependent on observer experience, for the HRT it was independent. Agreement between observers (SD of differences as a percentage of the median) for optic disc area was 4.0% to 7.2% (planimetry) and 3.3% to 6.0% (HRT), for neuroretinal rim area it was 10.8% to 21.0% (planimetry) and 5.2% to 9.6% (HRT). The mean interobserver coefficient of variation for optic disc area was 8.1% (planimetry) and 4.4% (HRT), for neuroretinal rim area it was 16.3% (planimetry) and 8.1% (HRT), and (HRT only) for rim volume was 16.3%, and reference height 9.1%. HRT variability was greater for the software version 1.11 reference plane than for version 1.10. The intraobserver coefficient of variation for optic disc area was 1.5% (planimetry) and 2.4% (HRT), for neuroretinal rim area it was 4.0% (planimetry) and 4.5% (HRT). CONCLUSIONS: Variation between observers is greatly reduced by the HRT when compared with planimetry. However, levels of variation, which may be clinically significant, remain for variables that depend on the subjective drawing of the disc margin.

Glaucoma↗

PubMed1999

Clinical factors influencing the visual prognosis of the fellow eyes of normal tension glaucoma patients with unilateral field loss.

AIM: To investigate the influence of several clinical variables on the development of visual field loss in the "second eye" of patients with normal tension glaucoma (NTG) presenting with unilateral field loss. METHODS: Patients with NTG and unilateral field loss at presentation were selected from a cohort of 403 consecutive diagnoses of NTG. The state of the visual field "normal" or with a visual field defect was defined using the Advanced Glaucoma Intervention Study (AGIS) template. Where available, optic disc planimetry was carried out on stereo photographs taken at presentation. Measurements of the topography of each of these optic discs were compared with morphometric values from a group of normal subjects, allowing for differences in age and disc size. For each patient the percentage of the relative neuroretinal rim (NRR) area was calculated. The time taken to develop a visual field defect was related to clinical factors including age, sex, peak and mean diurnal intraocular pressure (IOP), refraction, relative NRR area, and the AGIS score of the fellow eye at presentation RESULTS: 54 patients were included in the study. The median (range) follow up time was 49.2 (11.1-116.7) months. 14 (26%) patients developed field loss in the eyes with an initially normal field. The estimate of the median time to field loss onset was 95.1 months. Field damage developed more rapidly in women and in patients with greater AGIS score in the contralateral eye at the beginning of follow up ((adjusted hazard ratio, HR (95% confidence interval, CI) 0.20 (0. 04; 0.93); 1.19 (1.02; 1.41) respectively)). Little evidence of any association was found between time to onset of field loss and each of age, refraction, and peak or mean diurnal IOP. Planimetric disc analysis was carried out in 33 (61%) patients. Of these 10 (30%) developed field loss in the eyes with initial normal field at a median follow up of 95.1 months. After adjustment for sex and AGIS, relative NRR area was found to be significantly related to the time of onset of field damage, the greater the reduction in relative NRR area, the shorter the time to visual field loss (HR 0.93 (0.89; 0. 99)). CONCLUSIONS: NTG patients with unilateral field loss are at high risk of developing field damage in the eyes with an initially normal visual field. In this study, the visual prognosis of the eye with the normal visual field at presentation was found to be influenced by the extent of the reduction in relative NRR area together with the severity of field damage in the contralateral eye at presentation.

Female↗

PubMed1998

Frequency of asymmetric visual field defects in normal-tension and high-tension glaucoma.

OBJECTIVE: The purpose of the study was to evaluate the frequency of asymmetric visual field loss at presentation in patients with normal-tension glaucoma (NTG) and high-tension glaucoma (HTG). DESIGN: A retrospective cross-sectional study design was used. PARTICIPANTS: Four hundred and three NTG patients and 337 consecutive HTG patients (consecutive diagnoses between 1986 and 1996). INTERVENTION: Analysis of the frequency of unilateral field loss presentations in NTG and HTG. The visual fields of fellow eyes were compared to determine the side of more severe field loss. For the NTG patients, the relationship between the side with greater field loss and corresponding intraocular pressure (IOP) was investigated. MAIN OUTCOME MEASURES: Humphrey field analyzer mean defect (MD) and mean diurnal IOP. RESULTS: In the NTG group, 101 (25%) patients presented with unilateral field loss. The proportion of cases with unilateral field loss decreased with increasing age of presentation (chi-square test for trend = 26.9; P < 0.0001). Sixty-four percent of the patients had unilateral field loss in the left eye. Sixty-eight percent of the cases with bilateral field loss had a higher MD in the left eye. The diurnal IOP was estimated as 0.23 +/- 0.068 mmHg (mean +/- SE) higher in the left eye (P = 0.001). In the HTG group, 104 (31%) patients presented with unilateral field loss. The proportion of cases with unilateral field loss decreased with increasing age of presentation (chi-square test for trend = 4.6; P = 0.03). Right and left eyes had an equal chance of having field loss in unilateral cases and of being the side of more advanced field damage in bilateral cases. CONCLUSIONS: The frequency of cases with unilateral field loss was similar in HTG and NTG patients. Patients with unilateral field loss at presentation were more likely to be at the younger end of the age range. In the NTG population we studied, the left eye was more frequently the side of onset of field loss and 2.1 times more likely to present with a greater field defect than the right eye. In HTG patients, right and left eyes showed an equal chance of being the side of onset of field damage and the more affected side.

Aged↗

PubMed1998

Localization of the fourth locus (GLC1E) for adult-onset primary open-angle glaucoma to the 10p15-p14 region.

One of the major causes of blindness is primary open-angle glaucoma, which affects millions of elderly people worldwide. Genetic studies have so far mapped three loci for the adult-onset form of this condition to the 2cen-q13, 3q21-q24, and 8q23 regions. Herein, we report the localization of a fourth locus, to the 10p15-p14 region, in one large British family with a classical form of normal-tension open-angle glaucoma. Of the 42 meioses genotyped in this pedigree, 39 subjects (16 affected) inherited a haplotype compatible with their prior clinical designation, whereas the remaining 3 were classified as unknown. Although a maximum LOD score of 10.00 at a recombination fraction of straight theta=.00 was obtained with D10S1216, 21 other markers provided significant values, varying between 3.77 and 9.70. When only the affected meioses of this kindred were analyzed, LOD scores remained statistically significant, ranging from 3.16 (D10S527) to 3.57 (D10S506). Two critical recombinational events in the affected subjects positioned this new locus to a region of approximately 21 cM, flanked by D10S1729 and D10S1664. However, an additional recombination in a 59-year-old unaffected female suggests that this locus resides between D10S585 (or D10S1172) and D10S1664, within a genetic distance of 5-11 cM. However, the latter minimum region must be taken cautiously, because the incomplete penetrance has previously been documented for this group of eye conditions. A partial list of genes that positionally are considered as candidates includes NET1, PRKCT, ITIH2, IL2RA, IL15RA, IT1H2, hGATA3, the mRNA for open reading frame KIAA0019, and the gene for D123 protein.

Adult↗

PubMed1998

Simulating binocular visual field status in glaucoma.

AIMS: To simulate the central binocular visual field using results from merged left and right monocular Humphrey fields. To assess the agreement between the simulation and the binocular Humphrey Esterman visual field test (EVFT). METHOD: 59 consecutive patients with bilateral glaucoma each recorded Humphrey 24-2 fields for both eyes and binocular EVFT on the same visit. EVFT results were used to identify patients exhibiting at least one defect (< 10 dB) within the central 20 degrees of the binocular field. This criterion is relevant to a patient's legal fitness to drive in the UK. Individual sensitivity values from monocular fields are merged to generate a simulated central binocular field. Results are displayed as a grey scale and as symbols representing defects at the < 10 dB level. Agreement between patients failing the criterion using the simulation and the EVFT was evaluated. RESULTS: Substantial agreement was observed between the methods in classifying patients with at least one defect (< 10 dB) within the central binocular field (kappa 0.81; SE 0.09). Patients failing this criterion using the EVFT results were identified by the binocular simulation with high levels of sensitivity (100%) and specificity (86%). CONCLUSIONS: Excellent agreement exists between the simulated binocular results and EVFT in classifying glaucomatous patients with central binocular defects. A rapid estimate of a patient's central binocular field and visual functional capacity can be ascertained without extra perimetric examination.

Adult↗

PubMed1998

Pulsatile ocular blood flow investigation in asymmetric normal tension glaucoma and normal subjects.

AIMS: This study was designed to investigate pulsatile ocular blood flow (POBF) in normal tension glaucoma (NTG) patients and in normal controls. NTG patients with unilateral field loss were evaluated to compare POBF values between eyes with and without field loss. METHODS: POBF measurements from more than 1500 subjects were collected during a period of 6 months from six optometric centres. Subjects with systemic vascular diseases (such as systemic hypertension and diabetes), ophthalmic diseases, a positive family history of glaucoma, and those individuals receiving treatment with systemic beta blockers were excluded on the basis of a questionnaire. For comparison, 95 NTG patients with unilateral field loss, selected from 403 consecutive patients with NTG, underwent POBF testing. For each individual age, sex, intraocular pressure, refraction, and pulse rate were entered into a database. RESULTS: Data from 777 subjects were included in the analysis. POBF measurements of patients and subjects were compared allowing for differences in age, sex, intraocular pressure, refraction, and pulse rate. POBF was significantly lower in eyes of NTG patients with and without field loss (p < 0.001 and p = 0.01 respectively). Eyes of NTG patients with field loss showed significantly lower POBF than the contralateral eyes with normal field (p < 0.001). CONCLUSIONS: POBF was significantly lower in eyes of NTG patients with and without field loss than in normal subjects, suggesting that differences in ocular blood perfusion are relevant to the development of NTG and are detectable from the early stage of the disease. Furthermore, the finding of lower POBF in NTG eyes with field loss than in the contralateral eyes with normal field suggests that haemodynamic differences between fellow eyes contribute to determine the side of onset of the disease.

Adolescent↗

PubMed1997

Effect of surgery on visual field progression in normal-tension glaucoma.

PURPOSE: The effect of intraocular pressure-lowering surgery on the rate of visual field progression in normal-tension glaucoma (NTG) was studied. METHODS: Seventeen patients with NTG who underwent trabeculectomy in one eye for worsening visual field loss were included in the first part of the study. All patients had Humphrey 24-2 visual fields at the rate of 2-3 fields per year. Pointwise linear regression analysis of the visual field data was done separately for the preoperative and postoperative periods. This was performed for both operated and fellow eyes. The mean slope (MS), which indicates rate of visual field progression, was calculated. Change in MS was correlated with change in intraocular pressure (IOP). For the second part of the study, 11 patients who had a minimum of 4 visual fields and 18 months of follow-up before surgery were identified. Using the preoperative fields, the rate of sensitivity loss for each visual field location in the operated eye was ascertained for every patient. This rate of loss was extrapolated to generate the expected visual fields, assuming an unchanged rate of progression. The mean sensitivity of the expected visual field was compared with that of the actual field at the last follow-up. RESULTS: The MS in the operated eyes improved from -2.97 +/- 3.21 (mean +/- SD) in the preoperative period to 0.53 +/- 3.83 (P < 0.005; Student's t test) postoperatively. In the fellow eyes the MS changed from -1.78 +/- 2.55 to -1.43 +/- 3.01 (P = 0.754). There was a weak correlation between change in MS and percentage IOP decrease (correlation coefficient 0.39). The difference in mean sensitivity between the expected and actual visual fields was -3.72 dB (P = 0.002), and was better in the actual field. CONCLUSIONS: In this study, surgical lowering of IOP resulted in a slower rate of visual field loss in the operated eye.

Aged↗

PubMed1997

Variation of nerve fibre layer thickness measurements with age and ethnicity by scanning laser polarimetry.

AIMS: Scanning laser polarimetry is a new technique allowing quantitative analysis of the retinal nerve fibre layer in vivo. This technique was employed to investigate the variation of the retinal nerve fibre layer thickness in a group of normal subjects of different ages and ethnic groups. METHODS: 150 normal volunteers of different ages and ethnic groups were recruited for this study. Three consecutive 15-degree polarimetric maps were acquired for each subjects. Nerve fibre layer thickness measurements were obtained at 1.5 disc diameters from the optic nerve. Four 90-degree quadrants were identified. RESULTS: The mean nerve fibre layer thickness varied from a minimum of 55.4 microns to a maximum of 105.3 microns, with a mean thickness value of 78.2 (SD 10.6) microns. Superior and inferior quadrants showed a comparatively thicker nerve fibre layer than nasal and temporal quadrants. Retinal nerve fibre layer thickness is inversely correlated with age (p < 0.001). White people showed thicker nerve fibre layers than Afro-Caribbeans (p = 0.002). CONCLUSION: The results indicate a progressive reduction of the nerve fibre layer thickness with increasing age. This may be due to a progressive loss of ganglion axons with age as suggested in postmortem studies. A racial difference in nerve fibre layer thickness is present between whites and Afro-Caribbeans.

Adolescent↗

PubMed1996

Analysis of visual field progression in glaucoma.

BACKGROUND: Despite the widespread use of computerised perimetry the diagnosis of visual field deterioration in following glaucoma patients over time remains particularly difficult. A new method of analysis using a novel graphical display of longitudinal field data is presented. METHODS: A linear regression model of the luminance sensitivity at each stimulus location against time of follow up transforms the quantitative data from a series of fields into a colour coded form which illustrates the spatial configuration of change to aid the interpretation of field loss. The method of analysis and the developed computer software (PROGRESSOR) is described. Comparison with STATPAC-2 glaucoma change probability analysis is given including levels of agreement between the techniques using series of fields of 10 eyes from patients with normal tension glaucoma. RESULTS: Examples of this new method compare well with STATPAC-2 analysis. The level of agreement between the techniques to separate progressing from stable retinal locations is good (kappa = 0.62; SE = 0.04). CONCLUSIONS: This new technique, which combines the change in perimetric sensitivity over time with colour coding of significant change into one image may provide an efficient method to detect true progression in glaucomatous field loss.

Diagnosis, Computer-Assisted↗

PubMed1995

Motion detection threshold and field progression in normal tension glaucoma.

Psychophysical tests may demonstrate abnormalities of visual function before the appearance of conventional visual field loss in glaucoma. Motion detection thresholds (MDT) were measured in the normal fellow eye of 51 patients with confirmed normal tension glaucoma and initially unilateral field loss. Humphrey visual fields from the initially normal eye covering a mean follow up of 3.4 years were assessed using pointwise linear regression analysis. In 22 of the 51 eyes with normal visual fields at presentation, field deterioration occurred at one or more Humphrey locations within a mean of 1.7 (SD 1.6) years. An initially abnormal MDT test showed a sensitivity of 73% and a specificity of 90% in predicting field deterioration within the cluster of four Humphrey locations closest to the original MDT test site. Sensitivity was lower (40%) in predicting progression at retinal locations distant from the MDT test site, though specificity remained high (90%).

Aged↗