Effects of pupillary constriction on automated perimetry in normal eyes

Repeatability of a Virtual Reality Headset Perimeter in Glaucoma and Ocular Hypertensive Patients

Purpose

The VisuALL S is an automated, static threshold, virtual reality-based perimeter for mobile evaluation of the visual field. We examined same-day and 3-month repeatability.

Methods

Adult participants with a diagnosis of glaucoma or ocular hypertension underwent two VisuALL 24-2 Normal T- Full threshold strategy tests at baseline and one additional exam at 3 months for each eligible eye. Spearman, intraclass correlation coefficients (ICCs), and Bland-Altman plots were used to assess the correlation of individual point sensitivities and mean deviation (MD) among three tests.

Results

Eighty-eight eyes (44 participants) were included. Average age was 68.1 ± 14.3 years, and 60.7% were male. VisuALL MD was highly correlated between tests (intravisit: r = 0.89, intervisit: r = 0.82; P < 0.001 for both). Bland-Altman analysis showed an average difference in intravisit MD of -0.67 dB (95% confidence interval [CI], -6.04 to 4.71 dB) and -0.15 dB (95% CI, -8.04 to 7.73 dB) for intervisit exams. Eight-five percent of pointwise intravisit ICCs were above 0.75 (range, 0.63 to 0.93), and 65% of pointwise intervisit ICCs were above 0.75 (range, 0.55 to 0.91).

Conclusions

VisuALL demonstrated high correlation of MD between tests and good repeatability for individual point sensitivities among three tests in 3 months, except at the points around the blind spot and superiorly.

Translational Relevance

The preliminary reproducibility results for VisuALL are encouraging. Its portable design makes it a potentially useful tool for patients with glaucoma, enabling more frequent assessments both at home and in clinical settings.

A Single Low-Dose of Methylphenidate Improves Abnormal Visual Field Testing

PURPOSE

To evaluate the effect of methylphenidate on visual field testing in healthy adults with abnormal visual field results.

METHODS

This prospective, randomized, controlled interventional clinical trial comprised all patients who had abnormal visual field test results and normal eye examination and ophthalmic history. Eligible patients were randomly assigned to either the study group or the control group. All patients repeated their visual field testing. Study group patients received a single dose of 10 mg methylphenidate prior to that. The main outcome measures were the percent difference in mean deviation and pattern standard deviation between the second and first visual fields.

RESULTS

The methylphenidate group had greater improvement in all parameters. Mean deviation improved by median 68% (IQR 19%-78%) in the methylphenidate group vs. 27% [-5% to 55%] in the controls. However, this was not statistically significant (p = .83). Pattern standard deviation improved by median 49% (22%-59%) vs. 7% [-9% to 45%], respectively (p = .012). The visual fields were also reviewed by 3 masked experienced ophthalmologists. They indicated that the second visual field improved in 76.2% of the methylphenidate group vs. 48.5% of the controls (p = .04). A normal repeat visual field occurred in 57.7% vs. 21.2%, respectively. A subgroup analysis of patients with prior experience in visual field testing yielded an even more striking improvement in the methylphenidate group vs. controls.

CONCLUSIONS

A single low dose of methylphenidate can improve visual field testing in subjects without ocular pathology, and even more in those with prior experience in perimetry.

Ganglion Cell Complex Analysis as a Potential Indicator of Early Neuronal Loss in Idiopathic Intracranial Hypertension

Reliable visual field testing is the gold standard in identifying future vision loss in patients with Idiopathic Intracranial hypertension (IIH). However, when field performance is unreliable, GCC analysis may be useful. We evaluated IIH patients over three visits: initial visit, follow-up visit and a third visit, almost 1 year later. We evaluated mean deviation (MD), GCC and RNFL at presentation and the second visit and compared it to the mean deviation (MD) on fields at the third visit. As early as the second visit, GCC loss correlated with visual field results seen at the third visit.

Relationship Cataract Density and Visual Field Damage

In interpreting visual field results, two questions arise: a) what type of visual field damage is produced by cataract, and b) can the influence on the visual field somehow be predicted? To answer these questions, cataract density was quantified with the Opacity Lens Meter (OLM) 701, and visual field tests were done before and after IOL-implantation surgery with Octopus Program G1 in 58 eyes of 58 patients (mean age 71±8 years) with cataract but with no other detectable ocular diseases. The average improvement of mean damage (MD) after surgery was 5.4 dB, and that of D (20) (defect 20 on the Bebie Curve) was 5.7 dB. The improvement of the visual fields was, as expected, statistically highly significant (p<0.0001). The corrected loss variance (CLV), however, increased on the average only by 2.5 dB2, which was not significant. The predictive value of the OLM reading for opacity-induced MD depends on the type of cataract. It is good for cortical and nuclear cataracts but poor for posterior subcapsular opacifications. The overall predictive value (R = 0.66) is, nevertheless, better than for preoperative visual acuity (R = -0.54). If OLM and visual acuity (VA) are considered together, the predictive value is slightly higher (R = 0.72). Thus, optical density influences on visual field performance can be substracted from general visual field results.

Compass fundus automated perimetry

Background:

Compass (CenterVue, Padova, Italy) is a fundus automated perimeter which has been introduced in the clinical practice for glaucoma management in 2014. The aim of the article is to review Compass literature, comparing its performances against Humphrey Field Analyzer (Zeiss Humphrey Systems, Dublin, CA, USA).

Results:

Analyses on both normal and glaucoma subjects agree on the fact that Humphrey Field Analyzer and Compass are interchangeable, as the difference of their global indices is largely inferior than test -retest variability for Humphrey Field Analyzer. Compass also enables interesting opportunities for the assessment of morphology, and the integration between morphology and function on the same device.

Conclusion:

Visual field testing by standard automated perimetry is limited by a series of intrinsic factors related to the psychophysical nature of the examination; recent papers suggest that gaze tracking is closely related to visual field reliability. Compass, thanks to a retinal tracker and to the active dislocation of stimuli to compensate for eye movements, is able to provide visual fields unaffected by fixation instability. Also, the instrument is a true colour, confocal retinoscope and obtains high-quality 60° × 60° photos of the central retina and stereo-photos details of the optic nerve. Overlapping the image of the retina to field sensitivity may be useful in ascertaining the impact of comorbidities. In addition, the recent introduction of stereoscopic photography may be very useful for better clinical examination.

Effect of Pupil Size on Dynamic Visual Acuity

This study was conducted to assess the effect of pupil size on dynamic visual acuity (DVA). 60 young healthy men ( M = 28.1 yr., SD = 3.9) with normal vision were divided into three age-matched groups by pupil size: dilated ( n = 20), unchanged ( n = 20), and constricted ( n = 20). DVA was measured binocularly with free-head viewing before and at 30 min. after each drop was instilled. Each of the three groups got a different amount. The sizes of the constricted, unchanged, and dilated pupils were 2.8 mm ( SD = 0.5), 4.1 mm ( SD = 0.3), and 7.8 mm ( SD = 0.5), respectively. The pupil size x DVA interaction was significant ( F2,114 = 6.07). DVA in the constricted pupil decreased, but that in the dilated pupil increased (paired t test). DVA in the unchanged pupil did not change significantly (paired t test). Pupil size is possibly one of the factors which may affect DVA measurement.

Real-time imaging of RGC death with a cell-impermeable nucleic acid dyeing compound after optic nerve crush in a murine model

The retinal ganglion cells (RGCs) are the main source of therapeutic targets for neuroprotective glaucoma treatment, and evaluating RGCs is key for effective glaucoma care. Thus, we developed a minimally invasive, quick, real-time method to evaluate RGC death in mice. In this article we describe the details of our method, report new results obtained from C57BL/6J mice, and report that our method was usable in wild type (WT) and knockout (KO) mice lacking an RGC-death-suppressing gene. It used a non-invasive confocal scanning laser ophthalmoscope (cSLO) and a low molecular weight, photo-switching, cell-impermeant, fluorescent nucleic acid dyeing compound, SYTOX orange (SO). The RGCs were retrogradely labeled with Fluorogold (FG), the optic nerve was crushed (ONC), and SO was injected into the vitreous. After ten minutes, RGC death was visualized with cSLO in vivo. The retinas were then extracted and flat mounted for histological observation. SO-labeled RGCs were counted in vivo and FG-labeled RGCs were counted in retinal flat mounts. The time course of RGC death was examined in Calpastatin KO mice and wild type (WT) mice. Our in vivo imaging method revealed that SO-positive dead RGCs were mainly present from 4 to 6 days after ONC, and the peak of RGC death was after 5 days. Moreover, the number of SO-positive dead RGCs after 5 days differed significantly in the Calpastatin KO mice and the WT mice. Counting FG-labeled RGCs in isolated retinas confirmed these results. Thus, real-time imaging with SO was able to quickly quantify ONC-induced RGC death. This technique may aid research into RGC death and the development of new neuroprotective therapies for glaucoma.

Effect of Optical Defocus on the Kinetic Perimetry in Young Myopic Participants

PURPOSE

The prospective study evaluated the effects of optical defocus on kinetic sensitivity using automated kinetic perimetry.

MATERIALS AND METHODS

The 17 eyes of 17 healthy young participants were evaluated. All of the participants had myopia (≥ -5.00 D) and mild to no astigmatism (<1.00 D). Automated kinetic perimetry was performed using the Octopus 900 perimeter with Goldmann stimuli III4e, I4e, I3e, I2e, and I1e, with stimuli presented at 14 predetermined meridians, and a velocity of 3°/s. Optical defocus was induced with soft contact lenses, and varied in 1 D increments between 0 and +7 D. Kinetic sensitivity at each defocus was evaluated and compared to sensitivity with no defocus.

RESULTS

Although kinetic sensitivity with the III4e and I4e stimuli decreased slightly at the inferior nasal, total kinetic sensitivity measured with the III4e and I4e stimuli was unaffected by optical defocus. Conversely, kinetic sensitivity measured with the I3e, I2e, and I1e stimuli decreased at defocus greater than +6 D (p < 0.05), + 3 D (p < 0.01), and at a defocus greater than +1 D (p < 0.01), respectively.

CONCLUSIONS

Kinetic sensitivity was unaffected by defocus when measured with III4e and I4e stimuli. However, measurements with I3e, I2e, and I1e stimuli were affected, in particular measurements with I2e and I1e stimuli. Therefore, we conclude that optimal refractive correction with a contact lens or a spectacle lens is required in order to obtain accurate kinetic perimetry results, particularly for lower intensity stimuli.

Glaucoma Progression Detection: Agreement, Sensitivity, and Specificity of Expert Visual Field Evaluation, Event Analysis, and Trend Analysis

Purpose.

To assess sensitivity, specificity, and agreement among automated event analysis, automated trend analysis, and expert evaluation to detect glaucoma progression.

Methods.

This was a prospective study that included 37 eyes with a follow-up of 36 months. All had glaucomatous disks and fields and performed reliable visual fields every 6 months. Each series of fields was assessed with 3 different methods: subjective assessment by 2 independent teams of glaucoma experts, glaucoma/guided progression analysis (GPA) event analysis, and GPA (visual field index-based) trend analysis. Kappa agreement coefficient between methods and sensitivity and specificity for each method using expert opinion as gold standard were calculated.

Results.

The incidence of glaucoma progression was 16% to 18% in 3 years but only 3 cases showed progression with all 3 methods. Kappa agreement coefficient was high (k=0.82) between subjective expert assessment and GPA event analysis, and only moderate between these two and GPA trend analysis (k=0.57). Sensitivity and specificity for GPA event and GPA trend analysis were 71% and 96%, and 57% and 93%, respectively.

Conclusions.

The 3 methods detected similar numbers of progressing cases. The GPA event analysis and expert subjective assessment showed high agreement between them and moderate agreement with GPA trend analysis. In a period of 3 years, both methods of GPA analysis offered high specificity, event analysis showed 83% sensitivity, and trend analysis had a 66% sensitivity.

The rate of visual field change in the ocular hypertension treatment study

PURPOSE

To assess the rate of change of visual field (VF) mean deviation (MD) in the Ocular Hypertension Treatment Study (OHTS).

METHODS

OHTS data were filtered to exclude eyes that had fewer than 10 reliable VFs or less than 5 years of follow-up or that reached a nonglaucomatous endpoint. The rate of change of MD (MDR) was calculated for each eye. Differences were sought between groups of eyes differing in primary open angle glaucoma (POAG) outcome, how POAG was determined, and original randomization.

RESULTS

In total, 2609 eyes (1379 participants) met the selection criteria. The mean MDR was -0.08 ± 0.20 dB/y (±SD). POAG eyes (n = 359) had significantly worse MDRs (-0.26 ± 0.36 dB/y) than non-POAG eyes (n = 2250; -0.05 ± 0.14 dB/y; P < 0.001). Eyes that reached POAG endpoints based on only VF change (n = 74; -0.29 ± 0.31 dB/y) or only optic disc change (n = 158; -0.12 ± 0.19 dB/y) had significantly worse MDRs than non-POAG eyes (both P < 0.001). Eyes that reached POAG endpoints for both VF and optic disc change (n = 127) deteriorated more rapidly (-0.42 ± 0.46 dB/y) than eyes showing only VF change (P = 0.017) or only optic disc change (P < 0.001). There was not a significant association between MDR and original OHTS randomization (observe vs. treat, P = 0.168).

CONCLUSIONS

Eyes that develop POAG have significantly worse MDRs than eyes that do not. Eyes that reached endpoints due to both VF and optic disc change had worse MDRs than eyes displaying change in only one of these. MDR was not significantly associated with randomization, suggesting that MDR may not be the best measure of VF change in early-stage POAG. (ClinicalTrials.gov number, NCT00000125.).

Comparison of a five-degree visual field between two programs of different testing field range

PURPOSE

A five-degree visual field with two programs of different testing field size was studied, and the visual fields between them were compared.

DESIGN

Observational study.

METHODS

Forty-six patients with open-angle glaucoma were tested by Humphrey field analyzer (Carl Zeiss Meditec, Inc, Dublin, California, USA) programs 30-2 full threshold and 10-2 full threshold. Forty reliable results with both programs were analyzed.

RESULTS

Sensitivity of the same position within a five-degree field was significantly higher with the 10-2 program than with the 30-2 program. Higher sensitivity within a five-degree field with the 10-2 program significantly correlated with that with the 30-2 program.

CONCLUSIONS

Visual field determined by automated perimetry was influenced by testing field size.

The effect of artificial tear administration on visual field testing in patients with glaucoma and dry eye

AIM

To examine the effects of artificial tear administration on perimetry of primary open-angle glaucoma patients with dry eye.

METHODS

A total of 40 patients with primary open-angle glaucoma experienced in automated perimetry with symptoms of dry eye were enrolled in this study. After their pretest visit, they were instructed to use artificial tear four times a day in both eyes for 1 week. After 1 week, patients had visual field testing. Test taking time, reliability parameters (false-positive and false-negative errors) visual field indices and number of depressed points at different probability levels (P<5%, P<2%, P<1%, P<0.5%) in both total and pattern deviation plots were compared using paired Ttest.

RESULTS

We found significant improvement in reliability parameters (false-positive errors from 2.4+/-2.1 to 2.1+/-1.9, P=0.02; and false-negative errors from 7.3+/-6.4 to 4.8+/-3.6, P=0.01) and visual field indices (MD increased from 5.97+/-5.61 to 4.57+/-4.53, P=0.001; PSD from 4.67+/-2.95 to 4.13+/-2.77, P=0.04 and SF decreased from 2.24+/-1.23 to 1.83+/-0.77, P=0.04) in the second testing after artificial tear administration. Test time significantly increased from 11.66+/-2.55 min to 14.26+/-1.36, P=0.001. The number of depressed points at probability levels P<1% (P=0.03) and P<0.5% (P=0.04) at total deviation plot and P<2% (P=0.02) and P<0.5% (P=0.009) in pattern deviation plot decreased significantly.

CONCLUSION

Artificial tear administration in glaucomatous patients with dry eye seems to improve significantly reliability parameters and visual field indices.

Pupil size and Perimetry--a pharmacological model using increment and decrement stimuli

BACKGROUND

To assess the influence of natural and pharmacologically induced pupil size fluctuations on differential luminance sensitivity threshold (DLS) using bright (increment) and dark (decrement) stimuli.

METHODS

Twelve healthy volunteers (20-30 years) were examined under the effect of phenylephrine 2%, dapiprazole 0.5%, and placebo. Pupil size was recorded by infra-red video camera in sessions without and with visual field examination (Tübingen Computer Campimeter). DLS was estimated at 9 locations within the central 20 degrees visual field, using bright and dark 26 min-of-arc-stimuli (10 cd/m(2) background, 4-2-1 dB thresholding strategy, four reversals).

RESULTS

There were substantial inter-individual differences in pupil size and pupil size fluctuations. Intra-individual differences were small. Independently of medication, pupil size fluctuations were reduced by more than one-third when a subject was undergoing perimetric examination. Pupil size affected DLS on its own (slope 0.21 dB/mm; 95% CI: 0.09-0.33 dB/mm), differently at different stimulus locations, and to a greater extent with increment than with decrement stimuli (slope difference 0.13 dB/mm; 95% CI: 0.00-0.26 dB/mm).

CONCLUSIONS

Campimetric examinations have a stabilising effect on pupil size fluctuations. Pupil size affects DLS with bright stimuli more than with dark stimuli; in normal young subjects this effect is not relevant for clinical or normative studies.

Evaluating several sources of variability for standard and SWAP visual fields in glaucoma patients, suspects, and normals

PURPOSE

To quantify factors affecting test-retest variability of threshold measurements over a series of 3 serial visual fields (VF).

DESIGN

Prospective comparative observational study.

PARTICIPANTS

Forty-one normals, 10 suspects and 35 stable glaucoma patients.

METHODS

All subjects performed 3 standard and 3 short-wavelength automated perimetry (SWAP) VFs. At each VF location, severity (defined as age-corrected total deviation) and test-retest variability (TRV), defined as the standard deviation of 3 serial threshold values, were calculated. A multiple regression model (constructed separately for standard VF and SWAP) incorporated 13 factors: severity, location, eccentricity, study group, diagnosis, superior versus inferior hemifield, nasal versus temporal hemifield, one-versus-two thresholds, age, mean pupil size, pupil size variability, between-subject variation, and residual variation.

MAIN OUTCOME MEASURES

Variability in threshold sensitivity VF values.

RESULTS

Mean TRV (+/- standard deviation) for normal, suspect and glaucoma eyes, respectively, was: 1.28 +/- 0.87, 1.53 +/- 1.04 and 2.20 +/- 1.79 dB for standard VF, and 1.87 +/- 1.35, 1.86 +/- 1.24 and 2.68 +/- 1.85 dB for SWAP. The contribution of each factor to the model for standard VF and SWAP (SWAP in parentheses) were: severity 15.5% (6.9%); location 2.7% (4.1%); eccentricity 1.1% (0.64%); diagnosis 2.9% (5.9%); "superior versus inferior" hemifield 0.17% (1.7%); "nasal versus temporal" hemifield 0.06% (0.02%); one-versus-two thresholds 0.04% (0.16%); age 0.1% (0.06%); mean pupil size 0.59% (0.1%); pupil size variability 3.2% (2.8%); between-subject 8.0% (13.5%) and residual variation 61.0% (66.6%). Excluding between-subject and residual variation, the 11-factor model was able to account for less than one third of the variability seen in both standard VF and SWAP.

CONCLUSIONS

Severity of defect and between subject variation exerted the largest effect on TRV. However, even if all 11 factors could be adjusted for, it would reduce the magnitude of TRV by only 30%. More work is needed to reduce the remaining variability inherent in psychophysical testing and to better understand the intrinsic physiological variability present both in healthy and diseased eyes. It is possible that a larger number of VFs used for the calculation of TRV might further reduce the magnitude of the remaining variability found in this study.

Quality of life in glaucoma and its relationship with visual function

PURPOSE

The aims of this study were (a) to explore patients self-reported visual disability resulting from glaucoma by means of a questionnaire developed for this purpose; (b) identify activities strongly associated with a measure of visual field loss, (c) to quantify different psychophysical aspects of visual function; (d) to assess the relationship between objective measures of visual function and patients' perception of their vision-related quality of life.

PATIENTS AND METHODS

Three groups of glaucoma patients (n = 47) with mild (n = 18), moderate (n = 19), and severe visual field loss (n = 10) and a group of normal controls (n = 19) underwent a comprehensive clinical examination, completed a questionnaire and, on a separate visit, performed a number of psychophysical tests of visual function.

MAIN OUTCOME MEASURES

Questionnaire responses (vision-related quality of life, general health and psychosocial variables), visual acuity, visual fields, Esterman binocular disability scores, contrast sensitivity, critical flicker frequency, color vision, dark adaptation, glare disability (brightness acuity), and stereoacuity scores were measured.

RESULTS

Fifteen of the 50 questions were noted to have a strong significant relationship with a measure of visual field loss and were included in a new questionnaire scale, the Glaucoma Quality of Life - 15 (GQL-15). The scale validity showed a significant correlation with perimetric mean deviation (MD) values (r = -0.6; P < 0.0001), the reliability of the scale was high (Cronbach alpha = 0.95), and test-retest reliability of the questionnaire was strong (r = 0.87). An overall statistically significant decrease in performance-related quality of life was noted between normal subjects and all groups of glaucoma patients. A significant relationship was found between the scale questionnaire summary performance measure and a number of psychophysical tests: Pelli-Robson contrast sensitivity (r = -0.45, P < 0.001), glare disability (r = -0.41, P < 0.001), Esterman binocular visual field test (r = -0.39, P < 0.001), dark adaptation (r = 0.34, P = 0.007), and stereopsis (r = 0.26, P = 0.04).

CONCLUSION

Perceived visual disability relating to certain tasks (particularly involving dark adaptation and disability glare, activities demanding functional peripheral vision such us tripping over and bumping into objects and outdoor mobility tasks) was significantly associated with the severity of binocular visual field loss. As a result, a new glaucoma-specific questionnaire scale with good performance characteristics is presented in this study. The difficulties encountered by patients in everyday life (as measured with the questionnaire) were also mirrored in their performance on a number of psychophysical tests, especially contrast sensitivity, glare disability, Esterman binocular visual field test, and dark adaptation.

Senescent changes of the normal visual field: an age-old problem

PURPOSE

To examine the effect of normal aging on visual field sensitivity and identify the best-fitting function for normal populations.

METHODS

Full Threshold standard automated perimetry data (program 24-2, Humphrey Field Analyzer) was collated retrospectively from clinically normal subjects who had previously been recruited for studies of normal visual function. One eye of each subject was randomly selected for analysis. Linear, bilinear, and simple nonlinear candidate functions of mean sensitivity vs. age (independent variable) were applied to these cross-sectional population data. Differences in the aging effect by eccentricity and hemifield were also considered.

RESULTS

Data from 562 normal eyes were available for analysis. A significant negative relationship existed between age and mean visual field sensitivity within the cross-sectional population data. Coefficients of determination for the linear, bilinear, and nonlinear functions were 0.21, 0.20, and 0.26, respectively, indicating that the nonlinear function provided best characterization of the effect of age on mean sensitivity. A small but significant increase in the aging effect was present both peripherally (p < 0.001) and superiorly (p < 0.001).

DISCUSSION

The nonlinear function that provided the best fit to cross-sectional population data indicates that age exerts an increasing effect on perimetric sensitivity with age, which has implications for clinical devices that use linear age coefficients to correct for normal aging effects. A linear age correction will overestimate aging changes for younger subjects and, therefore, may miss early pathologic changes in visual sensitivity. Conversely, linear age correction will also underestimate aging changes for older subjects and, thus, may overcall pathological sensitivity loss in this group. The effect of age within subjects requires further investigation to provide reliable estimates of the effect of age on sensitivity.

Overcoming the language barrier in visual field testing

PURPOSE

To evaluate the effect of using recorded instructions in patients' native language compared with interpreter-assisted instructions on the reliability and duration of the visual field test.

PATIENTS AND METHODS

Sixty patients referred for visual field testing were included in the study. Thirty-five had limited or no knowledge of the Hebrew language, and 25 control patients were fluent in Hebrew, the native language. None had previous experience with automated perimetry. Patients were randomized to receive recorded instructions on the visual field test in their native language or translator-assisted instructions by the technician before performing the test. For each patient, the time required for instructions and test performance and the reliability indices were documented.

RESULTS

The method of instruction (recorded or interpreter-assisted) did not affect the time required for patient instructions (66 +/- 24 seconds and 57 +/- 30 seconds, respectively), the time for test performance (7.2 +/- 1.5 minutes and 7.8 +/- 1.8 minutes, respectively), and test reliability as measured by the rate of fixation losses. Regardless of the method of explanation, the time required for instructions and for performing the test were significantly shorter for Hebrew speakers than for non-Hebrew speakers.

CONCLUSION

The use of a recorded explanation in the patient's native language before visual field testing is an applicable method for patient instruction. Clinics in areas with multilingual populations may use this method to save technicians time, without adversely affecting the time required for performing the test and its reliability.

Patients' perception of visual impairment in glaucoma: a pilot study

BACKGROUND/AIMS

There is a paucity of useful information on the level of visual disability suffered by glaucoma patients. The aims of this study were to determine and rank the frequency of self reported visual disability in daily tasks performed by glaucoma patients; to examine the interrelation between disabilities using factor analysis; to study the relation between perceived visual difficulty and a measure of the severity of visual field loss; to develop a glaucoma specific subgroup of questions; and examine the validity and reliability of this subgroup of questions.

METHODS

63 glaucoma patients completed a questionnaire containing 62 questions covering 10 broad aspects of daily life activities using a five point answer scale. Patients were classified into three groups as having mild, moderate, and severe field loss on the basis of the perimetric results. The relation between a measure of the severity of visual field loss and subjective visual disability in the three groups was examined.

RESULTS

Using factor analysis, the most frequently reported problems were grouped into the following four categories: outdoor mobility, glare and lighting conditions and activities demanding functional peripheral vision, household tasks, and personal care. These four factors accounted for 72% of the variability in the patients' questionnaire responses. With increasing severity of binocular visual field loss there was an increase in the number of self reported visual problems. A loss of confidence in performing some routine daily tasks tended to precede self reported specific visual disabilities. The factor "glare and lighting and activities demanding functional peripheral vision" was found to have a significant relation with a measure of visual field loss and was used to create a glaucoma specific subset of questions. Cronbach's alpha showed a high degree of reliability and internal consistency (alpha =0.96) in this glaucoma specific subset of questions. Furthermore, the validity of this new subset of questions was shown to be significant (r=0.037, p<0.05) for the correlation between a measure of the severity of binocular visual field loss and the mean score of the variables used in the glaucoma specific subgroup of questions.

CONCLUSIONS

Outcome measures and quality of life issues need to be addressed in glaucoma. This pilot study identified common problems encountered by patients which at the present time are not assessed in routine glaucoma care. It also identified a subgroup of questions that seems to be specific for glaucoma. Further research is required if a significant impact on the quality of life of glaucoma patients is to be achieved.

The effects of cataract extraction on the visual field of eyes with chronic open-angle glaucoma

PURPOSE

To investigate effects of cataract extraction and intraocular lens placement on the visual field of eyes with chronic open-angle glaucoma.

METHODS

A retrospective review was conducted of 41 eyes of 41 patients with visually significant cataract and chronic open-angle glaucoma who had undergone automated static perimetry within 6 months before and 6 months after phacoemulsification with intraocular lens placement.

RESULTS

Comparison of preoperative and postoperative testing showed that the mean visual acuity, foveal threshold, and mean deviation improved significantly (P < .0001), while the mean pattern standard deviation and corrected pattern standard deviation worsened significantly (P < or = .03). Eyes not receiving miotics preoperatively did not have a significant postoperative change in the mean pattern and corrected pattern standard deviations. Increasing severity of glaucoma-related visual field loss was significantly associated with less improvement in the postoperative mean deviation (P = .0001). Only two (5%) of 41 eyes had worsening of the mean deviation of 1.0 dB or greater. The foveal threshold improved more than the mean deviation did but not significantly more, except in eyes with severe visual field loss.

CONCLUSIONS

Cataract extraction resulted in statistically significant improvement in visual acuity and foveal threshold in most eyes with glaucoma. In eyes with mild or moderate glaucoma-related damage, the mean deviation often improved significantly after cataract extraction, but improvement was less predictable in eyes with severe or end-stage damage. The pattern and corrected pattern standard deviations may be reliable indicators of glaucoma-related damage in eyes with cataract but without constricted pupils.

Lack of association between localized cataract and visual field loss: the Blue Mountains Eye Study

PURPOSE

To examine whether localized cataract is related to localized field defects on suprathreshold visual field testing.

METHODS

Suprathreshold screening visual fields (Humphrey 76-point test) and lens photographs, graded using the Wisconsin System, were performed on participants attending the Blue Mountains Eye Study, which examined 3654 subjects residing in an area west of Sydney, NSW, Australia. The results for 2276 subjects were analysed in the present study.

RESULTS

There were no significant relationships between total points missing in the visual field and the degree of cortical, posterior subcapsular (PSC) or nuclear cataract after adjusting for confounders (test for trend P = 0.9, 0.7 and 0.9, respectively). Adjusted prevalence ratios and 95% confidence limits for the association between 10 or more points missing and the presence of cataract were 0.94 (0.77-1.25) for cortical, 1.26 (0.82-1.93) for PSC and 1.06 (0.86-1.30) for nuclear cataract. Similarly, there was no relationship between the presence of cortical or PSC cataract and sectoral visual field loss in any quadrant or hemifield.

CONCLUSIONS

Neither cortical, nuclear nor PSC cataracts increase the total points missing on the 76-point suprathreshold field test. Similarly, neither cortical nor PSC cataracts cause sectoral visual field loss on this screening field test. In the presence of cataract, sectoral visual field loss on non-thresholding visual field screeners must be attributed to other causes, such as glaucoma. The present study provides a clinical alert that localized field loss is unlikely to be related to cataract.

Improving the prediction of visual field progression in glaucoma using spatial processing

PURPOSE

The authors show how the predictive performance of a method for determining glaucomatous progression in a series of visual fields can be improved by first subjecting the data to a spatial processing technique.

METHOD

Thirty patients with normal-tension glaucoma, each with at least ten Humphrey fields and 3.5 years of follow-up, were included. A linear regression model of sensitivity against time of follow-up determined rates of change at individual test locations over the first five fields (mean follow-up 1.46 years; standard deviation = 0.08) in each field series. Predictions of sensitivity at each location of the field nearest to 1 and 2 years after the fifth field were generated using these rates of change. Predictive performance was evaluated by the difference between the predicted and measured sensitivity values. The analysis was repeated using the same field data subjected to a spatial filtering technique used in image processing.

RESULTS

Using linear modeling of the unprocessed field series, at 1 year after the fifth field, 72% of all predicted values were within +/- 5 dB of the corresponding measured threshold. This prediction precision improved to 83% using the processed data. At the 2-year follow-up field, the predictive performance improved from 56% to 73% with respect to the +/- 5 dB criterion.

CONCLUSIONS

Predictions of visual field progression using a pointwise linear model can be improved by spatial processing without increased cost or patient time. These methods have clinical potential for accurately detecting and forecasting visual field deterioration in the follow-up of glaucoma.

Pressure increase following primary laser trabeculoplasty. Effect on the visual field

Possible damaging effects on the visual field of postlaser pressure elevations the first 24 h following primary laser trabeculoplasty were investigated in 61 patients with exfoliative or open-angle glaucoma. The intraocular pressure was monitored the first 24 h after treatment. Treatment with pressure reducing agents was started if the intraocular pressure was > or = 50 mmHg. The visual field was plotted before and 1, 3, and 6 months after laser treatment with the C-30-2 program on a Humphrey visual field analyzer. Peak pressures > or = 50 mmHg occurred with 15 (25%) patients. There was no relationship between visual field changes at 1 month and pressure increase, peak pressure, prelaser pressure, prelaser visual field indices, the use of timolol postlaser, or the pressure decrease or pressure level 1 month after laser treatment. From 1 to 6 months after laser trabeculoplasty the visual field parameters remained stable. Postlaser pressure spikes do not seem to damage the visual field providing they are detected and treated.

The effect of pilocarpine on the glaucomatous visual field

Patients with chronic open angle glaucoma are traditionally managed by medical therapy during the early stages of the disease. Pilocarpine is a well established topical agent, but suffers troublesome sequelae, the most apparent of which is pupillary constriction. This study assesses the effect of miosis (produced by one drop of 2% pilocarpine) on the static threshold perimetry of 20 subjects with chronic open angle glaucoma and documented visual field loss, using the 30-2 program of the Humphrey field analyser. Following miosis, the Statpac mean defect deteriorated by an average of -1.49 dB compared with baseline (p = 0.004). This dB deterioration is twice that reported in studies on younger normal subjects following miosis. The decrease in mean defect showed a positive correlation with the degree of pupillary constriction, the correlation being greater in those eyes with a miosed pupil diameter of 2 mm or less. There was no significant decrease in the other Statpac global indices following miosis. A parallel study using the fellow eye of the same glaucoma patients showed a high degree of intertest variability, but no significant learning or fatigue effect. We conclude that pilocarpine-induced miosis causes a significant deterioration in visual field in a population of patients with chronic open angle glaucoma: this factor should be considered when choosing therapy for glaucoma particularly in cases where field loss approaches the permitted legal minimum for driving.

Normal tension glaucoma: the value of predictive tests

Fifty-four normal tension glaucoma cases were studied to determine the value of several clinical tests for predicting the progression of the disease. Outflow facility, intraocular pressure (IOP) increase after water drinking, and diurnal changes in IOP were studied. Progression was determined on the basis of changes in visual sensitivity as measured on the Octopus 201. A minimum of four examinations of the central 30 degrees were conducted over a 3- to 7-year period. Progression of visual field defects was seen in 38.5% of eyes that had demonstrated some degree of abnormality in at least one of three clinical tests, while only 10.7% of those eyes that appeared normal on the basis of these tests showed such progression. The difference was significant (p < 0.04). These results suggest that the three clinical tests may be of value in detecting normal tension glaucoma eyes at risk for progression of visual field defects.

Effect of mydriasis on visual field area in retinitis pigmentosa

PURPOSE

The effect of mydriasis on Goldmann visual field area in patients with retinitis pigmentosa has not been suitably defined. The aim of this study is to determine whether visual field area in these patients varies with pharmacologic mydriasis.

METHODS

Fifteen adult patients with retinitis pigmentosa were studied prospectively. Goldmann visual fields with II4e and V4e isopters were obtained in both eyes before and after full pharmacologic mydriasis of the right eye. The isopter areas were quantified and analyzed to determine the effect of mydriasis on visual field area.

RESULTS

The difference in the right eye isopter areas was compared with the difference in the left eye isopter areas using paired t tests, where the differences were computed from areas obtained before and after dilation of the right eye. Mydriasis had no significant effect on the visual field in terms of isopter area difference (II4e, P = 0.87; V4e, P = 0.45) and percent change in isopter area (II4e, P = 0.81; V4e, P = 0.24).

CONCLUSION

Pharmacologic mydriasis had no appreciable effect on the Goldmann visual field area in a selected group of patients with retinitis pigmentosa. These findings suggest that visual fields of such patients obtained in the dilated or undilated state can be meaningfully compared.

Effects of pupillary dilation on automated perimetry in glaucoma patients receiving pilocarpine

The authors studied 18 glaucoma patients receiving pilocarpine 2% therapy with automated static threshold perimetry using the Humphrey Field Analyzer 30-2 and STATPAC programs before and after instillation of 10% phenylephrine. The mean defect improved by an average of 3.14 decibels (dB) (standard deviation, 1.89 dB0 after administration of phenylephrine (P less than 0.001). The pattern standard deviation and the corrected pattern standard deviation also improved with dilation by 1.42 dB (P less than 0.01) and 1.73 dB (P less than 0.05), respectively, after dilation with phenylephrine. Comparisons of the unweighted means of threshold values in three zones of increasing eccentricity showed that the outer zone of the visual field had the greatest improvement after dilation. These findings indicate that pupillary dilation in glaucoma patients receiving pilocarpine therapy produces a nonuniform increase in threshold sensitivities and support the importance of consistent pupillary diameters on serial automated visual field examinations.

Visual field global indices in patients with reversal of glaucomatous cupping after intraocular pressure reduction

The authors investigated visual field changes in 28 eyes of 28 adult patients with early-to-moderate chronic open-angle glaucoma (COAG) in whom reversal of glaucomatous disc cupping was documented by computerized image analysis (Rodenstock Optic Nerve Head Analyzer) after intraocular pressure (IOP) reduction from 29.3 (+/- 5.9) to 19.4 (+/- 4.3) mmHg over 34.8 (+/- 24.8) weeks. Humphrey Statpac global indices (mean deviation and pattern standard deviation) improved in direct proportion to the magnitude of IOP reduction even after controlling for the possible influences of learning effect, short-term fluctuation, reliability, duration of IOP reduction, age, and pupil size. The mean visual field global indices (mean deviation and pattern standard deviation) improved in patients with IOP reduction of 40% or greater, in statistically significant contrast to no improvement of mean global indices with IOP reduction less than 35%. The beneficial effect of IOP reduction is apparent in COAG patients with topographical evidence of reversal of cupping.

Effect of cataract on automated perimetry

Humphrey visual fields (30-2 program) were performed on 24 otherwise healthy patients before and after cataract extraction to examine the effect of cataract on automated visual fields. All patients met reliability index criteria and recovered visual acuity of 20/25 or better. The effect of learning associated with repeated testing was controlled with visual fields of the fellow eye. Although a greater absolute threshold recovery occurred in the central region of the visual field after cataract extraction, the percent of threshold recovery did not vary across the visual field except for the most peripheral testing points, which demonstrated less recovery. Thus, cataracts depress an automated visual field fairly uniformly. Clinical grading of cataracts by a single experienced clinician was generally a poor predictor of visual field loss. Only the presence of posterior subcapsular plaque in the visual axis and the preoperative visual acuity correlated significantly with postoperative central threshold recovery. Pattern standard deviation remained unchanged after cataract removal, confirming it as a useful way of estimating visual loss from cataracts.

The effect of topical antiglaucoma drugs on the results of high-pass resolution perimetry

We conducted a randomly assigned, double-masked, crossover study of the effects of betaxolol, epinephrine, pilocarpine, and timolol on the high-pass resolution perimetry results in normal subjects. The influence of topical administration of these intraocular pressure-reducing drugs was negligible, which confirmed the reliability of high-pass resolution perimetry results. The method seems appropriate for the diagnosis of glaucoma and the follow-up of patients with glaucoma.

Effects of pupillary dilation on automated perimetry in normal patients

The effects of pupillary dilation (tropicamide 1%) on automated static threshold perimetry were studied in 18 normal subjects using the Humphrey field analyzer 30-2 and STATPAC programs. The mean defect worsened by 0.83 decibels (standard deviation, 0.92 decibels) in dilated fields as compared with baseline visual fields (P = 0.001). These findings indicate that pupillary dilation in healthy subjects who are not receiving ocular medications produces statistically significant declines in threshold sensitivities. Valid comparison of results from serial visual field testing, therefore, depends on control of or adjustment for the effect of pupillary dilation.

The effect of stimulus size on the measured threshold values in automated perimetry

Patients with severely depressed visual fields as determined by automated static perimetry are often tested with larger test stimuli in order to obtain meaningful data. "Normal" threshold values are known and included in some perimeters' data analysis programs for stimulus III, but not for larger stimuli. Using a user-defined program on the Octopus 201 perimeter to determine mean retinal sensitivity, a study was conducted in 17 normal subjects to determine the effect of stimulus size on measured threshold. With stimulus III, the mean retinal sensitivity within the central 30 degrees was 28.4 +/- 2.3 dB; it was 31.9 +/- 2.3 dB for stimulus IV, and measured 36.00 +/- 2.5 dB with stimulus V. The differences between the values are statistically significant (P less than 0.001). It is not known whether these differences can be generalized from normals to patients with glaucoma or other diseases.

The influence of decreased retinal illumination on automated perimetric threshold measurements

Decreased retinal illumination (such as can be caused by pupillary constriction or light absorption by ocular media opacities) was simulated with a randomly ordered series of neutral density filters in front of the right eyes of five subjects with dilated pupils. Threshold measurements were performed on Humphrey and Octopus perimeters at 0, 5, 10, 15, 20, and 25 degrees nasally along the 180-degree meridian. A 0.6-log unit neutral density filter, which reduces retinal illumination the equivalent of halving the pupillary diameter, decreased the mean Humphrey thresholds by 1.1 +/- 0.8 decibels (dB) (mean +/- standard deviation) and the mean Octopus thresholds by 1.7 +/- 1.4 dB. Statistically significant (P less than or equal to .05, Dunnett's test) threshold depressions were observed at all eccentricities with a 1.5-log unit neutral density filter on the Humphrey perimeter (-4.5 +/- 0.7 dB) and with a 1.0-log unit neutral density filter on the Octopus perimeter (-3.5 +/- 1.0 dB).